Growth and distribution of dry matter in cotton (Gossypium hirsutum L.)

Abstract

The leaf area index (LAI) and crop growth rate (CGR) of field-grown cotton were measured in four experiments to study the effects of season, node position, cultivar and row space on the production and distribution of dry matter. Growth varied widely between seasons, rainfall being associated with extensive and rapid vegetative growth. The middle segment of a plant produced more bolls than the bottom or top segments. It was estimated that it is necessary for assimilates for bottom bolls to be translocated from upper leaves. When fruit growth starts, vegetative growth also occurs in other parts of the plant, resulting in competition between lower bolls and upper leaves for assimilates. Maximum CGR was obtained at an Lar of about 3, but a high LA1 was not required for a high early boll growth rate (BGR), and the highest BGR was sometimes associated with the lowest LAI. The possible reasons for this association are discussed.