Effect of senna stem treatments on growth, net photosynthesis, nitrogen metabolism and yield of pearl millet

Effects of senna stems @ 2.5 and 5.0 t ha⁻¹ and their extracts in chloroform and water were studied on pearl millet [Pennisetum glaucum (L..) Br. Cv. HHB-67] under rainfed condition. Application of senna stems and their extracts significantly increased leaf area, grain yield and dry matter production of pearl millet. Maximum favourable effects on plant growth and grain yield were observed with the application of water extract of senna stems. Leaf metabolites (viz. total chlorophyll, soluble protein, free amino acids), nitrate reductase activity and net photosynthetic rate at vegetative and flowering stages were significantly improved with the application of senna stems and their extracts in water and chloroform. Water extract of senna stems had maximum beneficial effects on leaf metabolites, nitrate reductace activity and photosynthetic efficiency. The results indicate a possibility of presence of growth promoting substance in senna stem because such dramatic increase within a short time can not be attributed to senna residue effects only. The occurrence of triacontanol in senna stems alongwith other nutrients and unknown factors might have contributed towards their positive effects on growth and metabolism of pearl millet.