SHEDDING OF FRUITING STRUCTURES IN COTTON: FACTORS, COMPENSATION AND PREVENTION

Abstract

The fruiting potential of advanced cotton cultivars is not a limiting factor for achieving yield targets but retention of squares and flowers for successful maturation into bolls is major challenge. In this article, we focused on why shedding occurs, its mechanism, yield losses, plant self-compensation, effects on plant growth and possible management to ameliorate its adverse effects. We concluded that it is quite unfair to blame single factor, instead it is an integrated effect of plant and stress factors i.e., high temperature, drought, thick plant stand, insects and diseases etc. contribute to accelerate shedding which ranges about 40-50%. The stresses induce the excessive production of degrading enzymes like pectinase, cellulose and hydrolase, while ethylene and abscisic acid is produced excessively to hasten the degradation process for shedding. The physiological disturbance contributes 7-35 and 42-64% abscission of unopened flowers and bolls, respectively. The square and flower are more frequent to shedding at high temperature compared to immature bolls. The flowers and boll shedding up to 30% is tolerable limit because cotton can recover yield provided weather support the crop later in season. The self-regulated abscission of floral parts is not easy to control under field conditions, however, the adverse effects of stress mediated shedding can be ameliorated with girdling and avoiding pest and stressful conditions, application of plant growth regulator (PGR) to control vegetative growth  and abscisic acid (abscission promoter) and ethylene inhibitors like naphthalene acetic acid, silver thiosulfate and 1-methylcyclopropene.