CR 29:167-179 (2005)  -  doi:10.3354/cr029167

ABSTRACT: Understanding the impact that climatic factors have on cotton production may help physiologists to determine possible control mechanisms which influence the flowering of cotton plants. This study was conducted to investigate the nature of the effects of climatic factors prevailing prior and subsequent to either flowering or boll setting on flower and boll production and retention in Egyptian cotton Gossypium barbadense L. Two uniform field trials using the cotton cultivated variety Giza 75 were carried out at the Agricultural Research Center, Giza, Egypt. Randomly chosen plants were used to record daily numbers of flowers and bolls during the production stage (68 d in Season I and 62 d in Season II). The daily records of the climatic factors (air temperature, diurnal temperature range, evaporation, soil surface temperature, sunshine duration, and humidity) were recorded during the entire period of production and also for the 15 d periods before and after anthesis. The effects of climatic factors on flower and boll production were quantified in non-limiting management techniques. Relationships in the form of simple and multiple correlations were computed between climatic factors and flower and boll production and retention. The data indicated that evaporation, minimum humidity and sunshine duration were the most effective climatic factors during preceding and succeeding periods on boll production and retention. There was a negative correlation between flower and boll production and either evaporation or sunshine duration, while the same correlation with minimum humidity was positive. Thus, it appeared that low evaporation rate, reduced sunshine duration and high humidity would enhance flower and boll formation. Accordingly, the deleterious effects of climatic factors on cotton production could be minimized through applying appropriate production practices, which would control and adjust the impact of these factors and thus potentially lead to an important improvement in cotton yield in Egypt.

KEY WORDS:Boll retention · Evaporation · Flower and boll production · Humidity · Sunshine duration · Temperature