Performance of Mandarin Trees (Citrus Reticulata Blanco.) At Different Altitudes and Nutrient Management in Mid-Hills of Nepal
Date
2008
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Publisher
Department of Horticulture
Abstract
This work entitled “Performance of mandarin trees (Citrus reticulata Blanco.) at different altitudes and nutrient management in mid-hills of Nepal” was initiated and achieved in two phases. In the first phase, a nutritional survey based on foliar and soil analyses of the mandarin orchards located at high, mid, and low altitude citrus growing belts representing Gorkha, Lamjung and Tanahun districts, respectively and different orchard performances mainly health and age of the trees in the regions were conducted during 2003 and 2004 to elucidate the roles of these aspects on foliar as well as soil nutrient composition and to the appraisal of nutrients constraints in these regions. Two years of results showed that there was a strong association between soil fertility trends and altitudinal variations. At high citrus growing altitude (> 1100 m amsl) the total leaf P, K, Fe and Zn were higher as compared to lower altitude (500 to 1100 m amsl). Soil pH, organic matter, total N, available P, Ca, and Mg contents in soils varied according to the altitudes. Generally, soil organic matter, total soil N, available soil P were more at high altitudes and pH, available Ca and Mg contents in soils decreased as the altitudes increased. The rest of the nutrients did not show the systematic patterns with altitude variations. High performing orchards of healthy matured and young trees out-performed unhealthy trees with respect to the amount of N, P, Ca, Fe, Mn and Zn in leaf. Young mandarin trees of both healthy and unhealthy had high content of leaf, N, P, K, Mn and Zn at all the altitudes compared to mature ones. However, soil organic matter, total N and available P and Zn were affected by the orchard performances. Remaining nutrients were either no response or highly erratic with the age and health of the trees. This implicated that while taking samples for leaf and soil analyses of mandarin orchards for close interpretation of the test results, the samples needed to be taken altitudinally besides consideration of several other cultural management factors primarily age and health of the trees. Majority of the high altitudes citrus orchards were deficient in leaf Zn, Ca, Mg and Mn; at mid-altitude leaf Zn, B and Mn in leaf were deficient; at low citrus growing belts mostly N, and Zn were deficient. Based on soil test results, low soil pH, and low availability of Ca and Mg were found at high altitudes whereas N and B were shown to be in low to medium ranges in most of the orchards at medium and low altitudes. Nitrogen fertilization was found to be the most problematic nutrients based on literatures reviews and findings of the first phase of the study. So, in the second phase of the studies, the plan for field N-management of experimentation in farmer’s field conditions were initiated in 2004/05 fiscal year at Chowk-8, Dudhenkuna mandarin growing pockets of Tanahun district which is located in mid-hills (600-700 m amsl) of Western Region of Nepal. Main objectives of these studies were to elucidate the efficient roles of various N fertilization managements through its interaction with the major nutrient packages, amount and method of N application to observe trees growth, yield and quality variables of local landrace mandarin. The results showed that the efficient N fertilization management includes the soil application of complete package viz. 200-100-200 g NPK/plant/year with 2 sprays of Plantoplex (commercial formulation) and 2 kg of agri-lime per tree, the positive N–K containing fertilizer treatments interaction, the optimal N application rate of 400 g N/plant/year applied in winter and early spring for 5-6 years old trees and two basally applied N plus one foliar applied N as urea just after blossoms significantly increased number of leaves, length of shoots, number of matured and immatured fruits, fruit size and total fruit yield, peel thickness, TSS, TSS:TA ratio, and juiciness. However, flower number, TA, fruit firmness and coarseness were decreased by the above mentioned good N managements practices. The overall, these studies were achieved to suggest efficient N fertilization practices for local landrace mandarin under low zones of mid-hills of Western regions of Nepal and that resulted in the optimal production with quality fruits.
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Keywords
soils nutritional dynamisms, soil test