Seeding Density and Row Spacing for Lentil in Rainfed Mediterranean Environments

Lentil ( Lens culinaris Med.) is largely sown by hand broadcasting at around 400 seeds m −2 in West Asia. Rising labor costs for hand harvest are forcing farmers to consider machine harvesting, which is economically feasible only on mechanically drilled, flat seedbeds. Seeding experiments were conducted at three sites between 1979 and 1986 to determine the effect of seeding densities (100–400 seeds m −2 ) and row spacing (0.2,0.3,0.4, and 0.5 m) on the seed yield, biological yield and economic return of rainfed lentil. The main site, Tel Hadya (Syria) had a mean annual rainfall of 315 mm over five seasons; Terbol (Lebanon) was wetter with 520 mm over two seasons; and Breda (Syria) was drier with 244 mm over two seasons. Seed yield and total biological yield were greater at the two wetter sites, but yields were significantly affected by seeding density within each site. The relationship between yield and seed density was best described by a quadratic curve. At the wetter sites (Tel Hadya and Terbol), seeding densities for maximum seed yield were 267 ± 33 seeds m −2 , considerably lower than the 334 ± 4 at the drier Breda site. for maximum total biological yield, the seeding densities were 276 ? 22 for Tel Hadya, 298 ± 16 for Terbol, and 346 ± 4 seeds m −2 for Breda. The results indicated that using a seed drill, the optimum density for gross economic return minus seed cost was 280 seeds m − at Tel Hadya and Terbol and 320 seeds m −2 at Breda. These rates represent a potential saving in seed costs of 20 to 30% over hand broadcasting. Yields were less responsive to row spacing than to seeding density. Narrowest row spacing (0.2 m) generally gave the greatest seed yields, which decreased linearly with increased row spacing.