The Use of a Tomato Landrace as Rootstock Improves the Response of Commercial Tomato under Water Deficit Conditions

Grafting onto drought tolerant rootstocks has been proposed as a useful strategy to overcome
future water scarcity periods. The ‘de Ramellet’ tomato is a drought tolerant landrace selected under
semiarid Mediterranean summer conditions under rain-fed or low irrigation. In this manuscript,
the responses of a commercial hybrid ‘de Ramellet’ genotype grafted onto a traditional ‘de Ramellet’
(RL) and a commercial Maxifort (Mx) tomato rootstocks under commercial greenhouse conditions are
studied. Non-grafted (NON) and self-grafted (SELF) plants were used as controls. Two water regimes
were established: well-watered (WW, covering plant water demands) and water deficit (WD, reducing
50% irrigation as compared to WW). The results confirm an improvement in agronomic performance
of Mx as compared to NON, but also show a similar improving eect of RL. Grafting enhanced plant
growth regardless of the rootstock underWWconditions. Similarly, water-use eciency (assessed
as leaf carbon isotope composition) increased in grafted plants under WD treatment as compared
to NON. Despite the lack of significant dierences, RL tended to promote higher fruit production
and fruit number than Mx, irrespective of the water treatment, whereas RL was the single graft
combination with higher fruit production than NON under WD. In conclusion, the results uncover
the potential of drought-adapted landraces to be used as rootstocks in order to increase plant growth
and fruit production under both well-watered and water deficit cultivation conditions.