甜高粱分蘖去留与糖产量及氮素利用的比较分析

大田条件下采用人工去除分蘖的方法，研究了两种种植密度下甜高粱高产品种分蘖特性对糖产量及其干物质生产和氮素吸收利用特性的影响。结果表明, 常规种植密度(每公顷75 000株)下，保留分蘖较单茎秆植株对主茎和分蘖茎含糖量影响较小；在较低种植密度(每公顷37 500株)下，保留分蘖植株主茎含糖量明显下降，分蘖茎含糖量与单茎秆植株接近。在不同种植密度条件下，保留分蘖植株较单茎秆植株开花前和开花后茎秆、叶片和穗各器官干物质积累量均显著增加，保留分蘖显著提高了总生物量，达21.9%和81.6%，总糖产量分别增加了17.1%和63.8%。保留分蘖植株开花后氮素向茎秆分配比高，同时，保留分蘖植株叶片氮积累及分配比例明显提高，叶片干重占植株总干重比例显著增加，单位氮素糖生产效率下降，但未达显著水平。常规密度和较低密度下分蘖茎糖产量的补偿效应分别可达20%和62%以上，说明常规种植密度下保留分蘖利于增加甜高粱糖产量，并能够达到简化栽培管理和降低经济人力投入的目的。

Comparison of Sugar Yield and Nitrogen Utilization in Tiller Removing or Remaining of Sweet Sorghum

Sweet sorghum is one of the most promising renewable energy crop because of its high biomass and soluble sugar content, particularly the intensive resistance to sterile soils and wide adaptability, as well as higher alcohol transformation efficiency compared to other crops, such as maize, sugarcane, rice, sweet beet, et al. To testify whether tillers of sweet sorghum could have distinctive effects on sugar yield, two mostly grown sweet sorghum varieties Rio and Sumac were chosen, which were introduced from America with similar growth duration and higher lodging resistance. Dry matter weight of various organs from anthesis to maturity was measured for plants with all tillers retained and uniculm plants (removed all tillers once they occurred under two plant densities, higher (75000 plants ha^–1) and lower (37500 plants ha^–1). Also the nitrogen (N) contents at both anthesis and physiological maturity periods were determined. The results showed that compared with uniculm plants at either higher or lower densities, plants with tillers had significantly higher biomass and sugar yield, with an averaged increase by 21.9% and 81.6%, 17.1% and 63.8%, respectively. The sugar content in main culms of plant with tillers was close to that removed tillers under higher density, while it deceased significantly under lower density, but the averaged sugar content of all tillers was nearly equivalent to or a little higher than that of plants removed tillers, this may be ascribed to the lower nitrogen content of tillers. The dry matter weight of whole plant consisting of stalks, leaves and sheaths, and panicles was higher than that of uniculm plants, and stalks of plants with tillers remaining maintained higher N accumulation and N distribution at both anthesis and maturing stages, that maybe the primary result of significantly increase in stalk biomass. In conclusion, the tiller remaining plants harvest higher sugar yield accompanied by both increased leaf and panicle biomass, since sugar yield produced by tillers could compensate for the decreased value of main culm caused by competition of nutrient uptake and utilization between main culm and tillers. Retaining tillers probably contribute to explore sugar yield potential of sweet sorghum, and at the same time may reduce the investment cost in cultivation.