Impact of heat stress on Fusarium wilt (F. solani) incidence in cultivated tomato and related species

Abstract

The incidence of Fusarium wilt on tomato is increasing with rising global temperatures. To assess the impact of this disease, a factorial experiment of ten tomato genotypes grown at two temperatures and two levels of disease severity was established using hydroponics in a poly tunnel house. Fusarium wilt inoculum was used to promote disease and the heat treatment produced temperatures >40 o C for most of the growing season. Genotypes varied significantly for disease incidence and response to heat stress. Significant temperature x disease treatment interactions were observed for number of inflorescences per plant (IPP), fruit set ratio (FSR), number of fruits per plant (FPP), fresh fruit weight (FFW), plant dry weight (PDW) and disease severity index (DSI). A highly significant correlation (R 2 = 0.98) was observed between disease incidence under both control and high-temperature treatments, even though the treatments were significantly different. Biomass was reduced under both heat and disease stress and was correlated across treatments (R 2 = 0.86). The genotype LA3847, characterized by relatively low fruit set inhibition and high fruit yield, was classified as tolerant to both heat and disease stress. Concurrent selection for improved disease and heat tolerance appears possible as the disease severity index and the heat stress response were not correlated (R 2 = 0.11).Keywords: tomato, genetic variability, heat stress, Fusarium wilt. Abbreviations: IPP_ number of inflorescence per plant; DSI_ disease severity index; FSR_ fruit set ratio; FPP_ fruit per plant; FFW_ fresh fruit weight; PDW_ plant dry weight.

Morpho-Physiological Traits Linked to High Temperature Stress Tolerance in Tomato <i>(S. lycopersicum L.)</i>

“…Relationship between change in dry weight and sucrose in heat tolerant and sensitive genotypes in ten genotypes selected on the basis of dry weight loss (A) and six genotypes selected on the basis of drop in fruit setting (B). American Journal of Plant Sciences (with the exception of sucrose) suggests that these compounds have a protective role in plant tissues under stress [41] (Figure 5). L-proline in particular was linked to enhanced stress response and may be responsible for maintenance of biomass under heat stress [41].…”

“…American Journal of Plant Sciences (with the exception of sucrose) suggests that these compounds have a protective role in plant tissues under stress [41] (Figure 5). L-proline in particular was linked to enhanced stress response and may be responsible for maintenance of biomass under heat stress [41]. Nevertheless, the stress response is likely to be complex as malic acid, pentaerythitol, and L-proline were all up-regulated in subset-B and this probably provided more stable fruit setting in tolerant genotypes under heat stress [41].…”