Saeed Navabpour; Ebrahim Hezarjaribi; Aboulfazl Mazandarani
Abstract
Soybean is an annual self-fertilized crop, belonging to leguminous family and glycine genus, with 40 chromosomes. Soybean is the most important oil crop worldwide since the composition of oil and protein which plays a significant role in public health. Soybean seeds have an average of 40 percent protein ...
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Soybean is an annual self-fertilized crop, belonging to leguminous family and glycine genus, with 40 chromosomes. Soybean is the most important oil crop worldwide since the composition of oil and protein which plays a significant role in public health. Soybean seeds have an average of 40 percent protein and 20 percent oil. Iran import more than 90% of edible oil annually. With 50 hectares of lands under soybean cultivation, Golestan province is the largest soybean cultivation area in Iran. The limitation of water is one of the serious problems in most cultivated lands. In order to solve this problem, relying on the genetic potential and identify drought tolerant varieties are most quick and economic ways. In this regard, pay attention to oil and protein content was quick valuable, which was considered in this study well. In order to evaluate the amount of oil and protein content as well as some related traits under drought stress conditions of soybean genotypes experiment carried out by using split plot format in randomized complete block design with three replications. Main factor was time-course of irrigation included three levels: FC irrigation (control), irrigation after50mm evaporation form a class evaporation pot, irrigation after 100mm evaporation form a class evaporation pot and irrigation after 150mm evaporation form a class evaporation pot. In each irrigation soil moisture to field capacity was reached. Water stress at the time of establishment of the plants began. Sub factor included 10 soybean genotypes: DPX, SARI, williams, Sahar, WE6, L17, HT2, Ds2, PE10 and DW1. Measured traits were included grain oil and protein content, grain yield, plant height, number of sub branches, number of pods, number of seed per pod, seed weight, and dry matter. The percentage of dry matter yield per plant were measured based. At the end of the growing period, to determine the percentage of protein and oil seed samples were taken from each treatment. The results showed that the grain yield and yield components had a significant positive correlation and its value fell under drought stress condition. The reduction of dry matter, seed weight and plant height was higher than other traits. The results of this study showed that the drought had negative impact on yield components which eventually comes to reduce of grain yield. In general, drought stress treatment at each level had more deteriorate effect on susceptible genotypes. Considering the significant positive correlation between seed yield and one thousand seeds weight and significant reduce seed weight in both stress levels (100 and 150 treatment), we can say that a lot of grain yield reduction was due to weight loss. In the meantime, more tolerant and better show for cultivation in areas with water shortages is more suitable. Interestingly, the amount of protein increased by effect of drought condition in most genotypes. It was the same for oil content just for 50mm drought treatment, while significant reduction occurred at 100mm and 150mm drought treatments. There was negative correlation between oil and protein content. PE10 and DS2 had the highest grain yield and sari variety had the lowest grain yield.
Ali Soleymani
Abstract
Introduction:
Sunflower is one of the most important oil crops which plays an important economical and agronomical role in crop rotation because of high oil quality. This crop is very flexible in bad environments. Water deficiency lessen net assimilation rate, dry weight of leaves, stem, and root and ...
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Introduction:
Sunflower is one of the most important oil crops which plays an important economical and agronomical role in crop rotation because of high oil quality. This crop is very flexible in bad environments. Water deficiency lessen net assimilation rate, dry weight of leaves, stem, and root and causes total dry weight and slow growth rate (Turrner and Sobrado 1987; Ren et al., 2016). Leaf area index is the most important growth index of sunflower which shows the highest sensitivity to water deficiency. Then, the main sign of water stress in vegetative phase of sunflower is reduction of number and size of leaves. Net assimilation rate Sunflower generally 10 to 20 days after germination increased or remained constant. Goksoy and Demir (2004)announced that restricted irrigation reduced leaf area index due to yellowing and falling leaves. Sunflower can reach to its maximum leaf area under full irrigation in proportion to water deficiency, water stress in vegetative phase caused shorter plants and lower dry matter of sunflower (Cox and Jolliff. 1986). This study was conducted to examine the effect of drought stress on growth properties of their sunflower cultivars in Isfahan (Iran).
Materials and methods:
The study was conducted in 2013 as split plot in randomized blocks design with three replications. Main plots were irrigation in four levels (80, 150 and 180 mm evaporation from evaporation pan class A) and sub plots were four sunflower cultivars (Azargol, Euroflor, Ghasem and Farrokh). Soil preparation was done and seeds were sown at June 8th. Every plot had five lines with six meter length, 60cm inter row space and 14cm distance between plants to reach to twelve plants per square meter. Irrigation was done according to 80mm evaporation until plant establishment and after that irrigation treatments were enforced. Sampling was done every 15 days and at the time of maturity considering marginal effects. In order to calculate trends of total dry matter, leaf area index, net assimilation rate, and crop growth rate the best regression equations were used (soleymani et al, 2003). MSTAT-C software and mean comparison with Duncan’s test in 5% probability were used.
Results and discussion:The effect of irrigation on maximum leaf area index was significant. The highest leaf area index was obtained by irrigation after 80 mm evaporation from class A .There was a significant difference with the other irrigation treatments. Lowest LAI by irrigation after 180 mm evaporation from class A pan evaporation so irrigation treatments had significant differences with other results show that with increasing severity of drought stress the leaf area index decreased. It seems that water stress during vegetative growth to remain small leaves and leaf area index during the period of reduced crop.The effect cultivars on the leaf area index was significant. Most leaf by leaf area index by as much as Euroflor significantly different from that of other varieties. Lowest leaf area index was obtained by the Qasem. Aargol and Farrukh was not significantly different. The results showed that by reducing crop water requirement LAI significantly reduced. Most of the dry weight of the plant by irrigation on 80 mm of Class A pan evaporation rate was obtained, which was significantly different to other treatments and the lowest plant dry weight by 180 mm evaporation from irrigation class A pan evaporation rate was 1080 g/m2, which is also a significant difference with other irrigation treatments. Effect variety on total dry weight of the plant is not significant. In all treatments, dry matter accumulation trend was maintained until maturity after the end of the dry season because of the falling leaves fell. With increasing drought stress reduced dry matter. The highest rates of net assimilation rate among irrigation treatments used for the treatment mm 180 and then to the moderate drought stress 150 mm evaporation from pan class (A) and then severe stress (80) mm evaporation from pan class A). Compare the net assimilation rate showed that NAR sunflower cultivars increased during the first growing season and then downward path and fell. So the Euroflora because more leaf area index and the shadow of the upper leaves on the lower leave NAR was less than the other varieties.Conclusions: Results showed that total dry matter, leaf area index, net assimilation rate and crop growth rate were decreased by drought increasing from 80 to 180mm. The least evaporation (150mm) had the highest amount of mentioned traits. Among cultivars, azargol had higher total dry weight because of having growth period and then higher LAI, total dry weight but it had lower NAR and CGR because of higher LAI and shading of upper leaves, then it is recommended to use Record cultivar.
