Hamid Reza Bagheri; Mohammad Hosein Gharineh; Abdolmehdi Bakhshandeh; Javad Taei; Abdolmohammad Mehnatkesh; Bahram Andarzian
Abstract
Introduction Potato (Solanum tuberosum L.) is one of the most important crops that plays a major role in feeding the world. The growing demand for potato, as both a fresh and processed food, along with the increase in world population, mean that yield will have to be improved through some combination ...
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Introduction Potato (Solanum tuberosum L.) is one of the most important crops that plays a major role in feeding the world. The growing demand for potato, as both a fresh and processed food, along with the increase in world population, mean that yield will have to be improved through some combination of germplasm enhancement, better crop protection and more efficient and productive management of irrigation and fertilization (Haase et al., 2007). Researches have proved potato is sensitive to drought stress at all stages of growth, especially at tuber formation stage due to reduction of leaf area and photosynthesis (Fabeiro et al., 2001; Ayas, 2013; Shock et al., 2013). Abiotic stress factors, such as drought, have severe, adverse effects on potato growth and yield. In particular, a regular water supply is necessary to achieve a high quality yield (Ierna and Mauromicale, 2006). In comparison with other species, potato is very sensitive to water stress because of its shallow root system (Ayas, 2013). Water shortage during tuber differentiation can delay growth and reduce earliness, whereas during tuber growth and bulking can decrease tuber size and have a drastic effect on yield (Alva et al., 2012; Liu et al.; 2006; Ayas, 2013). For processing potato, a careful N and water management is required to ensure regular growth, high dry matter content and marketable tubers (Shock et al., 1998; Zhang et al., 2006; Shahnazari et al., 2007). So this research was done to evaluate effects of different levels of water deficit and nitrogen fertilizer on tuber yield, yield components and water use efficiency of potato crop in Chahar Mahal va Bakhtiari province, in Iran. Materials and methods In order to study the effects of different levels of water deficit and nitrogen fertilizer on tuber yield and other agronomic traits of potato crop (Boren variety), a split plot experiment based on randomized complete block design, conducted at Chahar Mahal va Bakhtiari Research Center of Agriculture and Natural Resources, in 2013. The levels of water deficit were S1, S2 and S3 (100, 75 and 50% of the water requirement of potato crop after emergence by the end of the growing season, respectively), as the main plots and nitrogen fertilizer treatments were N1, N2, N3 and N4 (100, 66, 33 percent of plant nitrogen requirement and without nitrogen consumption, respectively) as sub plots. Results and discussion In this experiment water deficit had decreasing effect on tubers dry matter percent but nitrogen changes had no distinct effect on this trait. By applying water deficit and decreased levels of nitrogen, the number of tubers per plant and the average tubers weight also fell. The greatest and the lowest number of tubers per plant were seen at S1 and S3 treatments (8.4 and 7.4 respectively). The maximum weight of tubers observed at full irrigation treatment (118 g) that had no significant difference with S2, but at treatment S3 (50% of the water requirement), tubers were produced lighter with an average weight of 86.6 grams. So it can be concluded, in this irrigation regime, the average weight of tubers is closer to weight of seed tuber class. Many studies have confirmed these findings (Fabeiro et al., 2001; Ayas and Korukcu, 2010; Ayas, 2013). The results showed that maximum tuber yield gained from S1 treatment (55.9 ton/ha) that had no significant difference with S2, but intensive drought stress (S3) produced minimum tuber yield (31.7 ton/ha). N1 and N2 treatments led to highest tuber yield but the lack of nitrogen (N4) caused the lowest tuber yield (38.7 ton/ha). Generally, in S2 and S3 drought stress levels, N2 produced maximum tuber yield. The reduction of tuber yield in S2 and S3 treatments within increment of nitrogen consumption (N1), caused the significant interaction between drought stress and nitrogen on tuber yield. Ierna and Mauromicale (2006) reported that water deficit stress as much as 50% of the water requirement, had increased stomatal resistance and caused the reduction of leaves photosynthesis, biomass, tuber growth and tuber yield. Demelash, 2013; Alva et al., 2012 and Ayas, 2013 studies also confirm the results of this Research. The second level of nitrogen (N2) in S3 treatments led to maximum, but S1N4 led to minimum water use efficiency (9.21 and 5.24 kg/m3 respectively). Liu et al. (2006) reported, by reducing the amount of irrigation volume, tuber yield decreases baut water use efficiency will increase.The stepwise regression analysis showed that the average tuber weight explains most changes of marketable tuber yield per plot. Conclusions Based on the results of the present study, since there is no statistical difference in tuber yield, between S1 and S2 irrigation regimes, it is recommended that for proper utilization of water resources and achieve economic yield, potato crop, produce with 6400 m3 water per hectare with irrigation at 7 days period. Results showed, at S2 irrigation regime, N2 Treatment (consumption of 270 kg Urea/ ha) had produced the highest yield, so S2N2 treatments is the best option for potato crop production.
