Heterosis of Insect-Resistant Hybrid and Correlation Analysis on Economic Traits Upland Cotton under Various Environments

Transgenic Bt hybrid cotton has accounted for 80% of hybrid cotton area in China. The objective of the current study was to investigate hybrid performance and trait associations under different environments. The mating design used in the experiment was North Carolina II. Six female parents from Yangtse River Valley and Huanghe River Valley were crossed to four males with transgenic Bt. The 24 crosses and their 10 parents were planted at three locations: Wangjiang Cotton Experimental Farm, Anhui Province, Anyang Cotton Experimental Farm, Henan Province and Sanya, Hainan Province. The experimental design was randomized complete blocks. 50 normal opened bolls were picked for assaying the boll weight, lint percentage. Seed cotton was harvested for yield estimate. Fiber samples were tested using HVI system, Cotton Research Institute, CAAS. The results showed that yield heterosis in the transgenic hybrid cotton existed under various environments. In that, lint and seed cotton yield heterosis was the highest, followed by boll number. Under the high production environment, hybrids and their parents had higher yield, but heterosis was not relatively lower. Under the relatively low production conditions, hybrids had relatively lower yield, but heterosis was higher, The results indicated that hybrid yield performance was relatively stable in the three environments, while parental yield was greatly affected by environments. Fiber quality traits varied in environments, but the heterosis was not significant. Correlation analyses showed the boll number had the closest relationship with lint yield. There were also significantly positive correlations among boll number, boll size and lint percentage. However, correlations were inconsistent between fiber quality traits. Micronaire was significantly positive correlated with other fiber traits.