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Grafting is a valuable tool for managing problems of tomato soil-borne pathogens and pests, but often generates unpredictable effects on crop yield and product quality. To observe these rootstocks-induced changes, experimental designs including many rootstock-scion combinations are required. To this end, a greenhouse experiment was conducted on 63 graft combinations, involving seven cherry tomato scions grouped in large, medium and small-fruited, and eight rootstocks with different genetic backgrounds (crosses between Solanum lycopersicum and S. habrochaites or S. peruvianum or S. pimpinellifolium, plus an intraspecific hybrid), using ungrafted controls. The response of the graft partners was firstly analyzed individually using the environmental variance (σ2E), then by grouping them by classes. When analyzed individually, the scion genotype influenced fruit L*, b*, shape index, total soluble solids (TSS) and its ratio with tritatable acidity (TSS/TA), whereas plant growth and yield were unpredictable. After clustering the graft partners, some of these responses were attributable to the imposed classes. The S. habrochaites-derived hybrids maximized plant biomass, unlike the S. pimpinellifolium ones. Both classes reduced fruit biomass in small- and medium-fruited scions (by 11 and 14%, respectively). The S. habrochaites and S. peruvianum hybrids reduced a* and TSS, whereas promoted TA. L-ascorbic acid was reduced by grafting (from −23 to −45%), in the S. pimpinellifolium group too, indicating, even in low vigor rootstocks, a dilution effect worsening this nutraceutical trait of tomatoes.

A greenhouse experiment was conducted to study the effects of the O2 root zone level and grafting on chlorophyll fluorescence, photosynthesis and growth of cherry tomato grown in a hydroponic system. Two O2 concentrations in the root zone, namely Ox (saturation level) and Ox- (2–3 mg L−1), were applied for 30 days on self-grafted cherry tomato Dreamer or grafted onto the hybrids Arnold, Beaufort, Maxifort and Top Pittam. Root hypoxia increased minimum fluorescence (by 10%) while it decreased variable fluorescence and the maximum quantum yield of PSII (up to 16 and 8%, respectively). Moreover, it reduced leaf photosynthesis, transpiration and stomatal conductance (by 12, 17 and 13%, respectively), whereas it increased leaf electrolyte leakage (by 2.1%). The graft combinations showed a different ability in buffering the effects of root hypoxia on plant growth and related components, and these differences were related to their root biomass. The minimum fluorescence was negatively correlated to plant growth, so it may be a useful indicator to select tolerant rootstocks to root hypoxia. Our results suggest the occurrence of both diffusive and metabolic constraints to tomato photosynthesis under root hypoxia, a condition that can be mitigated by selecting rootstocks with a more developed root system.

The influence of ripening stage was evaluated on fruit characteristics of three widely cultivated eggplant cultivars (Birgah, Black Bell and Black Moon), with the aim to characterize their fruit residual waste for phytochemicals extraction. At overripening stage, eggplant fruits showed the highest average weight, dry matter content and weight incidence of the pulp. Total anthocyanins concentration of the peel (mainly represented by nasunin) was higher at commercial ripening, whereas total polyphenols (most of all 5-O-caffeoylquinic acid) and steroidal glycoalkaloids (α-solasonine and α-solamargine) peaked at the overripening stage. Because of these modifications, every ton of fresh fruit gave up to 59 g of total anthocyanins, 1054 g CAE of total polyphenols and 252 g of total glycoalkaloids, depending on cultivar and fruit ripening stage. This study highlighted the possibility to manage the choice of cultivar and harvest time in the view of valorise this raw material for phytochemical extraction.

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