田间状况下烤烟养分吸收动力学及其在平衡施肥中的应用

在土壤气候条件不同的南方湖南酸性红壤地区和北方河南石灰性土壤地区进行的田间试验表明：在烤烟移栽后的前３周中，烤烟烟株吸收的Ｎ、Ｐ、Ｋ、Ｃａ、Ｍｇ的速率极低，从第４周开始，烟株吸收Ｎ、Ｋ和Ｃａ的速率增加极快，并在第６至８周达到最大吸收速率，然后急剧下降。直到收获结束，Ｐ和Ｍｇ的吸收速率都增加极少。烤烟干物质累积速率在曲线形状上与养分吸收速率曲线相似，但二者不同步，干物质最大累积速率比养分最大吸收速率迟了约半周至１周。说明烤烟必须为其快速生长首先积累必需的养分。在烤烟移栽后的前６周，烟叶内的Ｋ／Ｎ比变化缓慢，从６周开始急剧增加并达到最大值。据此，建议在基肥中使用较高的Ｋ／Ｎ比，而在窝肥中使用较低的Ｋ／Ｎ比。河南襄县点的Ｋ／Ｎ比明显小于湖南慈利点，说明在襄县点应增加钾肥的施用，以提高烟叶中的Ｋ／Ｎ比。在慈利点，烤烟早期吸收的钾多于钙，晚期吸收的钾少于钙。然而在襄县点，烟株整个生育期吸收的钙均大于钾。烟叶早期的含钾量最高，随着生育期的发展而逐渐降低。慈利点烟叶钙含量随着生育期的发展稍微有所下降，而襄县点的烟叶钙含量却随着生育期的推移明显增加。

Dynamics of Nutrients Uptake 6y Flue-Cured Tobacco (Nicotiana tabacum L. ) in Field Conditions and Its Application in Balanced Fertilization

Field experiments with flue-cured tobacco were conducted at two locations with acid and calcareous soils and different climatic conditions of China. Results indicated that flue-cured tobacco absorbed very little nutrients N, P, K, Ca and Mg in the first 3 weeks after transplanting, then folloWed by a sharp increase in the uptake rates of N,K and Ca. Maximum absorption rates were reached about 6 to 8 weeks after transplanting. There were only a little increase in the absorption rates of P and Mg till harvesting of ripe leaves. The dry matter accumulation rate was similar to those of nutrients uptake in curve shape but the accumulation rate and absorption rate were not synchronous, the maximum accumulation rate of dry matter was about 1 week later than those of nutrients uptake. The K/N ratio of tobacco plant changed gradually before 6 weeks after transplanting, then increased greatly and reached maximum at about 8 weeks after transplanting. So a higher K/N ratio is recommended for basal fertilizer but a lower K/N ratio for start fertilizer. The K/N ratios of Xiangxian County was much less than those of Cili County. Tobacco plants absorbed more K than Ca in early stages and more Ca than K in later stages in Cili County. However it absored much more Ca than K in the whole growing period in Xiangxian County. K content of tobacco leaf was higher in the beginning, and decreased gradually with the growth of tobacco plants. There was a very slight decrease in Ca content of tobacco in Cili, but a significant increase in Ca content of tobacco plant in Xiangxian County.