Metabolic adjustments in forage oat (Avena sativa L.) genotypes under different sowing windows

The current investigation was aimed to study the influence of planting dates (9 Oct, 24 Oct, 13 Nov, 26 Nov, 11 Dec, and 26 Dec) and maturity stages (40, 50, and 60 DAS) on nitrogen metabolic enzymes and biochemical constituents. The experiment was laid out in randomized block design during the winter season of 2019 by using two oat genotypes (OL-10 and OL-11) with variable growing ability. The activity pattern of studied enzymes revealed upregulated nitrate assimilation during optimum (Oct 24) and sub-optimum (Oct 9 and Nov 13) planting dates but a reverse trend was observed during late planting dates; LPD (Nov 26, Dec 11, and Dec 26). The environmental constraints during LPD resulted in the accrual of nitrate above toxic levels (> 2000 ppm). The regression analysis depicted a significant relationship of nitrate assimilating enzymes and nitrate–N with temperature and sunshine hour. Examination of ammonia assimilation and transaminases suggested that the enzyme activities got uplifted during late planting dates but were stable or slightly low at optimum and sub-optimum ones. Additionally, OL-10 proved to be an N-efficient genotype in comparison with the OL-11 genotype because of its high N assimilation potential. Therefore, gaining a better understanding of planting time is crucial for sustainable livestock production.