Effect Of Combined Exogenous Regulating Substance On Cotton Bolling

This experiment was carried out with the variety of Nankang 98-7, differentcompound exogenous regulating substances were applied on cotton boiling period.Six combined exogenous regulating substances treatments were conducted as follows:BF₁ were sprayed on early flowering and CC, NAA, mixture of CC and BF₁, mixtureof NAA and BF₁ were sprayed on 15 days later to study effect on cotton bolling. Theresults were as follows:Yield and yield components were changed by six treatments. Number of bolls andboll weight were increased significantly by BC and BBC to abtain higher yield, BNabtained higher yield by increased boll weight. BBN reduced boll weight and its yieldwas influnced. BC, BBC and BN increased yield of high-quality bolls and BBCincreased high-yield of quality bolls most significantly. The proportion of yield ofhigh-quality bolls were above 97 percent had no significant differences on alltreatments,Mechanism of cotton bolling was changed by combined exogenous regulatingsubstances. From ratio of boll retained and intensity of fruit retention, BC, BBC andBN increased those in 28-42 and 56 days after spraying, BBN increased those in21-42 days after spraying; From spatio-temporal distribution of cotton, the number ofbolls in hot days and autumn were increased by BC, BBC, that in hot days and lateautumn by BN and BBN, the number of bolls in early autumn were reduced by BNand BBN, the number of bolls were increased on inner and outer branches by BBC,that on inner and middle and upper outer by BC, that on middle and lower innerbranches and upper outer branches by BN, that on middle and lower inner branchesand upper and lower outer branches by BBN. From boll weight of cotton, BBCincreased boll weight all the time, boll weight in hot days were increased by BC, BN,and BBN, that on lower inner and outer branches by BBN, that on lower outer andmiddle inner branches by BC, that on lower inner and outer branches and middle andupper inner branches by BN, BBC increased boll weight on middle and upperbranches and reduced that on lower inner branches. All treatments reduced bollweight on upper outer branches.Mixture dry weight of seedcotton and accumulation rate of seedcotton dry weight were increased by all treatments. Intensity of dry weight auumulatin of reproductiveorgan was inforced by BC all the time, inforced by BBC at 0-30, 45-60 days,inforced by BN and BBN at 0-15, 45-60days. Different combined exogenousregulating substances also increased net photosynthetic rate, LAI, Chlorophyll contentof leaves on lower, middle and upper sympodia brabches. Content of souble sugar ofleaves on middle and upper sympodia node were increased by BC and BBC, that onlower and upper sympodia node were increased by BN, that on lower, middle andupper sympodia node were increased BBN. POD activity of sympodia leaves wereincreased by four combined exogenous regulating substances treatment. SOD activityof sympodia leaves were increased by BBC, BC and BN, All combined exogenousregulating substances treatment reduced content of MDA of sympodia leaves.