| Based on researches of photosynthetic performance, some key physiological indices and the genetic physiological basis in different levels were studied with materials of mass genotypes for maize from 2001 to 2002, in 3 eco-regions where located in Beijing, Xianghe in Hebei province, Guyuan in Hebei province. The main results showed as follows:1.The difference in photosynthetic efficiency among genotypes of maize did existFrom different layers of the form of yield, the difference in photosynthetic efficiency was found and the correspond mechanism were studied. The results showed that high photosynthetic efficiency results from high accumulation and distribution of dry matter, NAD, and high value of Fv/Fm. This is the inner physiological basis of high yield.2. Increasing biomass accumulation after silking and grain weight-leaf area ratio were important approaches to increase the grain yield64 maize materials were used in order to identify the contribution of dry matter accumulation and distribution to the grain yield at different growth period. The results showed that harvest biomass was linearly positive interrelated with maize grain yield, while the correlation coefficients were 0.9094** and 0.9145** in Xianghe and Beijing, respectively. The correlation between biomass before silking and grain yield could be described as a general quadratic equation. But this curve was approximately a beeline since it was little declined from the peak. This was something different from those of wheat and rice. Correspondingly, the correlation degree were lower only to 0.6000** and 0.5670**. The biomass after silking was significantly positive correlated with the grain yield and the correlation coefficients were 0.9155** and 0.9181** respectively. Though economic coefficient was significantly interrelated with grain yield, the correlation coefficients were merely 0.4239** and 0.6168**. The correlation between biomass before silking and economic coefficient was not significant and was significantly negative in Xianghe and Beijing. Though analyzing by the relation of source-sink it showed that leafnumber-area ratio was not significantly correlated with grain yield whereas that of leaf weight-area was significantly correlated with grain yield (r=0.6153** and 0.6242** separately). The trend was unanimous at the two locations. Consequently, we considered the biomass after silking and leaf weight-area ratio as key photosynthetic physiological indices to influence the grain yield. At the same time, it could be concluded that increasing the value of leaf weight-area ratio and enhancing the biomass after silking were important approaches to high yield.3. Enhancing the photosynthetic efficiency of later growth period was the key to enhance the biomass accumulation after silkingFrom the results of what affected the biomass accumulation after silking at different levels we concluded that, leaf area for one plant at silking stage biomass after silking was significantly positive correlation with biomass after silking both in Xianghe and Beijing locations (r=0.6436** and 0.6302** separately). The later was significantly negative correlation with the decline of green leaf area.Large difference of leaf photosynthetic rate (Pn) was found among different genotypes of maize. The results showed that the variance of Pn at doughy stage among genotypes was higher than that of at silking stage. In addition, the correlation between Pn at doughy stage and biomass after silking was much consanguineous than that of Pn at silking stage. These results indicated that maintaining high values of photosynthetic potential and Pn at later growth period could remarkably enhance the biomass after silking. In sum, breeding hybrids with longer green persistent duration, at the same time, prolonging period with high photosynthetic capacity through cultivation were the key to increase the biomass after silking and enhance the grain yield.4.Leaf chlorophyll fluorescence characteristics among different genotypes of maizeThe main fluorescence par... |
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