Seed Priming and Foliar Application of Nutrients Influence the Productivity of Relay Grass Pea (Lathyrus sativus L.) through Accelerating the Photosynthetically Active Radiation (PAR) Use Efficiency

Abstract

The efficiency of a crop to intercept and utilize solar radiation for photosynthates production serves as one of the deciding factors of the productive potential of the crop stand. Interception and use efficiency of photosynthetically active radiation (PAR) were estimated in relay grass pea under different nutrient management schedules in consecutive two crop seasons of 2017–2018 and 2018–2019. Treatments were two levels of seed priming (i.e., 1. S1: Without seed priming and 2. S2: Seed priming with ammonium molybdate at 0.5 g kg−1 seed) and five levels of foliar-applied nutritions with various combinations of 2% Urea and 0.5% NPK (19:19:19) shuffling their times of application, replicated thrice laying out in a factorial randomized block design. Seed priming along with twice sprays of NPK (19:19:19) at pre-flowering followed by a second one after 15 days recorded maximum leaf area index (LAI) and total chlorophyll content augmenting greater interception and use efficiency of PAR with highest biomass accumulation, crop growth rate (CGR) and leaf nutrient contents leading to a significant increase in seed yield over control (1696.70 and 1182.00 kg ha−1, respectively) in a pooled analysis. LAI and total chlorophyll content established linear relationships with PAR interception explaining about 94 and 88% variations in intercepted PAR at 90 DAS. Intercepted PAR during different phenophases was positively correlated to dry matter accumulation and net photosynthetic rate with polynomial relationships. Seed yield of grass pea varied about 95 and 96% respectively during 2017–2018 and 2018–2019 with the variations in PAR interception at the pod developmental stage.