Growth,Crop Coefficient and Water Use Efficiency on Field-grown Alfalfa under Condition of Regulated Deficit Irrigation

A field experiment was carried out to study the effects of regulated deficit irrigation on alfalfa growth,crop coefficient and water use efficiency in desert oasis located in the downstream of Shiyang River Basin,Gansu province.The results showed that the differences between the final heights of the first crops were not significantly at the end of first crop growth stage.it could benefited the increasing of branches numbers when the lower irrigation limit was set to be 55%θf in the stage of growth stage and branching period.The diameters of stem increased with the increasing amount of water supplied.The overall trend in different treatments was that the rates of water consumption increased with the amount of water supplied.The value of Kc increased with flowing growth stages and decreased with flowing circles of growth.it could benefit the growth of following circle and increase the overall yield of alfalfa in the whole year when the lower irrigation was set to be 55%θf in the first circle of growth.It can be concluded that: regulated deficit irrigation in the oasis where water resource is scarce is an efficient irrigation method,and it could increase the yield of alfalfa as well as the water use efficiency in the condition of that the lower irrigation limit was set to be not less than 55%θf in the first circle of growth and(55%~70%)θf in the second and third circles.