Spraying Time of Nano Zinc Concentration in Relation to Yield and Quality of Egyptian Cotton cv. Giza 94

Two field experiments were conducted on a clay soil at the Farm of Sakha Agricultural Research Station (Kafr El-Sheikh Governorate), Agricultural Research Center, Giza, Egypt, during growing 2016 and 2017 seasons, to investigate the effect of foliar feeding by four concentrations of nano zinc fertilizer (distilled water {control}, 100 ppm, 200 ppm and 300 ppm) at three foliar application times (at the squaring stage, at the flowering initiation stage and at the top of flowering stage) on growth, yield components, yield and some fiber properties for the Egyptian cotton cv. Giza 94. The experimental design was split plot design with four replicates. The four concentrations of nano zinc fertilizer were randomly assigned for main plots and the three times of foliar application were randomly assigned for sub-plots. Results showed that, mean values of plant height (cm), No. of sympodial branches/plant, No. of opened bolls/plant, boll weight (g), seed index (g), lint percentage (%), seed cotton yield/fed (ken), lint cotton yield/fed (ken), upper half mean length (mm), fiber strength (g/tex), micronaire value and fiber maturity ratio were significantly increased with increasing zinc concentration in the form of nano fertilizer compared to plants receiving distilled water during the both seasons, cotton plants receiving the highest concentration of nano zinc fertilizer (300 ppm) gave the maximum mean values of above traits during the both seasons. Foliar feeding at the flowering initiation stage significantly achieved maximum estimates in mean values of plant height (cm), No. of sympodial branches/plant, No. of opened bolls/plant, seed cotton yield/fed (ken), lint cotton yield/fed (ken), upper half mean length (mm) and fiber strength (g/tex) followed by foliar feeding at the top of flowering stage then foliar feeding at the squaring stage during the both seasons. Cotton plants receiving the highest concentration of nano zinc fertilizer (300 ppm) at the flowering initiation stage significantly recorded the highest mean values of No. of sympodial branches/plant, No. of opened bolls/plant, seed cotton yield/fed (ken), lint cotton yield/fed (ken), upper half mean length (mm) and fiber strength (g/tex) during the both seasons, where this combination is the best treatment for good yield and fiber properties traits for Egyptian cotton cv. Giza 94 under the conditions of Kafr El-Sheikh location.