LEAF PHYSIOLOGICAL AND ROOT MORPHOLOGICAL PARAMETERS OF GRAFTED TOMATO PLANTS UNDER DROUGHT STRESS CONDITIONS

Grafting of tomatoes becomes more and more popular particularly under adversarial soil conditions such as low and high soil temperature, salinity, alkalinity and drought. This study focused on the interactions between tomato rootstock and scion varieties regarding growth, development and yield under different water supply levels to identify the morphological and physiological plant traits related to drought tolerance of a tomato crop. Different tomato scion (S) varieties (Pannovy and Treasury) were grafted on different tomato rootstocks (R) (Brigeor and Maxifort) varieties and were grown under well watered (WW) and drought stress (DS) conditions. As control plants the S varieties were grafted on themselves. To evaluate growth and morphological effects, various plant parameters such as leaf area, fruit fresh matter, fruit diameter, main stem length, total plant dry matter, root fresh and dry matter, fruit water use efficiency (WUE), shoot WUE, total root length, root length density and root diameter were investigated at final harvest. To determine physiological plant traits, leaf water potential, leaf relative water content and leaf osmotic potential were assessed. Morphological parameters such as fruit fresh matter, fruit diameter, main stem length, total plant dry matter, fruit WUE, leaf area, root dry matter, total root length, and root length density were higher under WW than under DS conditions. As well, in terms of physiological plant parameters such as leaf relative water content (LRWC) was higher under WW than under DS conditions. Whereas, LRWC and leaf osmotic potential increased with increasing water stress. Generally, the self-grafted S varieties decreased their morphological parameters while an increase exhibited when they were grafted onto R varieties under DS condition. As a result of higher fruit WUE and shoot WUE the best performance in fruit fresh matter was shown by Pannovy/Brigeor combination under limited water supply levels.