Suitable rootstocks can alleviate the effects of heat stress on pepper plants

In this study, different pepper rootstocks are tested for their ability to overcome heat stress situations. This work aims to evaluate: (i) the physiological mechanisms that occur during long heat stress periods (7 days) under controlled conditions in a pepper variety grafted onto accessions; (ii) the heat stress behaviour of these grafted pepper plants under greenhouse conditions in terms of marketable yields. For this purpose, plants of Lamuyotype sweet pepper 'Herminio F1' (VA), grafted onto six accessions (VA/A25, VA/A31, VA/A34, VA/A52, VA/ A57, VA/A6), and a self-grafted variety (VA/VA) were grown under controlled conditions in growth chambers (28/24 degrees C, day/night temperatures and 38/24 degrees C for control and heat stress, respectively) and under greenhouse conditions (38/24 degrees C). For the controlled conditions, relative growth rate, leaf area, electrolyte leakage, chlorophyll a fluorescence and heat shock proteins were determined. For the greenhouse conditions, fresh and dry weigh, electrolyte leakage and fruit yield were determined. Our results confirmed that grafting a pepper cultivar onto appropriate rootstocks such as A6, A25 and A57 can overcome the negative effects of heat stress conditions with a higher relative growth rate, leaf area and Fv/Fm, and lower electrolyte leakage under the controlled conditions, and with higher marketable yields under the greenhouse conditions.