Determination of sensitivity to ethylene in different types of tomatoes

In this study, the sensitivities of beefsteak (Tybif F1), cluster (Merkur F1) and heirloom (Yuksel Koy F1) types of tomatoes towards ethylene were investigated. For that purpose, tomatoes were harvested at the breaker stage and divided into three groups for different postharvest applications. First group of tomatoes was stored at 20°C and 60±5% relative humidity for 21 days. Second group of tomatoes were subjected to 150 ppm ethylene treatment after harvesting and fruits were stored for 35 days at 12°C temperature and 90±5% relative humidity and third group of tomatoes remained untreated and they were also stored for 35 days at 12°C temperature and 90±5% relative humidity. Second and third group of tomatoes were kept at 20°C and 60±5% relative humidity for additional 3 days to simulate their shelf-life period after different storage periods under cold storage. Data for weight loss, skin color (L*, C*, h°), total soluble solids (TSS), titratable acidity (TA), total chlorophyll content, lycopene content, ethylene production, respiration rates and amount of unmarketable fruits were determined for specific intervals of time under different storage conditions. Tomatoes stored at 20°C temperature exhibited increase in weight loss, C* values, lycopene content, ethylene production and respiration rate along with amount of unmarketable fruits however decrease in L* and h° values of fruit skin, titratable acidity, fruit firmness, total chlorophyll content were observed. Comparison of tomatoes stored under 20°C showed that maximum L*, C*, h°, fruit firmness, total chlorophyll content along with minimum weight loss, lycopene content and amount of unmarketable fruits were recorded in beefsteak type of tomatoes. Similarly, beefsteak type of tomatoes showed less ethylene production and respiration rates as compared to other types of tomato. Ethylene application increased weight loss, lycopene content, ethylene production, respiration rate along with amount of unmarketable fruits however it had decreased L*, h° values, titratable acidity, fruit firmness and total chlorophyll content in both cold storage and shelf-life conditions. During cold storage and shelf-life conditions maximal L*, h° values, fruit firmness, total chlorophyll content (only shelf-life conditions) were noted in beefsteak type of tomatoes. Furthermore, less ethylene production and respiration rates were also recorded in beefsteak type of tomatoes. Maximum titratable acidity, lycopene content, total chlorophyll content (cold storage only) along with less weight loss and amount of unmarketable fruits during both cold storage and shelf-life conditions were determined in heirloom type of tomatoes. Based on results obtained in our study, beefsteak type of tomatoes maintained the postharvest quality as compared to heirloom and cluster type of tomatoes for 21 days storage at 20°C. In contrast, beefsteak and heirloom type of tomatoes exhibited better performance when compared to cluster type of tomatoes during cold storage and shelf-life conditions. Consequently, beefsteak and heirloom type of tomatoes harvested at breaker stage can be commercially stored under cold storage at 12°C for 35 days with less postharvest losses. KEYWORDS: Beefsteak, Cluster, Ethylene, Heirloom, Postharvest, Quality, Solanum lycopersicum L., Tomato.