| To evaluate the photosynthetic performance and efficiency of maize verities,a field experiments was carried out during the summer of 2016 and 2017.High and low photosynthetically efficient maize varieties Rong yu 1210?yield loss 5%in intercropping?and Zhong wangyu 18?yield loss 20%in intercropping?were used in sole cropping systems of maize?70cm?as control and under two relay intercropping systems on the basis of different row spacing:20cm and 40cm.Measurements including light energy absorption,transmission,and conversion,and activity of enzyme related to photosynthesis under different treatments were noted during the experiment.The aim of this study is to reveal the mechanisms involved in high and low photosynthetic rate of maize,to study the differences between the high and low photosynthetic rates of maize varieties,and to provide a theoretical basis for the breeding of maize varieties with high photosynthetic efficiency in maize-soybean relay strip intercropping system.The main results of this research showed as follows:1.Intercropping high photosynthetic efficiency of maize varieties group on light distribution characteristicsThe light transmittance of ear leaves at the mid-lower part?0-100cm?of the high photosynthetic efficiency maize of S1210 at silking stage and filling stage were better than Z18.The transmittance of S1210 at the lower layer of ear leaf and ear position leaf layer under different line spacing treatment were significantly higher than that of Z18 by 1.72%to 65.83%and 12.51%to 77.56%,respectively.With the decreased in narrow row spacing,the decreased of photosynthetically active radiation at the mid-lower part?0-100cm?of S1210 was 7.52%to 31.74%,while that of Z18 was 12.37%to 68.47%,and the decreased in the transmittance of S1210 under each leaf layer was lower than that of Z18.2.Intercropping high light efficiency of maize on morphology and leaf structure characteristicsWith intercropping or not,the three ear leaves leaf area of S1210 under differentline spacing treatments were lower than that of the Z18 by 2.36%to 12.97%.With decreasing narrow row spacing,the three ear leaves leaf area of S1210 at silking stage and filling stage decreased by 5.04%and 6.54%,but Z18 decreased by 10.30%and 15.90%,respectively,while the whole leaf area changes in the opposite.The leaf thickness of S1210 were higher than those of Z18 from 0.43%to 9.36%,respectively.With the decreased of the narrow row spacing reduced upper epidermis thickness,under epidermis thickness and leaf thickness of S1210 and Z18.The decreased in the leaf thickness of S1210 by 1.31%to 5.11%,while Z18 was 0.88%to 7.48%.S1210 of chloroplast length was lower than Z18 by 21.20%with monocropping,while that of in intercropping was higher by 4.50%.As narrow spacing,the length of chloroplast in S1210 increased by20.09%,while that of Z18 decreased by 14.42%.With the decrease of row spacing,the stroma lamella and partial grana lamella between S1210 and Z18 were local expansion,but grana thylakoid arrangement of S1210 relatively clutter-free,and eosinophilic osmium granular starch grains was smaller,whereas the change of the Z18 degree was relatively serious.3.Intercropping high photosynthetic efficiency of maize varieties group on photosynthetic characteristics and fluorescence characteristicsWith intercropping or not,the photosynthesis rate and stomatal conductance of S1210were high aspect ratio than that of Z18 by 0.57%to 20.88%,0.71%to 38.31%,respectively,with row spacing decreases?40 cm to 20 cm?two varieties of photosynthetic rate and stomatal conductance decreased,but S1210 range decreased less than Z18.The intercellular CO2 concentration of S1210 was significantly lower than that of Z18 by1.83%to 41.42%,and with row spacing reduced S1210 and Z18 transpiration rate fell by3.76%to 27.07%,0.76%to 29.08%,respectively.Pn-PAR response curve fitted showed that the apparent quantum yield and the maximum net photosynthetic rate value of S1210were always higher than that of Z18,the apparent quantum yield increased by 19.85%to29.08%,the light saturation increased by 3.91%to 28.40%.The light compensation decreased by 28.99%to 44.74%,the light saturation and light compensation of S1210change range decreased less than Z18 with narrow row spacing decreased.The total chlorophyll content of S1210 were higer than that of Z18 by 4.19%to 19.16%.The chlorophyll content of both cultivars increased with decreasing row spacing,S1210 and Z18 increased by 0.97%to 10.46%and 0.26%to 7.02%,respectively.Two varieties in the maximum fluorescence?Fm?,the ratio of variable to maximum fluorescence?Fv/Fm?and non-photochemical quenching coefficient?NPQ?decreased,but the change range of S1210decreased less than Z18 with narrow row spacing decreased.4.Intercropping high photosynthetic efficiency of maize varieties group on photosynthetic enzymeThe enzymatic activity of the RUBP Case,CA Case,NADP-ME Case,PEPC and PPDK of S1210 in the intercropping system were higer than that of Z18.The enzymatic activity of RUBP Case,CA Case in two varieties were increased by decrease of narrow row spacing at a row spacing of 40cm,and then decreased when narrow row spacing at 20cm,but the decresed range of Z18 was bigger.Distinctions of PEP Case activity between varieties was large,the PEP Case activity of S1210 under different line spacing treatments were higer than Z18 by 1.61%to 12.33%,lowest narrow row spacing inceased enzyme activity.The PEP Case of S1210 and Z18 considerably improve activity from 2.56%to 23.52%,4.77%to 19.37%,respectively,in relay intercropping system compared to sole cropping.5.Intercropping high photosynthetic efficiency production mechanism at intercropping and sole croppingThe bald tip long of S1210 was lower than Z18 by 39.75%to 66.04%at two years,grain number per spikes was lower than 1.21%to 13.43%,respectively.With the row spacing reduced,the bald tip long of S1210 increased 7.41%,20.53%and Z18 increased17.92%,7.04%,respectively;grain number per spikes of S1210 by 4.52%,9.85%,that of Z18 by 16.99%,12.11%,respectively.Thousand kenerl weight of S1210 was the biggest,and the smallest row spacing insignificant effect on grain.The effective panicle number of S1210 higher than Z18 by 2.65%to 10.12%,and effective panicle number of Z18 reduced by 10.13%and 3.49%,respectively,at the narrow row spacing of 20cm,but that of in S1210 was insignificantly affected.The yield of maize-soybean relay intercropping system in S1210 were lower than sole cropping,but the decreased yield at the year of 2016 was insignificantly affected by 1.34%,and the yield at year of 2017 was decreased by 5.95%,but Z18 decreased by 18.34%,21.07%at two years,respectively.Path analysis results showed that there was a significantly correlation between light transmittance of narrow row and yield of maize with low photosynthetic efficiency,but the limition in high photosynthetic efficiency maize of yield formation was weaker than the low photosynthetic efficiency maize.At same time,The anatomical structure,photosynthetic enzyme activity in ear leaves had the significant effect on the photosynthetic efficiency of the low photosynthetic efficiency maize than the high photosynthetic efficiency maize.Above results showed that the each indexs of intercropping high photosynthetic efficiency maize variety within intecroping system have not changed much features compared with the monocropping cultivation,eventually make the intercroping high photosynthetic efficiency maize varieties can adapt to the uneven light distribution environment under the planting and enhance the utilization of light,ultimately forming a higher yield. |
PDF Full Text Request