| The deficiency of soil water and unreasonable utilization of nutrients are two key factors of limiting the sustainable development of agriculture in China. The pre-existing studies of water-fertilizer coupling were more aiming at wheat, corn and other crops than hybrid millet, and the less reported researches were on the comprehensive consideration of multi-factors of nitrogen, phosphorus, potassium and irrigation, affecting crops growth.Therefore, this experiment used orthogonal design with four factors and four levels, took hybrid millet as the objects, analized the effects of four factors of water, nitrogen,phosphorus and potassium（W, N, P2O5 and K2O） on the yield, growth, water and fertilizer use efficiency and so on. The objective of the study was to provide a theoretical basis of the optimal water-fertilizer ratio for high yield and efficiency of hybrid millet in the millet main producing areas of Hebei province, to promote sustainable development of agriculture. The main results were as follows:（1）The influences of different water-fertilizer treatments on hybrid millet yield were large. The highest yield was in T10 treatemnt（W180mm+N100kg/hm2+P2O5180kg/hm2+K2O200kg/hm2）. The millet yields under high irrigation treatments（T13T16） were significantly higher than other treatments（except T10）, the yields without irrigation（T1T4） treatments were significantly lower than other treatments. The better water and fertilizer combination to improve the yield was（W270mm+N200kg/hm2+P2O5120kg/hm2+K2O200kg/hm2）. The order of factors influenced yield was W>P2O5>N>K2O, and the influence of water（W） was very significant and P2O5 was significant. Hybrid millet yield showed significantly positive correlation to thousand kernel weight, number of spikelets,spike length, ear position and rate of grain of single spike, but there was no obvious difference between yield and spike diameter.（2）With the increasing of irrigating water, the number of tillers and panicles per plant were increased, the rate of effective tillers and spike rate per-plant were increased first,then reduced. The best water-fertilizer group to improve the percentage of earring-tillers of hybrid millet was（W180mm+N300kg/hm2+P2O5180kg/hm2+K2O200kg/hm2）, the order of different factors influencing earbearing tillers was W>N>K2O>P2O5, and the impact of W was significant extremely.（3） The puncture strength of the 2rd, 3rd, 4th stem basal internodes was reduced withthe growth process, and gradually decreased from the base upwards in turn, the puncture force was negatively correlated to internode length. And the puncture force of the 2rd, 4th internodes was decreased rapidly at heading-filling stage, was fallen slower at filling-maturity stage. The puncture force of the 3rd internode was declined sharply, so the3 rd internode could be used as one of main indicators to evaluate the stalk lodging resistance. The opyimal combination to improve was the order of factors influenced the puncture strenth of 3rd basal internodes of hybrid millet was W>N>P2O5>K2O, the influences of W and N were very significant and P2O5 was significant.（4） The net photosynthetic rates（Pn） of hybrid millet flag leaves were higher at heading stage than filling stage, but transpiration rate（Tr） was higher at filling stage than heading stage. The optimal combination of water and fertilizer to improve Pn of millet flag leaves was（W270mm+N200kg/hm2+P2O5120kg/hm2+K2O300kg/hm2）, the order of factors influenced Pn was W>N>P2O5>K2O, the effects of W 〠N 〠P2O5 and K2 O were all significant extremely.（5） The water consumption and wter use efficiency of millet biomass were greater with irrigation than that without irrigation treatments, and were enlarged with the increasing of irrigation. The wter use efficiency of millet grain（WUEg） was increased first and then decreased with increasing irrigation, and excessive irrigation was restrict ed the contribution of water to grain. The optimal combination to improve WUEg was（W180mm+N200kg/hm2+P2O5120kg/hm2+K2O200kg/hm2）, the order of factors influenced WUEg was W>P2O5>N>K2O, and the influence of W was significant extremely, P2O5 was significant.（6） The nutrients accumulation in plant and grain of hybrid millet was closely related to the supply of fertilizer and irrigation, and was proportional to the amount of fertilizer within a certain range. The absorption percentage of nitrogen, phosphorus and potassium in grain was accounted for 57.66%67.55%, 74.86%83.15%, 30.03%31.25% than that in all plant.（7）The soil alkali-hydrolyzable nitrogen,available phosphorus and available potassium contents with different water and fertilizer application in mature period of hybrid millet were reduced in soil profile 0100cm with depth, the difference were decreased gradually with the depth of soil profile.（8）Considering the yield, efficiency of water and fertilizer, harvest index, economic benefits and other factors, the optimal ratio of water and fertilizer coupling measures for hybrid millet cultivation of high yield and high efficiency at Zhangjiakou area was T10（W180mm+N100kg/hm2+P2O5180kg/hm2+K2O200 kg/hm2）. |
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