Removal of early fruit branches as potential regulator of Cry1Ac, antioxidants, senescence and yield in Bt. cotton

Excessive use of insecticides, degradation of Cry1Ac protein, insect resistance and premature senescence in cotton are serious threats to the sustainable cotton production. An experiment was conducted to manage these adversities and to determine dependence of morphological attribute on physiochemical responses. Experiments were conducted at University of Agriculture Faisalabad, Pakistan over two years (2015, 2016) and two locations. The experiment was laid out in randomized complete block design under factorial arrangement. Treatments were comprised of branch removal viz. R0 = No removal of early fruit branches; R1 = Removal of two early fruit branches (REFB) and genotypes V1 = MNH-886 and V2 = FH-142. Results revealed that Cry1Ac (33%) and nitrogen concentration (16%) were increased under REFB compared to no REFB over years and locations. Chlorophyll a and b contents were improved by 11 and 6% under REFB compared to no REFB over two localities and years. While, SOD, POD and CAT activities were increased by 13, 13 and 10%, respectively under REFB compared to no REFB. Nodes above white flower (5 days), nodes for first fruiting branch and seed cotton yield were enhanced by 14, 15 and 17%, respectively under REFB compared to no REFB over years and locations. Number of insect damaged bolls were decreased by 28% under REFB compared to control over years and locations. More promising responses were recorded for MNH-886 compared to FH-142 over REFB, years and locations. Conclusively, all physiochemical and agronomic attributes were improved, and senescence and insect attack were decreased in both genotypes over the spatial and temporal variations. Significant and strong correlation of physiochemical attributes with morphological attributes were recorded over years and locations.