| To investigate the effect of shading and planting density on physiological characteristics of flag leaf and yield of winter wheat,a field experiment under drip irrigation conditions was carried out in the year from 2015 to 2016,with five planting density,4 500 thousand plants·hm-2(M1),5 250 thousand plants·hm-2(M2),6 000 thousand plants·hm-2(M3),6 750 thousand plants·hm-2(M4),and 7 500 thousand plants·hm-2(M5) and 50 percent shading versus natural light circumstance. The responses of flag leaf SPAD,chlorophyll fluorescence parameters,photosynthetic characteristics and yield of winter wheat to different light and planting density were studied. The results showed that,with an increase of planting density,the SPAD value,Fv/Fm,ΦPSII,net photosynthetic rate(Pn),transpiration rate(Tr),stomatal conductance(Gs) and grain yield presented a trend of “first increasing and then decreasing”,but a reverse trend for intercellular CO2 concentration(Ci). Meanwhile,Fv/Fm,ΦPSII,Pn,Tr,and Gs under shading treatment were significantly lower than those under natural light treatment. The highest yield of shading and natural light were 5 250.26 kg·hm-2 under M2 and 9 190.07 kg·hm-2 under M3,respectively. Compared with the nature light treatment,the average yield and biomass of shading treatment in different planting density was decreased by 45.43% and 28.45% ,while harvest index was increased by 23.68%. Based on these results,there is an interaction effect between light and density,indicating that reducing the planting density properly under shading was beneficial to improve Fv/Fm,ΦPSII,Pn,Tr and Gs. 5 250 thousand plants·hm-2 was the appropriate planting density under 50% shading for good performance of the physiological indices and grain yield. |
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