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The response of chlorophyll fluorescence, photosynthetic CO 2 assimilation (PN), stomatal conductance (gs), electrolyte leakage, and transpiration (E) was observed in Jatropha curcas seedlings subjected to soil flooding. A strong reduction in growth, leafarea expansion (64%), and stomatal conductance (45%) impaired photosynthetic CO 2 assimilation (66%), which eventually reduced biomass yield. The ratio between variable-to-initial chlorophyll fluorescence (Fv/Fo) and the maximum quantum yield efficiency of the photosystem II (Fv/Fm) was used to explore damage associated with the functioning of the photosynthetic apparatus. A strong, nonlinear correlation between physiological parameters and soil flooding duration was found. Our study primarily revealed consequences of epigenetics, i.e. stagnant soil flooding, which affected growth, development, and performance of Jatropha curcas significantly. The activities of catalase (CAT), ascorbate peroxidase (APx), glutathione reductase (GR), and glutathione peroxidase (GPx) in leaves increased, implying an integrated pathway involving CAT, APx, GR, and GPx for protection against the detrimental effects of reactive oxygen species (ROS) during soil flooding.

Photosynthesis and the phenomenon of leakage have been studied in bryophytes Porella platyphylla (L.) Lindb., Plagiochila asplenioides (L.) Dum., Plagiothecium undulatum (Hedw.) B. & S., and Scapania undulata (L.) Dum. which were collected from habitats subjected to a wide range of moisture stresses. The percentage decrease in photosynthesis has been used as a measure of desiccation injury and the desiccation resistance has been denoted as number of days in which a particular injury level occurred. In all the species the rate of leakage reached the highest value in the first 2 min of re wetting, and the slowed down. Such reduction of leakage with time is believed to be due to the reassemblage of membrane structure, which results in a return of normal semipermeability, or to the rapid decrease of solutes in dead or injured tissues that occurs after rewetting. The solutes in the leachate are found to be reabsorbed by the viable cells. The leakage from viable tissues is likely to be due to the shock resulting from sudden immersion of desiccated shoots into water, while in injured or dead cells it is due to the disruption of membranes. The physiological and ecological implications of the leakage phenomenon are also briefly discussed.

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Stigmatic receptivity restricts the successful pollination in cereal crops. The present study deals with the biochemical test for enzymes producing in stigma of field crops such as Indian mustard, rice and wheat. The alcohol dehydrogenase and hydrogen peroxide assays revealed stigmatic receptivity as a violet color and oxygen bubbles released by the chemical reaction. Therefore, the 2 quick tests are in conformity to each other and supported the seed set data, which was utmost at blooming stage of flower ranged between 2–4 d All the 3 crops showed variation in stigmatic receptivity with respect to different time periods of blooming stages and hence, it may affects simultaneous pollen germination and tube growth, fertilization and seed set. The present finding suggests that the growth of pollen tube and stigma receptivity could be influenced by specific enzymes on stigma surface after 2–4 d of blooming stage, which contributes to proper seed set.

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