Zhaleh Zarei; Hasan Heidari
Abstract
Introduction: Drought is the most limiting factor for production in arid and semi-arid areas. Iran agricultural sector uses more than 90% of water (Masomi et al., 2015). So drought is an unavoidable problem in Iran. Wick irrigation system is a sub-surface system including an instrument for water conduction ...
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Introduction: Drought is the most limiting factor for production in arid and semi-arid areas. Iran agricultural sector uses more than 90% of water (Masomi et al., 2015). So drought is an unavoidable problem in Iran. Wick irrigation system is a sub-surface system including an instrument for water conduction by capillary movement from a source to plant roots. Sub-surface systems are more efficient than common irrigation system in terms of time and cost (Son et al, 2006). Research on bean showed that sub-irrigation method reduced water consumption by 55% compared to furrow irrigation (Sepaskhah et al., 1976). Because of rainfall reduction, global warming and remarkable surface water loss by evaporation, this study aim was to determine water consumption amount in wick irrigation compared to common irrigation (surface irrigation) and design and practice wick irrigation system in farm. Materials and methods: In order to investigate effect of wick irrigation on water use efficiency in sunflower, an experiment was research was carried out as a randomized complete block design with three replications at research farm, college of agricultural science and engineering, Razi Uinversity, Kermanshah, Iran in 2015. Treatments included common irrigation (surface irrigation) as a control and wick irrigation. Plant and stem height, leaf dry weight, stem dry weight and total dry weight were recorded. Leaf area was calculated by Digimizer (P30download, 2016). Turner and Kramer (1980) method was used for computing leaf relative water content. Specific leaf weight (SLW) was calculated using leaf dry weight (LDW) and leaf area (LA) as SLW=LDW/LA. Water use efficiency (WUE) was computed using water consumption (WC) and dry matter (DM) production as WUE= DM/WC (Farre et al., 2006). Data was analyzed using SAS (ver. 9.2) software and means were compared using LSD at probably level of 0.05. Results and discussion: Wick irrigation had more leaf relative water content than surface irrigation. It was probably due to more and stable access to water in wick irrigation. Wick irrigation had higher plant and stem height than surface irrigation. Our result is in accordance with Bhattarai et al., (2003) findings. Wick irrigation had leaf area as much as surface irrigation; however its water consumption was lower than surface irrigation. Rafeie et al., (2004) reported that drought reduced leaf area. There was no difference between irrigation systems in terms of specific leaf weight. Wick irrigation was more water-efficient than surface irrigation. It was due to that soil capping and soil surface wetting is lower in wick irrigation. Continuous availability to water and no waterlogging condition can also improve plant growth and increase water use efficiency. Wick irrigation produced higher dry matter than surface irrigation. Probably, wick irrigation increased dry matter production through improving soil ventilation, reducing soil capping and weeds. Conclusions: Wick irrigation had higher performance than surface irrigation in terms of many traits. For example water use efficiency and dry matter were increased by 46 and 43%, respectively. So, it seems that wick irrigation is one of the best irrigation systems in arid and semi-arid areas and more research should be conducted to economize and practice this method in farm.
Saeed Reza Hosseinzadeh; Hamzeh Amiri; Ahmad Ismaili
Abstract
IntroductionWater shortage is the main factor that limits growth in dry environments. Tolerant plant is able to absorb water from the soil even in conditions of limited availability so plants achieve maximum efficiency in terms of growth and productivity. Studies have shown that drought stress alone ...
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IntroductionWater shortage is the main factor that limits growth in dry environments. Tolerant plant is able to absorb water from the soil even in conditions of limited availability so plants achieve maximum efficiency in terms of growth and productivity. Studies have shown that drought stress alone is the reason for 50 percent reduction in chickpea yield. In Iran, this problem is more serious, as chickpea is often traditionally cultivated at the end of the rainy season. The rapid growth stage of this plant coincides with the time in which the level of moisture in the soil decreases significantly. Therefore, the use of bio-fertilizers seems to be effective for drought condition. Vermicompost production is a method of converting organic waste into usable material in which species of earthworm are employed to stabilize organic waste. Vermicompost is produced by the decomposition of organic material using non-thermal interaction between earthworms and microorganisms. Vermicompost is rich in humic compounds and researchers speculate that the hormone-like activities of humic substances play a role in amelioration of water stress. In comparison with other organic fertilizers, vermicompost consists of high levels of nutrients such as N, P, K, Ca and Mg, as well as micronutrients such as Fe, Zn, Cu and Mn. Agricultural land in Iran is facing water shortage and chickpea is an economically valuable crop that has a significant role in the human diet. The present study was done with the following aims: (1) to determine the effect of vermicompost in reducing the effects of water stress in chickpea plants; (2) to determine the best mixture of vermicompost fertilizer and soil in the greenhouse. Materials and methodsA factorial experiment with a completely randomized design and three replications was conducted. The first treatment prepared four ratios of vermicompost (VC) and soil as follows: control (100% soil); 10% VC + 90% soil; 20% VC + 80% soil; 30% VC + 70% soil. The second treatment was water stress as follows: control (non-stress; 100% of field capacity); moderate water stress (75% of field capacity); severe water stress (25% of field capacity). Chickpea seeds were soaked in water for 24 h and then planted four to a pot. The pots were kept under a photoperiod of 25ºC (12.5 h), and 15ºC (11.5 h), day and night, respectively. The samples were harvested approximately 45 d after planting (podding stage). The shoots and roots were separated and morphological traits of plant height, number of leaves, number of pod, root area, root diameter and dry weight of shoots and roots were measured. Na, Ca and K concentrations of leaves and roots were determined using the method cited in Chapman and Patt (1961). Results and DiscussionResult showed that under non-stress, vermicompost fertilizer resulted in a significant increase in all studied traits. Under moderate stress, application of vermicompost significantly increased plant height (19%), number of leave (23%) and pod (32%), root area (23%) and root volume (69%), K (37%), Ca (54% and 30%) concentrations in leaves and roots. Under severe stress, addition vermicompost to soil at 30% level led to significant increase on number of leave (22%) and pod (33%), root diameter (48%), K (45% and 36%), Ca (63% and 33%) concentrations in leaves and roots. Vermicompost containing high levels of nutrients, plant hormones, and with good water storage capacity leads to improved uptake of nutrients that serves to reduce the detrimental effects of drought stress. The increase in plant height, root traits, number of pods and leafs are the result of the stimulation of auxin-like substances, humic and fulvic acids produced during vermicompost consumption. It appears that the use of vermicompost provides better conditions for water and nutrient absorption and allowing plants to spend less energy for root growth. Conclusion The results of this study show that under non-stress and moderate conditions, application of vermicompost can improve chickpea growth. Vermicompost facilitates an increased uptake of mineral nutrients such as K and Ca from the soil under conditions of water stress. According to the results of this study, using of vermicompost and soil mixture recommended to ameliorate the negative effects of water stress.
