Effect of major nutrients on the yield and quality of nuts in graft-raised cashew (Anacardium occidentale Linn.)

Abstract

An experiment was conducted to study the "Effect of major nutrients on the yield and quality of nuts in graft raised cashew" at Cashew Research Station Madakkathara Kerala. The treatments consisted of three levels each of N, P and K on eight year old cashew trees. The salient findings are abstracted below. The study revealed that increasing levels of nitrogen significantly increased the height and spread of cashew trees, while the girth was significantly increased by the interaction effects of nitrogen and potassium. The yield parameters such as number of flushes, number of leaves per flush, number of panicles and the number of nuts per panicle were significantly enhanced by the application of nitrogen at increasing levels, while the application of phosphorus at increasing levels also significantly increased the number of nuts per panicle. The yield of cashew nuts and apples were significantly increased due to the highest level of nitrogen applications. Application of potassium at the highest level also significantly increased the apple yield per tree. Weight and volume of cashew apples was significantly increased by the application of increasing levels of potassium but nitrogen application was found to significantly decrease the weight of fruits. The juice percentage was positively and significantly influenced by the application of nitrogen and potassium. Potassium applications were found to significantly increase the nut length and weight while nitrogen applications were found to reduce the nut weight. Shelling percentage of cashew nuts was enhanced by the application of nitrogen and potassium at increasing levels. The kernel weight was increased due to the application of potassium. Ascorbic acid content of cashew apples was positively influenced due to the application of increasing levels ofNPK. The Total Soluble Solids of the apple was significantly enhanced by the application of nitrogen. Applications of nitrogen alone and in combination with phosphorus were found to increase the protein content of kernels. The carbohydrate, Non-reducing sugars and reducing sugars content of kernels were significantly enhanced by the application of different levels of nitrogen. Increase in the soil major nutrient content due to the individual effects of nitrogen, phosphorus and potassium applications were also observed. The leaf phosphorus and potassium content was enhanced specifically due to the application of increasing levels of phosphorus and potassium respectively, while the nitrogen content of leaves was positively influenced by the application of nitrogen and phosphorus. The average nutrient off-take through nuts and apples was computed to be 279.43, 4l.58 and I 86.40g of nitrogen, phosphorus and potassium respectively. The average nutrient off take per tree through nuts from an average yield of 2.89 kg tree" was found to be 93.56, 2.89 and 48.85g of nitrogen, phosphorus and potassium respectively and through apples was found to be 185.87, 38.69 and 137.54g of nitrogen, phosphorus and potassium respectively from an average yield of 18.20 kg tree". In 'general, among the major nutrients applied at different levels only nitrogen had shown exceedingly high effects in sustaining the growth, yield and quality parameters. The yield and quality parameters were also seen to be affected to a certain extent by potassium applications but the response of the crop to phosphorus was seen to be exceedingly limited.