Comparative Studies on the Photosynthetic Characteristics and Chlorophyll Fluorescence Parameters with Okra-leaf and Normal-leaf Hybrid Cotton Cultivars

The photosynthetic characteristics and chlorophyll fluorescence parameters of four commercial hybrid cotton cultivars with normal-leaf and okra-leaf were studied in field.The results showed that the leaves of normalleaf hybrid cotton cultivars indicated a higher photosynthetic rate(Pn) after the flowering stage then during the daytime of bolls setting stage were compared with okra-leaf cotton.The main reasons were that the leaves of normal-leaf hybrid cotton cultivars indicated higher E,Cs at the flowering stage,higher SPAD value,ФPSⅡ and lower E,Cs after the bolls opening stage,and higher E,Cs and Fv/Fm,φPSⅡ during the daytime of bolls setting stage.These were of benefit to enhance the Pn.Therefore,normal-leaf hybrid cotton cultivars can get more organic nutrition and produce bigger bolls and more boll number per plant,and both of seed cotton and lint yield were increased.Compared with Biaoza A_2 and Biaoza A_1,the lint yield of Yuza 35 were increased by 10.5%、14.2%,and CCRI 29 were increased by 2.4%,5.8%,respectively.