Abstract

Understanding the impacts of climatic factors on cotton production may help physiologists to determine the control mechanisms of boll retention in cotton. However, weather affects crop growth interactively, sometimes resulting in unexpected responses to prevailing conditions. Field trials, using cotton G. barbadense were carried out, to investigate the relationships between climatic factors, soil moisture status, and flower and boll production. The climatic factors considered were, i.e., daily data of maximum air temperature (°C), minimum air temperatures (°C), maximum-minimum temperature (diurnal temperature range or temperature magnitude) (°C), sunshine duration (hd-1), maximum humidity (%), minimum humidity (%) and wind speed (ms-1). It could be generally concluded that minimum humidity (water stress) and sunshine duration, were the most significant climatic factors affecting cotton flower and boll production and retention in Egyptian. Temperature appeared to be less important in the reproduction growth stage of cotton in Egypt than minimum humidity and sunshine duration. The soil moisture status showed low and insignificant correlation to flower and boll production. The positive correlation between minimum humidity value along with the negative correlation between each ofhigh maximum air temperature(temperature equalled or exceeded 37.5°C) and sunshine duration with flower and boll formation, indicate that high value of minimum humidity, short period of sunshine duration and low value of temperature would enhance flower and boll formation.

Keywords: Cotton flower and boll production; Humidity; Soil moisture status; Sunshine duration; Temperature