Compositional Differences in Peel and Juice of Cracked and Normal Fruits of Lemon (Citrus limon (L.), Burm.)

Fruit cracking is a predominant physiological disorder of lemon that limits its productivity. The present study aimed to compare the physiological and biochemical traits of cracked and normal fruits of lemon, to understand the cause of fruit cracking and find a viable solution for this disorder. This study was conducted on five-year-old uniform healthy trees grown at fruit research farm, Punjab Agricultural University, Ludhiana, during ۲۰۱۷-۲۰۱۸. Fruits of lemon cracked in different patterns and the cracking peaked due to sudden rainfall and high humidity after a dry spell during the two consecutive years of study. The peel thickness, peel percent and chlorophyll content of the cracked peel was significantly low as compared to the normal ones. Activity of peroxidase and two cell wall degrading enzymes, namely, cellulase and polygalacturonase were higher in cracked peels. Juice content and ascorbic content were low in cracked fruit juice as compared to normal ones. Meanwhile, calcium, potassium and boron content were higher in the normal peel and lower in the cracked peel. A significant positive correlation of fruit cracking incidence with proline, peroxidase, cellulase and polygalacturonase was established, whereas a negative significant correlation was established between fruit cracking percent and peel thickness, calcium, potassium, boron, juice percent and ascorbic acid content. Nutrient deficiency and higher activities of cellulase and polygalacturonase in peel of cracked fruits emerged as the cause of fruit cracking incidence in lemon. Hence, foliar application of calcium, potassium, and boron are recommendable as a remedial measure for prevention of fruit cracking in lemon.

Keywords:

Cellulase , Fruit cracking , Nutrient deficiency , Polygalacturonase.