Safieh Arab; Mehdi Baradaran Firouzabadi; Hamid Reza Asghari; Ahmad Gholami; Mehdi Rahimi
Abstract
Introduction
Drought stress is a major environmental constraint which inhibits the growth of plants and limits crop production. Nowadays, the application of antioxidants and plant growth regulators has discussed for decreasing the negative effect of different stresses. Ascorbic acid and sodium nitroprusside ...
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Introduction
Drought stress is a major environmental constraint which inhibits the growth of plants and limits crop production. Nowadays, the application of antioxidants and plant growth regulators has discussed for decreasing the negative effect of different stresses. Ascorbic acid and sodium nitroprusside have substance caused witch the resistance to biotic and abiotic stresses. Nitric oxide (NO) is a relatively stable free radical gas which may act as a key signaling molecule in plants and mediates various physiological, pathophysiological and developmental processes and recently it has been suggested that it is involved in plant response to environmental stress. It was found to play a crucial role in plant growth and development, starting from germination to flowering, ripening of fruit and senescence of organs. Ascorbate is a major metabolite in plants. It is an antioxidant and, in association with other components of the antioxidant system, protects plants against oxidative damage resulting from aerobic metabolism, photosynthesis and a range of pollutants. Recent approaches, using mutants and transgenic plants, are providing evidence for a key role for the ascorbate–glutathione cycle in protecting plants against oxidative stress.To examin the effect of ascorbic acid and sodium nitroprusside foliar application on seed yield, oil and some traits of safflower (Carthamus tinctorius), a field experiment design was carried out in split plot factorial based on randomized complete block in shahrood university in 2011.
Materials and methods
The experimental treatment included two levels of irrigation, including 8 days interval (well watered) and 16 days interval (water deficit stress) were in main plot, and foliar application of ascorbic acid in 3 levels (0, 10 and 20 mM) and sodium nitroprusside in 3 levels (0, 50 and 100 µM) were in sub plot. The experimental design was split plot factorial based on randomized complete block in 3 replication. Stress treatment applied after plants establishment completely. The foliar application of sodium nitroprusside and ascorbic acid were performed in 63 and 65 days after sowing respectively and then repeat after 1 week.
Results and discussion
Results showed that relative water content (RWC(, seed coat weight and number of seed per capitol decreased by water deficit stress. Stress increased seed coat to kernel ratio significantly. Number of capitol per plant increased (2.5capitol per plant on average) by ascorbic acid foliar application in 10mM concentration, but RWC decreased in this concentration of ascorbic acid. 1000 seed weight, seed yield (13.2%), oil yield (17.2%) and oil percentage (4.6%) increased significantly by sodium nitroprusside (100 µM) foliar application.
Conclusions
20 mM Ascorbic acid and 100 mM sodium nitroprusside concentration can introduced as the best treatment compound and it seems that the foliar application of sodium nitroprusside with appropriate concentration can be helpful in reducing stress intensity. which suggests that the protective effect of SNP is exerted through NO release. The protective effects of NO in drought stress may be due to its ability to counteract reactive oxygen species (ROS) and reduce the oxidative damages.
