施肥量对烟田土壤氮素供应及烟叶产质量的影响

通过田间试验研究了肥料施用水平对烟田土壤氮素供应、烟株生物学性状和体内物质累积、养分吸收及产质量的影响.结果表明:氮肥施用水平明显影响到烟株生长初期根系生长密集区域土壤的无机氮供应状况.氮肥施用水平愈高,团棵时根系生长密集区域土壤无机氮供应也愈多.但烤烟根部以及整株的干物质积累在一定的施氮量范围内,随着施氮量增加而增加;但施肥量过多对烟株生长前期的根部以及整株体内干物质积累有一定的抑制,而后期则表现出促进.打顶前烟株体内氮、磷、钾养分的累积在不同施氮量处理间无明显差异,而在打顶后总体上表现出随施肥量增加而增加的趋势,但不同施肥量间增加幅度存在较大的差异.在适宜施氮量及其以下时,烟株打顶后体内的氮素累积量与打顶时相比增幅不大,而过高的氮肥施用水平会导致烟株生长后期体内有过多氮的积累,致使中、上部叶片变厚、叶片扩展不好,而不利于烟叶质量的提高.综合衡量,在本试验条件下,施肥量以纯氮75 kg/hm2为宜.

Effect of Different Fertilization Rate on Mineral Nitrogen Supply of Soil Leaf Yield and Quality of Flue-cured Tobacco

The field experiment was conducted to determine the effect of application rate of fertilizer on the mineral nitrogen supply of soil,agronomic characters,dry matter accumulation and nitrogen,phosphorus and potassium uptake,as well as the yield and quality of flue-cured tobacco.The results showed that the fertilization rate significantly influenced the mineral nitrogen supply of soil in the root growth area at the early growth period.Higher the fertilization rate,more the mineral nitrogen supply.The root growth was improved and more accumulation of dry matter of flue-cured tobacco was obtained when the application rate of nitrogen was increased from 45 to 90 kg per hectare,while application rate at 105 kg per hectare resulted into lower growth of tobacco at early growth period,but more vigorous growth at later growth period.Tobacco uptake of nitrogen,phosphorus and potassium dramatically differed among different application rate of fertilizer after topping.The more uptake of N,P and K was observed for the tobacco applied with 90 or 105 kg per hectare respectively,which resulted to decrease the length and width of leaves on upper and middle position of the stalk and into lower yield and quality of flue-cured leaves.It was suggested that the fertilization rate should be kept at 75 kg N per hectare in the condition similar to the experiment site.