Plants respond to prevailing environmental conditions in complex and dynamic ways. Seasonal environmental patterns and the age of the plant parts profoundly influence plant physiology.Abelmoschus esculentus (Okra) and Lycopersicon esculentum (Tomato), the test materials, were grown in pot culture in summer, rainy and winter seasons under the tropical environmental conditions of Kolkata, West Bengal, India and the leaf samples collected in the three above mentioned seasons and two developmental stages - preflowering (vegetative) and postflowering (reproductive).Summer for Abelmoschus and winter for Lycopersicon were the favourable seasons while winter for Abelmoschus and rainy for Lycopersicon were periods of seasonal stress.The parameters under study served as useful bioassay indices of environmental stress, while the two crop plants acting as a measure of the prevailing environmental conditions, can serve as efficient bioindicator species. Thus, plant response to environment indicates the enormous impact of environmental stress on agricultural productivity.