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

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.

Alterations in activities of acid phosphatase, alkaline phosphatase, ATPase and ATP content in response to seasonally varying Pi status in okra (Abelmoschus esculentus).

Phosphorus (P) is the second most important macronutrient for plant growth. Plants exhibit numerous physiological and metabolic adaptations in response to seasonal variations in phosphorus content. Activities of acid and alkaline phosphatases, ATPase and ATP content were studied in summer, rainy and winter seasons at two different developmental stages (28 and 58 days after sowing) in Okra. Activities of both acid and alkaline phosphatases increased manifold in winter to cope up with low phosphorus content. ATP content and ATPase activity were high in summer signifying an active metabolic period. Phosphorus deficiency is characterized by low ATP content and ATPase activity (which are in turn partly responsible for a drastic reduction in growth and yield) and enhanced activities of acid and alkaline phosphatases which increase the availability of P in P-deficient seasons.

Season-dependent mineral accumulation in fruits of Okra (Abelmoschus esculentus) and Tomato (Lycopersicon esculentum).

Season-dependent mineral accumulation was recorded in fruits of Okra and Tomato. The highest concentration was in summer in Okra and in winter in Tomato. Lowest concentrations were in winter in Okra and rainy in Tomato. Both crop plants indicated that the mineral contents were in the order of P > K > Ca > Mg > Na > Fe which also signify their relative functional importance in growth and metabolism.