Hosein Sartip; Ali Reza Sirousmehr
Abstract
Introduction Cumin of the apiaceae family is a annual plant with thin and aromatic branches that height is variable between 15 -50 cm that depending on the environmental conditions (Kaffi et al., 2002). Drought stress as a factor in reducing plant growth in many regions of the world is that seriously ...
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Introduction Cumin of the apiaceae family is a annual plant with thin and aromatic branches that height is variable between 15 -50 cm that depending on the environmental conditions (Kaffi et al., 2002). Drought stress as a factor in reducing plant growth in many regions of the world is that seriously limit crop production and climate changes in the world, the situation is more serious (Anjum et al., 2011). Salicylic acid as a phenolic hormone, within a plant setting performs and its role in the immune system against abiotic (pathogens) and abiotic (drought, salinity, heavy metals and ozone) is well known (Klessig and Malamy, 1994). It has been reported that application of salicylic acid in the tomatoes has helped to improve the growth in drought stress (Senaratna et al., 2000).
Materials and methods This research during the crop year 2014 was conducted at the research farm of Zabol university Institute. The experiment was done as a split plot in a randomized complete block with three replications. water availability in three level: 50 mm (control), 100 mm and 150 mm evaporation (high stress) from evaporation pan class A as the main factor and different levels of foliar application of salicylic acid ] 0 (no spraying), 1 and 3 mM) were considered as subplots. Measuring photosynthetic pigments by lichtenthaler (1994), proline by Bates et al (1973) and soluble carbohydrate by Keles and Oncel method (2004) were measured. Harvest, in order to calculate yield cumin seed, was done in ripening stages. Statistical analysis was performed using SAS version 1.9 and averages were compared with Duncan's multiple range test at the 5% level.
Results and discussion The results of data analysis showed that the interaction of water availability in salicylic acid on proline of leaf was significant at 1 percent probability level. The highest leaf proline (7.78 micromoles per gram) was obtained by 150 mm evaporation of pan and foliar application 3 mM salicylic acid that compared to control treatment (50 mm evaporation of pan and foliar application 0 mM of salicylic acid) increase 96.96 percent indicated. Drought stress caused a significant increase in carbohydrate of cumin leaves at 1 percent probability level. Results showed that the interaction of water availability in salicylic acid on chlorophyll b at 5% and carotenoids leaves was significant at 1% probability level. Results showed that interaction water availability in salicylic acid on grain yield were significant at the 5% level and the highest grain yield (98.9 grams per square meter) in 50 mm evaporation from pan irrigation and foliar application of 1 mM salicylic acid was obtained.Reduce the rate of growth under drought stress, the compatibilizer state of to survive the adaptation under stress condition, because plant instead of used nutrients and energy for shoot grow, used for the storage molecule leads against stress (Khalid, 2006). In fennel suitable irrigation leads to better growth, more leaf area, followed by the growth gets better (Buchanan-Wollaston et al., 2003). Salicylic acid by increasing the activity of Rubisco enzyme and chlorophyll increases the photosynthetic rate (Sing and Ushs, 2003). Foliar application of salicylic acid was significant effects on yield and yield components of cumin (Asfini Farahani et al., 2013). The salicylic acid by inducing Protection interactions through the hormone abscisic acid leads to the accumulation, osmolytes especially proline in the plant (Yoshiba et al., 2005). Accumulation of organic compounds such as carbohydrates and amino acids in the cytoplasm plays an important role in the regulation of osmotic pressure plant (Flagella et al., 1995). Increase the amount of carbohydrates and proline under drought stress has been reported in in chamomile (Arazmju et al., 2010). Lowering the activity of photosystem ІІ, reduced RuBisCO enzyme activity and inhibits the synthesis of ATP, causes the formation of free oxygen species in chloroplasts increase. In drought stress, lack of water causes decomposition of chlorophyll and glutamate that is chlorophyll and proline precursor the effect of drought has become as a proline and thus reduced chlorophyll content (Lawlor and Cornic, 2002). A significant increase in chlorophyll and carotenoid in the foliar application of salicylic acid has been reported and The results of this affair have considered increasing the photosynthesis rate (El-Tayeb, 2005).
Conclusion The results showed that cumin to when faced with drought stress, the osmotic regulation mechanism used by the accumulation of proline and soluble carbohydrates and in this way to tolerate the water shortage conditions.
Marzieh Farsi; Farzin Abdollahi; Amin Salehi; Shiva Ghasemi
Abstract
IntroductionMarjoram is an annual medicinal plant of Labiatae family. This plant is native of south-east of Mediterranean regions and grown in different countries including Iran. Marjoram has great economical and industrial importance and since ancient times was known for its medicinal properties (Baatour ...
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IntroductionMarjoram is an annual medicinal plant of Labiatae family. This plant is native of south-east of Mediterranean regions and grown in different countries including Iran. Marjoram has great economical and industrial importance and since ancient times was known for its medicinal properties (Baatour et al., 2011). Water deficit is one of the most important factors limiting crop yield (Munns, 2002). Drought stress can cause changes in the morphological, physiological and biochemical characteristics of plants including medicinal plants (Hasani and Omidbaigi, 2002). In drought conditions, chemical compounds, including sugar, protein and chlorophyll content differ between plants and this could be involved plant resistance to drought. Plant nutrition with microelements such as Zn, can improve plant tolerance to drought stress (Alloway, 2004). Some researcher indicated that Zinc contributed in improvement of plant growing conditions especially in drought conditions (Misra, 1992). The present study was conducted in order to evaluate the physiological responses of marjoram to Zn application levels under drought stress conditions. Materials and methodsIn order to study the physiological responses of marjoram (Origanum Majorana) to use of zinc under drought stress, a factorial experiment was conducted as a completely randomized design with three replications during 2014-15 in the greenhouse of the University of Hormozgan. Experimental factors were included three drought stress levels (soil moisture equal to 50, 75 and 100% of field capacity) and three concentrations of zinc fertilizer (concentrations of 0, 1 and 3 per thousand as foliar spraying). Drought stress was applied in 8 to 10 leaves stages. Fertilizer solutions sprayed on the 20th day after onset of drought stress for four times (before flowering) at intervals of ten days. Ten days after the third application of zinc solutions, physiological traits such as chlorophyll, soluble sugars, anthocyanin contents and catalase activity were measured. In order to measure dry weight, essential oil content, the marjoram plants were harvested in complete flowering stage. Data analyses were carried out using SAS. Means were compared with LSD (Least significant difference, P=0.05) values. Results and discussionDrought stress had significant effect on all traits except the essential oil content. Spraying of Zn fertilizer had significant effects on all evaluated traits with the exception of chlorophyll a content and catalase activity. Interaction of Zn fertilizer with drought stress had significant effects on chlorophyll a, b and total and anthocyanin contents, and essential oil percent. Results of this study showed that when marjoram grown in soil with moisture equal to 75% of field capacity, chlorophyll a, b and total increased significantly, while in 50% of field capacity soil moisture, carotenoid, soluble sugars, anthocyanin content and catalase activity increased significantly. Some researchers indicated that in drought stress conditions synthesis and accumulation of plant pigments and soluble sugars can increase plant tolerance to stressful conditions through adjusting and maintaining osmotic pressure and maintain cell membrane stability (Kleff et al., 1994). Results of mean comparison indicated that Zn spraying at three per thousand concentration increased chlorophyll b and total significantly, while Zn spraying at one per thousand concentration increased soluble sugar and essential oil content significantly. Spraying of Zn solution, improved physiological characteristic of marjoram plants, so that at drought stress condition equal to 75 and 100% field capacity Zn spraying at one per thousand concentration, increased chlorophyll a, b and total and anthocyanin content and essential oil percentage, significantly. Spraying of marjoram plants with low concentration of Zn increased plant tolerance to drought stress and therefore increased plant growth characteristics via increasing in chlorophyll, carotenoid, anthocyanin and soluble sugar. Cakmak (2000) reported that Zn can improve physiological characteristics of plants via cell protection against reactive oxygen species.Conclusion Based on these results, the effect of drought stress on all traits except for essential oil content was significant. As well as the effect of different levels of zinc fertilizer on chlorophyll b, carotenoids, soluble sugars and anthocyanin were significant. These results indicated that Zn application at drought stress condition may be through promote plant pigment synthesis improved marjoram growth and therefore essential oil percentage.
