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In this study, the effects of repeated cycles of drying and rehydration on some physiological traits were assessed in long shelf-life tomatoes cultivated in a typical semi-arid area of Southern Italy. Three Sicilian landraces ('Custonaci', 'Salina', and 'Vulcano') from the germplasm collection at CNR-IBE (Catania, Italy) and a commercial tomato mini-plum ('Faino Hy., control) were investigated under three water regimes: DRY (no irrigation), IRR (long-season full irrigation) and REW (post-drought rewaterings). Net photosynthetic assimilation rate (Pn), leaf transpiration (E), stomatal conductance (gs), instantaneous water use efficiency (WUEi), leaf intercellular CO2 (Ci, ppm), and leaf temperature (°C), were measured during the growing season. At harvest (late July), fruit production per plant was measured and ripened fruits were analysed for total solids (TS), soluble solids (SS), reducing sugars (RS), vitamin C (AscA), and total phenols (TP). Pn promptly responded to rewatering (REW), quickly increasing immediately after irrigation, and declined with soil drying up. All genotypes had similar physiological pathways in DRY, but in IRR, 'Faino' had higher Pn (up to 31 μmol CO2 m−2s−1) and E (up to 18 mmol H2O m−2s−1). Stomatal conductance (gs) after rewatering steeply increased and quickly declined after that. All local landraces had the same gs in IRR and REW. Variations in RWC were less pronounced than those in other physiological parameters. WUEi in REW and DRY proceeded similarly (up to 3 μmol CO2 mmol H2O). Irrigation in REW significantly promoted plant productivity over the DRY control (up to +150% in 'Vulcano'). TS and SS in REW were lower than those in DRY, but higher (+19 and +7%, respectively) than in IRR. Vitamin C was greater in DRY and REW (26 and 18% higher than in IRR, respectively). TP in all local tomatoes were significantly higher (up to +29% in 'Vulcano') than those in the commercial control. Water regime had a minor effect on TP in 'Custonaci' and 'Salina'. Principal Component Analysis (PCA) provided information on the changes in physiological and fruit quality traits in tomatoes in relation to cultivars and water regimes. The results of this study also revealed that a water-saving irrigation strategy where few irrigations are applied after prolonged periods of drought might be profitable in terms of fruit production enhancement in long shelf-life tomatoes and that limited rewaterings in most cases, help retaining high levels of fruit quality traits. [ABSTRACT FROM AUTHOR]

Wheat landraces are traditional varieties that have evolved over generations in response to local environments and farming practices and therefore exhibit remarkable adaptability to challenging climatic conditions and low-input farming systems. While the suitability of Mediterranean landraces to non-optimal climatic conditions during anthesis and grain ripening stage have been previously assessed, the role of photosynthesis efficiency and stomatal control on this resilience remains unexplored. This study aims to evaluate the relationship between grain yield and the post-anthesis flag leaf gas exchanges of Sicilian wheat landraces under irrigated and rainfed conditions and to compare these traits to modern durum (Triticum turgidum subsp. durum) and bread wheat (T. aestivum) varieties. Results indicate that wheat landraces respond to water availability similarly to modern varieties, reducing stomatal conductance by 26.8% and net photosynthesis by 18.1% under rainfed conditions, resulting in 10.6% lower grain yield compared to irrigated conditions. However, some landraces demonstrate comparable or even higher flag leaf net photosynthesis rates and lower transpiration levels, leading to higher yields in both rainfed and irrigated conditions, confirming their value as a source of gene pool for wheat breeding programs in drought-prone Mediterranean regions. [ABSTRACT FROM AUTHOR]

Verticillium wilt of olive (VWO), caused by the soil borne fungus Verticillium dahliae, is one of the most relevant diseases affecting this crop worldwide. One of the best VWO management strategies is the use of tolerant cultivars. Scarce information is available about physiological and structural responses in the leaves of olive cultivars displaying different levels of tolerance to VWO. To identify links between this phenotype and variations in functional characteristics of the leaves, this study examined the structural and physiological traits and the correlations among them in different olive varieties. This evaluation was conducted in the presence/absence of V. dahliae. On the one hand, no leaf trait but the area was related to VWO tolerance in the absence of the pathogen. On the other hand, after inoculation, susceptible cultivars showed lower leaf area and higher leaf mass per area and dry matter content. Furthermore, at the physiological level, these plants showed severe symptoms resembling water stress. Analyzing the relationships among physiological and structural traits revealed differences between tolerant and susceptible cultivars both in the absence and in the presence of V. dahliae. These results showed that olive leaves of VWO-tolerant and VWO-susceptible cultivars adopt different strategies to cope with the pathogen. [ABSTRACT FROM AUTHOR]

Deficit irrigation is a valid alternative to conventional irrigation to save water while maintaining high productivity in tomatoes. However, crop sensitivity to water stress due to deficit irrigation may change with the growth stage. To assess the physiological and agronomic responses of processing tomatoes to deficit irrigation applied at critical stages, a field experiment was conducted in a coastal site of Southern Italy, where seven irrigation treatments differing for daily evapotranspiration (ETc) restored (100%—full or 50%—deficit) and the time of watering (long-season or limited to the vegetative period or to flowering) were applied to processing tomatoes cv. Hypeel F1. Plants continuously irrigated and those irrigated only at flowering maintained higher rates of leaf transpiration (E) and stomatal conductance (gs) over those irrigated only during the vegetative period. Fruit yield was the greatest under long-season full irrigation (51 t ha−1). Severe soil water deficit during flowering, more than during the vegetative period, adversely affected crop productivity. Irrigation water use efficiency (IWUE) was maximized under long-season deficit irrigation (>19 kg m−3) or deficit irrigation during flowering (>16 kg m−3). E and gs measured at early or mid-flowering may be adopted as valuable indicators to predict crop productivity; however, they may be altered under high vapor pressure deficit (VPD). Predawn water potential, being little affected by VPD, is a more reliable parameter than leaf transpiration and stomatal conductance under these climatic conditions. [ABSTRACT FROM AUTHOR]