EFFECT OF SALINE IRRIGATION ON THE BIOMASS YIELD, AND THE PROTEIN, NITROGEN, PHOSPHORUS, AND POTASSIUM COMPOSITION OF ALFALFA IN A POT EXPERIMENT

Effect of saline irrigation was studied on the germination, biomass yi eld, protein content, and nitrogen (N), phosphorus (P), potassium (K) composition of three alfalfa (Medicago sativa) cultivars in a pot expe riment. The percent germination of alfalfa cultivars decreased to 15% (Hassawi), 13% (Supreme), and 30% (CUF-101) receiving irrigation water having total salinity of 12.3 dS/m; and up to to 30% (Hassawi), 22% ( Supreme), and 64% (CUF-101) with irrigation water salinity of 16.5 dS/ m. The mortality of young alfalfa seedlings was 100% after two weeks o f germination with irrigation water salinity of 12 dS/m and above. The mean green-matter yield was 56.72 g (Hassawi), 54.29 g (Supreme), and 59.91 g (CUF-101) per pot irrigated with water having total salinity of 7.8 dS/m. The difference in yield was not significant among the thr ee cultivars. Overall, a green-matter yield of 11-12 tons/ha per cutti ng (equivalent to 2.69-3.14 tons/ha dry matter per cutting) could be o btained with irrigation water having an EC of 7.8 dS/m. There was no s ignificant difference in the salt tolerant level between the local (Ha ssawi cultivar) and the imported (Supreme and CUF101) alfalfa cultivar s tested. The mean protein contents of alfalfa plants were 22.58% (Has sawi), 29.10% (Supreme), and 23.09% (CUF-101) irrigated with water hav ing total salinity of 7.8 dS/m. The ranges for the mean concentrations of different macro-elements in alfalfa plants were 2.51 to 3.94% N, 0 .22 to 0.44% P, and 1.48 to 3.22% K. The analyses of regression indica ted a strong interaction between N, P, and K in alfalfa plants. In con clusion, there was no significant difference in biomass yield, salt-to lerant level, and the protein contents between local and the imported alfalfa cultivars irrigated with water having salinity of 7.8 dS/m. An appreciable alfalfa green forage yield of 11-12 tons/ha per cutting c ould be obtained under moderate saline water irrigation.