Abstract
Drought is a major abiotic stress factor limiting cotton yield. It is important to identify the genotypes that can conserve water under drought stress conditions and improve yield. The objective of the current study was to evaluate cotton genotypes for water conservation traits, i.e., high FTSW (Fraction of Transpirable Soil Water) threshold for transpiration. Plants utilize water slowly by declining transpiration at high FTSW and conserving soil water, which can be used by the plant later in the growing season to improve yield. Fifteen cotton varieties were selected based on their differences in transpiration response to elevated vapor pressure deficit (VPD) to study drought responses. Two pot experiments were carried out in the greenhouse to determine the FTSW threshold for the transpiration rate as the soil dried. A significant variation (p < 0.01) in the FTSW threshold values for transpiration decline was observed, ranging from 0.35 to 0.60 among cotton cultivars. Genotypes with high FTSW thresholds also displayed low transpiration under well-watered conditions. Further studies with four selected genotype contrasts in FTSW threshold values for transpiration showed differences (p < 0.05 to 0.001) in gas exchange parameters and water potentials. This study demonstrated that there are alternate traits among the cotton genotypes for enhancing soil water conservation to improve yield under water-limited conditions.
Highlights
The recent climate change investigations have reported an escalation in extreme weather events, such as droughts, floods, storms, and high temperatures, disrupting crop production
The current study identified genotypic differences among cotton cultivars for their transpiration response to progressive soil drying
There was a clear difference among cultivars in f transpirable soil water (FTSW)-threshold values; at the point where the plants started to decline, their transpiration ranged from 0.35 to 0.60
Summary
The recent climate change investigations have reported an escalation in extreme weather events, such as droughts, floods, storms, and high temperatures, disrupting crop production. Severe lint yield reductions in cotton due to drought stress has become a significant challenge for sustainable crop production under water-limited environments. Past efforts in improving germplasm for water-limited environments focused on specific traits for particular crops and drought conditions [7]. While these studies have given useful insights into the potential effects of drought, they are based primarily on deterministic methods reporting yield losses. Despite extensive studies on plant sensitivity to drought stress, less attention has been paid to plant traits that conserve water under water-limited conditions [8]
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