Hamid Reza Fallahi; Morteza Ghorbani; Mahsa Aghhavani-Shajari; Alireza Samadzadeh; Mehdi Khayyat; Zahra Maraki; Amir Hossein Asadian
Abstract
IntroductionRoselle or Hibiscus sabdariffa L. is an annual herbaceous plant which grows properly in tropical and sub-tropical areas. Sepals are the main commercial part of roselle with unique brilliant red colour and flavor which are containing many nutritional compounds such as anthocyanin and vitamin ...
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IntroductionRoselle or Hibiscus sabdariffa L. is an annual herbaceous plant which grows properly in tropical and sub-tropical areas. Sepals are the main commercial part of roselle with unique brilliant red colour and flavor which are containing many nutritional compounds such as anthocyanin and vitamin C. Accordingly, sepals commonly are used in food industries for production of beverages, juices, jams and syrup (Duangmal et al., 2008; Sanjari-Mijani et al. 2015). Therefore, production of high quality sepals via the good agronomic practices is an important topic in roselle cultivation. So far, the effect of irrigation management (Rahbarian et al. 2011), mycorrhizal inoculation (Sembok et al. 2015) and humic acid application (Sanjari-Mijani et al. 2015) on some qualitative and quantitative indices of roselle has been evaluated in some studies. However, the impacts of mentioned factors on colour characteristics of dried sepals including hunter color values, colour intensity and hue angle has not been studied. Therefore, due to the impact of colour on marketability and drug quality, the aim of this study was to evaluate the effect of water availability, mycorrhizal symbiosis and humic acid application on colour indices of dried sepals in roselle.Materials and methodsIn this experiment, the influence of irrigation regimes [irrigation after 100 mm (normal irrigation) and 200 mm (deficit irrigation) pan evaporation], humic acid application (0 and 4 kg.ha-1) and mycorrhizal inoculation (Glomus versiforme, Glomus intraradices and control) were studied on colour characteristic of roselle sepals. For this purpose an experiment at the form of split-split-plot layout based on a randomized complete block design with three replications was carried out during 2015-16 at research field of Sarayan Faculty of Agriculture (33ºN, 58ºE, 1450 masl, annual precipitation of 150 mm and annual temperature of 17ºC.) in east part of Iran. Seed planting was done on 20 April using Sistan & Balochestan ecotype with 10×50 cm intra and inter-rows distances. Humic acid was used in irrigation water two times during vegetative growth of roselle i.e. 15 and 35 days after emergence. All plots were irrigated similarly two times during the first week after seed sowing and then irrigation treatments were exerted separately in each plot until November 15 when irrigation was stopped. After that, calyces belonged to each treatment were harvested and dried separately in ambient temperature and shade condition of laboratory and then were used for colour analysis. Color of dried sepals was evaluated using a colorimeter (TES 135, Shenzhen Youfu Tools Co., Ltd. - TAIWAN). Results were expressed as Hunter color values (l*, a* and b*). L is the brightness ranging from 0 (black) to 100 (white). The value a* is the redness ranging from negative values for green to positive values for red. The value b* is the yellowness ranging from negative values for blue and positive values for yellow. In addition, color intensity (Chroma), hue angle and browning index were calculated using equations presented by Duangmal et al., (2008). Finally, data were statistically analyzed using SAS 9.1 and means were compared by duncan test at 5% level of probabilityResults and discussionResults showed that the effect of experimental factors was significant on most of colour indices in roselle calyces. Droughts stress reduced a* value, hue angle and chroma by 22, 53 and 15% respectively. Humic acid application also reduced the amount of hue by 63% while increased the b/a by 25%. Both mycorrhizal species enhanced the hue index by 66% compared with control treatment. Results of interaction effects revealed that the highest amount of b/a (0.19) was obtained at droughts stress × humic application × mycorrhizal inoculation, while its lowest value (0.02) observed at no stress ×no-humic ×no-inoculation treatment. In addition, the maximum amount of hue (215 º) was obtained at no water stress × humic application × mycorrhizal inoculation using Glomus versiforme. The treatment of no stress × no humic × mycorrhizal symbiosis produced the maximum amount of redness index. Moreover, a significant correlation was observed between a* with chroma (+0.64**) and browning index (-0.71**) as well as between hue and redness index (+1.00**). Overall, colour quality of roselle sepals was more suitable under appropriate water supply. In addition, mycorrhizal inoculation partially reduced the negative impacts of droughts stress on calyxes colour characteristics. The reducing effect of sever water stress and the positive role of mycorrhizal inoculation on growth, yield and quality of roselle has been previously reported by other researchers (Rahbarian et al., 2011; Sembok et al. 2015). It has been reported that red anthocyanins in sepals of roselle are responsible of its brilliant red colour (Duangmal et al., 2008). Our qualitative analysis revealed that the amount of anthocyanins in drought stress condition was 12% lower than no stress treatment. Furthermore, mycorrhizal symbiosis using G. intraradices and Glomus versiforme improved the amount of this index by 20 and 5%, respectively (data are not presented). These observations are in accordance with the trend of redness change in dried sepals. Accordingly, it seems that more redness and a*, hue angle in no stress and inoculation treatments is because of more anthocyanin content in related plants. This finding is also understandable from positive regression relation between redness index and sepals anthocyanin content. ConclusionsConsidering to colour characteristics and regards to yield and qualitative indices such as anthocyanin and vitamin c content (data are not presented), it seems that appropriate water availability and use of mycorrhizal symbiosis are two good strategies for roselle production.
