Effect of nitrogen and various shade levels on Coriander (Coriandrum sativum L.) production

Plant grown under full sunlight (0%) had significantly greater height increments, and more leaflets, vertically oriented branches, umbers/plants, umbellets/umber, flowers/umbellets and dried seed yield than the shaded plants. Stomatal density was also greater in plants grown under full sunlight. However, the leaf area, shoot/root ratio and leaf chlorophyll content of those in the open were lesser than the shaded ones. The increase in nitrogen treatments caused significant increase in the number of leaflets and chlorophyll content. Significant increase in percent fruit set and seed yield was also observed with increasing nitrogen level. A significant reduction in number of umbellets per umber was observed as the N level was increased and this is particularly evident at higher shade level. Significant reductions were observed in height increments, number of leaflets, umbellets/umber, flowers/umbellet, fruit/umbellet, % fruit set and seed yield with high nitrogen treatment and higher shade levels. However, under open condition or at 25% shade, favorable effects of higher N levels were noted especially in terms of number of leaflets, fruits/umbellet, % fruit set and seed yield. Anatomical studies showed that the shaded leaves have poorly developed palisade layer; the thickness of palisade layer increases as the level of nitrogen is increased. The phosphorus content in the soil at 75% shade were relatively higher than those with higher light intensities. Tissue analysis of the leaves showed that % N and % K were higher at greater shade levels, while the reverse was observed for % P. Oil extraction from dried seeds by steam distillation was done from plants grown under sunlight and at 25% shade. No seeds were harvested at higher shade levels. Plants grown at 25% shade level have relatively higher yield of essential oil than at 0% shade