Factors Affecting Early Growth of Cotton and Subsequent Effects on Plant Development1

Seedling cotton (Gossypium hirsutum L.) growth rate is frequently retarded due to adverse environmental conditions and the effects are often reflected in retarded development and performance later in the season. In efforts to find ways of enhancing the ability of the seedling to grow under adverse conditions, cotton plants were grown under field conditions with black plastic mulch, NaNO₃, NH₄NO₃, and (NH₄)₂SO₄ sources of N, and irrigation treatments. Vegetative development, nitrogen uptake, and fruiting behavior were measured in early stages of growth and final yields taken at maturity. Ammonium sources of N resulted in enhanced seedling vigor, plant height, rate of early-season dry weight accumulation, and rate of early flowering compared to nitrate N sources. A complete ground cover of black plastic mulch gave an additional increase in the early-season growth and fruiting parameters above that obtained from ammonium N alone. Nitrogen concentration in the tissue in early season did not differ among the treatments; therefore, total N uptake followed closely the response in dry weight accumulation. Yield of cotton was not materially affected by source of N. In general yields were higher from plots receiving NH₄NO₃ plus plastic mulch than from plots treated with NaNO₃ and no plastic mulch.