Shahla Tawana; Jalal Saba; Farid Shekari
Abstract
Introduction With increasing the world population and need to provide food, the enhancement of crops yield has become very important. One of the most important actions to achieve this goal is to identify the factors affecting the enhancement of yield. based on studies conducted on balancing the yield ...
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Introduction With increasing the world population and need to provide food, the enhancement of crops yield has become very important. One of the most important actions to achieve this goal is to identify the factors affecting the enhancement of yield. based on studies conducted on balancing the yield components in so many crops was concluded that grain yield is a result of interaction between numerous genes and environment and for this reason direct selection has not proven so successful for that and does lead to remarkable increase in yield and so that the selection for yield components has been suggested as a solution for evermore progress in yield increase (Adams,1967). These results indicated that the number of spike/m2 was the trait related to higher grain yield under irrigated and late season water stress conditions (Okuyama et al., 2004). The correlation between yield and its components alone is not sufficient to understand the importance of each one of these components in determining the grain yield. while, path analysis not only measures the direct influence of one variable upon another, but also provides means of partitioning both direct and indirect effects and effectively measuring the relative importance of causal factors which helps to build an effective selection program (Ali and Shakor, 2012). This experiment was conducted to determine the most effective traits on grain yield and its components in bread wheat under rainfed conditions. Materials and methods A field experiment was conducted at the research farm of agricultural faculty of University of Zanjan, Iran (North Longitude 36°41', East Latitude 48°27' and 1620 m Altitude). A square lattice experimental design in two replications was conducted in 2012-2013. Evaluated traits included grain yield, number of spike per plant, number of grain per spike, 1000-grain weight, relative water content, rate of water loss from excised leaves, canopy temperature, difference of canopy with its environment temperature, stem diameter and number of xylem vessels. MSTAT-C and SPSS-20 software were used to analyze the data and LSD test was used to compare the means of traits at 0.05 probability level. The stepwise regression analysis was also carried out to test the significance of the independent variables affecting the grain yield. Then, path analysis was calculated for the traits. For this purpose, a simple coefficient correlation was obtained between all traits and the partial coefficient regression (direct effects) of traits was calculated by SPSS. The indirect effects were also calculated by multiplying the direct effects in simple coefficient correlation. Results and discussion Number of spike per plant and number of grain per spike had positive and significant correlation with grain yield with values of r = 0.41** and r = 0.36**, respectively. Previous authors also reported similar results for relationships of grain yield and these traits (Aycicek and Yildirim, 2006). No significant correlation was found between 1000-grain weight, Relative water content, number of xylem vessels and stem diameter with grain yield. Number of xylem vessels had negative and significant correlation with 1000-grain weight (r= -0.39**). Stepwise regression is a semi-automated process of building a model by successively adding or removing variables based solely on the t-statistics of their estimated coefficients. In order to remove effect of non-effective characteristics in regression model on grain yield, stepwise regression was used. Results of stepwise regression showed that the number of spike per plant, grain number per spike and 1000- grain weight with R square of 0.87, had justified the maximum of yield changes. Path coefficient analysis helps to estimate the influence of each variable upon the resultant variable directly as well as indirectly by partitioning the genetic correlation coefficients. Grain yield per plant was selected as resultant variable and number of spike per plant, number of grain per spike and 1000-grain weight as causal variables. The direct effect of number of spike per plant on grain yield was positive (0.89). The indirect effects of number of grain per spike and 1000-grain weight had values of -0.58 and 0.10, respectively. On the other hand, the traits leaf relative water content and stem diameter had positive and significant correlation with number of grain per spike. On the other hand, direct effects of stem diameter and relative water content on grain number per spike were recorded positive with values of 0.42 and 0.28, respectively. In other words, the increase in stem diameter and RWC can be somewhat increased the number of grains per spike in the experimental conditions. Conclusions Results of correlation analysis showed that selecting lines with more effective spikes and less number of grains per spike can be recommended as approach of indirect selection for improving grain yield in wheat under rainfed conditions. As a second approach, the selection for more grain per spike in limited number of spike is recommendable. Selection for greater stem diameter also can indirectly lead to grain yield improvement by increasing number of grains per spike.
