旱地春谷子不同生育期吸收氮、磷、钾养分的特点

试验研究了在施肥与不施肥处理情况下，半湿润偏旱区春谷子不同生育期氮、磷、钾养分的吸收特点。结果表明，在供试土壤条件下，施肥可明显提高春谷子产量、干物质累积量、体内氮、磷、钾含量及其累积量。施肥或不施肥，春谷子地上部干物质的累积量随生育期呈典型“S型”曲线增长，其中抽穗灌浆期为累积高峰期，占总累积量的50%左右。植株氮含量随生育期呈曲线下降趋势；整个生育期植株含磷量呈 “W型”变化；植株含钾量呈单峰曲线变化,峰值出现在拔节期。植株氮、磷、钾累积吸收量随生育期的延长和施肥水平的提高而增加，但各生育期相对累积吸收比例，施肥与否差异不大。苗期氮、磷、钾的吸收量约占总吸收量的1%~3%，拔节期约占总吸收量的30%、20%、37%，是钾素吸收的高峰期，孕穗期约占22%、21%、34%，抽穗灌浆期约占43%、53%、23%，是氮、磷吸收的高峰期，籽粒形成期约占3%~5%。不论施肥与否，地上部氮、磷、钾累积吸收量与干物质累积量之间均呈极显著正相关，而与植株氮、钾含量之间呈极显著负相关。

Characteristics of N, P and K uptake at different growth stages of spring millet on dry land

The field experiment were conducted in semi-humid region to investigation the characteristics of N, P and K uptake of spring millet at different growth stages. Two fertilization treatments were set up (N 150 kg/ha、P2O5 75 kg/ha、K2O 90 kg/ha and CK) with four replicates. The results showed that application of N,P,K fertilizers remarkably increased grain yields ,weights of dry matters, and N, P and K contents and accumulates. Whatever fertilization levels, the above-ground dry matter accumulate increased with the growth stages and showed a typical S-shape. There were a peaks of dry matter accumulation occurred at filling stages and account for about 50% of total accumulation. The content of N in plants showed a downward tendency with growth stages; the content of P law of spring millet appeared“W”model; the content of K in plants showed a unimodal curve during the growing stage ,and reached the maximum at jointing stages. Under all experimental condition, N, P and K accumulation increased with both growth stages and fertilization rates, and the proportion of nutrient accumulate at different growth stages was almost same. On average, N,P,K uptake accounted for 1%-3% of the total uptake at seedling stages. During jointing period, the absorbed rates accounted for 30%, 20%, 37%, respectively, which the K uptake was highest at this stages comparing with the others. The absorbed rates accounted for 22%, 21%, 34% at pregnant ear stage, for 43%、53%、23% at heading and filling stages which the N, P uptake was highest at this stages comparing with the others, for 3%~5% at ripening stages. The uptake rates of N, P, K by plants were significantly positive correlated with the accumulated rates of dry matters, but were significantly negative correlated with the contents of N, K in plants either high fertility or low fertility.