Cotton Management Strategies for a Short Growing Season Environment: Water-Nitrogen Considerations
- M. R. Morrow and
- D. R. Krieg
The Southern High Plains of Texas represents the largest contiguous cotton (Gossypium hirsutum L.) production area in the USA. Water supply represents the greatest limitation to production under rainfed conditions. Where supplemental irrigation is used, growing season length represents a major limitation to attainment of high yields of desirable quality fiber and seed. The primary objective of this research project was to determine the inter-relationships between H2O, N, and heat unit supplies as they affect lint yield of cotton. Field experiments were conducted during a 4-yr period at a sandy soil (fine, loamy, mixed, thermic family of Aridic Paleustalf) site. Water supply was varied through irrigation with treatments ranging from dryland to fully irrigated. Superimposed on the water supplies were N rate treatments applied preplant and sidedress in a factorial design. Lint yield (LY) was defined as a function of components including plant density, bolls per plant and average boll size. Regression analysis was used to determine LY response to treatments. Lint yield was most highly correlated with boll number per unit ground area with equal contribution from plant density and bolls per plant. Water supply was most responsible for boll number; however, increasing N supply within each H2O regime resulted in a positive response in boll number per plant. Multiple regression analysis revealed that LY responded to H2O and N supplies during the fruiting period to a greater extent than to preflower supplies. Within any heat unit regime, LY was maximized as water supply increased by maintaining a constant ratio of 0.2 kg N ha−1 mm−1 H2O.
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