Yaeghob Arefi; Elnaz Farajzadeh Memari Tabrizi
Abstract
Introduction Water stress is the most important non-disease stress with adverse effects on plant growth and yield. The inadequate emergence of seedlings and inappropriate establishment of the factors limiting the growth and yield of plants, especially in areas with low rainfall. Successful deployment ...
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Introduction Water stress is the most important non-disease stress with adverse effects on plant growth and yield. The inadequate emergence of seedlings and inappropriate establishment of the factors limiting the growth and yield of plants, especially in areas with low rainfall. Successful deployment of seedlings increases the competitiveness of crops against weeds and increases plant resistance to dehydration and pests. On the other hand, by expediting the treatment, provided enough time to plant a second plant. Studies have shown that priming improves germination, reduces the time of emergence of seedlings, and results in improved plant deployment. Selection of suitable cultivar and seed priming modify the adverse effects of moisture stress on plant growth and development. The aim of this study was to investigate the effect of different levels of irrigation and duration of priming on growth and yield and corn cultivars.
Materials and methods
This research was carried out in 1394 in laboratory and field conditions. In laboratory conditions, factorial experiment was conducted based on a completely randomized design. The first factor consisted of three levels of polyethylene glycol application (irrigation with distilled water, irrigation with polyethylene glycol solution (distilled water, concentration of 12% by volume and irrigation with polyethylene glycol solution with concentration of 25% by weight), the second factor of priming time (zero, 8, 12 and 24 hours), the third factor consisted of two cultivars of maize (704 and 604). In this study, the effect of simultaneous priming (zero (no priming), 8, 16 and 24 hours) in the field conditions, and two varieties Corn (706 and 604) under three moisture conditions (irrigation after 70, 110 and 150 mm evaporation from class A evaporation pan) was investigated. The experiment was carried out in three replicates and split factorial based on randomized complete block design. The application of irrigation levels after plant deployment of corn in the 6-8 leaf stage in the field began. Priming seeds were done before planting.
Findings
In laboratory conditions, in 704, 25% m/v of polyethylene glycol treatments decreased germination percentage by 3.8%. The highest seedling dry weight was obtained in two treatments of distilled water, 16 hours priming and 604, and 12% by weight of polyethylene glycol, 8 hours priming and 704 with a value of 1.06. In this study, in distilled water, priming had no significant effect on dry weight of seedlings of corn, but in 25% of treatment weight of polyethylene glycol, priming treatments of 16 and 24 hours reduced to 86 and 80% in 704 and priming treatments 8, 16 and 24 Hours at 604 significantly increased 52, 52 and 72% in seedling dry weight. In this study, the highest germination rate coefficient was obtained in distilled water and 8 hours priming with 0.85 per day, and the lowest in treatment of 25% by weight of polyethylene glycol day and non-priming with 0.4%. The treatment of 25% polyethylene glycol in non-priming and 8 hours priming treatments caused a significant decrease of 0.36 and 0.20 per day in germination rate, but did not affect germination rate in priming treatments of 16 and 24 hours. There was no significant difference in grain yield between cultivars in terms of field conditions. Moisture stress had a significant effect on yield loss, so that in case of non-priming, irrigation after 150 mm of evaporation caused a decrease of evaporation of 52% in grain yield compared with irrigation after 70 mm evaporation. However, priming of corn seeds over a period of more than 16 hours prevented this decrease in water-induced function. In the absence of priming, priming for 8 and 16 hours, irrigation treatment after 110 mm evaporation from the pan had no effect on grain yield. Dehydrated weight, ear weight, and shoot dry weight, leaf chlorophyll content, leaf area and plant height decreased 20.7, 21.9, 14.9, 42.9 and 10.6%, respectively. Priming had a significant positive effect on traits and 8 hours priming increased 19.9%, 15.3% and 19.2%, leaf area, shoot weight and seed number, but depending on the treatment time, the effect of priming was different.
Conclusion considering the results of the effect of priming against water deficit, there was no significant effect on seed yield under full irrigation conditions. There were no differences between the cultivars in most of the traits. In general, it seems that in the studied traits under full irrigation conditions, the lower periods of pre-treatment had a more positive effect, while in dehydration conditions, the effect of longer priming periods was better. The total priming of 8 and 16 hours was the most effective period of priming for grain yield.
Mohammad Reza Ramezani; Mohammad Javad Seghatoleslami; Mohammad Hasan Sayyari Zohan; Seyyed Gholamreza Moosavi
Abstract
Introduction Today salinity stress and salinization of soil is one of the most important environmental stress. As the amount of salt increases the plant growth rate decreases. Salinity cause imbalance in soil nutrient content. At this condition we have to use suitable nutrients to achieve appropriate ...
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Introduction Today salinity stress and salinization of soil is one of the most important environmental stress. As the amount of salt increases the plant growth rate decreases. Salinity cause imbalance in soil nutrient content. At this condition we have to use suitable nutrients to achieve appropriate yield. This experiment was conducted to evaluate the effect of salinity and zinc and iron application on yield and some morphological traits and quality of ajowan. Material and methods A split plots based on randomized complete block design with three replications was used in Khezri, South Khorasan in 2010. Salinity levels of irrigation water (970, 3500 and 7700 µs.cm-1) andfoliar application of micronutrients (control, Fe, Zn and Fe + Zn) were as main plot and sub plot, respectively. Each plot consisted six rows. The length of rows was 4 m. Distance between rows and plants on the rows was 40 and 20 cm, respectively. Data analysis was conducted by MSTATC and SPSS software and means were compared by Duncan’s multiple range tests at 5 % probability level. Result and Discussion Seed yield significantly affected by salt stress and its interaction with foliar application treatment. The highest (258.11 g.m-2) and the lowest (171.56 g.m-2) seed yield respectively was related to treatments low salinity+ iron and high salinity+ (iron+zinc). In high salinity conditions, which showed a significant reduction in seed yield than low and common salinity, there was no significant difference between the levels of foliar application with control. In fact, iron foliar application in low salinity (control) significantly increased seed yield, but iron + zinc spray application did not significantly change seed yield in comparison with control (without foliar application). On the other hand, in common salinity stress, foliar application treatments did not increase the yield, but in high salinity, the treatments increased seed yield. In low salt stress conditions foliar application of iron increased significantly seed yield, however foliar application of iron+zinc could not affect seed yield. On the other hand, in the common salt stress conditions, foliar application treatments could not increase seed yield, but under severe salt stress these treatments enhanced the yield. In general, under low, common and high salinity stress, the highest seed yield respectively was related to foliar application treatments iron, control and zinc. Seed yield reduction under salinity stress is related to its impact on shoot growth. In this experiment seed yield reduction was related to the decline of umbel number per plant. Correlation coefficient between seed yield and umbel number per plant also was positively significant. Like seed yield, salinity stress reduced different growth parameters such as plant height and branch number per plant. Effect of foliar application on seed essential oil percent and yield was not significant. However, in sever salinity stress, like seed yield, essential oil yield also declined. Although in high and common salt stress, foliar application had not any significant effect on essential oil yield, but under low salt stress, iron foliar application significantly increased essential oil yield. The results of this experiment show that the response of plant height and branch number per plant to irrigation treatments are opposite to each other. Considering that in all foliar application treatments, plant height increased, it can be concluded that the stimulus effect of these treatments on stem longitudinal growth causes the competition of the main stem with lateral branches. Therefore the number of branch per plant in iron and zinc foliar application treatments has declined. It has been reported that zinc deficiency can reduce plant height and yield due to adverse effects on biosynthesis of auxin. Conclusion Totally, the results of this experiment showed that, due to the significant interaction between salinity and foliar application, microelements should be used with care and after further studies in this plant. Possibly, some plant responses to foliar application and salinity interactions can be related to the presence of different compounds in water used in salinity treatments. Also, the lack of response of some growth parameters such as yield and plant height to the foliar application can be due to complicated plant nutrition relationships with soil conditions such as pH and other soil nutrient concentrations.
