| Rapeseed is one of the widely cultivated oil crops in world, is the most important source of vegetable protein and vegetable oil, at the same time, is also one of the important oil crops in our country. The yield of rapeseeds in China has beyond10million tons per year, accounting for40%of domestic oil production. However, as the main rapeseed production area in China, Yangtze River Basin has less precipitation which easily lead to drought and serious reduction of output, especially in the upper reaches of the Yangtze River in the spring in recent years. For this reason, the effects of water stress on physiological characters and agronomic traits of bud stage of rapeseed were studied. The aims were to reveal the drought resistance mechanism of rapeseed in bud stage, and to provide a theoretical basis for drought-resistant breeding. The changes of associated physiological indicators and agronomic traits of rapeseed were studied by drought resistance coefficients of each character using two different drought resistance rapeseed varieties during the bud stage (zhongshuang10with low drought resistance and94005with high drought resistance) with drought stress experiment in pot. And filtered out some indicators that apply to the local area, which can be used to identificate drought resistance in bud stage of rapeseed. The results showed that:1. The influence of drought stress on rape photosynthetic parameters showed that the drought resistance coefficients of net photosynthetic rate, stomata conductance, transpiration rate, intercellular CO2concentration tended to decrease with the extension of drought stress time, and the decrease range was positively related to the time of drought stress. The drought resistance coefficients of stomata limitation value and water use efficiency of low drought resistance variety presented upward to downward and downward trend, respectively, but both of that showed increase trend in high drought resistance variety.2. Under drought stress, the drought resistance coefficients of leaf relative water content, total water, free water (FW) and FW/BW tended to decrease, but the drought resistance coefficients of bound water(BW) tended to increase. The change range of these indicators was positively related to the time of drought stress.3. With the extension of drought stress time, relative value of the content of chlorophyll, Chla, Chlb and Chla/Chlb of rapeseed leaf showed downtrend, the reduction range was increasing, and it was negatively correlated with the drought resistant ability of material.4. Under drought stress, the drought resistance coefficients of RuBP carboxylase activity and nitrate reductase avtivity tended to be decrease with the prolonging of drought stress, and the decrease range of the high drought resistance variety was lower than that of the low drought resistance variety. The relative value of activity of the three kinds of antioxidant enzymes SOD, POD, CAT increased firstly and then decreased, and increase range was positively related to the drought resistant ability of rapeseed, but decrease range was contradictory to it.5. Under drought stress, relative value of malondialdehyde content, cell membrane permeability and proline of rape leaf tended to be increase with the extension of drought stress time, and the increase range of relative value of the first two indicators was negatively related to the drought resistant ability of rapeseed, but the increase range of relative value of proline was positively related to it. Relative value of soluble sugar content, soluble protein content and root activity increased firstly and then decreased, and the increase range of the high drought resistance variety was higher than that of the moisture sensitive materials.6. Relevant indicators of agronomic traits and yield per plant of rapeseed affected to different degrees of impact after rehydration. drought resistance coefficient of plant height, stem diameter, straw dry weight, leaf dry weight, total root volume, lateral root volume, total root dry weight, lateral root dry weight, lateral root number, primary branches number, effective pods number, per pod seeds number,1000seeds weight and seed yield per plant showed a downward trend, and the decrease range was negatively related to the drought resistant ability of rapeseed, but it was positively related to the time of drought stress.7. The correlation analysis showed that the yield was extremely significant positively correlated with the drought resistance coefficients of net photosynthetic rate, leaf relative water content, chlorophyll content, Chla, Chlb, Chla/Chlb, lateral root volume, total root dry weight and primary branches number, and it was significantly positively correlated with the drought resistance coefficients of total water, RuBP carboxylase activity, nitrate reductase avtivity, root activity, plant height, stem diameter, straw dry weight, leaf dry weight, total root volume, lateral root number and effective pods number, whereas it was significantly negatively correlated with the drought resistance coefficients of cell membrane permeability and MDA content.8. The principal component analysis divided the net photosynthetic rate, intercellular CO2concentration, stomata limitation value, relative water content, chlorophyll content, Chla, Chlb, Chla/Chlb, RuBP carboxylase, POD, SOD, CAT, cell membrane permeability, MDA, soluble sugar, nitrate reductase avtivity, root activity, height per plant, stem diameter, straw dry weight, leaf dry weight, total root volume, lateral root volume, total root dry weight, lateral root number, primary branches number, effective pods number and yield per plant into the first component and stomata conductance, transpiration rate, water use efficiency, total water, free water (FW), bound water(BW) and FW/BW, proline, soluble protein, lateral root dry weight, per pod seeds number and1000seeds weight were divided into the second component. |
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