Growth response and nitrogen metabolism of sunflower (Helianthus annuus L.) to vermicompost and biogas slurry under salinity stress

Sunflower was grown under saline media with or without vermicompost amendment and biogas slurry, the organic fertilizers. A randomized complete block design with five replications was used. Forty-five pots were divided in three sets comprising of 15 pots each. Out of 15 pots of each sets, five pots of each were subjected to different levels of saline water irrigation i.e. electrical conductivity (EC): 0.5, 4.8 8.6 dS/m). Amendments of vermicompost and biogas slurry have shown some reduction of sodium induced inhibitory effects. Analyses of fresh and dry weight of leaves, ions, amino acid, protein and nitrogen metabolism enzymes in leaves etc., have been undertaken with reference to above-mentioned treatments. Organic manure amendments improved growth yield, nitrate and protein content and decreased the amount of sodium (Na+), chloride (Cl-), ammonium and total amino acid under saline or non-saline condition. Activities of nitrogen (N)-assimilating enzymes i.e. nitrate reducatse (NR, EC 1.6.6.1), nitrite reductase (NiR, EC 1.6.6.4), glutamine synthetase (GS, EC 6.3.1.2) and glutamate synthase (NADH-GOGAT, EC 1.4.1.14) were enhanced to some extent irrespective to non saline or saline condition. Under salinity NADH-glutamate dehydrogenase (GDH, EC 1.4.1.2) activity was stimulated concomitantly with the increasing ammonium contents and proteolysis activity in the leaves and organic manure did not show a significant difference as compared to their respective control. With respect to salt stress, among the two above-mentioned organic manure, vermicompost showed better result in the entire studied parameter as compared to the biogas slurry.