Mahmood Nazeri
Abstract
Introduction Wheat cultivars that are more tolerant to terminal drought are more suitable to Mediterranean conditions. To increase water use efficiency, the target environment shound be taken in to account, because one trait might be effective in an environment but ineffective in another environment. ...
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Introduction Wheat cultivars that are more tolerant to terminal drought are more suitable to Mediterranean conditions. To increase water use efficiency, the target environment shound be taken in to account, because one trait might be effective in an environment but ineffective in another environment. Phenological adjustment with pathern of seasenal precipetation adaptation, improve water use efficiency in drought conditions. Suitable flowering time is the most important trait that is correlated with increasing water use efficiency in drought conditions. Seed size is also important in moisture stress prone environment. Larger grains facilitate germination and emergence, good early ground cover and biomass, because at seedling stage when plant is more dependent on seed storages (heterotrophic stage), it provides adequate reserves for seedling growth. Spike growth period is a crucial stage and significantly affects grain yield determination. During this stage demand for assimilate increases due mainly to enhanced growth and competition between growing structures and organs, particularly, growing spike and elongating stem. This study was carried out to investigate the effect of moisture deficit yield on potentional and effective traits inpromising winter and facultative bread wheat genotypes. Materials and Methods In order to evaluate yield potentional and effective traits inpromising winter and facultative bread wheat genotypes, the present investigation, was carried out in 2008-09 and 2009-10 growing seasons in Torogh Agricultural Research Field Station, Mashhad in the North East of Iran in 36º 13´ N, 59º 40´ E and 985 m above see level, in split plot arrangements using randomized complete block design with three replications. Main plots were water limited conditions with three levels (L1: Optimum condition, L2: water deficit using rainshelter from milky grain stage to maturity; L3: water deficit using rainshelter from anthesis stage to maturity). Ten bread wheat genotypes, suitable for cold and dry regions (V1: (Toos), V2: (C-81-10),V3: (pishgam),V4: (C-84-4), V5: (Mihan), V6: (C-D-85-15),V7: (C-D-85-9),V8: (C-D-84-5502),V9: (C-D-85-5502), V10: (C-85-6)) were assigned to subplots. Grain yield and biological yield were measured by harvesting of whole plot, weighing and then thrashing. Harvest index was calculated using following equation: HI= Grain yield / Biological yield *100. Number of kernel per spike (NK/S), Kernels weight per spike (KW/S) were obtained by using at least 20 spikes. Number of fertile spikes per square meter, 1000 kernel weight (1000KW) also were measured. Anthesis and physiological maturity were determined by observing of anters in %50 spikes and changing color of %50 pedancles to yellow, respectively. Results and Discussions The results showed that water stress (L2 and L3 treatments)decreased grain yield (18.6% and 45.6%, respectively) due to reduction in thousands kernel weight (TKW) and kernels per spike in compairin with optimum conditions. The results showed that genotypes V5 and V4 had higher grain yield (7593 and 7170 Kg/ha, respectively) due to optimum amount of yield component, such as fertile spike per square meter (806 and 765 spike), thousands kernel weight (37.87 and 38.33 gr), kernels per spike(36.2 and 36.0 kernels) and grain weight per spike(1.17 and 1.23 gr) respectively. The results showed that the highest harvest index(HI) is happended in optimum condition (40.95%). The lowest harvest index(HI) was belong to (L3)water limited conditions from anthesis to maturity(36.37%), due to reduction in water use in post anthesis staegs in compairin with optimum condition. genotypes V5 (Mihan) and V4 were the best in both optimum and stress conditions, so could be recomanded to cultivation for similar conditions of this study. Conclusions Results indicated that genotypes, V5: (C-84-8, recently released and named Mihan) and V4: (C-84-4) had the best performace amoung other genotypes, respectively. These cultivars had higher grain yield in both optimum and stress conitioms other genotypes, wich is the most important charachter for slow stressing. So these cultivars could be recomanded to cultivation for similar conditions of this study.
Mohammad Zabet; Saman Seddigh; Alireza Samadzade
Abstract
Introduction Rapeseed is an annual plant of the Brassicaceae family (Mobasser and Piri, 2008). The Rapeseed is one of the most important crops in the world for oil extraction. It has the highest annual growth rate among the most important vegetable oils in the worlds. Statistical analysis shows that ...
