Effect of Water Stress and Rehydration on the Cluster and Fruit Quality of Greenhouse Tomatoes

The water needs for tomato crops are very high and could limit the viability of cultivation in semiarid environments. There is no agreement among works on irrigation regarding the sensibility of the flowering period. In addition, there is a lack of studies about the effects of water stress on fruit and cluster development under severe water stress. The aim of this work was to evaluate the effect of water stress and rehydration during cluster development. The experiment was conducted in a greenhouse (Seville, Spain) in two different growth cycles (autumn 2021 and spring 2022) using three different cultivars. Two irrigation treatments were applied: a control, with full irrigated conditions, and severe stress, without irrigation during the development of the fifth cluster (43 days (autumn) and 21 days (spring) after transplantation) followed by rehydration. Plant height was significantly decreased, by approximately 10%, in the irrigation treatment during the autumn cycle, however, not in spring. A delayed cluster emergence occurred, however, the final number per plant at the end of the experiment was the same when rehydration was applied (73 and 56 days after transplanting). In the autumn cycle, only the fruit size was considerably affected, with more than a 50% reduction on some dates, though not in the first cluster. However, the extremely severe water stress during the spring cycle, with strong defoliation, reduced the number (around 50%) and size (around 40%) of the fruit. Total soluble solids increased only on isolated dates of the harvest in the stress plants. The response of cherry cultivars to water stress was similar in terms of quality parameters. Fruit size was the most sensitive yield component, and no recovery was detected at harvest after rehydration. The effect of severe water stress was different depending on the evaporative demand and, more importantly, on fruit size