Season-controlled changes in biochemical constituents and oxidase enzyme activities in tomato (Lycopersicon esculentum Mill.).

ABSTRACT

Season-controlled changes in biochemical constituents viz. carotenoids (carotene and xanthophyll) and pectic substances along with IAA-oxidase and polyphenol oxidase (PPO) enzyme activities were estimated/assayed in leaves of Lycopersicon esculentum Mill. (tomato) in two developmental stages – pre-flowering (35 days after sowing) and post- flowering (75 days after sowing) in three different seasons – summer, rainy and winter.Carotenoid content along with pectic substances were highest in winter and declined significantly in summer followed by rainy i.e. winter>summer>rainy. Carotenoid content was significantly higher in the pre- flowering as compared to postflowering in all three seasons while pectic substances increased in the post- flowering as compared to pre- flowering throughout the annual cycle. IAA oxidase and PPO enzyme activities were enhanced in rainy and decreased sharply in summer and winter i.e. rainy>summer>winter. Both the enzymes exhibited higher activity in the post- flowering stage as compared to pre- flowering in all three seasons. These results indicate winter to be the most favourable season for tomato plants while rainy season environmental conditions prove to be unfavourable (stressful) with diminished content of carotenoid and pectic substances and low activities of IAA oxidase and PPO, ultimately leading to poor growth and productivity.