Effects of canopy structure on photosynthesis and yield in cotton

Using hybrid cotton‘Shuoza 2'as the test variety,three different canopy structures of dwarf type(L),wave type(W)and high type(H)were created through chemical control and top-cutting,and their light transmittance,photosynthetic rate,dry matter accumulation,ball rot rate and yield components were studied.The results indicated that,in the late growth period,the light transmittance at the middle and bottom canopy positions of the L and H canopy structures was significantly lower than that of W canopy.Compared with W canopy,the total dry matter accumulation of L canopy was decreased by 13.52%.Among them,the vegetative organs of L canopy decreased by 20.87%,H canopy increased by 7.95%,the reproductive organs of L canopy decreased by 15.34%,and H canopy decreased by 10.43%.The bollrot rate and the dropout rate of W canopy were at an intermediate level between L and H canopy structures.The boll weight of W canopy increased by 7.91% and 8.10% than that of L and H canopy ones.The theoretical yield of W canopy structure increased by 12.08% than that of H canopy structure.The test results indicated that the higher light transmittance at the middle and bottom canopy positions of W canopy structure guaranteed the lower rate of boll rot and boll dropping rate,and improved the accumulation of the whole plant photosynthetic products,and ultimately promoted cotton reproductive growth for higher yield.