Fardin Ghanbari; Fakhrodin Salehi; Mohammad Sayyari
Abstract
IntroductionExposure of tropical and subtropical plants, such as tomato, to low temperatures may stunt the plant’s growth, induce wilting and necrotic lesions on leaves, and increase susceptibility to diseases and pathogens (Hällgreen and Öquest, 1990). The symptoms of stress-induced ...
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IntroductionExposure of tropical and subtropical plants, such as tomato, to low temperatures may stunt the plant’s growth, induce wilting and necrotic lesions on leaves, and increase susceptibility to diseases and pathogens (Hällgreen and Öquest, 1990). The symptoms of stress-induced injuries in these plants appear from 48 to 72 h, however, this duration varies from species to species and also depends upon the plant sensitivity to chilling stress. Various phenotypic symptoms in response to chilling stress include reduced leaf expansion, wilting as well as chlorosis (yellowing of leaves) and may lead to necrosis (death of tissue). Chilling also severely hampers the reproductive development of some plants (Mahajan and Tuteja, 2005).A strategy, which has recently been investigated in plants under stress condition, is cross-resistance, i.e., exposure of tissue to stress conditions often induces resistance to other stresses. For example, salt stress stimulates cold hardiness in potato and spinach seedlings(Ryu et al., 1995). Various mechanisms explaining the phenomenon of cross-resistancehave been proposed and often, although not always, it has been suggested that specific proteins are induced by one type of stress and these are involved in the protection against other types of stress.Artificial Neural Networks (ANN) are as an analytical alternative to conventional modeling techniques, which are frequently limited by strict assumptions of normality, linearity, homogeneity, and variable independence (Salehi, 2014). Neural network model was used for potato storage process modeling (Abdulquadri Oluwo et al., 2013), detecting chilling injury in red delicious apple (ElMasry et al., 2009), to detect defects (leaf roller, bitter pit, russet, puncture and bruises) in Empire and Golden Delicious apples(Kavdır and Guyer, 2004) and Lettuce (Lactuca sativa L.) yield prediction under water stress (Kizil et al., 2012) . In this study, artificial neural network modeling was used to predicting chilling resistance of tomato seedlings following imposing drought stress pretreatment with application 0, 10 and 20% poly ethylene glycol (PEG).Materials and MethodsTomato seeds, cultivar Falaat CH, which is one of the most important cultivars grown in Hamedan, were disinfected in 1% (active ingredient) sodium hypochlorite solution for 10 min to eliminate possible seed-borne microorganisms, then they were rinsed for 1 min under running water prior to drying for 30 min at room temperature. After that, Seeds were planted into plastic pots filled with a 2:1 mixture of coco peat: perlite. The pots were then transferred to the greenhouse with average temperature of 25.5/19.5°C (day/night) and natural light. When the seedlings developed four true leaves, they were pretreated with 10 or 20% PEG for 7 days or not. After drought, the seedlings were subjected to chilling 6 h/day at 3°C for 6 days. All plants were assessed 72 h after the end of chilling stress to determine the extent of chilling injury and data were collected.In present study, data were collected from experiments and then all data were randomly divided into 3 partitions: training (40%), validating (20%), and testing data (40%). The testing data was used for estimating the performance of the trained network on new data. The Neurosolution software 6.01 (USA) was used for designing the ANN model.In order to predicting chilling effects on tomato seedling attributes, multi-layer perception neural network with 2 input (drought stress and chilling stress effects) and 8 outputs (chlorophyll a, chlorophyll b, total phenol, relative water content, root electrolyte lekage, F0, Fm and proline) was used.
Results and DiscussionThe results showed that the ANN with 7 hidden neurons had the minimum mean absolute error values and high correlation coefficients. The overall agreement between ANN predictions and experimental data was also significant (r=0.92). A plot of the MSE and the number of epochs is shown in Fig. 2. A sharp drop was observed for MSE in the first little iteration (fast training) and training was completed after about 9 epochs. This is a well-known characteristic of the LM optimization method (Salehi and Razavi, 2012). Feed-forward back-propagation ANN models were developed by ElMasry et al. (2009) to investigate the ability of hyperspectral imaging and ANN techniques for the detection of chilling injury in Red apples. They reported that classification accuracy of above 90% was obtained with the use of selected five optimal wavelengths. In another study neural network models was used to predict shelf life of greenhouse lettuce by Lin and Block (2009). Using 2-stage neural network models, an R2 of 0.61 could be achieved for predicting remaining shelf life. This study indicated that neural network modeling has potential for predicting chilling tolerance of tomato seedlings following imposing drought stress pretreatment.
Mohsen Tarighaleslami; Mohammad Kafi; Ahmad Nezami; Reza Zargham
Abstract
IntroductionPlants are affected by many unfavorable environmental factors and therefore crop growth and development is retarded. Cold and water stress impose a considerable damage to the economy and country’s agricultural production every year. Salicylic acid is of phenolic compounds which is found ...
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IntroductionPlants are affected by many unfavorable environmental factors and therefore crop growth and development is retarded. Cold and water stress impose a considerable damage to the economy and country’s agricultural production every year. Salicylic acid is of phenolic compounds which is found in many plants, and considered as quasi hormonal substance that plays an important role in the growth and development of plants. Salicylic acid plays an important role in resistance to environmental stresses. The aim of this study was to investigate the effects salicylic acid spraying on alleviating the chilling and drought stresses on yield and agronomic traits of maize single cross 400.
Materials and methodsThis experiment was performed as a split-split plot in a randomized complete block design with three replications during 1394 in the greenhouse and the Research Farm of Faculty of Agricultural Ferdowsi University of Mashhad. The main plot of cold stress at two levels (non-stress and cold stress at 5ºC for 12 hours at 4th leaf stage), sub factors were three levels of irrigation (100, 75 and 50% of water requirement) and sub-sub plot was spraying with salicylic acid (non- (control) , 200 and 400 µM spraying After cold stress, seedlings of Single cross 400 were planted in the field. The plots were prapared with four meters length and three meters widths and row spacing of 75 cm with 75000 plants per hectare. At the end of the growing season to determine yield components, five plants were randomly taken from each plot from one square meter and biomass and kernel yield was recorded. MSTATC software implemented for statistical analysis and the means were compared using LSD test.
