Structural, physiological and metabolic integrated responses of two tomato (Solanum lycopersicum L.) cultivars during leaf rehydration

The aim of this work was to characterize the recovery responses of two tomato cultivars, Rio Grande (RG) and Pera Quibor (PQ), to rehydration after water deficit. Recovery responses were measured in terms of timing and magnitude, and analysed as indicative of tolerance. The parameters evaluated were: soil water potential (soil Ψw) and leaf water potential (leaf Ψw); leaf osmotic potential (leaf Ψs); leaf relative water content (LRWC); stomatal conductance (gs); Rubisco activity; protein content; fresh mass (FM) and dry mass (DM); leaf area (LA); specific leaf area (SLA) and leaf density (D). Different types of responses were observed: as common responses of both cultivars, full recovery of soil Ψw, Ψs, and LRWC were found regardless of stress level and length of rehydration time. Recovery of protein was full in PQ and partial in RG. Full recovery of gs and fresh mass and partial recovery of Ψw and leaf area was observed in both cultivars regardless of the level of stress but regarding rehydration time. Full recovery of Rubisco activity was found regarding level of stress and rehydration time. As different responses between cultivars, full recovery of DM was found in PQ and of SLA and leaf D in RG regardless of the level of stress but regarding rehydration time. Partial recovery of SLA and leaf D was found in PQ regarding both level of stress and rehydration time. The delayed recovery of leaf structural changes promoted full recovery of DM and protein in PQ. The correlations between physiological and metabolic parameters and observed sclerophylly indices, reveal integrated tolerance mechanisms intended to protect plant cultivars from intermittent changes in water conditions.