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Introduction Rapeseed is an annual plant of the Brassicaceae family (Mobasser and Piri, 2008). The Rapeseed is one of the most important crops in the world for oil extraction. It has the highest annual growth rate among the most important vegetable oils in the worlds. Statistical analysis shows that there have been significant developments in Iran, so that the production has increased from 76 to 350 tons during 2003 to 2013 (FAO, 2014). Today Rapeseed is most important source of oil in America and Europe. Among the oil crops, Rapeseed has specific priority for several reasons. Due to the necessary need for the country to produce oil, has increased the area under Rapeseed cultivation (Pessarakli, 1994; Shekari et al, 1998). Drought stress, especially in the end of season is one of the most important factors limiting plant growth in arid and semiarid areas (Turhan and Baser, 2004). Drought stress has a negative effect on many plant processes, including photosynthesis and evaporation (Ohashi et al., 2006). During the drought stress reduce the number of flowers per plant, number and size of seeds (Malcom and Doug, 2002). Fanaei (Fanaei, 2008) by research on Rapeseed found that yield components for example the number of pods per plant had a significant difference during the two years of testing. As well as a significant reduction were observed in yield due to the reduction of yield components such as number of pods per plant, number of seeds per pod and seed weight under stress conditions. In another study it was found that the yield of Rapeseed was severely affected by drought stress and decreased flowering period and days to maturity, but did not change significantly the number of days to flowering, grain filling period, plant height and number of pods per plant. The number of seeds per pod and seed weight decreased (Nasiri et al., 2003). The aim of this study was to evaluate the effect of drought stress on ten rapeseed genotypes and identification of tolerant genotypes after flowering stage in Birjand region. Materials and methods This research was conducted in an area of about 600 square meters in the College of Agriculture, University of Birjand in 2010-2011. The study was performed in a randomized complete block design with three replications and 10 treatments in both normal and stress conditions. Irrigation was done after 90 mm evaporation from class A pan until flowering stage. After flowering stage, irrigation was done after 90 and 180 mm evaporation from class A pan in normal and stress conditions, respectively. Each plot was composed of 4 lines with a length of 2 m. The distance between row and on row was 60 and two cm, respectively. The measured traits was including, day to 50% flowering, seed yield, biological yield, seed weight, harvest index, pod length, number of seeds per pod, number of branches, number of pods per main stem, number of pods per auxiliary branch and the total number of pods per plant. Results and discussion Analysis of variance showed that all genotypes had significant differences for all traits in normal and stress conditions. The effect of stress was significant in the number of days to 50% flowering, seed yield, biological yield, seed weight, pod length and number of seeds per pod. The stress had no effect on harvest index, number of branches, number of pods per main stem, number of pods per auxiliary branch and the total number of pods. Mean comparison of different genotypes showed that Hyolla308 and Licord had the highest seed yield in normal conditions. Genotypes Modena, Okapi, Hyolla401, Zarfam and RGS003 did not show significant differences with them. Mean comparison of different genotypes showed that Hyolla308 and Modena had the highest seed yield in stress conditions. Genotypes Okapi, Zarfam, Licord SLMO46 and RGS003 did not show a significant difference with them. Correlation analysis showed that seed yield had a significant positive correlation with biological yield and number of pods per main stem at %1 and %5 levels, respectively, in normal conditions. In stress condition, seed yield had a significant positive correlation with biological yield, harvest index, number of pods per auxiliary branch and the total number of pods per plant at %1 level. Number of pods per plant can be regarded one of the most important components of yield, because the pods contain seeds. In the other hand the seeds involved in growth and development at early stage of seed filling through photosynthesis. Clarke and Simpson (Clark and Simpson, 1978) reported that the number of pods per plant increased the number of seeds per pod, but decreased seed weight. The negative poor correlation between the number of seeds per pod and seed weight decreases seed yield. Mendham et al., 1975 found that increasing the number of seeds per pod is considered a key factor in increased seed yield. Increasing the number of seeds per pod is limited and depends on the length of the sheath that this trait is under genetic control. Factor analysis showed that the first four factors explained %85 of the total variation in normal conditions. The first, second, third and fourth factor explained %36/76, %20/54 %14/76 and %11/72 of the total variation, respectively. These factors named pods production, yield, seed production and phonological- quantitative factors, respectively. Factor analysis showed that the first four factors explained %86/63 of the total variation in stress conditions. The first, second, third and fourth factor explained %43/78, %18/54, %12/93 and %11/37 of the total variation, respectively. These factors named yield, pods production, morpho-phenological and seed weight factors, respectively.
