Evaluation On Drought Tolerance Ability Of Rapeseed Resources

Rapeseed is one of the four major oil crops, and is also the most important oil crop in south of China. But severe yield losses often happen because of drought, so drought research about rapeseed is significant meaningful. Lots of comprehensive and deeply researches on drought tolerance ability have been conducted in corn, rice, soybeans, wheat, peanuts and so on, while those in rapeseed are just a little.There are three stages (the germination stage, the seedling stage and the flowering stage) analyzed in this experiment. The effect of drought on rapeseed is comprehensively studied from several aspects. Drought tolerance abilities of different stages are compared. The effect on all indexes is comprehensively evaluated by membership value. Then rapeseed resources with good performance to drought stress and indexes by which we can evaluate rapeseeds' drought tolerance ability are chosen out. These will give genetics and breeding of drought tolerance ability a big help.Experiment of germination on the tested 42 rapeseed varieties was conducted in laboratory. Drought treatments in seedling stage and flowering stage were done in greenhouse, and the relevant indexes were measured in laboratory after drought stress ends. The results of experiments indicated:1. The root length, shoot length and germination index of rapeseed under drought stress simulated by Polyethylene glycol (hereafter refers to as PEG) reduced significantly in germination stage, while the germination percentage rise first and decreased then with ascension of PEG density. Under drought stress stimulated by PEG, the rank correlation coefficients between root length and membership value and those between germination index and membership value reached significantly at 5% level and 1% level, respectively. So root length and germination index could be used for evaluating the drought tolerance ability of rapeseed in germination stage. Among the tested 42 rapeseed varieties, 23.8% varieties had strong drought tolerance ability, 14.3% weak and 61.9% in the middle. Line 88009, sanliuai and [(Tower×81008)×Tower]×81008 were the best and Qianyou No 4 was the worst on drought tolerance ability in germination stage.2. Relative water content, shoot fresh matter weight, shoot dry matter weight, superoxide dismutase (hereafter refers to as SOD), stem diameter and leaf area under stress of water deficiency all reduced significantly in seedling stage, water-holding ability of leaf rise significantly at 5% level, and root vitality, membrane permeability, chlorophyll, soluble sugar, soluble protein, MDA and proline all increased significantly at 1% level. Under drought stress, the rank correlation coefficients between shoot dry matter weight and average membership value, between chlorophyll and average membership value, between stem diameter and average membership value and between leaf area and average membership value all reached significant level among 14 indexes. Shoot dry matter weight, chlorophyll, stem diameter and leaf area could be used for evaluating the drought tolerance ability of rapeseed in seedling stage. Drought tolerance abilities of 07W288-3 and GH01×(pin90-1871×zhongshuangNO.1) were the strongest and those of 88009 and sanliuai were the weakest in seedling stage.3. The performance of plant height, height of the lowest branch on main stem, branch number on main stem, the number of pod per plant, 1000-grein weight, seed yield per plant and plot seed yield decreased significantly at 5% or 1% level under drought stress in flowering stage. Length of main inflorescence, silique number in main inflorescence and seed number per silique had no difference between different treatments. The rank correlation coefficients between height of the lowest branch on main stem and average membership value and those between the number of pod per plant and average membership value both reached significantly among 10 indexes in flowering stage. Height of the lowest branch on main stem and the number of pod per plant could be used for evaluating drought tolerance ability of rapeseed in flowering stage. Drought tolerance ability of TL17-10B was best, and those of ai×74-317 and kelina-2 were weak among the tested 13 rapeseed varieties in flowering stage.4. Integrated performance of drought tolerance ability of line GH01×(pin90-1871×zhongshuangNO.1) was best among the tested 11 rapeseed varieties in three stages. Drought tolerance ability was different in different stages. So, the effect on drought for rapeseeds in different stages were different..