Khaled Eidizadeh; Farshad Ebrahimpour; Mohammad Ali Ebrahimi
Abstract
Introduction
Wheat (Triticum aestivum L.) is the most important cereal used as staple food in Iran. Despite higher yield wheat potential in Iran, average grain yield of wheat in Iran is much less than most of the wheat growing countries of the world (FAO., 2013). Nowadays increase of population and ...
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Introduction
Wheat (Triticum aestivum L.) is the most important cereal used as staple food in Iran. Despite higher yield wheat potential in Iran, average grain yield of wheat in Iran is much less than most of the wheat growing countries of the world (FAO., 2013). Nowadays increase of population and need for food and limitation of water for food and limitation of water resources have, increase yield in the volum e of water have a crucial inpact. Limitation of water resources in order to increasing tolerant Cultivars to severe conditions with high water use productivity. Earlier research showed that irrigation consistently increased wheat yield (Rahim et al., 2007). Wajid et al. (2002) reported that wheat yield by applying irrigation at all definable growth stages. Jamal et al. (1996) concluded that grain yield of different wheat cultivars were significantly reduced by water stress at all critical growth stages and greatest reduction was at anthesis stage. The present study was therefore undertaken to examine the yield response of wheat cultivars to different water irrigation in Ramin climate conditions.
Materials and methods
In order to a field study pertaining to the effect of irrigation intervals on yield and yield components of wheat cultivars was conducted during 2011-2012 growing season at Agronomic Research Field of Ramin Agriculture and Natural Resources University of Khouzestan. Khouzestan Province is south-western Iran, its covers and area 63633/6 km2 between lattitudes 29o-33o N and longitudes 47o 40`- 50o 33` E. The climate of the province is affected by weather systems from the Mediterranean and the Persian Gulf so that the weather is typically that of a semi-arid/temperate climate. The experiment was laid out using RCBD with split plot arrangement. Treatment were three cultivars wheat (Chamran, Aflak and Verinak) which were kept in main plot and five irrigation intervals I1 (irrigation after two leaf stage), I2 (irrigation after two leaf stage + tillering stage), I3 (irrigation after two leaf stage + Tillering stage + booting stage), I4 (irrigation after two leaf stage + Tillering stage + booting stage + anthesis stage) and I5 (irrigation after two leaf stage + Tillering stage + bootingstage + anthesisstage + milking stage) that were placed in sub plots. Experiment was replicated thrice having plot size of 1.5m × 6m with six rows per plot. Half does of nitrogen and full does of phosphorus was applied during seed bed preparation while remaining half does of nitrogen was applied with first irrigation post emergency. Data on plant height, number of fertile tillers, number of spikelets per spike, number of fertile tillers, number of spikelets per spike, number of grains per spike, 1000-grain weight, grain yield, straw yield and harvest index were recorded by using standard procedures. Data were analyzed statistically by using SAS analysis of variance technique and treatment means were compared by using least significant difference (LSD( test at 5% probability level (Steel and Torrie., 1984).
Results and discussion
Chamran cultivar recorded highest grain yield (4822.5 kg ha-1), number of tillers (335m-2) and harvest index (45/33) which were significantly higher than the other two cultivars. Highest grain yield in Chamran cultivar might be due to the increase in number of tillers m-2 (Sharif et al., 1999) and with higher 1000-grain weight (Wajid et al., 2002). Howover minimum plant height (73cm) and number of spikelets spike-1 (17) recorded at Chamran cultivar. Wheat crop supplied with five irrigations at irrigation after two leaf + Tillering + booting + anthesis + milking recorded the highest grain yield (5670.4 kg ha-1) which was significantly higher than all the other intervals irrigation. Interaction between cultivars and irrigation levels was significant for grain yield. At I5, cultivars Chamran and Aflak increased yields (52.68% and 57.07%) over I1 which were statistically at par with each other.