Hoda Kadkhodaei; Hamid Sodaeizadeh; Asghar Mosleh Arany; Mohammad Ali Hakim Zadeh
Abstract
Introduction
Drought is considered as one of the most important factors limiting crop yields around the world especially in the dryland area. The response of plants water stress has been assessed using different physiological techniques, such as chlorophyll, proiline and water soluble hydrocarbons measurement. ...
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Introduction
Drought is considered as one of the most important factors limiting crop yields around the world especially in the dryland area. The response of plants water stress has been assessed using different physiological techniques, such as chlorophyll, proiline and water soluble hydrocarbons measurement. In response to environmental stress, plant species accumulate different kind of osmolytes like glycine betaine and proline in their cytoplasm and subsequently adjust their cells osmotic potential. Of different osmolytes occurring in plants in response to environmental stresses, glycinebetaine (GB) has been studied extensively. Significant advances have been made in mitigating the inhibitory effects of environmental stresses by exogenously applied glycinebetaine in different plant species. Exogenous application of glycinebetaine as foliar spray has been employed to enhance drought tolerance in a number of crops. This study was conducted to evaluate the role of application of glycine betaine (GB) in improving drought tolerance of sorghum halopens under different stress treatments.
Material and methods
The study was performed in an experimental greenhouse at Yazd University in 2012 based on randomized complete block design with 3 replications. Different amount of GB i.e. 0, 100 and 200 mM in combination with various irrigation periods i.e. 3, 6 and 9 days were considered as experimental treatments. Irrigation treatments were applied after germination and establishment of sorghum seedlings. Foliar sprays of GB were applied two times during growth period of sorghum. Different plant parameters including sorghum fresh and dry weight, proline and water soluble hydrocarbons were measured. Proline content of leaves was determined according to Bates et al. (1973). Soluble carbohydrate content was determined in aqueous solution phenol sulfuric acid reagent according to Kochert (1978). After testing the normality distribution of data, two way analysis of variance was used for data analyzing and Duncan multiple range test was used to compare mean of treatment. SPSS (version 16) software and EXCEL were used for data analysis and drawing graphs.
Results and discussion
Results indicate that increasing GB concentration cause a significant increase in water soluble carbohydrate at 9 days irrigation period. None significant difference in sorghum carbohydrate content was observed at 3 and 6 days irrigation period when compared to control. Gorham et al., (2000) found that exogenous GB application was very effective in increasing carbohydrate content of cotton. In another study Makhdum and Shababuddin., (2006) reported that exogenous application of GB significantly increase the carbohydrate concentration of bean. Result also indicated that at 6 days irrigation period, with increasing GB concentration the proline content of sorghum leaves significantly increased. In this irrigation treatment, application of 200 mM GB cause a 62 percent increase in proline when compare to control. Exogenous application of GB to low-accumulating or non-accumulating plants may help reduce adverse effects of environmental stress. Externally-applied GB can rapidly penetrate through leaves and be transported to other organs, where it would contribute to improved stress tolerance (Ashraf and Foolad, 2007). According to our result increasing irrigation period from 3 to 6 and 9 days cause a significant decrease in fresh and dry weight of sorghum. The main consequences of drought in crop plants are reduced rate of cell division and expansion that can decrease dry matter accumulation of plant. On the other hand with the development of drought stress, as the plant photosynthesis decreased, plants need more carbohydrate compounds to adjust osmotic potential and subsequently available carbohydrate for grown and accumulation of dry material diminished. At 3 days irrigation period, application of GB had no significant effect on fresh and dry weight of sorghum whereas both GB concentrations significantly increase sorghum fresh and dry weight in water deficiency condition. Application of GB ameliorate the adverse effect of drought stress on fresh and dry weight of sorghum. This can attributed to this fact that GB-treated plants exhibited a slower decrease in leaf water potential during drought stress and developed wilting symptoms much later than untreated plants. Generally, they protect plants from stress through different courses, including contribution to cellular osmotic adjustment, detoxification of reactive oxygen species, protection of membrane integrity, and stabilization of enzymes/proteins (Bohnert and Jensen, 1996). Different studies demonstrated the positive effect of exogenous GB application in decreasing adverse effects of drought stress on dry material accumulation of some plant species such as corn (Wyn Jones, 1984), tomato (Makela et al., 1998(, bean (Webing and Rajashekar, 1999) and cotton (Gorham et al., 2000).
