Photosynthesis characteristic, yield and fiber quality of insect-resistant hybrid cotton with different potassium application types

The effects of different potassium application types on photosynthesis characteristic,yield and fiber quality of insect-resistant hybrid cotton were studied with varieties CCRI 29 and SCRC15.The results showed that when applying KCl 112.5 kg/hm2 before seedling transplanted and 112.5 kg/hm2 at early flowering stage or just applying once KCl 225 kg/hm2 before seedling transplanted,LAI,SPAD readings,PSⅡmaximal photochemical efficiency(Fv/Fm),PSⅡ potential activity(Fv/Fo),PSⅡactual photochemical efficiency(ФPSⅡ),net photosynthetic rate(Pn),stomatal conductance(Gs) in leaves of cotton was higher than that of control without KCl appling.Total bolls per hectare,boll weight,lint percentage were also enhanced in some degree and lint yield were increased significantly.Some fiber qualitative characters such as 2.5% span length,tenacity and length uniformity were improved.Seed cotton yield and lint yield of cotton applying KCl two times were increased by 4.43% and 5.87% respectively when comparing with applying KCl once before seedling transplanted.