Conclusions
Finally, the results revealed that soil moisture stress causes low grain yield, by inducing low 1000-grain weight, number of tillers m-2. Thus, wheat, a staple food, appears to be suffering yield losses due to deficiency of irrigation water at any critical stage. Therefore, wheat grower must be careful about water stress on critical stage which can cause tremendous yield losses. It is also clear that there is a considerable span to exploit the yield potential of wheat cultivars in irrigation area of Iran.
Mohammad Mirzakhani
Abstract
Introduction
Overall, more than three-quarters of energy and protein required for half of mankind comes from cereals (Emam, 2005). The most sensitive stage to drought stress in cereals between heading to flowering and cultivars, before flowering to increase a high dry matter production and assimilate ...
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Introduction
Overall, more than three-quarters of energy and protein required for half of mankind comes from cereals (Emam, 2005). The most sensitive stage to drought stress in cereals between heading to flowering and cultivars, before flowering to increase a high dry matter production and assimilate in stem, the cultivars are drought tolerant (Niknam, 2005). Osmotic adjustment for drought tolerance as a trait known (Richard, 2004). So osmotic adjustment in leaf and pollen can be used as an indicator in breeding for increased tolerance to drought stress used (Delperee et al., 2003 ; Maghsoudi Moud and Yamagishi, 2005). Drought stress has significant effects on traits related to reproductive growth stage of crops including grain yield, yield components, harvest index and day to physiological maturity (Gol-Abadi et al., 2008). Also drought stress from flowering to grain handling, accelerated aging and reduce grain filling period (Royo et al., 2000). The aim of this study was to evaluate the chlorophyll concentration and wheat biological yield under drought stress and different levels of zeolite.
Materials and methods
This study was carried out in field of Arak Payam Noor University in 2009. A split-plot arrangement of treatment in a randomized complete block design with three replications was used. Water stress (I0= Control irrigation, I1= Irrigation about 85% plant water requirement, I2= Irrigation about 70% of plant water requirement, I3= Irrigation about 55% of plant water requirement, were assigned in the main plots and different levels of zeolite application (Z0= without zeolite application, Z1= 3 ton ha-1, Z2= 6 ton ha-1, Z3= 9 ton ha-1) in sub plots. Each sub plot consisted of 4 rows, 5 m long with 50 cm between rows space and 5 cm between plants on the rows. In this study characteristics such as: Harvest index of spike, Biological yield of plant, Special leaf area, Spike density, b Concentration of b chlorophyll, Electrical conductivity of methanol treatment and Electrical conductivity of aseton treatment were assessed.
Results and Discussion
Results indicated that un-stress irrigation (control irrigation) with average electrical conductivity of methanol treatment (2835 µs cm-1) and zeolite application (9 ton ha-1) with average (2829 µs cm-1) were significantly superior to the other treatment. With increasing water stress, due to limitations in the absorption of water and nutrients to the plant caused reduced the growth of the plant. So finding ways that they can reduce the limitations caused by water stress, will be very convenient. In this experiment, the traits chlorophyll b, the electrical conductivity of methanol treatment (12 hours), electrical conductivity treatment with acetone (3 hours), specific leaf area, spike density, grain yield, biological yield and harvest index were affected by water stress. Also, Zeolite consumption as well as improved characteristics of electrical conductivity treatment of methanol (12 hours), specific leaf area, yield and biological yield of the plant.9 tons per hectare zeolite increased grain yield relative to the treatment of no zeolite was 20.18 percent. So we can say that the use of Zeolite to reduce the adverse effects of water stress on the plant.
Malek Azhdar Afshari; Farid Shekari; Kamran Afsahi; Roghieh Azimkhani
Abstract
To study the effect of foliar application of salicylic acid on yield and yield components of cowpea (Vigna unguiculata.L) parastu varieties under water deficit stress, the experimental design was split block (strip plot) experiment was conducted in 2008 in Zanjan University Research Farm. Treatments ...
