Influence of cluster thinning on quantitative and qualitative parameters of cherry tomato

The practice of cherry tomato cluster thinning may contribute to increased quality of the remaining fruit. The objective of our study was to evaluate selected quality traits and the content of primary and secondary metabolites in fruits of cherry tomato subjected to two fruit thinning intensities (thinned to 1/2 or to 2/3 of the initial cluster length). Cluster thinning induced higher fruit yield at the beginning of the harvest period, between 98 and 115 days after transplanting (DAT). On later samplings, the yield of the control plants increased and remained higher until the end of the experiment, which resulted in higher total yield of control plants. Both thinning treatments significantly increased average mass of fruits from the distal cluster section in comparison to the control treatment. Redder fruits with significantly higher a*/b* ratio were characteristic for the proximal and distal sections of the control clusters in comparison to the fruits from the thinning treatments. Tomato cluster thinning caused periods with no yield between 117 and 128 DAT and between 142 and 152 DAT during the harvest period. Moreover, cluster-thinned tomatoes accumulated less sugar and more organic acids than the control fruit. The content of total analyzed carotenoids was comparable between cluster-thinned and control fruit. Regardless of the treatment, 22 individual phenolic compounds from four phenolic groups have been identified in cherry tomato fruit. Significant differences among treatments have been determined in approximately one half of analyzed phenolics, particularly from the group of hydroxycinnamic acids. It can be concluded that cluster thinning only moderately affected secondary metabolite composition of cherry tomato and had little positive effect on the levels of the two most important groups of antioxidant compounds (phenols and carotenoids).