Cracking of lychee fruits: responsible factors and control

Abstract

Lychee, a juicy, attractive and excellent fruit of Sapindaceae family, is preferred by consumers for its extraordinary taste and aroma. India, the second largest producer of the crop, has got an important position in the export of lychee as it possesses attractive colour, good size and excellent taste. However, fruit cracking is the most serious problem of quality lychee production in major lychee growing belts of India, viz. Bihar, West Bengal, Jharkhand, Assam, Tripura, etc. During seven years (2007-2013), systematic research on lychee fruit cracking at the Horticulture Research Station, BCKV, West Bengal, revealed that occurrence and extent of fruit cracking differed among the lychee cultivars and it was found that relatively early cultivars with more tubercle density and thin pericarp were more prone to cracking than late cultivars or with less tubercle density. High temperature during rapid growth period coupled with low relative humidity was the potential reason behind this disorder. It was observed that internal pressure of developing fruits had positive correlation with cracking whereas aril or peel calcium had no coinciding relationship with it. Fruits located at west and north side or at inner canopy had minimal cracking problem. Application of irrigation at 40% pan coefficient through sprinkler irrigation had significant effect to overcome the cracking problem of fruit. Drip irrigation and mulching with fallen lychee leaves was also found effective to tackle the disorder. Use of agro-shade net (50% light transmission) and foliar application of Boron at 0.5% had potential influence to control this disorder. Besides, delayed harvesting by the application of gibberellic acid (50 mg L(-1)) at 21 days after fruit set also reduced the problem.