Water-use efficiency of soybean (Glycine max) using line-source oprinkler technique

A field study was conducted with a line-source sprinkler technique during rainy season (kharif) 1995 at Ludhiana to characterize evapo-transpiration and water-use efficiency of soybean [Glycine max (L.) Merr.]. Four water-application treatments (I-1, I-2, I-3 and I-4) with progressively decreasing amounts of irrigation were marked in the direction perpendicular to the line source. The I-1, I-2, I-3 and I-4 treatments received differential irrigation of 187.8, 136.6, 109.1, and 57.9 mm respectively, in addition to season's monsoon rainfall. The cumulative seasonal soil-water use by the crop amounted to 661, 654, 644 and 571 mm for the I-1, I-2, I-3 and I-4 treatments respectively. The water-use efficiency of 2.48, 2.46, 2.34 and 2.46 kg/ha/mm for straw yield and 0.826, 0.716, 0.688 and 0.711 kg/ha/mm for seed yield was obtained under the I:, I, I; and I, treatments respectively. A linear relationship between water use and dry-matter production existed for various treatments. Dry-matter production and seed yield were maximum in I-1, followed by I-2, I-3 and I-4 treatments (in the decreasing order).