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To study the effect of foliar application of salicylic acid on yield and yield components of cowpea (Vigna unguiculata.L) parastu varieties under water deficit stress, the experimental design was split block (strip plot) experiment was conducted in 2008 in Zanjan University Research Farm. Treatments included a water deficit as the first factor in three levels (control and regular watering, drought stress during flowering and 50% flowering and stress at the onset of pod formation, 50% pod) and Foliar application of salicylic acid, the second factor at five levels, including levels of 150, 300, 450 and 600 µM, respectively. Results showed that water deficit stress reduces yield compared to non-stress conditions in plants. Use of salicylic acid at 150 and 300 µM increased performance and reduced plant dry weight loss was stress. However, the opposite effect was observed at higher levels. Stress and non-stress treatments at 150 Mµ level pod formation increased harvest index. Water deficit in both flowering and plant dry weight was reduced pod formation. Low levels of stress and stress at flowering stage, 150 and 300 µM salicylic acid increased the dry weight of the plant. In general, it seems that salicylic acid at 150 and 300 µM as a protector can reduce the damage caused by water deficit in the cowpea plant.
Somayeh Nezami; Seyed Hosein Nemati; Hosein Aruee; Abdolreza Bagheri
Abstract
Introduction
Water is the most important factor for production of agricultural crops. Adequate water supply is necessary to obtaining maximum productivity of horticultural crops (Jones and Tardieu, 1998). According to Global Circulation Models precipitation scarcity might become worse in the near future ...
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Introduction
Water is the most important factor for production of agricultural crops. Adequate water supply is necessary to obtaining maximum productivity of horticultural crops (Jones and Tardieu, 1998). According to Global Circulation Models precipitation scarcity might become worse in the near future over the world. Severe drought periods might decline yield and quality of crops (Delfine et al., 2005). Unfortunately, water deficiency is increasingly becoming a serious problem in agriculture in Iran whereas the national average annual precipitation is less than 249 mm (Baghalian et al., 2011). Therefore in our country, production of agricultural crops always accost many problems because of water scarcity (Hassani et al., 2009). Thus it is important to understand to what extent water stress impairs plant growth and yield in alternative crops (Delfine et al., 2005).
Plants respond quickly to water stress in order to prevent the photosynthesis. Stomata closure in response to water deficit stress primarily results in decline in the rate of photosynthesis.
Photosynthesis limitation causes growth and yield decreasing (Alaei et al, 2013).
Shortage of water in arid and semiarid regions of the world can reduce growth and production of medicinal and aromatic plants, especially Mentha species. Frequent irrigation is necessary during mint plant growth, as mentha species need moist soil conditions in the 100 centimeters of soil where rhizomes are located. This layer of soil has the greatest root density and always must be kept moist (Mitchell and Yang, 1998). But excessive irrigation may decrease mints yield because of limitation of oxygen for plant roots, promoting root diseases, leaching of plant nutrients especially nitrogen and losing more leaves than normal (Mitchell, 1997). According to the results of statistical analysis of Alaei et al (2013), irrigation treatments had significant effects on growth and yield of Dracocephalum moldavica. In this experiment as the amount of irrigation water declined, the plant height, leaf area, leaf number, fresh and dry weight of root and shoot, root length, branch number, and yield per pot decreased. This was while root to shoot ratio, and days to first bloom, first flower and first fruit increased. Study on effects of water deficit stress on Balm (Mellisa officinalis L.) showed that the effect of this stress on shoot yield, leaf and stem yield, stem height was significant at 1% probability level. This was while the number of lateral stem was not significant (Ardakani, 2007). Petropoulos et al., (2007) showed that parsley growth (foliage weight, root weight and leaf number) was significantly reduced by water stress, even at 30-45% water deficit levels. Water deficit has been revealed as effective on growth parameters, yield and biomass. Water stress has decreased plant height, number of secondary branches, dry and fresh weight of shoot, root mass, dry and fresh weight of root and length root (Babaee, 2010). The study on the effect of different levels of water stress on moldavian balm demonstrated that there was not a significant effect of water stress on leaf area and number of leaves, but it was significant on fresh and dry herb (Gholizadeh, 2007).
