seed quality properties of grass pea (lathyrus sativus l.) in response to

in order to evaluate effects of plant density and planting date on quality properties of grass pea (lathyrus sativus l.), a factorial experiment was conducted during 2008, based on complete randomized block design with four replications in research farm of faculty of agriculture, the university of birjand, birjand, iran. plants were planted at march 5 and 20, and apr 3, with 30, 40, 50 and 60 pl m-2. delaying in planting and/or increasing plant density caused protein content per grain dry matter to be reduced. there was a negative correlation between grain protein percentage and grain ash content. the highest grain ash percentage (4.3%) was observed in the last planting date. tannin content reduced significantly with delaying in planting date, from 0.32% in march 5 to 0.14% in apr 3planting dates, and showed a negative correlation with ash content. seed energy content also was reduced with delaying in planting date and/or increasing in density, and showed a positive correlation with seed protein percentage. it seems early planting of grass pea with a density of 40-50 pl m-2 results in a high quality seed yield.