Effect of fruit stalk on post-harvest physiology of tomatoes.
Abstract
This study investigated the effect of fruit stalk on the postharvest physiology and therefore shelf
life of tomatoes in two common commercial tomato varieties grown in Uganda namely Top 22,
12 F1 and Ansal F1. Top 22,12 variety tomatoes were harvested from the Smart Green House
Hydroponics Facility at Makerere University Agricultural Research Institute Kabanyolo
(MUARIK), and Ansal F1 variety tomatoes were got from a vegetable farm near Semuto
Township in Nakaseke district. Harvesting was done at the breaker stage of ripening considering
the two treatments of with and without stalks, then stored for fifteen days using the experimental
excogitation of Completely Randomized Design (CRD) inside cabinets in a laboratory
environment at the School of Agricultural Sciences Plant Biotechnology laboratory set at Room
temperature (25 ± 50C) and 70 ± 5 % Relative Humidity.
The experimental materials were analyzed, and data collected at intervals of three days for fifteen
days on percentage weight loss using an electronic balance, color development using Color Grab
phone application, Total Soluble Solids (TSS) using hand refractometer, changes in pH using
electronic pH meter, chlorophyll and carotenoid content using spectrophotometer.
Data analysis was done using R-studio software (Version 4.3.1). Analysis of variance (ANOVA)
was performed to test the difference between the two factors of variety and treatment, Fisher’s
LSD at 5% significance level was to separate the means of the factors.
The results showed that tomatoes harvested and stored with stalks were superior to those
without. Stalked fruits had a lower (18%) percentage weight loss than stalked fruits (15%).
Chlorophyll content was higher in stalked fruits (2.43 μg/ml) than in destalked fruits (2.39
μg/ml). Green peel color percentage was higher (52.1%) in stalked fruits than in destalked fruits
(48.7%) while red peel color percentage was higher in destalked fruits (58.8%) than in stalked
fruits (53.7%) implying that stalked fruits could last longer in storage due to delay in the
physiological processes leading to above changes. Carotenoid content was not affected by
treatments applied or variety as an individual factor but rather affected by the interaction
between the two factors whereby destalked fruits of the two studied varieties had a higher mean
carotenoid content (0.561 μg/ml) than in stalked fruits (0.433 μg/ml) on the third day of the
experiment. This further revealed the effect of stalk removal in quickening ripening and eventual
fruit spoilage.
Total soluble solids were higher in destalked fruits (6.9%) than in stalked fruits (6.5%) implying
that destalked fruits ripened and accumulated sugars faster than stalked fruits, however, faster
ripening of destalked fruits leads to faster degradation and short shelf life. The pH of stalked
tomato fruits was higher (4.6) than that of destalked fruits (4.4).
The findings of this study suggest that harvesting tomatoes with stalks can help to improve their
postharvest quality and shelf life because the stalk helps to maintain the moisture content of the
fruit and may contain substances that help to delay ripening and senescence. These findings have
implications for the tomato industry. By harvesting tomatoes with stalks, producers can help to
ensure that their products reach consumers in good condition. This can lead to increased profits
and satisfaction for producers and consumers alike.