Material and methods
In order to evaluate response of three Mentha species to water deficit stress, an experiment was carried out in a factorial-randomized design with five replications in controlled conditions and Mentha longifolia (wildmint), Mentha spicata (spearmint) and Mentha piperita (peppermint) species were subjected to four soil moisture regimes (100 (control), 80, 60, 40 of field capacity (FC)) and studied characteristics were included percent of survival, number of branches and stolon, number of leaves, length of branches and relative chlorophyll content were measured every ten days Besides all characteristics that were mentioned before, total dry weights were determined after both harvest.
Results and discussion
The results showed that soil moisture treatments had significant effect on survival of three mint species. Trends of branch’s number and length and number of leaves indicate that adequate soil water could achieved better growth in wildmint than two other species in control and 80% of FC, but number and length of stolon in peppermint were significantly excel as compare as two other species in all treatments. However reduction of soil moisture to the 60% of FC severely decreased number and length of branches, number of leaves and number and length of stolon in all species, but spearmint had better growth in this treatment. There were low differences among SPAD of these species in control treatment, though spearmint’s SPAD was higher than two other species in 60 percent of FC in whole growing season. Total dry weight of spearmint in 80% of FC was 31 percent lower than control treatment, while in peppermint and wildmint 40 and 61 percent reduction were observed, respectively. In 60% of FC leaf dry weight of peppermint and wildmint were 92 and 96 percent lower than control, but in spearmint the mentioned parameter in this treatment was 66 percent lower than control treatment.
Conclusion
Water deficit stress reduced growth characteristics of all three species, but growth of spearmint in 20 and 40% deficiency of soil water (as compare with control) was better than two other species. Although spearmint was more tolerant than two other species to water deficit stress, but more study must be achieved for better understanding of mint responses to water deficit stress.
Our results regarding the effect of water stress on dry weight were in coincidence with those reported by Simon et al., (1992) in basil; Ardakani (2007) in balm; Johnson (1995) in Spanish thyme and Safikhani (2007) in moldavian balm who confirmed that water deficit could affect yield by decreasing growth.
Ahmad Nezami; Shahram Rezvan Beidokhti; Sara Sanjani
Abstract
Introduction
Saffron (Crosus sativus L.) is a perennial and herbs plant, belongs to the Iridaceae family and reproduces via corms (Behnia, 1991). Saffron is native to the mediterranean floristic region, extending eastward into the Iran-Turanian region and lie within the longitude 10°W to 80°E ...
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Introduction
Saffron (Crosus sativus L.) is a perennial and herbs plant, belongs to the Iridaceae family and reproduces via corms (Behnia, 1991). Saffron is native to the mediterranean floristic region, extending eastward into the Iran-Turanian region and lie within the longitude 10°W to 80°E and latitude 30°N to 50°N. These areas are characterized by cool to cold winters and warm summers with very little rainfall. Iran is the most important saffron producers and exporters in the world market (Kafi et al, 2002). Saffron is cultivated in northeast of Iran which are characterized by cold winters and warm summers. The main part of the Saffron’s growing season is exposed to cold and winter frost, and low temperatures limits its production. Therefore, it is likely that a cold weather or frost during winter waste the saffron, so that it is necessary to identify cold tolerant ecotypes of saffron and determine the range of low temperatures that saffron may withst and without any considerable damage.
The objective of this experiment was to evaluate and compare the response of saffron ecotypes to freezing temperatures under controlled conditions.
