Cuticle cracking in tomato fruit

Abstract

The effects of fruit pruning and deleafing practices on fruit cuticle cracking were investigated in greenhouse tomato plants. Three treatments were established: (1) a standard practice of fruit pruning to three or four fruit per truss, with deleafing up to the ripening truss, (2) increased fruit pruning to one or two fruit per truss and deleafed to the ripening truss or (3) increased deleafing up to the fifth leaf above the ripening truss with fruit pruning to three or four fruit per truss. Fruit pruning substantially increased the plant leaf/ fruit ratio and significantly increased the incidence of cracking. The increased cracking with fruit pruning was not attributable to the increase in fruit size and growth rate observed in that treatment. Increased deleafing slightly reduced the plant leaf/fruit ratio and did not significantly affect cracking incidence. Further analysis of the individual treatments revealed a relationship between fruit size and cracking only in the deleafed plants. No correlations were found between the degree of cracking and the fruit relative growth rate at the time of incipient cracking, approximately six weeks after anthesis, or at two earlier times (two and four weeks after anthesis). Cracking was significantly and positively correlated with a seasonal change in weekly average irradiance in the standard and deleafed treatments. The data suggests that assimilate supply influences cracking but does not act through changes in fruit growth rate or size.