Penetapan rekomendasi pemupukan N, P dan K tanaman duku (Lansium domesticum) berdasarkan analisis daun

Abstract

Fertilizer recommendation rate of N, P and K for duku (Lansium domesticum) based on leaf analysis have been established. The study comprise of four parts, i.e. (1) Determination of N, P, K concentration to built nutrient level category for duku seedling, and to find out the optimum rate of fertilizer aplication, (2) Correlation study to find out the best leaf sample for nutrient leaf analysis, (3) Callibration study to determine leaf N, P, K level category and recomendation study determine the optimum fertilizer rate for each nutrient level category (4) NPK fertilization to find out the effect of NPK fertilization on fruit yield and quality. The first study was conducted from March 2010 to March 2011 at Jambi and the second to the fourth study were carry on from December 2008 to April 2012, in area of duku central production at Kumpeh Ulu District, Muaro Jambi Regency. The first study consist of three experimens each for N, P and K study. Nitrogen treatment (0, 100, 200, 400, 800 ppm), P treatment (0, 50, 100, 200, 400 ppm), and K treatment (0, 50, 100, 200, 400 ppm) was arranged in the Randomized Completely Block Design (RCBD) with three replication. In the second study, the treatment were three leaves sample from the most recently mature leaves with position in the first and the third leaves from fruiting and nonfruiting branches, and sampled before harvest time, at harvest time, and after harvest. The third and fourth research treatment were N (0, 400, 800, 1,200, 1,600 g N/plant/year), P (0, 500, 1,000, 1,500, 2,000 g P2O5/plant/year), and K (0, 600, 1,200, 1,800, 2,400 g K2O/plant/year). Each treatments were arranged in RCBD with 5 replications. The results showed that leaf nutrient status on duku seedling of N was deficiency: < 1.36% dry weight, adequacy: 1.36–1.46%, and excessive > 1.46%; status of P was deficiency < 0.14%, adequacy: 0.14–0.25%, and excessive > 0.25%; status of K was deficiency < 1.26%, adequacy: 1.26–1.62%, and excessive > 1.62%. The optimum fertilizer rate of duku seedling for very low nutrient status was 398 ppm N, 195 ppm P and 177 ppm K, each of 50 ml per plant aplied two days times or equivalent to 79 g urea, 115 g SP-36 and 32 g KCl/year. The best leaf sample of duku was the third mature leaves at harvest time of non fruiting branches (correlation coefficient 0.87, 0.74, and 0.71 for N, P and K respectively). The second alternative were the third or the first mature leaves at harvest time of fruiting branches. The leaf nutrient status of N was very low (< 1.81%), low (1.81 ≤ N < 2.82%), and medium (≥ 2.82%); status of P was very low (< 0.09%), low (0.09 ≤ P < 0.17%), and medium (≥ 0.17%); status of K was very low (< 1.16%), low (1.16 ≤ K < 2.19%) and medium (≥ 2.19%). Fertilizer recommendation rate on duku plant (1) for very low nutrient status were 858 g N, 1,770 g P2O5 and 1,900 g K2O/plant/year, (2) for low nutrient status were 622 g N, 1,335 g P2O5 and 1,107 g K2O/plant/year, (3) multinutrient approach were 920 g N, 1,565 g P2O5 dan 1,488 g K2O (lower production cost) Fertilization of N, P and K can increased fruit yield and quality of duku.