Grafting Affects Tomato Growth, Productivity, and Water Use Efficiency under Different Water Regimes

The effects of grafting greenhouse tomato cultivars (Durinta and Valouro F1) onto three tomato rootstocks (Beaufort, Maxifort, and Spirit) under different irrigation regimes (50, 75, and 100% crop evapotranspiration [ETc]) were studied by evaluating the vegetative growth, proline, chlorophyll, and mineral content of the leaves as well as yield productivity, total yield water use efficiency (TYWUE), and yield response factor (Ky). Plant height, stem diameter, leaf area, and total yield decreased, whereas proline and TYWUE increased, with increasing water stress. Durinta showed more vigorous growth than Valouro. Plant growth, proline, Ca+2 and K+ concentrations, yield, and TYWUE were higher in grafted plants than in non-grafted plants. Negative effect of high water stress (50% ETc) was evident in the non-grafted plants, particularly in Valouro. A positive effect of grafting was observed when Beaufort was used as the rootstock. Durinta grafted onto Beaufort (DB) under moderate watering regime (75% ETc) exhibited water savings (25%) and higher yield (21.55–30.81%) and TYWUE (55.06–55.54%) than fully irrigated (100% ETc) control (non-grafted Durinta). Ky was lower in Durinta (1) than in Valouro (1.2), indicating lower tolerance of Valouro to water stress. Grafted DB showed higher tolerance to water stress (Ky = 0.5) than other combinations. The results indicated that grafting could alleviate some of the negative effects of water limitation on greenhouse tomato plants.