| In order provide scientific bases for the regulation of wheat growth and development with irrigation and fertilization measures, field experiments were carried out during 2007-2008 (rich rainfall year) in Baoding, and 2008-2009 (moderate rainfall year) in Gaocheng with local commecial winter wheat cultivar Henong 822 and Ji 5265, respectively. The experiments during the two years were designed as split plot arrangement, with irrigation time as main plots (including 0, 1, 2 and 3 times, expressed as W0, W1, W2 and W3 respectively), and phosphorus application rate as split plots (including 0, 75 and 150 kg·hm-2 P2O5, expressed as P0, P1 and P2 respectively). The results showed that, both irrigation and P application increased the accumulation of N, P and K by wheat plant, but the increaments were affected by rainfall. The effects of irrigation times on nutrient accumulation was less significant in rich rainfall year than that in moderate rainfall year, when the accumulation amount of N and P increased with the increase of irrigation times. The effects of P application rate on the accumulation amounts of N and P during mid late growing period increased with the increase of irrigation times, but the effect of irrigation on the accumulation amount of K was different at various growing stages. In rich rainfall year, the accumulation amount of N was less affected by P application, but that of P increased with the increase of P application rate, and that of K was higher in the treatments P0 and P2 during mid early growing period. In moderate rainfall year, however, the accumulation amounts of N and K increased with the increase of P application, but that of P was less affected by P application. The production efficiencies of all the three nutrients, i.e., N, P and K, and the harvest indices of N and P of wheat increased in the treatments with appropriate irrigation and P fertilization, but the harvest index of K was less affected by irrigation and P fertilization. The grain yields of W1, W2 and W3 with irrigation were all significantly higher than that of W0 without irrigation during the two growing years. The grain yield of W1 was the highest during 2007-2008, but the grain yields increased with the increase of irrigation times during 2008-2009. The grain yields of P1 and P2 were all significantly higher than that of P0 during the two years. The grain yield of P1 was the highest during 2007-2008, but that of P2 was the highest during 2008-2009, showing the compensation effect between phosphorus and water supply, i.e., high grain yield can be achieved by different pathway either "less water and more phosphorus" or "more water and less phosphorus". According to the results, it is recommended that two irrigations during the growing period be needed, with 150 kg·hm-2 P2O5 applied for satisfactory grain yield of winter wheat under moderate rainfall (about 100 mm during winter wheat growing period) in Hebei Plain of China. In rich rainfall year, however, one irrigation be sufficient, with 75 kg·hm-2 P2O5. |
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