Phenotypical Responses of Cotton and Relation to Lint Yield Under Deficit Irrigation Schemes in Semi‐Arid Environments

Adoption of regulated deficit irrigation scheme changes phenotypical responses but not lint yield. Adoption of suitable deficit irrigation scheme would result in the same lint yield as full irrigation. Morphological parameters can be used as predictors of lint yield before harvesting. Physiological parameters failed to show a consistent close relationship to lint yield under various deficit irrigation schemes. Increasing water productivity in semiarid regions is a critical sustainable production strategy to mitigate the challenges posed by depleting water resources and unpredictable climate change. Deficit irrigation has been a widely investigated practice to save water, improve water productivity, and maximize crop yield. A field experiment was conducted at the Texas AgriLife Research and Extension Center at Uvalde, TX, in 2008 and 2009 to examine the water saving potential of four traditional (fixed deficit ratios ranging from 50–80%, referred as T) and two regulated (dynamic deficit ratios of 75 and 50% overall, referred as R) deficit irrigation treatments against a full irrigation treatment. Four cultivars were assigned to the experimental field each year to test irrigation and cultivar effects on lint yield and morphological and physiological responses of cotton ( Gossypium hirsutum L.). Morphological parameters showed no interaction between irrigation scheme and cultivar; however, most physiological parameters showed significant interaction between the irrigation scheme and cultivar ( P < 0.05) in both years. The results also showed that: (i) two deficit irrigation treatments (80T and 70R) were found to maintain lint yield similar to the control (CTRL) in most of the cultivars; (ii) morphological parameters reflected the differences in lint yield and may be used as predictors before harvest; and (iii) physiological parameters failed to show a close consistent relationship to lint yield under various deficit irrigation schemes. Using seasonal cumulative net assimilation rate, transpiration rate, and water use efficiency may be better parameters for predicting lint yield before harvest.