Standardization and estimation of nitrate reductase activity in the leaves of Ammi majus L. (Bishops weed) in relation to sulphur deficiency and seed yield

Field experiments were conducted to determine the interactive effect of sulphur (S) and nitrogen (N) in relation to nitrate reductase activity as the enzyme catalyze rate-limiting step of the assimilatory pathways of nitrate and sulphate, and seed yield of Ammi majus L. (commonly called as atrilal). To carry out this study we cultivated atrilal in experimental field and used two combinations of sulphur (S) and nitrogen (N) nutrient (-S+N & +S+N in kg ha(-1)) along with control group (without S & N) in soil during sowing. Sulphur & nitrogen nutrients were applied into field as single basal dose. To the best of our knowledge, no report has been published so far to get the reliable protocol for NR activity in terms of medicinal plant productivity and quality; hence, we standardized the NR activity in leaves prior its estimation in the experimental materials. Results show that sulphur application significantly enhanced the nitrate reductase activity (NR) in fresh leaves of atrilal as well as seed yield (P<0.05) when compared with the sulphur deficient (-S+N) and control group. Internal CO2 concentration and stomatal conductance were also high in the leaves of Atrilal at different growth stages and this increase may be correlated with increased photosynthesis rate and higher NR activity in the leaves of plants grown with combined application of S and N when compared with N alone. The results obtained in this study suggested that sulphur is involved along with nitrogen in regulation of enhanced NR activity and physiological changes which results higher seed yield.