Anatomical features of pericarp and pedicel influencing fruit splitting in Daisy mandarin

Abstract

Preharvest fruit splitting is a significant concern for Daisy mandarin cultivation due to its adverse effects on both fruit quality and yield. This study, which was conducted at Punjab Agricultural University, aimed to analyze the anatomical changes in the peel, pedicel and stem end of healthy and split fruits of Daisy mandarin. Light microscopy and Scanning Electron Microscopy were employed to examine the different sections of the peel, stem end and pedicel of the fruits. Significant differences were observed between the healthy and split fruits in terms of peel thickness, epidermal cell arrangement and vascular tissue organization. Split fruits, exhibited structural deformities in vascular bundles with limited functioning of the vascular bundles. Displaced xylem tissues in split fruits formed damaged cell masses in the pith and the parenchymatous cells lacked intercellular spaces. Additionally, pedicel vascular bundles in split fruits were often deformed and fused with adjacent bundles. Scanning Electron Microscopy analysis revealed a smooth and uniform epidermis with well-developed oil glands in healthy fruit peels, in contrast to disorganized and ruptured oil glands with empty spaces in split fruits. Thinner, coarser peels with larger oil glands and smaller epidermal thickness were found to be more susceptible to fruit splitting. Disorganized xylem tissue disrupted the flow of water and minerals to growing fruits, potentially due to irregular water transport and pulp expansion, leading to fruit splitting. This disruption of vascular tissues impaired the transport of water and nutrients to the albedo and flavedo, contributing to fruit splitting.