Effects Of Irrigation Frequency And Application Of Phosphate Diamine On Alfalfa Seed Production In The Yellow River Irrigated Region

In the Yellow River Irrigation region of Gansu province, crops were irrigated in a fixed regime according to crop’s water requirement. However whether this irrigation regime is suitable to the forage legumes has rarely investigated. Present study was conducted to determine the optimum irrigation frequency and fertilizer amounts for alfalfa seed production by designing of four irrigation frequencies(two, three, four and five times) and four phosphate diamine application rate(0, 180, 360, 540 kg/hm2). The main results obtained were as follows.(1) Seed yield was significantly influenced by irrigation frequencies(P<0.01). The highest seed yield was obtained at three times irrigation treatment. Too many times irrigation caused severe lodging and limiting seed production.(2) With increase of phosphate diamine rate, seed yield increased at first and then decreased. Under three times irrigation treatment, the highest seed yield was achieved at a phosphate diamine rate of 360 kg/hm2(seed yield were 757, 963 and 767 kg/hm2 in 2013 to 2015, respectively). Seed yield was significantly influenced by interactions of irrigation frequencies and phosphate diamine rate.(3) Irrigation frequency and phosphate diamine rate have significant effects on inflorescences number and racemes number per stem(P<0.05). The highest racemes number per stem was achieved at the treatment of three-times irrigation combined with phosphate diamine rate of 360 kg/hm2(22.7 in 2013 and 25 in 2014); Seed yield was significantly correlated with stems per square meter(R2=0.503) and inflorescence number(R2=0.835); Racemes number per stem is an important component for achieving of high seed yield.(4) Seed quality indexes(hard seed percentage, germination percentage, germination energy, and germination index) was not affected by any irrigation and fertilizer treatment(P>0.05).Three times irrigation in one year combined with phosphate diamine rate of 360 kg/hm2 is recommended for alfalfa seed production in the Yellow River irrigated region.