Study On The Changes Of Photosynthetically Active Radiation And Lodging Resistance Of Soybean Canopy

Soybean is Chinese traditional grain and oil crops,which occupies an important position in the national economy.And Chinese soybean production process is also facing a low yield,weak market competitiveness and other issues.Therefore,it is imperative to increase soybean production.Light energy is the important energy for the green plant photosynthesis,and play an important role on the formation of soybean production.The difference in canopy structure will have different effects on the light energy utilization of soybean,which will affect the yield of soybean.At present,to improve the planting density has become a key measure of soybean high yield potential mining,but the planting density over the standard,the risk of soybean lodging would increase,and not conducive to soybean production.Appropriate planting density can improve the distribution of available photosynthetic radiation in canopy,and promote the light energy utilization and yield of soybean.Therefore,in order to improve the yield of soybean and soybean canopy photosynthetic active radiation and lodging resistance change,the formation of production has important theoretical significance and reasonable canopy structure.The experiment was conducted in 2015-2016,and Kenfeng 16 and Henong 60 were used as test materials.Four planting densities were set up,respectively,200 000 plants/ha,300 000 plants/ha,400 000 plants/ha and 500 000 plants/ha.The changes of photosynthetic active radiation and plant lodging resistance of soybean canopy under different density were studied.The relationship between photosynthetically active radiation and net photosynthetic rate was studied by different shading conditions.The net photosynthetic rate was estimated by the correlation equation.The results showed that:The diurnal variation of photosynthetic active radiation in the middle and base of soybean canopy was consistent with the change of photosynthetically active radiation in the sun above the canopy,and showed a single peak curve.At near noon,the photosynthetically active radiation in the middle of the canopy was significantly higher than that in the base smaller.During the period of R1-R6,the photosynthetic active radiation of soybean canopy decreased first and then decreased,and the photosynthetically active radiation in the middle of canopy decreased with the increase of density,and the change of R1 period was the highest,followed by R6 period,The difference was the smallest;the rule of the base of the canopy with the density was not obvious.The translocation rate of canopy decreased with the growth and development of soybean,and the R5 was the smallest and decreased with the increase of density.The net photosynthetic rate of soybean decreased with the increase of density.The leaf area index of soybean canopy was significantly affected by density,and the leaf area index increased gradually with the increase of density.The trend of single peak curve increased first and then decreased in the R1-R6 period,and the leaf area index reached the peak in the R5 period.The index is mainly concentrated in the upper part of the canopy,and the proportion of the leaf area index of the upper canopy is gradually increased with the growth of the soybean,while the proportion of the lower leaf area index decreases gradually.The R5 and R6 periods Increase the upper leaf area index accounted for a significant increase.The effects of seeding density on lodging resistance,mechanical properties and lodging resistance of soybean stalk were obvious.With the increase of density,the plant height of soybean increased gradually,while the stem diameter gradually decreased.The settling force,elastic modulus and gravity moment of soybean stalk were significantly decreased with the increase of density,and the change degree of the bending force with density was greater than the change of gravity moment.The lodging resistance of soybean plants decreased with the increase of density,so it was not necessary to increase the planting density when the seeding density reached the high yield density.The content of cellulose,hemicellulose and lignin in the stalk decreased with the increase of planting density,which was consistent with the trend of lodging resistance of stem.In the four densities of 200 000 plants/ha,300 000 plants/ha,400 000 plants/ha and 500 000 plants/ha,the highest yield of the agricultural production was 400 000 plants/ha,and the highest yield of Kenfeng 16 was 300 000 plants/ha.The number of grains per plant and grain weight decreased with the increase of density.The number of grains per plant and the grain weight were mainly distributed in the upper part of the canopy and the proportion of the upper part of the canopy increased with the increase of the density Large,the lower part of the canopy is the opposite.