نوع مقاله : مقاله پژوهشی
نویسندگان
1 دانشجوی دکتری زراعت دانشگاه زابل و کارشناس ارشد آموزشی دانشگاه بیرجند
2 عضو هیئت علمی
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Background and objectives: Water shortage is one of the most important limiting factors for crop production, that affected on growth by changing physiological conditions. Millet is an important plant to investigate the mechanisms of stress tolerance in plants which are relatively resistant to drought. The assimilation and dry matter production is high in this plant in dry conditions and its reason is the mechanism of condensed carbon dioxide. Chavez (2003) stated that the first plant response to stress is stomatal closure and the impact of drought on photosynthesis can be evaluated based on stomatal conductance (4,25). Relative water content is as well as an indicator of plant water status in stress conditions (22). Resistant varieties show high relative water content (27). Low electrolyte leakage indicates membrane integrity (22). electrolyte Leak and membrane lipid peroxidation are indexes of drought resistance (3).
Materials and methods: This study was carried out in Research greenhouses of Birjand University in 2014. A factorial arrangement of treatments based on randomized complete block design (Due to the lack of uniformity of light) with four replications was used .The studied factors were drought stress with three levels including 100, 75 and 50 percent of plant water requirement (non-stress, moderate and severe stress respectively) and millet cultivar with three levels (including Bastan, promising lines KFM5 and KFM20). Relative water content, stomatal conductance, electrolyte leakage was measured in 30 and 45 day after stress and yield in maturity.
Results: The results showed that relative water content (RWC) and stomatal conductance decreased as intensity and duration of drought stress increased in all three varieties. Membrane lipid peroxidation, permeability of membranes and electrolyte leakage increased and membrane stability decreased as intensity and duration of drought increased in all three cultivars. Drought stress reduced number of grains per panicle, seed weight and seed yield compared to control. The highest and lowest seed yield was observed in control and severe stress respectively in all three cultivars. All three variety or cultivar had similar status in stomatal conductance and leaf relative water content in 30 day after stress. Although among the varieties, Bastan had the highest stomatal conductance and was less affected under moderate and severe stress (50 and 33 percent respectively compared to control) in 45 day after stress but Bastan had an appropriate realative water content (0.43 and 0.41 respectively) and had not significantly different with other lines. The malondialdehyde content (MDA) was low in Bastan compared to other cultivars and the membrane lipid peroxidation was less affected by increasing drought stress indicating that the variety is of more potential to protect membrane integrity. Bastan indicated greater performance than the other lines, this performance was more drastically decrease compared to KFM20 line under stress treatments.
Conclusion: Bastan is better than the other lines and is advisable to drought stress conditions. Realative water content and stamatal conductance are mechanisms of adaptation and resistance to drought stress and Malondialdehyde is an indix of the amount of damage to the cell membrane that used in order to identify the susceptible and resistant variety to drought stress.
کلیدواژهها [English]
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