Manipulation of source sink relationship for management of fruit drop in kinnow mandarin

Abstract

A field experiment to study the effect of plant growth regulators and mineral nutrients as foliar application on source-sink relationship during fruit drop was carried out in Kinnow mandarin during 2013–2014. The plant growth regulators viz., 2,4 - D and gibberellic acid (@ 20μg/ml each) and mineral nutrients viz., FeSO4, MnSO4, ZnSO4 (@ 3.0% each), CaSO4, MgSO4 (@ 0.6% each), combination of FeSO4 +MnSO4 + ZnSO4 (@ 0.3% each), MnSO4 + ZnSO4(@ 0.1% each), KNO3 +2,4-D (@ 2.5% + 20μg/ml), KNO3 + 2,4- D (@ 5% + 20μg/ml) were tested as foliar application on eight year old Kinnow fruit plants at Punjab Agricultural University, Ludhiana. The results revealed that there was a significant reduction in fruit drop and increase in fruit yield with the tested plant growth regulators and mineral nutrients by strengthening the sink capacity. The metabolites viz. total soluble proteins, free amino acids, total soluble sugars and starch were more in the leaves as compared to fruits at both the stages of fruit drop, ie., May and August. KNO3 +2,4D (@ 2.5% + 20μg/ml) application resulted in maximum metabolic content in the fruits at the two diagnostic stages.