Heterosis for yield and some physiological traits in hybrid cotton Cikangza 1

The characterization of yield and yield components, chlorophyll, soluble sugars and N, P, K concentrations, and SOD, POD activities and MDA content was compared between F1 Bt hybrid cotton Cikangza 1 and its male (transgenic Bt gene bollworm resistant lines and female parents, and commercial hybrid Xiangzamian 2 under field condition. The result showed that the hybrid Cikangza 1 had distinct heterosis in lint yield as reflected by HOBP and HOMP values of 25.7% and 28.9%, and the heterosis of bolls per plant was significantly higher than that of boll weight and lint percentage. Significant HOBP, HOMH and HOCP in Chl a, Chl b and Chl (a+b) at SS and FFS were observed in Cikangza 1, suggesting that the higher Chl content at SS and FFS is important for achieving potential yield, and thereafter may aid in identification of parental lines and hybrid combination. The results also elucidated that the HOBP and HOMP of N, P and K concentrations, and SOD and POD activities were much smaller in comparison with those of Chl parameters. However, Cikangza 1 has higher soluble sugars content, and N and K concentrations at FFS and BOS, than that of commercial hybrid Xiangzamian 2, denoting that N and K nutrient might perform an important function in senescence, and more additional application of N and K fertilizer at late growth stages of hybrid may be beneficial to keep more nutrient for late growth stage and delay the senescence.