Conclusions
Overall results indicate the negative effect of drought stress on growth and development of sorghum. Application of GB ameliorate the adverse effect of drought stress and accumulation of proline and soluble carbohydrate in abovegrounds tissue of sorghum improved plant water relation under stress. However, more study on the mechanism of action of this substance under different experimental conditions is still needed. Also it is suggested that the time of application and frequency use of GB investigated in future research.
Masood Khazaei; Mohammad Galavi; Mahdi Dahmarde; Seyed Mohsen Moosavi-Nik; Gholam Reza Zamani; Nafiseh Mahdi-Nejad
Abstract
Introduction Drought stress is one of the most important factors limiting crop productivity, and reduce crop production more than 50% in the world (Lata et al., 2011). Development of drought-resistant plants can be a useful strategy for avoiding drought induced damages to the crops. Using C4 plants such ...
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Introduction Drought stress is one of the most important factors limiting crop productivity, and reduce crop production more than 50% in the world (Lata et al., 2011). Development of drought-resistant plants can be a useful strategy for avoiding drought induced damages to the crops. Using C4 plants such as foxtail millet is a suitable alternative (Vitkauskaite and Venskaityte, 2011). These plants are known to be resistance to water shortage. Drought stress effect on physiological traits such as Osmotic adjustment, chlorophyll pigmant and morphological trait such as plant height and ear length (Mohammadkhani and Heidari, 2008). Understanding the physiological and morphological basis of drought tolerance and its relation with yield in this plant would possibly contribute greatly to the understanding and planting development of drought resistant plants species. In this regard howeverlittle information is available on millet. So the aim of this study was to evaluate the physiological and morphological traits under drought stress in millet. Material and methods This study was carried out in Research field of Birjand University in 2014. A split-plot arrangement of treatments in a randomized complete block design with four replications was used. The main factor was drought stress with three levels including 100, 75 and 50 percent of plant water requirement (non-stress control, moderate stress and severe stress respectively) and the sub-factor was millet cultivar with three levels (including Bastan, KFM5 and KFM20).. Osmolyte regulated and photosynthesis pigments was measured 30and 45 days after drought stress (Schlegel, 1956; Bates et al., 1973; Sairam and Saxena, 2000). Seed yield and its component and morphological traits were measured after plant maturity. Software SAS software (ver 9.1 windows edition) was used for statistical analysis and means were compared using tukey test. Results and discussion Results showed that drought stress at different growth stages increased proline content and soluble Carbohydrates and reduced photosynthesis pigment and carotenoid content compared to control treatment. Drought stress also reduced plant height, internode length, ear length, number of ears per square meter, number of grains per ear, seed weight and seed yield compared to control treatment but had no effect on the number of nodes per plant. Highest and lowest seed yield was observed in control treatment(461.88 g.m-2) and severe stress (171.08 g.m-2) respectively. Reduced height possibly resulted in reduced yield by affecting radiation use efficiency. According these results plant height, ear length, seed number in ear a,d 1000 seed weight have direct effects on seed yield in Foxtail Millet so that their enhancement would result in seed weight improvement. Conclusions According to results a reduction in height, osmolyte compatible and carotenoids are Compatibility and drought resistance mechanisms.
Seyed Ali Alaviasl; Sirous Mansourifar; Seyed Ali Mohammad Modarres Sanavy; Kamal Sadatasilan; Seyed Ali Tabatabaei; Mehrdad Moradi Ghahderijani
Abstract
Introduction Sesame (Sesamum indicum L.) is an annual plant, with self-pollinating flowers which belongs to the Pedaliaceae family. This crop is one of the most important oilseed plant in Iran with 6500 and 42 thousand hectares cultivated area in Iran and the world (Golestani and Pakniyat, 2007). India, ...
