Varietal Differences in Tomato Intumescence under Changing Water Conditions

Abstract

Tomato (Solanum lycopersicum L.) intumescence severely affects tomato plants and thereby crop yields. In this study, we investigated the differences in intumescence between varieties. We assessed the shoot:root (S/R) ratio and incidence of intumescence in seedlings of 12 tomato varieties subjected to sudden increases in ambient humidity and soil moisture. The S/R ratio and severity of intumescence injury were positively correlated. Next, three tomato varieties with different S/R ratios and intumescence incidence were assessed. Changes in xylem pressure potential of seedlings occurred in response to a changing water environment in a controlled environment chamber, i.e., from a dry condition (50% relative humidity, no irrigation) to a wet condition (90% relative humidity, sub-irrigation). The xylem pressure potential decreased under dry conditions in relation to the S/R ratio and intumescence incidence but increased rapidly after exposure to wet conditions. Tomato varieties with large S/R ratios showed large changes in their water potential in response to changes in the surrounding water environment, and it is thought that cells are more likely to rupture when water potential increases after a transition from dry to wet conditions.