Dynamics of mineral nutrients in tomato (Solanum lycopersicum L.) fruits during ripening: part II—off the plant

Abstract

Tomato (Solanum lycopersicum L.) fruits of nine popular varieties in India were analysed for change in the levels of different nutrients (P, K, Fe, Zn, B, Cu, Mg, Ca and Mn) during the period of their postharvest ripening (fruits harvested at green mature stage and stored at 25 ± 1 C). This work is in continuation of our previous and related work wherein similar studies were done on the tomato fruits undergoing ripening while attached to the plant (Ramesh in 1–15, 2020). Here in this study, nutrients were estimated in the outer pericarp of tomato fruits at the time of their harvest (at green mature stage) and during the storage period at 5, 10 and 14 days after harvest (DAH). Under above said storage conditions, ripening behaviour of tomato fruits of different varieties was also determined by ripening index (RI %) at 3, 5, 8, 10 and 14 DAH. The results on nutrients showed net increase in P, K, Fe, Zn, B and Cu with static levels for Mg, Ca, and Mn at 14 DAH in comparison to their levels at green mature stage. The increase is explained in view of remobilization of nutrients from other parts of the fruit to the outer pericarp. While, internal mobilization of nutrients within the fruit might have helped in maintaining the static level of nutrients. Correlation analyses revealed that lower content of K and Ca along with higher content of B and Cu can impart slow ripening to tomato fruits. Comparison between plant-attached (our earlier study) and plant-detached tomato fruits (this study) indicated that in contrast to the fruits at green mature stage there is net increase in Zn, B, Cu, Mg, Ca and Mn in the outer pericarp of plant-detached ripened fruits. This was due to the internal mobilization of nutrients within the fruits towards the outer pericarp and absence of any remobilization or back flow of nutrients away from the fruits as the fruits were off the plant.