Influence of potassium fertilization and foliar application of zinc and phosphorus on growth,yield components,yield and fiber properties of Egyptian cotton(Gossypium barbadense L.)

Aims Supplying optimal quantities of mineral nutrients to growing crop plants is one way to improve crop yields.Nutrients need to be used rationally in order to avoid a negative ecological impact and undesirable effects on the sustainability of agricultural production systems.Excessive application of nutrients also affects the farmer’s economy.In order to calculate the amount of fertilizer to be applied to crops,it is necessary to develop recommendation programmers that adjust nutrient rates to crop requirements.Methods Experiments in two successive seasons were conducted to investigate the effect of K fertilization and foliar application of Zn and P on yield and fiber properties of cotton cv.Giza 86.Potassium(0.0 and 47.4 kg of K ha^(-1))was soil applied,while chelated zinc(0.0 and 57.6 g of Zn ha^(-1),applied twice at 70 and 85 days after sowing‘DAS’)and phosphorus(0.0,576,1152 and 1728 g of P ha^(-1),applied twice at 80 and 95 DAS)were applied to the foliage.Important findings Dry matter yield,total chlorophyll concentration,K,Zn and P uptake per plant,number of opened bolls per plant,boll weight,seed index,lint index,seed cotton yield per plant,seed cotton and lint yield ha^(-1) and earliness of harvest increased with the application of K,Zn and P.Treatments generally had no significant effect on lint percentage and fiber properties,with exceptions,for micronaire reading and flat bundle strength,and uniformity ratio,where the mean values of these characters were significantly increased over the untreated control by applying K,and for the micronaire reading in the first season,when applying P at 1728 g ha^(-1),and uniformity ratio in the second season,when applying Pat 1152 and 1728 g ha^(-1),where the mean values of these characters were significantly increased over the untreated control by applying P.Under the conditions of this study,applying K fertilization at 47.4 kg ha^(-1) combined with spraying cotton plants with zinc at 57.6 g ha^(-1) and also with P at 1728 g ha^(-1) improved growth and yield of Egyptian cotton.

Climatic variables: Evaporation, sunshine, relative humidity, soil and air temperature and its adverse effects on cotton production

Cotton yield is a function of growth rates,flower production rates,and flower and boll retention during the fruiting period.Information on the relationship between climatic factors and the cotton plant’s ability to produce and sustain flower buds,flowers,and bolls will allow one to model plant responses to conditions that frequently occur in the field and to predict developmental rate or the formation of these organs.This study investigates the statistical relationship between various climatic factors and overall flower and boll production.Also,the relationship between climatic factors and production of flowers and bolls obtained during the development periods of the flowering and boll stage.Further,predicting effects of climatic factors during different convenient intervals(in days)on cotton flower and boll production compared with daily observations.Evaporation,sunshine duration,relative humidity,surface soil temperature at 1800 h,and maximum air temperature,are the important climatic factors that significantly affect flower and boll production.The five-day interval was found to be more adequately and sensibly related to yield parameters.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 that correlation with minimum relative humidity was positive.