Materials and methods
In order to evaluate the effect of freezing stress on three saffron ecotypes (Ghaen, Kashmar and Torbat heydarieh) a factorial experiment based on completely randomized block design with three replications was carried out under the controlled conditions in the Faculty of Agriculture, Ferdowsi University of Mashhad, Iran. Three native saffron ecotypes (Ghaen, Kashmar, and Torbate Heydarieh) were subjected to six different temperatures (0, -4, -8, -12, -16 and -20 oC). Two saffron’s corms were sown in plastic pots with 25 cm diameter and 23 cm hight to a depth of 8 cm. The pots were primarily filled with an equivalent ratio of sand, compost and soil. For cold acclimation, plants were grown in natural conditions and after that, transferred to the thermogradiant freezer with the six freezing temperatures. The seedlings were sprayed with the Ice Nucleation Active Bacteria (INAB) to help the formation of ice nuclei in the seedlings. Plants were kept at the nominated freezing temperature for 1 h. Following the freezing treatments, all samples were kept at 5±2°C for 24 h to decrease the rate of thawing. Leaf and corm cell membrane integrity were measured via electrolyte leakage percentage (%EL) index and lethal temperature 50 according to %EL (LT50el) was determined. Three weeks after plants growth in cold frame, survival percentage of each saffron ecotype was measured by counting the plants and determining their proportional with the number of plants before freezing.
Results and discussion
Results showed that %EL was significantly affected by experimental treatments. The highest and the lowest electrolyte leakage values were observed in the Kashmar and Torbat heydarieh ecotypes at -20 ºC, respectively. Rezvan beydokhti et al (2011) showed that there were significant different amoung Persian shallot ecotypes for electrolyte leakage percentage. The EL increased markedly as temperatures decreased and the peak of EL% obtained at 20 ºC. The EL% of Organs (Leaf and corm) in response to the freezing temperature was different. It seems that the cell memberace of saffron’ leaf is more sensitive than corms to freezing stress. Interaction between temperature and organs showed that the highest and lowest %EL was observed in the leaf and corm at -20ºC and 0ºC, respectively. The temperature resulting in 50% leakage has been known as LT50el i.e. freezing temperature that causes 50% mortality (Cardona et al., 1997). There was significant difference (P ≤0.01) among saffron ecotypes in terms of LT50el. The lowest and highest LT50el was observed in Torbat heydarieh, Ghaen and Kashmar, respectively. Shashikumar and Nus (1993) reported that Bermuda grass cultivars were different in LT50el. The more tolerance cultivars showed the lower LT50el. There were significant correlation (r=0.82**) between %EL and corm’s LT50el where by reducing %EL, ecotypes’ LT50el decreased.
There were significant differences (P≤0.01) among freezing temperatures for the survival percentage. Survival percentage of all ecotypes did not affected up to -12°C, however, it is reduced by decreasing temperature, and the lowest survival percentage was obtained in -20°C.
Survival percentage varied among saffron ecotypes. Torbat heydarieh ecotype showed the highest (96.1%) and Kashmar ecotype had the lowest (94.4%) survived seedling.
The results of correlation analysis demonstrated a negative, significant correlation between leaf and crom’s EL% and survival percentage (r = -0.98**). Such results showed in other studies for different plants (Rife and Zeinali, 2003).
Conclusions
The results of this experiment showed significant effect of freezing temperatures on EL% where EL% increased as temperature decreased. Amoung ecotypes Torbat heydarieh ecotype showed the lowest %EL, lowest LT50el and the most tolerant to the freezing stress. The saffron’s corm was more tolerant than leaf in freezing temperatures. Therefore, the EL method could be used as a fast and efficient method in evaluating the cold tolerance of saffron ecotypes.
Acknowledgements
This study has been supported by the grant approval of the Ferdowsi University of Mashhad, Iran and the authors would like to appreciate it.
Hamid Reza Khazaei; Ahmad Nezami; Bijan Saadatian; Omid Armand Pishe; Rihaneh Pordel
Abstract
Introduction
Seed emergence and seedling growth can be major factor limiting the establishment of plants under saline conditions (Patade et al., 2009; Jafar et al., 2011). Salinity can affect germination and seedling growth either by creating an osmotic pressure that prevents water uptake or by toxic ...
