) Brassica napus L.( بررسي اثرات تنش خشكي بر شاخص هاي جوانه زني 6 رقم كلزا

Effects of Water Stress on Germination Indices in Six Rapeseed Cultivars (Brassica napus L.)

Environmental stresses, such as drought stress can play an important role in disturbing different stages of plant growth, development, and especially seed germination in arid and semiarid regions in bran. Rapeseed is one of the valuable oilseed crops. Breeding of cultivars which can tolerate drought stress at germination stage, can increase the number of seedlings, resulting in a higher yield of grainin rapeseed. In order to study the effects of water stress on germination indices in rapeseed cultivars, an experiment was conducted in factorial form, using a completely randomized design of three replications. In this experiment, six rapeseed cultivars (Cobra, Okapi, S.L.M 046, Reg.cob, Elite & Ebonite) were evaluated in three levels of drought treatment (distilled water,-9 and--15 bar). Results indicated high significant differences among cultivars, drought stress levels as well as their interactions. However, the interaction between germination rate and coefficeint of germination velocity was not significant. In all traits, a significant decrease was observed with increase in stress level. The decrease was different for different cultivars as well as different traits. The results indicated that velocity of germination was the most sensetive trait to drought stress. Traits in tolerant cultivars did not show a significant decline till upto -9 bar. The most tolerant cultivar was Reg.cob, however cultivar S.L.M046 exhibited the highest germination percentage at -9 bar. Considering all germination indices, Ebonite was the most susceptible cultivar. Also, results indicated that under a high risk of drought stress during germination ,cultivars with sensitivity to moisture stress should not be planted while attention must also be paid to the quality of seed produced.