Research On Photosynthetic Performance Of Different Temperature Characteristics Wheat

Cold type wheat exhibits certain superiorities on the physiological ecology and source-sink balance relative to warm type wheat. Therefore, this receives much academic attention. How about the repeatability of characteristics with low temperature in some new materials, and how effect on yield formation? Those issues worth further research.This study selected 18 representative wheat varieties (lines) inside and outside the province with large planting areas as materials, observed and analyzed photosynthetic matter production and yield related traits of tested materials, including disparity phenomenon of canopy temperature, active oxygen metabolism, resistant physical characteristics, photosynthesis and chlorophyll fluorescence parameters, dry matter production, transfer and accumulation during the grain filling stage. This study researched photoassimilate performance, and its relationships with canopy temperature and yield of different temperature characteristics wheat by using factor analysis and regression analysis. The major conclusions were as follows:(1) The repeatability of characteristics with low temperature in some new materials was good.(2) Chlorophyll contents of low temperature wheats were higher than high temperature wheats, with low degradation and long duration of green leaf functional period.(3) Pn, Gs, and Ls of low temperature wheats were higher than high temperature wheats except Ci. Ls was the most closely photosynthetic parameter with canopy temperature.(4) Chlorophyll fluorescence parameters Fo, Fm, Fv, Fv/Fm, Fv/Fo,△Fv, Ft, Yield, Fm', Rfd andφPSⅡvalues of low temperature wheats were better than high temperature wheats.(5) Low temperature wheats had high soluble protein content, SOD content, CAT content, and strong antioxidant capacity compared to high temperature wheats. And low temperature wheats had high Pro content, GSH content, AsA content, and strong adverse-resistant capacity compared to high temperature wheats. Low temperature wheats had low MDA content and MDA accumulation rate, and low superoxide anion radical O2-content, which indicated that low lipid peroxidation level of low temperature wheat flag leaves in filling stage.(6) There were significant differences among different position leaves, sheathes, canes. The average dry matter transfer efficiency of low temperature wheats flag leaves, penult leaves and third from top leaves were higher than that of high temperature wheats by 3.49%, 2.97 % and 3.15 %, sheathes and canes were lower by 2.33% and 5.53%, respectively. Those indicated that leaf source was relative enough, transport contents of sheathes and canes were small, transfer of dry matter was fluent. Single grain fresh volume, dry volume, fresh weight and dry weight all showed rising trend as close to mature stage ( expect single grain fresh volume in dough stage ), corresponding indexes of low temperature wheats were significant higher than high temperature wheats.(7) The correlation of canopy temperature index with net photosynthetic rate score and plumpness index were significant or highly significant negative. Standard partial regression coefficients of canopy temperature index, leaf area, plumpness index and latent storage capacity with yield were 0.04592, 0.1861, 0.4258 and 0.3900, respectively. Standard partial regression coefficients of canopy temperature index, plumpness index and latent storage capacity with yield were highly significant level. Partial correlation coefficients of canopy temperature index, net photosynthetic rate score, leaf area, plumpness index and latent storage capacity with yield were 0.5735, 0.08934, 0.4273, 0.5393 and 0.6008. Partial correlation coefficients of canopy temperature index, plumpness index and latent storage capacity with yield were significant level. This showed that canopy temperature index, plumpness index and latent storage capacity were the main factors affecting the yield.The above research conclusions further revealed the essence of canopy temperature acting on wheat yield formation process, and provided theoretical basis on using new germplasm resources and new selecting indicators, speeding up the breeding efficiency and process in variety breeding practice.