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Introduction Sesame (Sesamum indicum L.) is an annual plant, with self-pollinating flowers which belongs to the Pedaliaceae family. This crop is one of the most important oilseed plant in Iran with 6500 and 42 thousand hectares cultivated area in Iran and the world (Golestani and Pakniyat, 2007). India, Sudan, Myanmar and China are the main production centers of this crop (Rajeswari et al., 2010). Water deficit stress reducing photosynthesis, stomata closure due to reduced plant growth, lack of assimilates for grain filling and lower grain filling period of plants (Reddy et al., 2004). Chitin is polysaccharides found in nature and has multiple applications in industry, medicine and agriculture (Wang et al., 2003). Chitosan is a glucosamine polysaccharide derived from chitin that more than 50% of acetyl groups refer has removed. Zeolites are a group of natural porous minerals that acts as a molecular sieve with its crystal structure practices and allow some passage of some ions and block the passage of some others, due to open channels in their ionic lattice. Materials and methods A split plot factorial experiment was conducted in a randomized complete block design with three replications at the Research field of Yazd Center of Agriculture and natural resources, Yazd, Iran (31°N 54°E and 1220 m above sea level with sandy loam soil, 7/67 pH = and organic matter) during 2012 growing season. Treatments were three irrigation regimes (irrigation at 50, 65 and 80 percent depletion of plant available water in the soil, as the control, average stress and severe stress) placed in the main plots and foliar application in four levels (concentrations of chitosan with 0.4 percent and 0.05 percent, distilled water (control) and one percent acetic acid (This material is the solvent of chitosan and may affect traits separately)) and zeolite application (not application and use 4.5 tons per hectare) arranged as sub-plots. After determining the moisture content (TDR), field capacity and wilting point, experimental applied. Mean comparisons were performed by Duncan’s multiple range test (DMRT) using in SAS 9.2. Results and discussion Results showed that the interaction effects of all treatments were significant on grain and oil yield, number of seeds per pod and height of the first pod from the ground application of zeolite at the average stress level of irrigation led to 85 percent and 67 percent decreases in oil and seed yield, respectively, averaged over all levels of foliar application. It was also observed that non application of zeolite in average stress level decreased 70 percent of total dry weight, 10 percent oil percentage and number of pod per plant 4 times in comparison with using this mineral material in normal level. Zeolite did not affect the number of pod per plants significantly under controlled condition. By increasing water deficit stress, number of pod per plant was reduced. Zeolite increased number of pod per plant in both moderate and severe water deficit stress condition (29%). Maximum pod length (2.3 cm) was observed in controlled condition which was (30%) higher than severe stress (2.2 cm). Conclusions We concluded that Chitosan and zeolite as growth enhancer materials increased yield of sesame under water deficit stress. Results also showed that water deficit stress reduced oil yield, height of first pod and seed in pod that reduce yield being through impact on yield components. Zeolite and chitosan could reduce negative effects of water deficit on plants and improve crop yield and its yield components.
Somayeh Malekzadeh; Seyfollah Fallah
Abstract
Introduction Water scarcity is one of the main problems in the agricultural land around the world. The climate changes indicate a rise in temperature and a decrease in average rainfall, which that its augments the drought stress effects in future (Farre and Faci, 2006). Tolerance to dehydration plants ...
