Growth and nutrient uptake of cashew (Anacardium occidentale, L.) seedlings as affected by nut-size in the nursery

摘要

Cashew (Anacardium?occidentale) is a tree crop with economic values traded for its nuts world-wide. Seedlings growth and uptake of N, P, K, Ca and Mg as influenced by size of nuts sown was investigated in the nursery. Three nut sizes: Jumbo (> 16 g), medium (4 to 8 g) and madras (< 2 g) were tried. The experiment was in completely randomized design with 4 replications. Data were collected on seedlings height, stem girth, number and area of leaves and dry matter yield. Nutrient uptake was calculated monthly from nutrient content and dry matter yield of the seedlings’ samples for 3 months. Cashew seedlings raised from jumbo nut-size had 71.5, 55.5 and 83.3% height advantages, compared with the seedlings raised from madras nut-size at 1, 2 and 3 months after sowing (MAS) respectively. The leaf production of cashew seedlings raised from jumbo nut-size was more than those of seedlings raised from medium and madras nut sizes by 41.4 and 43.6% at 1 MAS, 14.7 and 28.0% at 2 MAS, 13.4 and 73.0% at 3 MAS in that order. The stem girth of the seedlings raised from jumbo nut-size was 51.6, 41.4 and 64.1% larger than the stem that of the seedlings raised from madras nut-size at 1, 2 and 3 MAS respectively. The differences were all significant (P < 0.05). The dry matter analysis shows that at 1 MAS, seedlings raised from jumbo nut-size had 31.7 and 311.6% higher dry matter yield, than the seedlings raised from medium and madras nut sizes respectively. At 2 MAS, seedlings raised from jumbo nut-size had 34.2 and 140.8% dry matter advantages compared with the seedlings raised from medium and madras nut sizes respectively.? The differences were all significant at P < 0.05. Nitrogen content was highest in all seedlings irrespective of the nut-size.? This was followed by Ca, Mg, K and P contents in that order. Uptake of these nutrients was used to predict nutrient needs of the seedlings in the nursery. Uptake of N was highest followed by uptake of Ca, while that of P was lowest irrespective of nut-size used to raise the seedlings. Seedlings raised from jumbo nut-size had highest uptake of each of these macronutrients with 0.111, 0.011, 0.0154, 0.0379 and 0.0206 g/plant of N, P, K, Ca and Mg respectively.? It can be concluded that, Jumbo sized nut of cashew is hence preferred for cashew seedlings production followed by medium sized nut.