EFFECTS OF ROOT PRUNING AND N-NO3 SOLUTION CONCENTRATION ON TOMATO PLANT-GROWTH AND FRUIT YIELD

Confining and air pruning roots of tomato plants during growth in containers of limited volume occur often in protected horticulture and may reduce tomato yield and fruit quality. The objective of the present work was to determine if a high nitrate (NO3) concentration in the solution can compensate for pruned roots in relation to shoot growth, fruit mean weight, total yield and the occurrence of blotchy ripening of tomato (cultivar F 121). Treatments included intact roots and mildly and severely pruned roots (leaving two-thirds and one-third of the roots, respectively) which were factorially combined with 1.5 mM or 9 mM N-NO3 complete culture solution. Although root pruning reduced shoot growth, fruit yield and average fruit weight, it increased the percentage of fruits lacking internal and external blotchy ripening. There were no significant interactions between root pruning and NO3 solution concentration in terms of vegetative growth or fruit yield. The lower NO3 solution concentration significantly reduced dry weights of the vegetative organs, but had no significant effect on fruit yield and quality. Thus high NO3 solution concentration could not compensate for the pruned roots regarding tomato yield and did not affect the occurrence of blotchy ripening.