Assessing the heat stress tolerance potential of tomato lines under poly-house and open field conditions

Abstract

AbstractTomato, an important vegetable crop cultivated worldwide is an essential component of the Ghanaian diet. However, production in Ghana is hampered by heat stress (HS) during certain periods of the year. Tomato is sensitive to HS, especially during the reproductive stage, inducing pollen sterility, floral and fruit abortion, and culminating in low yield. This necessitates development of HS-tolerant tomato varieties. The HS-tolerance potential of 13 tomato lines was assessed under both poly-house and open field conditions at day temperatures of ~35°C. Evaluation was based on agro-morphological and physiological traits. Most lines had their highest fruit yield (FY) under poly-house conditions, but declined drastically (up to 92%) in the field when day/night temperatures reached 40/28°C respectively. A second field experiment revealed that the low FY was due to poor fruit set despite the many flowers produced. Correlations between days to 50% fruiting and physiological traits (ΦII, chlorophyll content, and leaf temperature) were high and significant, whereas those between FY and all physiological parameters were negligible. Lines KAC13 and KAU03 consistently had high FY, ΦII, and chlorophyll content. Nevertheless, KAU01 had the highest FY in two out of three experiments in addition to having the highest percentage fruit set. The lines that show high potential tolerance to HS may be incorporated into breeding programmes to further improve the tolerance of tomatoes to HS.

Keywords

• heat stress
• tomato
• physiological parameters
• agro-morphological parameters