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Introduction Water scarcity is one of the main problems in the agricultural land around the world. The climate changes indicate a rise in temperature and a decrease in average rainfall, which that its augments the drought stress effects in future (Farre and Faci, 2006). Tolerance to dehydration plants to grow in arid and salty is very important. Germination and establishment of plants due to low viability is difficult and environmental stresses, especially drought than other factors are reduction of green. Priming one of the ways to increase the germination under stress conditions. The aim of this study is to investigate the effect of seed priming treatments on emergence parameters improve of ajowan (Carum copticum L.) medicinal plant. Material and methods A split plot experiment was conducted in randomized complete block design with three replications at farm of agricultural college, Shahrekord University, 2014. Different levels of irrigation (irrigation after 11, 22, and 33 mm evaporation from pan evaporation class A) were evaluated as the main plot and seed priming treatments consisted of no priming (control), hydropriming (seed soaking in distilled water for 36 hours), KNO3 (seeds were placed on potassium nitrate 4%), ZnSO4 (seeds were placed on potassium nitrate 0.1%), PEG600 (seeds were placed on -12 bar of polyethylene glycol) and GA3 (seeds were placed on 100 ppm of gibberellic acid) as subplot. Treatments were chosen according to a preliminary priming experiment. The amount of potassium nitrate required is calculated using equation Want hoof (Siebert and Richardson, 2002). In this experiment, parameters such as rate of emergence, percentage of emergence, root dry weight, shoot dry weight, root length, shoot length, shoot dry weight, allometric coefficient, and vigor index were evaluated. data were analyzed by using both one- or two-way analysis of variance (ANOVA) and mean comparisons were performed by LSD test if F-test was significant at (p < 0.05) to determine whether differences among means were significant between treatments drought stress and seed priming. Results and discussion The results showed that emergence percentage, root dry weight, soot dry weight, vigor index were influenced by drought stress (p < 0.05, p < 0.01, and p < 0.01, respectively). The seed priming effect for emergence rate, emergence percentage, root dry weight, shoot dry weight, root length, shoot length, shoot dry weight, allometric coefficient, and vigor index was significant (p < 0.01, p < 0.01, p < 0.01, p < 0.05, p < 0.01, p < 0.01, p < 0.01, p < 0.01, and p < 0.01, respectively). The drought stress × seed priming interactions for emergence rate, emergence percentage, root dry weight, shoot dry weight, root length, shoot length, shoot dry weight, allometric coefficient, and vigor index was significant were statistically significant. Means comparison results indicated that in mild stress (irrigation after 22 mm evaporation), the highest rate and percentage of emergence were obtained in PEG treatment. The greatest of root dry weight was observed in GA3, KNO3, and ZnSO4, and PEG treatments. In addition, root length, shoot length, shoot dry weight, allometric coefficient of primed seed not only not improved but also values of these characters declined in compare to non-primed seed. In severe stress (irrigation after 33 mm evaporation), rate and percentage of emergence and vigor index increased in PEG, GA3, ZnSO4. Also, The maximum root length (6.7 cm) and shoot length (4.4 cm), were observed GA3 and ZnSO4, respectively.Primed seed with ZnSO4 increased shoot dry weight (16.12mg) and the allometric coefficient (0.82), as well as. Conclusions In overall it can be concluded that in drought stress conditions, seed priming of ajowan medicinal plant with gibberellic acid and zinc sulfate improves germination and seedling growth in farming systems. Thus, these pretreatments increases root growth and strengthen and better establishment seedling under drought stress conditions that it would be appropriate for the development of production in such semi-arid environments. In addition, by reducing the frequency of irrigation for optimum seedling establishment can make good use of water resources in these areas.
Seyed Abdolreza Kazemeini; Mohammad Hossein Alborzei Hagighi; Hadi Pirasteh-Anosheh
Abstract
Introduction Environmental stresses represent a major constraint to meeting the world food demand. The estimation of potential yield losses by individual environmetnal stresses are estimated 17% by drought, 20% by salinity, 40% by high temperature and 15% by low temperature. Salt stress is among the ...
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Introduction Environmental stresses represent a major constraint to meeting the world food demand. The estimation of potential yield losses by individual environmetnal stresses are estimated 17% by drought, 20% by salinity, 40% by high temperature and 15% by low temperature. Salt stress is among the most important abiotic stress, depended to severity and stage, reducing growth and changing accumulation and distribution of ions in rapeseed (Brassica napus). Rapeseed sensitivity to soil salinity continually changes during the growing season. Most crops are tolerant during germination, but the young developing seedlings are susceptible to injury during emergence from the soil and during early juvenile development. Once established, plants generally become increasingly tolerant during later stages of growth. Althought effect of salt stress was well docucmented on rapseed