Diallel Analysis of Agronomic and Fiber Quality Traits in Upland Cotton

Germplasm and Genetic Stocks

poster

Liu, Yan-gai; Yang, Daigang; Ma, Xiongfeng; Zhou, Xiaojian; Pei, Xiaoyu; Zhou, Kehai

Liu, Yan-gai

Yang, Daigang

In our study, 8 upland cotton varieties (lines), which were selected from Yangtze River valley and Yellow River valley in recent years, were used as parents. Hybrid crosses were made according to Griffing’s diallel cross design method (4). 8 parental lines, 28 F1 and 28 F2 hybrids in two different ecological environments were analyzed for main agronomic and fiber traits by the genetic model of additive- dominance- additive× additive epistasis with environment interaction (ADAAE model, http://ibi.zju.edu.cn/software/qga/ ). The main findings were as follows: Genetic analysis of main agronomic and fiber traits showed that, growth period, flower and boll stage, plant height, fruit branch number, seed index and fiber elongation were mainly controlled by dominance by environment effect, with large environmental impact. Yield and its component traits existed significant dominance effect, and the proportion of dominance variance in the phenotypic variance varied from 20.9% to 59.2%. What’s more, lint index, fiber uniformity index and micronaire were also mainly controlled by dominance effect. Fiber strength and upper half mean length were mainly controlled by additive effect. Correlation analysis among all kinds of traits showed that, phenotypic and genetic correlation coefficients between lint yield and plant height, fruit branch number, boll weight, lint percent, lint index, seed cotton yield, fiber uniformity or micronaire were positively significant or highly significant. What’s more, lint yield, which had low heritability, could be selected by fruit branch number and lint percent indirectly. For fiber quality traits, fiber upper half mean length and strength were easily to achieve simultaneous improvement, but fiber elongation and upper half mean length or strength had highly significant negative phenotypic and genetic correlation coefficients. The evaluation of all parents and hybrids: P1 (612085-1), P4 (sGK958), P5 (YOU lu272), P6 (3392154-55), P7 (380027-030) and P8 (2028) showed outstanding general combining ability. Analysis of dominance and dominance by environment effect of lint yield in 28 hybrid crosses showed that, there were 18 crosses with high and positive dominance effect. What’s more, dominance by environment effect had the same direction with the dominant main effect for most hybrid crosses, so hybrid crosses in our research had stable lint yield. Heterosis analysis results showed that, seed cotton yield and lint yield of F1 and F2 exhibited heterosis. 9 heterosis crosses were selected from 28 hybrids, and F2 population heterosis over parent better of these 9 crosses ranged from 16.3% to 26.3%. Competitive advantage analysis of 9 heterosis crosses in Yellow River valley showed that, competitive advantage of lint yield of F2 varied from -10.6% to 11.2%, but there were no significant difference between each F2 combination and check variety Zhongzhimian2 for lint yield. Through two years of experimental verification, yield heterosis in cross P1╳P8, P3(ZHONG 41)╳P5 and P3╳P7 could be used to F2 generation, so these crosses should be further investigated.