Relationship between leaf nutrients & yield in coconut

Abstract

An investigation on the nutritional status of coconut palms as reflected in the 10th fronds and its relation with the yield of palms was carried out at the College of Agriculture, Vellayani during 1987 from samples drawn from palms of three yield groups (low, medium and high yielders). Chemical analysis of leaves for N, P, K, Ca,Mg,S Na and CI were undertaken at 45 days interval for one year from April 1987, statistically analyzed and correlated in various ways with the yield at the same intervals. The already established relationship that coconut yield is significantly influenced by the level of major nutrients viz. N,P and K on the 10th leaf at all the yield levels was confirmed in the present investigation. The benefit of Na application seemed due to the substitute effect of this nutrient for K. Significance of CI nutrition emerged positively during the investigation. Irrespective of the genetic variations and consequent yield differences it was found that N,P,K, S and CI could influence the yield directly as well as through their interactions. However, higher levels of Ca and Mg had a negative impact on yield. Analysis of variance studies revealed that there is significant seasonal variation in the yield of coconut palms irrespective of the nutritional status. The optimum time for foliar diagnosis is suggested between April and July. Higher levels of N,P and K in the index leaves do not imply immediate yield benefits but will be reflected in the yield consequently. Better yields were associated with high S content in the leaves. So was the case with the C1 content. The eight nutrients considered for study viz. N,P,and K Ca, Mg, S, Na and CI were found to explain 23 to 27 percent variations in the yield. The favourable influence of major nutrients viz., N, P and K was quadratic in nature while the other essential elements helped in maintaining optimum nutrient ratios. The N,P and K content in the 10th leaf for maximum yield is predicted as 1.91,0.12 and 1.33 per cent respectively for high yielding palms. Multiple regression analysis suggested that coconut yield is not a function of individual effects of nutrients but is determined by the simultaneous interaction of all the nutrients.