Cotton Boll Period Response to Water Stress and Pink Bollworm¹

Abstract

Rapid cotton (Gossypium hirsutum L.) boll development and opening can be beneficial in late season. It can result in increased lint yield, earlier harvest, higher grade, less insecticide use, and reduced storm damage. Research was conducted in the field on a fine loamy, mixed (calcareous), hyperthermic, Anthropic Torrifluvent soil. This study evaluates the effects of water stress in late season (early irrigation termination) and pink bollworm [Pectinophora gossypiella (Saunders)] infestation on time required for cotton bolls to develop from flower to open boll in the field. Water stress speeded boll opening. Bolls from stressed cotton were obtained from field tests with five dates of final irrigation. They opened an average of 17 days earlier than bolls of unstressed cotton in late season. Boll period averages ranged from 41 to 76 days depending upon the degree of water stress and time of year. On droughty (shallow) soil [fine loamy, mixed (calcareous) hyperthermic Anthropic Torrifluvent], water stress effects were significant, but smaller. Delayed boll opening may explain reduced lint yield which at times is associated with late final irrigation. Pink bollworm infested bolls opened about 3 days earlier than non‐infested bolls in two tests with deep soil, but only 0.5 days earlier in a test on droughty soil. Boll period population resembled a normal distribution around the mean until 93% of the bolls were open. For a given day of flowering, 80 % of the bolls (from 10 to 90 %) opened within a 8‐ to 11‐day period.

Efeito do manejo da irrigação e de populações de plantas sobre o rendimento do algodoeiro herbáceo

“…Porém, os trabalhos de Oliveira & Campos (1997), em condições similares, com as cultivares de algodoeiro herbáceo CNPA Precoce 1, CNPA Acala 1, CNPA-6H e IAC-20, concordam que aos 95 dias seja o momento apropriado para a última irrigação, mas discordam que aos 80 dias seja cedo demais e 110 dias muito tardio para o momento da última irrigação. Por outro lado, Kittock et al (1983), no Arizona, constataram que a última irrigação aos 108 dias foi cedo demais para a cultura do algodoeiro atingir produtividade significativamente elevada.…”

“…Vários pesquisadores (Spooner, 1958;Stockton et al, 1967;Ferry et al, 1976;Kittock Última irrigação População 2 (mil plantas/ha) , 1983) concordam que o momento inadequado para a última irrigação concorre para reduzir significativamente a produtividade da cultura do algodão.…”

“…Estabelecer o momento correto para a irrigação final, no algodoeiro herbáceo, é de grande importân-cia, pois acelera a abertura dos capulhos maduros sem reduzir o rendimento da cultura e a qualidade da fibra (Stockton et al, 1967;Marani, 1973;Ferry et al, 1976). Se o momento da última irrigação for bastante cedo poderá concorrer para reduzir o rendimento da cultura, e para que os capulhos mais novos não atinjam a completa maturação (Bruce & Shipp, 1962;Levin & Shmueli, 1964;Miller & Grimes, 1967;Ferry et al, 1976;Kittock et al, 1983;Oliveira & Silva, 1987). Porém, se retardar demais a época da última irrigação, poderá favorecer o desenvolvimento vegetativo, atrasar a abertura dos capulhos maduros, retardar a colheita, e aumentar o apodrecimento dos frutos, com reflexos negativos sobre o rendimento e a qualidade do produto (Spooner et al, 1958;Ferry et al, 1976).…”

Soil drought duration and severity affect cotton boll biomass by altering recovery times and carbon dynamics of subtending leaf

“…Depending upon severity and duration, drought has been shown to negatively impact boll mass and mass of intra-boll components (Hu et al 2018;Sharma et al 2015), and in this study, seed cotton biomass and total boll biomass were observably decreased by 38-day drought during the flowering and boll formation of cotton, compared with a well-watered control (Table 1). This is not surprising given the fact that 38 days would encompass the entirety of the boll development period (Kittock et al 1983), and the result was in accordance with the study and SRWC (45 ± 5)%, boll biomass still obviously reduced; and under 17-day drought at SRWC (60 ± 5)% and 10-or 17-day drought at SRWC (45 ± 5)%, boll biomass still diminished, even average values of three years were continued to reduce more than 10%, compared with the control, suggesting that cotton plant growth were damaged and boll biomass could be not fully recovered, even if restoring irrigation, when moderate drought was more than 17 days or severe drought was more than 10 days. However, under a 10-day drought of SRWC (60 ± 5)%, boll biomass was wholly recovered after re-watering.…”