Promotive effects of phosphorus on crop productivity, enzyme activities, anthraquinone and sennoside content inCassia toraL. – a medicinal herb

The plants of Cassia tora L. were grown in pots containing soil, supplied with five levels of phosphorus: 0 (Control), 0.1, 0.2, 0.3 and 0.4 g P per kg soil. The fresh and dry weights, number of leaves and leaf-area per plant were recorded. The leaves were analyzed for inorganic elements, such as nitrogen, phosphorus, potassium and calcium. Physiological and biochemical attributes including chlorophyll and carotenoid content, nitrate reductase activity, carbonic anhydrase activity, net photosynthetic rate, stomatal conductance and transpiration rate were determined. Yield attributes including number of pods, number of seeds per pod, 100-seed weight, and seed-yield per plant were recorded. In addition, protein, total anthraquinone glycosides (in seeds) and total sennoside content (in pods) were also estimated. The results showed that phosphorus at the level of 0.3 g per kg soil proved optimum and significantly enhanced most of the attributes studied.