Uptake pattren of major & minor nutrients in selected cashew types

Abstract

An investigation was undertaken at the Kerala Agricultural University during 1990-92 to study the varietal difference in growth and nutrition of 18 cashew varieties. The study was also aimed to assess the variability in nutrient concentration in plant parts and the nutrient offtake. The variation in the absorption of soil applied 32p at different physiological phases was also assessed. The experimental trees were at the fifth year of planting. The most important findings are abstracted below. Two cashew varieties viz. M 44/3 and M 26/2 originated from Cashew Research Station, Vridhachalam gave higher nut yield. The concentrations of major and minor nutrients (N, P, K, Ca, Mg, S, Fe, Mn, Zn and Cu) differed among plant parts (leaf, apple, kernel and shell) and between the varieties. The cashew kernel had the highest concentration of N, P, Ca, S, Zn and Cu compared to leaf and apple. The concentrations of K, Mg and Fe were high in apple. The Mn concentration was high in leaf. The nutrient concentration was low in the shell. A four year old cashew tree yielding 4.08 kg nut and 4.15 kg apple on dry weight basis removed 239 g N, 7.51 g p, 110 g k, 14.2 g ca, 6.40 g mg, 6.46 g S, 1709 mg Fe,233 mg Mn, 252 mg Zn and 86 mg Cu. Among apple, kernel and shell, the nutrient removal was largest through apple. Leaf nutrient status of cashew varied with physiological phases. The concentrations of N, P and K in the leaf were high at “flushing and early flowering’’ phase. Absorption of soil applied 32p differed between physiological phases but not between the varieties and the absorption peak was noticed in the “flushing and early flowering’’ phase. Irrigation of cashew trees during summer increased the absorption of soil applied 32p.