Irrigation strategies for cotton production under limited water supply
1988
Ganotisi, N.D.
Results showed that water stress significantly reduced seed cotton yield, number of bolls per plant, weight per boll, plant height at maturity, leaf area index and biomass at 110 DAE, and evapotranspiration ratio, compared to the unstressed plants. Mean comparisons among treatment groups showed that flowering stage was the most affected in terms of seed cotton yield and its component, followed by bolling, squaring, and vegetative stages for single growth stage stress. For double stress stage, water stress at flowering and bolling stages was the most critical. These results were reinforced by the results obtained using the sensitivity index values which showed the same results. The prediction equation which relates the varying degrees of moisture deficiency to seed cotton yield, Y is Y = 2.308 - 0.035X2 - 0.086X3 + 0.002X32 - 0.062X4 + 0.002X42 where X2, X3, and X4 refer to the number of stress days of the plants at squaring, flowering, and bolling stages, respectively. The coefficient of determination, R2 is 0.774. The recommended irrigation guidelines for maximizing seed cotton yield under water deficit condition are as follows: (a) for moderate water supply, cotton may be subjected to water deficit condition at vegetative stage to the extent of reaching temporary wilting stage for 15 days, after which irrigation schedule will be based on the 50 to 60 percent available moisture; (b) for limited water supply, cotton may be subjected to water deficit condition once at vegetative stage and again at squaring stage to the extent of reaching temporary wilting for 10 days, after which irrigation schedule will be based on the 50 to 60 percent available soil moisture.
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