Study On Effects Of Irrigation On Alfalfa Seed Produce And Its Water Requirement

Through setting up different irrigation treatments on the basis of the frequency and the quantity, we studied on the effect of different irrigation on the growth, the relative water content, the leaf area index, the reproduction allocation and the seed yield of two-years Alfalfa for seed ; Passed to analysis the effect factors of Alfalfa water requirement, we tried to find the water demand regulation of Alfalfa at different growth stages under different soil water conditions, according to the regulation of water movement in Soil-Plant-Air continuum and the theory of field water budget, we defined the key water requirement stage on the high yield of Alfalfa seed produce ,and the model of water need forecast and predication for Alfalfa seed produce was established by potential evapotranspiration(ETo)index. Results showed that two-years Alfalfa growth and fructification was influenced by the time and quantity of irrigation, and the time is important. The nutrition matter accumulation is fast during branching stage, so to control irrigation is necessary that it can reduce excessive growth. At budding to initial flowering stage irrigation, its benefit for the flower bud differentiation, so to promote bear pod can gain a higher seed yield. At podding stage complement water properly, it's advantage to plump seed of Alfalfa. The seed yield of T6 is highest and increase 53.13% than CK, it reached 773.41 ㎏/hm2. The process of Alfalfa water demand is a parabola, and Alfalfa water requirement is more during the mid-season than during the initial and the end of season stages. Evaporation power is weaker and water requirement is lower during Alfalfa growth stage to branching. At the budding flowering stage, Alfalfa water demand is highest, it reached a peak value. It is the key water requirement stage for Alfalfa seed produce. In this stage ,the average ET reached the peak of 7.5mmd-1and satisfied water demand of Alfalfa was critical. If you did, you can attain a higher and stable yields. When the average ET of Alfalfa reached 7.0 mmd-1,it need to irrigation immediately. During the period of podding to maturity, Alfalfa water demand intensity cut down and water requirement reduced. Budding-initial flowering stage irrigation has a greatest contribution for Alfalfa seed yield, this stage, the water use efficiency is higher and irrigation benefit is better. Secondly, it is podding. Branching stage irrigation is not much effective. In semi-dry area, the best irrigation pattern is two times at budding-initial flowering stage and podding stage to irrigation separately. So, crop coefficient of Alfalfa for seed was established in North area of Xinjiang. and we concluded preliminarily an estimate model of water need forecast and predication for Alfalfa seed produce that is ET=Kc ·ETo。...