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Introduction
Seed emergence and seedling growth can be major factor limiting the establishment of plants under saline conditions (Patade et al., 2009; Jafar et al., 2011). Salinity can affect germination and seedling growth either by creating an osmotic pressure that prevents water uptake or by toxic effects of sodium and chloride ions (Jafar et al., 2011). Seed priming is a technique in which seeds are partially hydrated until the germination process begins, prior to radicle emergence (Patade et al., 2009; Rehman et al., 2011). Priming allows the metabolic processes necessary for germination to occur without actual germination. In addition, primed seeds usually exhibit an increased germination rate, greater germination uniformity, greater total germination percentage (Patade et al., 2009; Rehman et al., 2011; Jafar et al., 2011). Gel chamber technique is new method for root study in early stage (Bengough et al., 2004).
Materials and Methods
Two experiments were carried out evaluate the effect of seed priming to improve salinity stress on seedling growth of barely. First experiment was conducted as factorial based on completely randomized design with four replications. Treatments were included two cultivars of barely (Yusef and Maquie) and four levels of nitrogen priming (2, 4, 6 and 8 gN.L-1 of urea) and hydropriming with un-prim seeds.
Before priming, seeds staid on hypochlorite 2.5% for 5 min then washed with distilled water three times. Disinfected seeds were in the room temperature for 24 hours. In following, barely seeds were soaked for 6 hours with hydropriming and nitrogen priming levels. Twenty seeds were put in glass Petri dishes adding 10 ml distilled water. Petri dishes placed into germinator with 20ºC and dark condition. Finally, germination percentage, time to get 50% germination and seedling vigor index was measured.
In second experiment, hydropriming, priming with 0.002 (w/v) N (Best treatments of one experiment) with un-prim seeds were used. Salinity stress levels of 0, 200 and 300 mM induced by Sodium chloride used in preparation stages of phytogel and each cultivar investigated in separated factorial experiment based on a completely randomized design in gel chamber condition.
Chambers were constructed from two plates (generally with one black polyviniychloride, one transparent Perspex), each measuring 215×300×3 mm. strips of Perspex (3mm thick) were used as spacers around each plate, giving a plate separation of 6 mm, leaving three gaps, each approximately 25 mm long, along the top surface, to allow gas exchange with surrounding atmosphere and unimpeded shoot extension. Each Perspex plate was covered with a layer of phytogel approximately 1.5 mm deep, sandwiching an air gap of approximated 2.5 mm width between the plates in which root growth occurred (Bengough et al., 2004). Roots grown within the air gap to avoid problems of poor aeration.
After priming, seeds placed to germinator for 24 hour. Uniform seedling barley were placed to gel chambers and fixed into phytogel. Afterward, gel chambers were placed to germinator with 12/12 light and dark at 12ºC. After 21 days, plumule length, fresh and dry weight of plumule, green area, radicle length and volume, fresh and dry weight of radicle was measured
Results and Discussion
Results of first experiment showed that seed priming led to significant increment of radicle length, plumule length and seedling vigor index and on the contrary, reduced time to get 50% germination (T50). By increasing the nitrogen concentration of two percent, in most of traits didn’t show statistical difference and even had negative effect on measured traits.
Results of second experiment were indicated a positive significant effect of utilized two priming treatments on plumule length, fresh and dry weight of plumule, green area, radicle length and volume, fresh and dry weight of radicle at different levels of salinity stress in Maquie cv. In Yusef cv., seed priming was improved all studied traits except radicle volume. Both barely cultivars didn’t show similar reaction to seed priming. In Yusef cv. by increasing salinity to 300 mM, hydropriming and priming with 0.002 (w/v) N led to significant enhancement in most of traits, than control. While positive and considerable influence of priming on Maquie cv. was to salinity level of 200 mM, 11, 8 and 19 percent, respectively.
Conclusions
In addition, priming with nitrogen were enhanced two barley germination characters and 0.002 w/v was best treatment. In salinity stress, priming influenced growth of barley seedling.
