| In order to elucidate the physiological mechanism and inheritance of leaf stay-green traits, a full diallel was designed by crossing three stay-green inbred lines and three non stay-green inbred lines. The studies were conducted combining the field experiment and analysis in the lab by using physiological analysis, biochemical methods, and their integrations. Leaf photosynthesis and photochemical mechanism, enzymology characten'stic related to carbon assimilation, physiological characteristic of nitrogen metabolic activity, some cell protective enzymes to eliminate active oxygen, and regulation of endogenous hormone were researched, the genetic effect of leaf green trait and physiological heterosis were estimated. The main results were as follows:1. The changes of relative green leaf area after silking were fit the equation: y=aeb-cx/(1+eb-cx) There were significant differences in stay green degree, leaf reducing velocity, and the time of beginning to senescence between maize genotypes. According to Hierarchical's classify method, based on the stay green degree in maturity and leaf reducing velocity, all the maize genotypes were classified into two analogs: one was stay green type(SG), its stay green degree was higher than 60 percent, its reducing velocity was in the range of 0.516 to 0.868%-d-1; another was non stay green type(NSG), its average stay green degree was 20.56 percent, the range of reducing velocity was 0.798 to 2.371%-d-1. Correlation analysis proved that there was positive correlation between stay green degree and yield per plant and leaf area duration.Maize hybrid with stay green trait accumulated more dry matter after silking, had lower translocation rate and economic index; Its soluble sugar content in plant was higher than that of non stay green types; and its root number added, root vigor increased; the time of its leafs beginning to senescence was delayed, and leaf reducing velocity was very low, which resulted in higher green leaf area and longer leaf area duration; the ratio of sink capacity to source supplying ability was smaller, and bald length and abortive kernel number decreased, which resulted in higher sink capacity realize;!; its kernel filling duration was longer, ADPGPPase activity, UDPGPPase activity, SSS activity and GBSS activity in kernels were higher than that of non stay-green type after filling stage, and this was very helpful to increase kernel weight.2. Maize hybrid with stay green trait had higher photosynthetic pigment and chlorophyll-protein binding degree. Its photosynthetic rate, stomatal conductance, quantum efficiency and carbonxylation efficiency had not significant difference between the stay greemand non stay green in silking stage, but after filling stage, stay .green type was superior to non stay green in all the photosynthetic traits. PEPase activity, RuBPase activity, SPS activity and SS activity in ear leaf of stay green were higher than that of non stay green.Changes of fluorescence parameters indicated that there were steady Fm and Fv within silking stage and waxy maturity stage, but after waxy maturity stage, Fm, Fv, Fv/Fm, and Fv/Fo began to decrease, and PS ,qP, ETR decreased too, but NPQ increased. The stay green type had higher PS potential activity and Maximum photochemical efficiency.3. There was higher nitrogen content in leaf, stem and sheath of stay green type, and its nitrogen accumulation before silking, nitrogen accumulation after silking, total nitrogen accumulation were also higher, but its nitrogen translocation, translocation rate and nitrogen harvest index were significantly lower than that of non stay green type. Some key enzymes to physiological characten'stic of nitrogen metabolic activity such as nitrate reductase. activity(NR), glutamate synthetase(GOGAT), glutamine synthetase(GS) in leaf of stay green type were significantly higher than that of non stay green type, and their activity were positive related to stay green degree.4. SOD activity, POD activity, and CAT activity in leaf of s... |
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