Studies On Inheritance And Correlation Of Three Main Diseases In Upland Cotton

A genetic model with genotype by environment interaction (G by E) was employed to analyze the genetic behavior of the Fusarium, Verticilliwn wilts and boll rot, meanwhile analyzed the correlation between the diseases and the yield, quality, using the materials of Recombinant Inbred Lines (RILs), HM188. which derived from female parent of HS46 and male parent of MARCABUCAG8US-1-88 (MAR). The experiments were conducted during 2001 and 2002 in the fields of Hangzhou. Zhejiang, and Fugou, Henan. under both natural field infection and inoculation of artificially cultivated fungi. The main results of the experiment are as follows.1. Genetical analysis of Resistance to cotton Fusarrium andVerticillium wilts(1) The genetic variances of Fusarrium and Verticillium wilts of upland cotton: Additive variances for disease index of Fusarrium wilts was significantly influenced, which account for 34.8% (namely narrative heritability) of the phenomenon variance. Additive variance for disease percentage has a percentage of more than 50, but which was not significant. Correlation coefficient between disease index and disease percentage of Fusarrium wilts is 0.8389, which is highly significant. Compared to the two indexes, disease index should be as the selective parameter for breeding. And additive effect of Verticillium wilts was not significant in this experiment.(2) Infested-capacity Equation of Verticillium dahliae to the plant population according to the disease index of Verticillium wilts:Where 'P' means infested capability, 'x' means disease index of Verticillium wilts.Primarily predicted population resistance to certain germplasm species. While the value is higher, the resistance is lower. Infested capability of some germplasm species can be estimated by the equation. Similarly, another equation can be attained according to the disease percentage of Verticillium wilts:P = (-283.55x2+357.35x-90.672)otc (0.3215 0.9611) 188 A' 'Where, 'P' means infested capability too, 'x' means disease percentage of Verticillium wilts.2. Genetical analysis of cotton resistance to boll rot and relatedagricultural traitsThe results revealed that the cotton resistance to boll rot was influenced significantly by additive-additive epistasis by environment, and non-significantly influenced by additive-additive epistasis. Domain Effective was not significant, either.The genetics of the plant height and the number of fruit branches follow the same genetical rule, which were having negative correlation with genetic phenomenon and genotype of resistance to cotton boll rot. The parent genetic effect of additive-additive epistasis by environment was not significant, but they were very significant in the offspring at 0.01 level.3. The correlation analysis among the Fusarrium and Verticillium wiltsand some yield and quality traits.Significance of correlation coefficient between disease index of Fusarrium wilts and the cotton yield traits was not obtained, and the coefficient value was mostly negative. The significant correlation between disease plant percentages tested by stem cutting section and the yield traits was obtained at 0.01.Correlation coefficient between disease index and disease percentage of Verticillium wilts and yield traits was negative, either. More than a half of the coefficient was significant at 0.1 or 0.01 probability level. The correlation coefficient between traits of boll rot and the yield traits was minus, and the damage result from cotton boll rot was similar with that of Verticillium wilts.Among the effects on the cotton yield, the Fusarrium wilts was noticed lower effect than cotton boll rot and Verticillium wilts, which were important breeding objects focusing at the present time. Moreover, the parameter of the disease plant percentage tested by stem cutting section was not proper to estimate the yield and the related traits, which was more proper to analyze inheritance of th...