MAPPING THE PRODUCTION AND SURVIVAL OF FRUIT ON FIELD-GROWN COTTON

The location and size of bolls on cotton (Gossypium hirsutum L.) plants influence yield and earliness, so plant mapping is being used to define plant fruiting patterns in response to pest damage or crop management. This study aimed to define patterns of fruit location, survival percentage, and final boll size that could provide base data for simulation models. The observations also measured differences created by irrigation treatments. Dates of fruit appearance or loss were recorded from three seasons of high-yielding crops in field experiments on a gray clay (very fine, montmorillonitic, Typic Pellustert). The interval between squaring and flowering and between flowering and boll opening (boll period) was shorter at the top of the plant than at the bottom. Fruiting branches near but not at the bottom of the plant were the longest; they had the greatest survival of fruit to maturity, the largest bolls, and therefore the greatest contribution to yield. Boll size patterns up the plant reflected leaf size profiles, with largest bolls on fruiting branches at mainstem Nodes 7 to 13. The loss of a boll did not appear to be fully compensated for by more or larger bolls on the same fruiting branch. Fruit were most likely to be shed as young squares or as young bolls: fruit on the lower portion of the plant shed more often as squares; upper fruit shed more often as young bolls.