Grass pea (Lathyrus sativus L.) is a dual-purpose annual legume grown for its seeds for human consumption, and fodder for livestock feeding. But most of the farmers are not aware of proper varieties and proper phosphorus dose of grass pea. Keeping those problems in view a field experiment was carried out at the Instructional farm, School of Agriculture and Allied Sciences, The Neotia University, Sarisha, Jhinga, South 24 parganas, West Bengal to study the growth and yield response of grass pea (Lathyrus

sativus L.) varieties under varying levels of phosphorus. The soil was a medium-textured new alluvial inceptisol with a loam texture and moderate water holding capacity. Soil characteristics include sand (58.89%), silt (21.64%) and clay (20.03%) in the top 15 cm layer. The soil’s chemical composition includes a pH of 7.43, electrical conductivity (EC) of 0.62 dS m^-1, and nutrient levels such as 368 kg ha^-1 of available nitrogen, 25.75 kg ha-1 of available P₂O₅ and 323 kg ha-1 of exchangeable K and 0.36% organic carbon.

The experiment was laid out in a split plot design, replicated thrice, including four phosphorus levels as main plot treatments viz. P0: No P₂O₅ application, P1: application of 20 kg P ha^-1, P2: application of 30 kg P ha-1 and P3: application of 40 kg P h^a-1 and three V1: Pratieek, V2: Bidhan Khesari-1, V3: Ashutosh as subplots. Results indicated that the highest plant height (48.34 cm), dry matter accumulation (249.06 g m-²), LAI (3.74) and CGR (4.21 g m-² day?¹) were observed with the application of 40 kg P/ha. It also recorded highest number of pods plant-1 (24.51), seeds pod-1 (3.63), seeds plant-1 (90.42), seed weight plant-1 (4.73 g), 100 seed weight (5.25 g), seed yield (13.57 q ha^-1) and biological yield (33.58 q ha-1) were obtained by P3 i.e. 40 kg P2O5/ha. Among the varieties, maximum Pods plant-1 (23.05), Seeds pod-1 (3.69), Seeds plant-1 (85.31), Seed wt. plant-1 (4.33 g), Seed yield (12.42 q ha-1) and biological yield (30.77 q ha^-1) were obtained by V2 i.e. Bidhan Khesari-1. The maximum cost of cultivation (` 42963 ha<sup>-1</sup>), gross return of (` 61065 ha^-1), net return (` 18102 ha^-1) and cost: benefit ratio (1: 1.42) were recorded by P3 i.e. 40 kg P₂O₅ ha^-1.