Results and discussionThe effect of drought stress and salicylic acid on the seed number per plant was significant. So that 100% irrigation %cause to improve 34.2% %in seed number per plant compared to 50% %of water requirement. Spraying plants with 200 and 400 µM improved the trait at a rate of 13.6 % compared to non-spraying (control). Effects of drought stress, salicylic acid and interaction of salicylic acid with drought on seed yield were significant. The treatment of 100% water requirement with 400 µM spraying with an increase of 54.3% showed the highest seed yield compared to 50% water requirements with spraying. In another study also corn foliar spaying with salicylic acid in flowering stage increased seed yield (Bayat et al., 2010). Effects of drought stress and salicylic acid and their interaction on biological yield were significant. The highest biological yield was obtained in 100% water treatment with 400 µM salicylic acid spraying with 55.2% higher biomass compared to 50% water treatment with similar salicylic acid spraying.Harvest Index in treatment of 400 µM salicylic acid spraying in irrigation conditions of 100% water requirement was 11.1% more than in irrigation conditions of 50% water requirement with the same salicylic acid spraying. Setter et al (Setter et al., 2001) similarly reported that corn grain yield reduced under drought stress.
ConclusionsThe results of this study showed that cold stress did not have negative impact on SC400 corn hybrid on tested traits. But the drought stress reduced corn yield components (such as the number of seeds and rows in corn), seed weight, biological yield, seed yield, and harvest index. 400 µM salicylic acid applications can be significantly increased biological yield and seed yield SC400 corn.
Ahmad Nezami; Ebrahim Izadi-Darbandi; Maryam Janalizadeh Ghazvini; Rouhollah Hassanbeigy
Abstract
Introduction Flixweed is an annual dicotyledonous winter herb from Cruciferae (Brassicaceae) family which grows in many countries of the world. In Iran it is seen in many of wheat and canola producing regions. Flixweed is used for healing a variety of diseases such as measles and smallpox, cough, asthma, ...
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Introduction Flixweed is an annual dicotyledonous winter herb from Cruciferae (Brassicaceae) family which grows in many countries of the world. In Iran it is seen in many of wheat and canola producing regions. Flixweed is used for healing a variety of diseases such as measles and smallpox, cough, asthma, edema and tumor. It also has diuretic, anticancer, antipyretic, antioxidant, anthelmintic, analgesic and tonic activities [2]. In temperate and cold regions of Iran, winter cold is one of the most important environmental stresses which affect growth, development and yield of plants. So determination and improvement of freeze tolerance of winter plants such as Flixweed might promote their cultivation and utilization in cold regions. At present measuring the survival after a recovery period which is followed by a freezing test in controlled conditions is a common method for determining the level of plants freeze tolerance. Calculation of LT50 point or critical temperature based on survival percentage of plant is considered as a quantitative and simple method for evaluating the cold tolerance [1]. But sometimes this criterion is not enough alone and other indices (for example dry weight and Reduced dry matter temperature 50% of plants (RDMT50)) are used to achieve a more accurate estimation of cold tolerance level [3]. In spite of numerous medicinal and industrial properties of Flixweed, there is not a lot of information about freeze tolerance of this plant, so the objective of this study was evaluating the freeze tolerance of Flixweed by survival % and some of growth traits after recovery period. Materials and methods In order to evaluate freeze tolerance in some of Flixweed, a factorial experiment was conducted based on completely randomized design with three replications in faculty of agriculture, Ferdowsi University of Mashhad in autumn of 2009. Experimental factors include five ecotypes of Flixweed (Eghlid, Sabzewar, Hamedan, Torbat-e-Jam and Neyshabour) and 10 freezing temperature levels (from zero to -18 with 2 °C intervals). For this aim, Flixweed seeds were cultivated in pot in autumn and they were grown in natural weather until 5-7 leaf stage. Afterward for applying freezing temperatures, plants were transferred to a thermo gradient freezer. The initial temperature of programmable freezer was 5°C; but gradually decreased in a rate of 2°C.h-1 until reached to desired temperatures. When the freezer temperature reached to -2°C, the plants were treated by the Ice Nucleation Active Bacteria (INAB) to help the formation of ice nuclei in them, also to prevent from super-cooling of samples and to ensure that the mechanism of freeze resistance is tolerance not avoidance. After artificial freezing stress applying (which lasted up to two hours for each freezing temperature); Flixweed seedlings were transferred to greenhouse for recovery. Three weeks after freezing stress, survival percentage (SU %), Lethal temperature for 50% of plants according to the survival% (LT50su), number of leaf and reduced number of leaf temperature 50% (RNLT50), number of node and reduced number of node temperature 50% (RNNT50), dry weight and reduced dry matter temperature 50% (RDMT50) were evaluated. Analysis of variance was performed by MSTAT-C software and correlations between data were carried out by MINITAB 16 program. Mean separation was conducted by least significant difference (LSD) test at 1% probability level.
Results and Discussion Results showed that Hamedan ecotype had the highest SU% and Neyshabour ecotype had the lowest SU%. In Eghlid and Neyshabour ecotypes, decline of SU% begun from higher temperarures (-8 °C) compared with other ecotypes (-10 °C). This trend was seen for dry weight and number of leaf too. At -12 °C, number of node in Hamedan ecotype decreased 30% approximately than control, while in Eghlid and Neyshabour ecotypes, this reduction was much higher. In this experiment LT50su ranged between -10.2 to -12.1 °C depending on the ecotypes. Ranking of Flixweed ecotypes according to the LT50su, RNLT50, RNNT50 and RDMT50 indices showed that the Neyshabour and Hamedan ecotypes were the most sensitive and tolerant Flixweed ecotypes to freezing stress respectively. In this survey, there was high and positive correlation between survival percentage and dry weight (r=0.69***), in addition there was negative and significant relationship between SU%, LT50su and RNNT50 (r=-0.67*** and r=-0.82*** respectively).
Conclusion According to these results, it seems that temperature threshold for winter injury happening in Flixweed is -12 °C. Despite this for better understanding of cold tolerance of Flixweed, further researches are required under controlled and field conditions.
Mahmood Attarzadeh; Hamidreza Balouchi; Majid Rajaie; Farzaneh Pooladi
Abstract
IntroductionAbscisic acid (ABA) is a phytohormone which has a main role in plant life cycle and regulates many physiological processes including plant development and adoptability to environmental stresses. ABA controls water status of plants under stress and noticeably decreases undesirable heat stress ...
