effect of irrigation water salinity on yield and quality of two forage millet cultivars

the effect of different salinity levels (1.7, 5, 10, 15 and 20 ds.m-1) on yield and forage quality of two millet cultivars (nutrifeed and bastan) was investigated in this experiment. a factorial test based on randomized complete block design with three replications was conducted during 2010-11 growing season. the results showed that with increase in salinity, dry matter yield decreased. the highest total dry matter was observed in the control treatment of nutrifeed millet (83.2 g. plant-1) and the lowest was measured in 20 ds.m-1 treatment  of bastan millet (23.5 g. plant-1). the results indicated that the forage quality and the mineral material in the aerial organs of the two studied cultivars were under the effects of the salinity stress. by increasing the salinity stress, the protein percentage, potassium content, and the shoot calcium and magnesium content decreased, but pure fiber percentage and the sodium content increased. the results of correlation of traits in salt stress conditions showed that there was a significant negative correlation between protein percentage and pure fiber percentage (r=-0.6*).  increase in pure fiber percentage decreased protein percentage. treatment 20 ds.m-1 sodium chloride decreased dry weight of nutrifeed and bastan varieties (44% and 57%, respectively) compared to the control conditions. treatment of 10 ds.m-1 sodium chloride decreased dry matter yield of nutrifeed and bastan varieties (24% and 34%, respectively) compared to the control. therefore, the results of this experiment indicated that salinity tolerance threshold of nutrifeed and bastan varieties were 5 ds.m-1and 1.7 ds.m-1 (control treatment), respectively.