Nitrogen metabolism and nitrate reductase activity in different parts at three phases of cajanus cajan (l.) genotypes

In the present study twelve genotypes of pigeonpea (Cajanus cajan (L.) Millspaugh), which were divided into three groups based on the duration for flower initiation i.e. Short duration (ICPL151, ICPL87, ICPL1, ICPL6), Medium duration (T21, HY2 mutant, Pusa agheti, C11) and Long duration (ICPL270, ST1, PDM1, LRG30) were selected and was raised at the Experimental Farm of the Department of Botany, Andhra University, Waltair, Visakhapatnam, A.P., India, on the total nitrogen, soluble nitrogen, insoluble nitrogen, total protein and nitrate reductase activity in the whole plants, leaves, stems and roots of the pigeonpea genotypes at three different phases of crop growth i.e. vegetative, flowering and seed maturation phase. The total nitrogen, insoluble nitrogen and protein content of the stems and roots showed an increasing trend from the vegetative to the seed maturation phase in all the pigeonpea genotypes. Among the different parts studied the leaf recorded higher values of total nitrogen, insoluble nitrogen and protein content than the stems and roots. The soluble nitrogen content of the whole plant, stems and roots exhibited an increase from the vegetative to the flowering phase and declined at the seed maturation phase and the leaf exhibited a decreasing trend towards the seed maturation phase. Maximum value of total nitrogen exhibited in ICPL87 at the vegetative phase and maximum amount of insoluble nitrogen exhibited in PDM1 at the flowering phase in crop growth. At the vegetative phase ICPL87 of short duration genotypes exhibited higher quantity of protein content in the whole plant and total leaves. A continuous decrease of nitrate reductase activity was observed in all the genotypes studied, except in the ICPL87 of short duration group recorded highest nitrate reductase activity.