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IntroductionAbscisic acid (ABA) is a phytohormone which has a main role in plant life cycle and regulates many physiological processes including plant development and adoptability to environmental stresses. ABA controls water status of plants under stress and noticeably decreases undesirable heat stress damages. Since high temperature stress is a limiting factor for many crops growth and according to literature review there are evidences that ABA can induce thermo tolerance in plants, the present study was designed to evaluate the response of corn to heat stress when seeds are pretreated by ABA.Materials and methodsThe experiment was factorial in a completely randomized block design with three replications and was done in agricultural college of Vali-e-Asr University of Rafsanjan in 2013. First factor was seed pretreatment by ABA solutions (zero, 50, 100 and 200 µM L-1) and second factor was different durations (zero, 8, 16 and 24 h) of heat stress in 40º C exerted on hybrid S.C.704 corn seedlings. In darkness seeds were soaked in ABA solutions for 24 h at the temperature of 25 ± 1º C. Following pretreatments seeds were sterilized by distilled water and finally were planted in pots in the depth of 1.5 cm. Seedlings were transported to growth chamber with the temperature of 40º C in four foliate stage to be treated by different heat durations. After thermo treatments seedling were transported to green house and plant responses were measured two weeks later. Results and discussionResults indicated that the highest dry weight of shoots was obtained in ABA concentration of 50 µM L-1 but there were no significant differences at probability level of one percent among other concentrations. In addition corn seedlings were able to tolerate 8 h heat duration but negative effects of heat stress was significantly increased in 16 and 24 durations which led to the reduction of shoot dry matter production. Increase in heat duration and ABA concentration caused a significant raise in shoot to root weight ratio so that the highest ratio (31.66 percent) was observed in control treatment and the lowest (3.83 percent) in heat duration of 24 h accompanied with 200 µM L-1 ABA. Leaf relative water content in ABA concentrations of 50 and 100 µM L-1 showed a significant increase at probability level of five percent in respect to control and ABA concentration of 200 µM L-1 which can probably be due to stomata resistance in these treatments and may be used as suitable approach to increase plant thermo tolerance. Negative effect of ABA concentration of 200 µM L-1 on leaf relative water content indicated that ABA concentration must be chosen precisely. Increase in heat duration caused a significant raise in leaf temperature. In heat durations of 16 and 24 h the highest leaf chlorophyll index (27.2 and 24.5 respectively) was obtained in 50 µM L-1 ABA and the lowest ones (21.9 and 18.7 respectively) in 200 µM L-1. Increase in ABA concentration and heat stress led to a significant reduction of chlorophyll a content in corn leaf so that in heat duration of 24 h and ABA concentration of 200 µM L-1 a reduction of 36.9 percent was observed compared to control. In addition a reduction of 17 percent in carotenoids was associated with 24 h heat stress in respect to control. In all three durations of heat stress, rise in ABA concentration up to 100 µM L-1 made a decline in ion leakage while in the highest concentration (200 µM L-1) an increment in ion leakage was observed. ConclusionsIn conclusion the results of the present study showed that high levels of heat stress in combination with undesirable concentrations of ABA can create negative effect on plant ability to preserve leaf relative water content and can lead to the destruction of chlorophyll and carotenoids structure and increase the ion leakage. On the other side ABA concentration of 50 and 100 µM L-1 decreased ion leakage while increased the leaf relative water content and chlorophyll index. By these simultaneous effects the corn shoot dry weight was improved under heat stress condition. It seems that external use of ABA can have positive and negative effects on plant growth depending on its concentration. Concentrations higher than threshold tolerance to ABA can cause disturbance in plant physiological processes and restrict plant growth and development.
Abdolhossein Rezai; Hamidreza Balouchi; Mohsen Movahhedi Dehnavi; Ebrahim Adhami
Abstract
Introduction
In recent years, soil pollution with heavy metals such as cadmium had a progressive trend and causes serious problem in production of crops in polluted zones. Heavy metals released from stationary and mobile origins can be transported in water, air and soil and can be even absorbed by plants, ...
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Introduction
In recent years, soil pollution with heavy metals such as cadmium had a progressive trend and causes serious problem in production of crops in polluted zones. Heavy metals released from stationary and mobile origins can be transported in water, air and soil and can be even absorbed by plants, animals and human bodies. Trace elements are currently of great environmental concern. Nowadays, one of the most important environmental problems is pollution of agricultural soils occurs by heavy metals due to human activities. Nowadays, soil pollution with heavy metals as a result of human activities is considered one of the most important environmental stresses in plants, which can lead to the production of reactive oxygen species such as hydrogen peroxide cause. Priming application of gibberellic acid, salicylic acid and potassium nitrate as a suitable option is considered to reduce the toxic effects of cadmium.This study was designed to investigate the effects of priming on physiological traits and sorghum seed germination under cadmium chloride and nitrate stress was conducted in the greenhouse of Yasouj University in 2015.
Materials and Methods
experiment was conducted as a factorial based on CRD design with three replications. Treatments first factor were including 800 mg/l gibberellic acid, 0.3 mM salicylic acid, 1% potassium nitrate and control (non-prime). The second factor was included cadmium chloride and nitrate each in four levels (0, 7.5, 15 and 30 mg per kg of soil). Then cadmium chloride and nitrate was added by spraying into soil. Then planting pots were filled with seven kilograms of soil, and after one month (because of the homogeneity of the heavy metal), 4 seeds primed for planting in pots were planted with different levels of cadmium chloride and nitrate. The chlorophyll index, chlorophyll fluorescence, leaf soluble protein and antioxidant enzyme activities were measured. Also, post-harvest seed quality traits including percentage and germination rate, uniformity and vigor and seed weight and seedling length and weight were measured.
Results and Discussion
The results showed that the interaction of cadmium and priming for soluble protein, Catalase enzyme, Superoxide dismutase enzyme and seedlling height was significant. The effect of cadmium showed that cadmium chloride 30 mg per kg of soil seed weight decreased to 24% compared to control. Generally all levels of cadmium compared to the control (no cadmium) had a depressing effect on seed weight. Priming planted seeds with 0.3 mM of salicylic acid leads to increase the germination rate and length vigor index of seeds of sorghum under cadmium stress. Also the most weight vigor index was observed in 15 mg per kg of soil cadmium chloride and nitrate and the lowest was belonged to 7.5 and 30 mg per kg of soil cadmium chloride treatments. In relation to the slow germination under stress cadmium cell membrane probably one of the important points is that it is severely damaged cell to leak out and vigor will be reduced. Priming with the reconstruction of damaged cells and reduce barriers to the growth of the fetus and increase the quality and quantity of protein synthesis, increases the development and tolerance to environmental stresses. Speed up seed germination can as a result of increasing enzymes such as Alpha-amylase, increased levels of bio-energy charged in the form of increasing the amount of ATP, increase the synthesis of DNA and RNA, increasing the number and improving mitochondrial function is at the same time.
Conclusions
In general, seed priming with 800 milligrams per liter of gibberellic acid, and 0.3 mM of salicylic acid, improved the biochemical and physiological indices of main plant such as increased soluble protein and chlorophyll content, cause to sorghum seedlings resistance to cadmium toxicity and improved the seedling growth and seed weight. As a result, seeds produced in these conditions, have more germination rate and vigor index than the control (non-use of priming).
Volume 10, Issue 4 , January 2017, Pages 572-572
