Effect of high temperature on quality of processing-tomatoes of various genotypes ripened off the vine

High-temperature effects on the quality of several genotypes of processing-tomatoes were studied. The quality parameters included colour, carotenoid concentration, acidity, pH and content of total soluble solids. Fruits exposed to either 27.5 or 30°C during ripening showed a significant decrease in carotenoid concentration and colour score as compared with fruits kept at 25°C. Soluble solid content did not change and acidity increased with high temperatures. Among the individual carotenoids, although lycopene concentration decreased, a more pronounced decrease occurred in the concentration of its precursors, phytoene and phytofluene. Different tomato lines responded differently to high-temperature exposure. UCX100 15-2-2 was found to be generally insensitive. However, a crimson, high pigment (og, hp) line, which is characterized by high levels of carotenoids, was found to be sensitive. Under high temperature, UCX100 15-2-2 exhibited higher fruit quality than either the og, hp line or the cultivar UC82-C in all parameters examined.