The Research On Mechanisms Of Acid Rain Stress Of Rapeseed And Mitigative Effects Of Exogenous Ascorbate Acid On Acid Rain Damage

Oilseed rape is an important economic and the only winter oil crop in China, which is growing in the season of acid rain more seriously occurring, so the frequency of acid rain sufferred is relatively high.The influence of acid rain to yield and quality has been becoming the top piont, and the reseach focus in priority is also gradually turning from early stage to the mid-end stage. In order to probe into mechanisms of simulated acid rain (SAR) on florescence growth and yield and Exogenous Ascorbate Acid (ExAsA) mitigation effects on SAR damage in rape, damage of SAR of varying pH value and illivative effects of ExAsA on injure were investigated with a pot experiment in rape(B. napus cv. Qinyou 9). That will provide theoretical basis and technical support for ExAsA applied in the actual production of rape. The results were as follows:1 The results showed that weak acidity of SAR (pH>4.0) stimulated rape growth to some extent, leading to a little (not significant) increase in biomass, chlorophyll content, photo synthetic characteristics, and yield components compared with the control (pH 6.0). With the further increase of SAR acidity, biomass. chlorophyll content, photosynthetic rate, antioxidative enzyme activities, and non-enzyme antioxidant contents all decreased gradually, while malonyldialdehyde(MDA) content and relative conductivity increased significantly, As a result of strong acid rain, yield and yield components of oilseed rape decreased. However, different yield components showed different sensitivity to SAR. Number of pods per plant and number of seeds per pod decreased significantly, while grain weight was not significantly affected by SAR.2 The results showed that weak acidity of SAR (pH>4.0) leaded to a little (not significant) increase in content, accumulation and harvest index of mineral elements with the control (pH 6.0). With the further increase of SAR acidity, content, accumulation and harvest index of mineral elements all decreased gradually.The decrease amplitude of mineral elements accumulations in rapeseed is more than stem and pod at maturity stage, but the decrease amplitude of K, Na, Ca and Mg contents in rapeseed is equivalent with stem and pod, N and P contents in rapeseed is less than stem and pod at maturity stage. 3 The results showed that pH 3.0 SAR restrained the growth of oilseed rape, biomass,chlorophyll content, photosynthetic characteristics and yield components all decreased gradually, while malonyldialdehyde content increased significantly. With the application of a certain concentration of ExAsA before SAR treatment, it showed that ExAsA could increase AR resistance of rape effectively. Biomass, chlorophyll content, photosynthetic characteristics and non-enzyme antioxidant contents are more than SAR treatment, while malonyldialdehyde (MDA) content decreased significantly. These led to number of pods per plant, number of seeds per pod and yield increased significantly. With the increasing concentraions of ExAsA applied, its effects of increasing AR resistance on the damage of pH 3.0 AR first enhanced then declined.4.0 mmol·L-1 ExAsA had the best alleviative effects.