Effect of time and different doses of N and K on growth, yield and quality of Thompson Seedless grape (Vitis vinifera L.)

Abstract

A field experiment was carried out with the object of improving the efficiency of nitrogenous and potassic fertilizers by split application in Thompson Seedless grape. Four annual doses, viz., 250, 500, 750 and 1000 kg each of N and K 2O/ha were tried in 12 split combinations. Application of potassium in April resulted in increased prunings weight in the following April. Higher weights of prunings were associated with reduced number of bunches/vine. Increasing levels of N and K2O resulted in reduced length of the internode below the index leaf in December. Internodal length in December was negatively related to the cane and vine productivity and Brix-yield. Area of the index leaf in May and petiole length in June were positively correlated with mean bunch weight at harvest, though they did not vary significantly among the treatments. Petiole nutrient contents in June did not vary significantly among the treatments, while the interaction effects on the petiole nutrient contents in December were significant. Reciprocal antagonism between N and K was observed. Petiole NO 3-N and total N contents correlated positively with the mean bunch weight at harvest. Through the leaf chlorophyll ‘b’ content in December did not vary significantly among the treatments, it was positively related to the reducing sugars content of the berries. Growth and vigour of the vines under all treatment combinations were far in excess than that required for productivity and affected it adversely. A cane load of 50-60/vine was found to be optimum for vines spaced at 3m x 3m. An annual dose of 500 kg each of N and K 2O at a P2O5 dose of 500 kg/ha was found to be optimum. Split application of either N or K 2O during the growth season was not found to be favourable.