Cotton growth and yield dynamics across canopy layers in response to soil waterlogging

Abstract

Due to an indeterminate growth habit, we hypothesised that different canopy layers of cotton might be variably influenced by soil waterlogging. The field-grown cotton cultivar (Sicot 71BRF) was waterlogged at early (WLearly, 77 days after planting [DAP]) and late reproductive phases (WLlate, 101 DAP) for 120 h. Data from different canopy layers e.g. bottom eight (MSN1-8), middle five (MSN9-13), and upper five main stem nodes (MSN14+) were collected 1 d (post-WL) and 7 d after termination of waterlogging (post-recovery). Both waterlogging events significantly reduced post-WL dry biomass, leaf N concentration and fruit development on MSN1-8. In addition, WLearly significantly reduced photosynthesis and increased total soluble sugars (TSS) in the MSN1-8 and MSN14+ leaves, although MSN14+ leaves restored photosynthesis, N levels and TSS at recovery. It suggested that WL plants maintained photosynthesis of the upper leaves possibly by transporting N from the lower canopy leaves. Reduction (22%) in seed cotton yield under WLearly was the result of fruit loss from first position fruits of the upper and lower sympodial fruiting branches (FB1-5 and FB11+). Despite restoring the growth through improved photosynthesis and N supply, no yield recovery on FB11+ suggested that the plants used these assimilates for growth of the established fruits. No significant yield reduction in response to WLlate suggested that the established cotton bolls were less sensitive to abscission across all canopy layers.