Quantifying the Effects of the Timing of Water Deficit Stress and Water Deficit Stress Alleviation on Cotton (Gossypium hirsutum L.) Growth and Yield under Rain-Sheltered Controlled Conditions
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Water deficit is a major limitation for cotton yield in drought-prone Texas croplands. Where underground or surface water is available and cost affordable, water is applied to crops using a variety of irrigation techniques to mitigate the yield-limiting effects of water deficits. However, dwindling water resources and increased costs can restrict the use of this practice considerably. Most of the work on the effects of timing of water deficits on cotton has focused on yield under variable field growing conditions. A better understanding of the responses of growth and yield would be achieved by quantifying these effects under controlled environmental conditions, where soil variability can be eliminated and water supply accurately controlled. Two studies were conducted in 2014 in the Drought Tolerance Laboratory (Texas AgriLife Research and Extension Center in Corpus Christi, TX) to i) quantify the effects of the timing of water deficits on growth and yield of cotton, and ii) quantify the effects of water deficit stress alleviation at different phenological stages on growth and yield of moderately water-stressed cotton. This facility consists of two joined modified greenhouses where computerized systems control the irrigation regime and collect and process plant water use data automatically. Both studies used cultivar PHY375WRF, which is an early-medium maturity variety with an indeterminate growth habit. Plants were grown in 13.5-L (3.6-gallon) pots filled with fritted clay soil. The experiments were laid out as complete randomized designs with 4 treatments and 4 replications. Data collected shows that water deficits from 1st bloom to mid bloom and from mid bloom to 1st cracked boll had severe effects cotton’s dry biomass production and partitioning, primarily through its decreasing effects on fruit retention, which led to lower economic yield and lower water use efficiency. Supplemental irrigation increased whole-plant transpiration irrespective of phenological timing, but increased total dry biomass of moderately water-stressed cotton only when applied from match head to 1st bloom and from 1st bloom to mid bloom. But these effects did not impact significantly yield or water use efficiency.
Da Ros Carvalho, Henrique (2015). Quantifying the Effects of the Timing of Water Deficit Stress and Water Deficit Stress Alleviation on Cotton (Gossypium hirsutum L.) Growth and Yield under Rain-Sheltered Controlled Conditions. Master's thesis, Texas A&M University. Available electronically from