RESUMO
Responses of six varieties (Suwannee, Coast cross, Tifton44, Tifton68, Tifton78 and Tifton85) of Cynodon dactylon to irrigation-water salinity were investigated in field by means of a double line source experimental design. The digestibility of the grass by goat was analyzed using the rumen gastric justice digestion method. The results showed that the six varieties grew well, and had a high yield of fresh grass when eletro-conductivity (Eci) < 10 ds.m-1. Particularly when Eci = 4.4 ds.m-1, the fresh grass yield of Coast cross, Suwannee, Tifton44, Tifton68, Tifton78 and Tifton85 was respectively increased by 142.1%, 61.1%, 136%, 121.1%, 202.3% and 109.7%, in comparison with fresh water (Eci = 1.2) irrigation. Dry matter yield was also elevated with the increasing salinity of irrigated water. There was no obvious effect of salinity on crude protein, fiber and ash contents in the six varieties. Goats were fond of eating the hay irrigated by saline water, perhaps because of its higher digestibility. At least, the yield and quality of Cynodon dactylon were not effected by saltwater irrigation.
