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Pak. J. Bot., 44: 259-265, Special Issue March 2012.

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CONTROL OF Excessive fruit drop and improvement in yield and juice quality of Kinnow (Citrus deliciosa x Citrus nobilis) through nutrient management

M. YASIN ASHRAF¹, M. YAQUB¹, JAVED AKHTAR¹, M. ATHAR KHAN²,  M. ALI KHAN² AND G. EBERT³

Abstract: Fruit yield and quality of citrus, especially Kinnow (Citrus deliciosa x Citrus nobilis) in Pakistan is not competitive with that of other countries which could be attributed mainly to the lack of appropriate nutrient management for citrus orchards. The yield losses in citrus occur mainly due to excessive fruit drop. Experiments to overcome these problems were conducted at four different sites one each in Faisalabad, Toba Tek Singh, Jhang and Sargodha districts of Punjab, Pakistan. The soil and leaf chemical analysis showed severe deficiency of Zn in Kinnow. In the present studies, effect of foliar application of Zn, K and salicylic acid (SA) alone or in combination was investigated on fruit yield, excessive fruit drop and juice quality. The fruit trees were pretreated with a selected NPK level. Zinc (0.25% ZnSO₄ solution), K (0.25% K₂SO₄ solution) and salicylic acid (10 mM) were sprayed at three different stages, i.e. the onset of spring/flush of leaves or flowers, fruit formation and color initiation on fruit. Overall, application of Zn, K and SA or Zn+K+SA was effective in improving the yield and quality parameters of citrus fruit at all sites. Although fruit drop was   reduced by the foliar spray of Zn, K, SA or Zn+K but three foliar sprays of 10μM SA + 0.25% each of Zn and K reduced the citrus fruit drop by 30% and also improved the juice quality. Kinnow fruit yield and juice quality can be effectively enhanced with proper nutrient and hormone applications depending on site conditions.

¹Nuclear Institute for Agriculture and Biology (NIAB), Jhang Road, Faisalabad, Pakistan

²Nuclear Institute of Agriculture (NIA), Tanojam, Sindh, Pakistan

³ Agricultural Advisory Department, K+S KALI, GmbH Kassel, Germany

*Corresponding author: niabmyashraf@gmail.com