Water and fertilizers use efficiency in grafted and non grafted tomato plants on soilless culture
The improved rooting environment and the absence of pathogens in substrates used in soilless cultures, make the use of grafted plants unnecessary when grown hydroponically. The worldwide water shortages and the increased environmental pollution indicate the use of any technique that increases the production with the highest possible water and fertilizers use efficiency. In this work water use efficiency (WUE) and fertilizer use efficiency (FUE) in agronomical and biological terms (g marketable fruit and g dry matter per litre of transpired water and g of absorbed nutrients, respectively) have been determined on non grafted 'Big Red' tomato plants (Lycopersicon esculentum Mill.) as well as 'Big Red' plants grafted on 'Big Red' and 'He-mans' rootstock. Plants were grown in an open hydroponic system. Measurements of leaf area and transpiration and nutrient concentrations in shoots, leaves and fruits as well as plants fresh and dry weight were performed on grafted and non grafted plants. The results indicate that non grafted tomato plants had 25 to 44% higher leaf area (and for this reason the highest water consumption) and 30% higher shoot and leaf dry weight compared to the grafted plants. In contrast grafted plants had 31 to 39% higher fresh fruit production. Finally grafted plants had 50 and 48% higher WUE and FUE, respectively, compared to non grafted plants as the latter consume more water and nutrients on unmarketable biomass (shoots and leaves).