PRELIMINARY N, P AND K FOLIAR DRIS NORMS FOR COCONUT

Abstract

The efficiency of predicting nutrient imbalances and deficiencies in coconut was tested using Diagnosis and Recommendation Integrated System (DRIS) developed by Beautils which utilizes the ratio of tissue nutrient concentration rather than the concen- tration per se. DRIS consistently produces more accurate diagnosis and imbalances than critical concentration studies. Plant samples were collected from 14th leaf (diagno- stic leaf) from a population of 183 palms and palms yielding less than 35 nuts/annum/ palm were considered low yielding and those producing more than 35 nuts/palm/annum were considered high yielding or desirable population. Cocouut leaf norms were formulated for different forms of expression for nitrogen, phosphorus and potassium and the variance ratios for K. NK, PK, K/P, K/N were found to be highest and signifi- cant. Indexes for N, P, and K were obtained integrating values of nutrient ratio of a test sample, mean value of the ratio for high yielding population and CV of high yielding population for that form of expression. Nutrient indexes were calculated from the leaf analysis values obtained from individual treatments from a factorial experi- ment. The indexes indicated marked deficiency for nitrogen, which was confirmed by experimantal data. The foliar levels of K which were below the suggested critical levels did not give any negative index DRIS method of diagnosis suggested the order of importance of limiting nutrient for a given situation. Hence based on the norms developed, nutrient application can be suggested for a targetted production. There is ample scope for refinement of DRIS norms by sampling a larger population. and utilizing it as an effective tool for fertilizer recommendation for coconut.