Effect of grafting on eggplant leaf gas exchanges under mediterranean greenhouse conditions

Grafting is an easier and faster approach than plant breeding to take advantage of both existing resistant plants, especially wild cultivars, and high-bred cultivars. The aim of this study was to investigate the changes in leaf photosynthetic capacity of a hybrid eggplant Solanum melongena L., cv. Rima (R), widely used in Greece] when grafted on tomato rootstocks known for their resistance to nematodes and diseases. For this purpose, a hybrid egg-plant has been used as a control and has been self-grafted (grafting of a scion on its own roots used as rootstock) RR and also as a scion on two hybrid tomatoes rootstocks, as follows: Primavera (RP) and Heman (RH). Leaf photosynthetic capacity was estimated by measuring the leaf gas exchanges under several light levels at ambient CO2 concentration to approximate the leaf light response curve. The measurements performed control plant R and self-grafted eggplants RR show that the leaf respiration per unit leaf area is not altered by the scion/rootstock combination. These elements point out a scion controlled respiration, independent of the rootstock. The leaf photosynthetic capacities of the R and RR treatments were not different, while one of the scion/rootstock combinations (RH) showed a significant change with respect to the control treatments. The rootstock therefore seems to be able to modify the scion leaf photosynthetic capacity, but this may not be true for some scion/rootstock combinations (RP in our case). Leaf stomatal conductance and transpiration were not modified by the grafting, so that the water use efficiency was only altered by the modifications of the net assimilation.