growth; however, sensitivity of different growth stages of this plant has not fully studied. So, the main objective of this research was to examine salinity tolerance at different growth stages in rapeseed. Materials and methods In this research the effect of different saline waterat different growth stageswas evaluated on some morpho-physiological traits on rapeseed (cv. Talaye) in controlled greenhouse in College of Agriculture, Shiraz University at 2014. The treatments included 0.4 (tap water as control), 4, 7 and 10 dS.m-1imposed at different growth stages consisted of 5 leaves, stem elongation and flowering. The pots (5 L size) were filled with field soil, sand and humus as 2:1:1 ratio. The used soil texture was sandy clay with pH = 7.05 and EC= 0.52 dS m-1.Saline solutions were achieved using 1:1 weight ratio of NaCl: CaCl2 and controlled by a portable EC-meter.In this research, plant height, leaf number per plant, leaf area index, chlorophyll content index, dry weight of shoot and root, water content of shoot and root, sodium concentration of shoot and root as well as potassium concentration of shoot and root were measuered. Relative salinity tolerance at different growth stage of rapeseed for dry matter production also was assessed based on Van Genuchten and Hoffman method. Results and discussion The result generally showed that salt stress reduced plant height, leaf number, leaf area index, shoot and root dry weight, shoot and root water content and shoot and root potassium concentration. On the other hand, chlorophyll content index and shoot and root sodium concentrations were enhanced as affected by salinity. These changes were intensified in parallel with increased salinity levels. In the most cases, the negative effects of salt stress in all levels were more at 5 leavesstage, and delay in salinity impose decreased these negative effects. For example, salt stress in the highest level (i.e. 10 dS.m-1)imposed at 5 leaves, stem elongation and flowering stages were associated with 78.0%, 50.7% and 26.5% reductions in shoot dry weight and with 61.8%, 41.2% and 21.0% reductions in root dry weight, respectively. Salinity thresholds (50% reduction) for rapeseed cv. Talaye were determined by 1.2, 2.8 and 7.5 dS m-1 for 5 leaves, stem elongation and flowering stages, respectively. Therefore, it could be concluded that this plant was sensitive, mild tolerance and tolerance at 5 leaves, stem elongation and flowering stages, respectively. Conclusions The results of this experiment revealed that salt stress limited growth of shoot and root as well as changed potassium and sodium accumulation and distribution to the detriment of rapseed plants. It was also showed more sensitivity of rapeseed to salinity at early growth; which salt stress tolerance was enhanced with plant aging.
Iman Javadzarin; Babak Motesharezadeh; Mahdi Tafvizi
Abstract
Introduction Food security mentions to availability of sufficient and nutritious food by all population at all situations to ensure a healthy life, on the other hand, wheat is one of the crops that has an important role especially in developing countries for feeding people. Therefore pay attention to ...
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Introduction Food security mentions to availability of sufficient and nutritious food by all population at all situations to ensure a healthy life, on the other hand, wheat is one of the crops that has an important role especially in developing countries for feeding people. Therefore pay attention to the most minor issues with related to this crop strategy has a great importance role in ensuring food security and maintaining the independence of the country. Cadmium (Cd) is available in soils naturally and because of addition from different anthropogenic sources. Knowledge of destructive effects of cadmium on content of potassium in different wheat cultivars, as a strategic crop to provide food security of country has an important role. The aim of this research was study about nutritional status of Potassium (K) in different cultivars of wheat under cadmium stress. Material and Methods This research was conducted in a factorial experiment as a completely randomized design. The treatments consisted of three levels of Cd (0 (as control, Cd0), 40 (Cd40) and 80 (Cd80) mg Cd kg-1 soil) and fourteen different wheat cultivars (Bahar, Alvand, Niknezhad, Pishtaz, Azadi, Shahriyar, Pishgam, Marvdasht, Parsi, Sivand, Shiraz, Omid, Roshan, Navid), respectively. All pots before planting the seeds were incubated for three months in order to create balance between Cd and soil particles. At the end of period of incubation, we planted seeds of all cultivars. After 35 days of planting seeds, nearly at the stage of stem elongation in control treatment, shoot of all cultivars were harvested. Results and Discussion Highest and lowest absorbed K in Cd40 was recorded by Alvand (2.08%) and Bahar (0.81%) respectively. in Cd80 highest and lowest absorbed K was recorded by Shahriyar (1.1%) and Pishtaz (0.54%) respectively. Highest and lowest absorbed Cd in Cd40 was recorded by Niknezhad (7mg kg-1) and Parsi (2 mg kg-1). On the other hand, highest and lowest absorbed Cd in Cd80 was observed in Pishgam (20mg kg-1) and Navid (6 mg kg-1). Conclusion Generally, Niknezhad and Pishgam had highest reliability of cadmium uptake, Also the lowest reliability of cadmium uptake was observed about Parsi and Navid. On the other hand, Alvand and Shahriyar showed highest and Bahar and Pishtaz showed lowest content of K in shoot under Cd stress, respectively.
Volume 9, Issue 2 , July 2016, Pages 200-200
