| Rapeseed is one of the most important oil crops in our country, and the Yangtze River is the largest producing area. However, this region often has much rainfall in critical period of rapeseed, combined with high groundwater levels, long-term specific area floods, heavy clay soil, which made waterlogging happen frequently. Waterlogging not only caused the drop of production but also had a serious affect on its quality. In this study, rapeseed (B. napus cv. Qinyou7and B. napus cv. Suyou10) was used to study the effect of waterlogging stress of different waterlogging time on growth and physiological characteristics; Rapeseed (B. napus cv. Qinyou7and B. napus cv. Suyou4) was used to study the alleviated effects of IAA on growth, physiological characteristics and yield under waterlogging stress, which helped to find the waterlogging inner mechanism, as well as the mitigative effect and regulation mechanism of IAA toward waterlogging stress, thus providing theoretical basis and technical support for cultivation of rapeseed resistance. The results were as follows:1Waterlogging stress inhibited the growth of rapeseed, top dry weight decreased. Waterlogging made a large number of rape ROS accumulate, with prolonged waterlogging time, the O2-production rate and H2O2content increased, and showed a significant difference with the control. To adapt to and withstand the damage of waterlogging, leaves antioxidant enzyme SOD, POD, CAT activities increased first and then reduced, non-enzymatic antioxidant GSH and AsA contents increased. With the deepening of waterlogging stress, leaves antioxidant system was broken, membrane lipid peroxidase MDA content increased, while soluble protein content decreased. Physiological indexes had a certain recovery upon termination of waterlogging stress, and the recovery capability of rapeseed after lifting of waterlogged7days was stronger than that of others. The sensitive variety Qinyou7had a greater changes in physiological indexes than the Suyou10.2Waterlogging accelerated the degradation of chlorophyll, chlorophyll a, chlorophyll b and carotenoid contents of the two varieties of oilseed rape reduced, which accelerated leaf senescence, and were worse with waterlogging stress time developing. Waterlogging resulted in SS and SPS activities significantly higher than the control, thereby increased sucrose and soluble sugar contents, and enhance the osmotic adjustment ability of the blade to ease the damage caused by waterlogging. SPS activity increased which helped accelerate the conversion of starch to sucrose, and starch content in the leaves significantly reduced. Waterlogging forced to eliminate two varieties of oilseed rape indicators have different degrees of decline, stress the shorter the time to recover sooner. Physiological indexes had a certain recovery upon termination of waterlogging stress, and the recovery capability of rapeseed after lifting of waterlogged7days was stronger than that of others. The sensitive variety Qinyou7had a greater changes in carbon metabolism than Suyou10.3Waterlogging stress inhibited the growth of rapeseed. Biomass and chlorophyll content decreased; the balance of antioxidant system was broken, GSH, AsA content and SOD activity increased; MDA content increased; soluble sugar, sucrose sugar, sucrose synthase (SS) and sucrose phosphate synthase (SPS) all increased. After the application of IAA, the photosynthetic pigment contents in rape leaves increased, which helped enhance the photosynthetic ability, and promoted leaf growth; the decrease of SPS activity lead to reduce the synthesis of sucrose, then the sucrose content was decreased; the decrease of SS activity lead to reduce the decomposition of sucrose, then the soluble sugar was reduced, indicated that IAA could enhance the rape leaves sugar transport, accelerate the recovery of Carbon metabolism, reduce the damage caused by waterlogging, alleviate the yield, but the effect on the oxidation system of IAA was small. The effects of IAA on Qinyou7were better than on Suyou4. |
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