How potassium deficiency alters flower bud retention on cotton (Gossypium hirsutum L.)

Potassium (K) is fundamental for plant growth and development but despite the increased quantities of fertilizers applied, incidents of K deficiency are commonly observed. The objective of this study was to record the effects of K deficiency during cotton’s (Gossypium hirsutum L.) early reproductive stage on carbohydrate content and metabolism, total antioxidant capacity and oxidative damage of cotton flower buds as well as the physiology of the leaf, subtending to the flower buds. Growth chamber experiments were conducted using cotton cultivar DP0912 and treatments consisted of normal K and deficient K fertilization for the duration of the experiment. Potassium deficiency resulted in significant oxidative damage in the cotton flower buds, despite the substantial increase in their total antioxidant capacity. Sucrose metabolism of the flower buds was markedly affected resulting in significant reductions in all non-structural carbohydrate concentrations. Furthermore, K deficiency disturbed leaf physiology leading to increased membrane damage, decreases in chlorophyll and carotenoid content and ultimately leaf photosynthetic rates. Concomitant increases in specific leaf weight under K deficient conditions indicated reductions in photoassimilate translocation, which in conjunction with the disruptions observed in flower bud sucrose metabolism, due to the insufficient antioxidant response, resulted in significant decreases in flower bud retention.