Photosynthetic Physiological Mechanisms Of The Grain Yield Of Maize (Zea Mays L.) By Altering Plant-type

The experiment takes two hybrids which DengHai3719 (DH3719) is erectophile type that gained China's record of high-yielding of maize in 2005 and NongDa108 (ND108) is semi-erectophile type whiah was the main hybrid in our country during 1990s for material. Set up two plant density as 15,000 plants/ ha and 67,500 plants / ha. Comparativly studied the impaction that plant-type differences to maize production and it's the physiological mechanisms by altering plant type. The principal results were as follows:1 Effect of altering plant-type on grain yield and characters of matter accumulation in maizeIn lower density, grain yield of altering to erectophile-type (AE) significant decreased , the yield decrease rate of DH3719 and ND108 were 14.71%and 12.15%, while altering to plantophile-type(AP) yiled decrease rate being 2.22% of DH3719 and yiled increase rate being 2.23% of ND108. In higher density, the reduction in yield rate of DH3719 was 10.37% (P<0.05)and the increase in yield of ND108 was 19.30% by AE, and the reduction in yield rate of DH3719 and ND108 were 18.78%(P<0.05)and 4.38%. In lower density, the 1000-kernel weight of two maize variety were no significant difference between AE and CK, while the 1000-kernel weight were significant decreased by AP. And in higher density, the 1000-kernel weight was significant decreased on DH3719 as well as that was significant increased on ND108 (P<0.01) by AE, while the 1000-kernel weight were significant decreased on the two maize variety by AP. The economic index (EI) was significant influenced by altering plant-type. In lower density, the apperence of EI were CK>AP>AE on DH3719 and AE > CK>AP on ND108,while the apperence of EI were CK>AE>AP on DH3719 and AE > CK>AP on ND108 in higher density, so we could seen the yiled difference on DH3719 and ND108 were determined by EI in higher density.2 Effect of altering plant-type on canopy configuration in maizeThe extinction coefficient (k) were no significant difference between AE and CK on DH3719 and ND108 in lower density, while the apperence of k on DH3719 was no significant than ND108 (P<0.05) in higher density. And the k was significant increased by AP on the two hybrids in the two plant density. The treament of AE could delay leaf-senescence and the reduction of leaf area index (LAI) is declined slowly than CK, and the treament of AP could accelerate leaf-senescence and the reduction of LAI is declined quickly than CK. Compare the two hybrids and the two treatment , the varity of leaf-senescence and LAI of ND108 is significant than DH3719, and that in higher density is significant than the lower density.3 Effect of altering plant-type on chlorophyll content in maize different levels of leavesIn lower density, the chlorophyll content in upper leaves of DH3719 and ND108 were decreased by 4.49% and 6.69% by AE, that were siginificant decreased by 20.38% and 12.18% by AP (P<0.05) , as well. And the chlorophyll content in middle leaves of DH3719 and ND108 were decreased by 3.90% and 0.36% by AE, as well as that were decreased by 3.67% and 0.68% by AP. As well as the chlorophyll content in lower leaves of DH3719 and ND108 were significant increased by AE and AP. In higher density, the chlorophyll content in upper leaves was decreased by 7.16% and by AE of DH3719, while that was increased 1.98% of ND108, which were siginificant decreased by 13.57% (P<0.05) and 1.27% by AP, as well. And the chlorophyll content in middle leaves of DH3719 and ND108 were increased by 5.32% and 6.85% by AE, as well as that were increased by 5.36% and 3.13% in the lower leaves. Compared to AE, the treament of AP decreased the chlorophyll content in middle leaves and lower leaves were 9.09% and 6.07%, 6.46% and 15.67% of DH3719 and ND108.4. Effect of altering plant-type on photosynthetic in maize different levels of leavesIn lower density, the net photosynthetic rate (Pn) were decreased by AE on the upper leaves and middle leaves of DH3719 and ND108, and the Pn were raise by AE on the lower leaves .While the Pn on the three levels of leaves of DH3719 and ND108 were no significant difference between AP and CK. In higher density, the Pn on the upper leaves of DH3719 and ND108 were decreased by AE at earlier growing stage , but raise at later growing stage, while the treament of AP of DH3719 and ND108 the Pn on upper leaves have advantage at earlier growing stage ,but decreased rapidly at later growing stage. The Pn on middle leaves of DH3719 was no significant difference between AE and CK, while that of ND108 was significant increased during the whole growing stage and has obvious advantage after 30d since anthesis. The Pn on middle leaves of DH3719 and ND108 were significant decreased by AP compared to CK (P<0.05). The Pn were significant increased by AE on lower leaves of DH3719 and ND108, which were significant decreased by AP, as well, especially ta later growing stage.5. Effect of altering plant-type on the diurnal variations of photosynthesis and chlorophyll fluorescence during grain-filling stage in maize ear leafThe diurnal trends of net photosynthetic rate (Pn) were raise by AE, especially the peak value have been increased 10.41% and 9.72% of DH3719 and ND108, while AP decreaseed 15.22% and 9.72%. AE also increased the primarily photochemical efficiency (Fv/Fm), actual photochemical efficiency (ΦPSII) and photochemical reactions (P) of two varieties, and the peak value of non-photochemical quenching of chorophyll (NPQ) of DH3719, while the peak value of NPQ and fraction of heat dissipation (D) of ND108 were decreased. The Fv/Fm,ΦPSII and P of two varieties were decreased by AP, when the peak value of NPQ and D were increased.