Studies on fruit pedicel concerning fruitlet abscission in kinnow mandarin

Abstract

Fruit drop is a major constraint for the production of kinnow mandarin. The present investigation compared the physical, biochemical and anatomical dynamics in abscised and non-abscised fruit pedicels of Kinnow mandarin at physiological and pathological fruit drop stages. The pedicel parameters (length, girth and weight) were higher in non-abscised than the abscised fruits. The activities of polygalacturonase (4.01 μg D-glucose released g-1 FW min-1) and cellulase (4.34 μg D-glucose released g-1 FW min-1) enzymes were significantly low in non-abscised as compared to abscised fruit pedicels. The transverse sections of non-abscised healthy fruit pedicels revealed intact phloem and long xylem vessels in the vascular tissue. However, pedicels of abscised fruits showed degradation of cells and formation of the abscission zone. Fruit pedicel parameters positively correlated with mineral nutrients, total soluble sugars and total soluble proteins. However, non-abscised fruit pedicels were negatively correlated with cell wall degrading enzymes. The fruit pedicel health has been found essential and positively associated with the diminution in physiological and pathological fruit abscission in kinnow mandarin.