Cotton Response to Seasonal Patterns of Flower Removal: II. Growth and Dry Matter Allocation

Abstract

Development of a cotton (Gossypium hirsutum L.) crop is a full‐season process involving a complex balance between vegetative and reproductive allocation. Despite this fact, fruit removal studies have seldom examined the effects of flower removal during late anthesis. Flower removal treatments were imposed on two cotton cultivars to assess effects on vegetative and reproductive dry weights (DW) and boll maturation patterns. Flower removal treatments were imposed during early‐, mid‐, and late‐anthesis. Removal of 1st and 2nd and 1st through 3rd week flowers caused a decrease in the reproductive/vegetative ratio (RVR) at 105 d after planting (DAP) or 93 DAP 1991 and 1992, respectively. However, no difference in RVR was found between these treatments and the control (no removal) at either 133 or 131 DAP (1991 and 1992). Early removals (3rd week and earlier) increased number of bolls developing above Node 10 and decreased the number of bolls developing at first positions on sympodial branches. Flower removal during the 4th week and later decreased the RVR at 133 and 131 DAP (1991 and 1992) by at least 23% as compared with the controls. Late‐season removal treatments decreased the final number of total bolls and significantly reduced the number of bolls residing at main stem Nodes 11 and higher. Although fruit retention early in reproductive growth is often important for early maturity and maximal yield, this study found that subsequent development of distal and more apical flowers adequately replaced fruit lost durin early anthesis. In contrast, later developing bolls, often thought to be unimportant, were needed to achieve maximal yield.