Effect Of Irrigation Times And Fertilization Rate On The Yield And Quality Of Alfalfa Seed In Yellow River Irrigated Region Of Gansu China

In order to provide scientific basis for alfalfa seed production in Yellow River irrigated region of Gansu China, the effects of irrigation times and fertilization rates on alfalfa seed yield and quality were studied under a optimum planting density at the second year of plant growing. The treatments included3irrigation frequency (3times,4times, and5times a year, where5times as the control) and4fertilizer rates (0kg/hm2,180kg/hm2,360kg/hm2,540kg/hm2). One of the assumptions of this study was that both water saving and seed yield improving could be achieved by reducing conventional watering times (5times a year). The results obtained are as follows.1. Compared with the conventional irrigation (5times a year), actual seed yield was significantly increased by3or4times irrigation a year. A interaction existed between the irrigation and fertilization treatments. With the increase of fertilization rates, actual seed yield increased first and then decreased under3or4times irrigation, while under5times irrigation, the yield was decreased first and then increased. The maximum actual seed yield was3365.24kg/hm2which was obtained at3times irrigation and180kg/hm2fertilization treatment.2. Potential seed yield was not significantly affected by irrigation frequency, but by fertilizer application. The yield of0kg/hm2fertilization was significantly lower than other fertilizer treatments. The maximum potential seed yield was40417.6kg/hm2which obtained at4times irrigation and540kg/hm2fertilization treatment. The actual seed yield accounting for the potential seed yield ranged from5.5%to11.0%among the treatments..3. Irrigation frequency and fertilizer rate significantly positive correlated with floret number/inflorescence and thousand-seed weight, but no significant influence presented on other seed yield components. 4. Among the seed yield components, the reproductive branch number/plant showed the highest correlation with both actual seed yield (r=0.656, p=0.05) and potential seed yield (r=0.767,p=0.05) of alfalfa.5. Less irrigation times brought a higher rate of germination and lower rate of hard seeds content. Less irrigation times and lower fertilization rates produced a higher quality of alfalfa seeds.6. In conclusion,3times irrigation and180kg/hm2fertilization was the promising technique for alfalfa seed production at the present experimental conditions. It not only produce quality high seed yield, but also saving water compared with the conventional technique.