半干旱区盐碱地种植甜高粱对磷钾和有机肥的响应

Response of sweet sorghum grown in saline soils to phosphorus and potassium, and to manure in a semi-arid area

  • 摘要: 甜高粱是一种未被充分利用的禾谷类作物, 作为再生的、清洁型生物质能源作物, 被当作化石燃料的重要替代资源, 进而受到全球关注; 其高生物量和对逆境的强耐受性为盐碱地的植物修复提供了巨大潜力。以低投、高产、改土为目标, 在黄河三角洲缺磷富钾盐碱地区开展了为期2年的大田试验, 通过测定不同施肥处理下甜高粱各茎节糖锤度、养分含量、植株生物量及土壤性状等指标, 确定甜高粱对磷、钾和有机肥的响应及施肥策略。研究发现: 甜高粱茎秆中的糖分含量呈中间高两端低的正态型分布, 中段茎节是高储糖茎段, 可重点利用。与单施磷肥相比, 追施磷钾肥能促进茎节糖分积累以及氮、磷含量提高。单施磷肥, 无论基施还是追施, 均无法提高茎节糖锤度。与单施磷肥相比, 磷肥与有机肥配合基施则促进了甜高粱临近成熟期糖分的快速积累, 增加茎节钠含量, 抑制钠向籽粒转移, 节长缩短, 提高了0~60 cm土层土壤有机质和钙含量, 降低了0~30 cm土层土壤pH。推荐甜高粱基施P2O5 80~120 kg ∙hm−2、有机质213 kg∙hm−2、N 90 kg ∙hm−2, 拔节期追施K2O 52 kg ∙hm−2, 出苗后138 d砍收茎秆, 从而获得较高糖产量。本研究结果为盐碱地区种植生物质能源作物甜高粱提供了施肥依据, 将促进缺磷富钾盐碱地土壤植物修复技术的发展。

     

    Abstract: Sweet sorghum, an underutilized cereal crop but a raw material for renewable bioethanol production by utilizing its juice, has been of global interest as an essential alternative energy crop for fossil resources and has excellent potential for the phytoremediation of arid saline lands because of its high biomass and adaptation to harsh environments. With the objectives of increasing sugar prodcution, lowering input, and improving soil, a two-year field experiment was conducted in the saline soils of the Yellow River Delta, where the soil is rich in potassium (K) but deficient in phosphorus (P). To evaluate the response of sweet sorghum to fertilization with P, K, and manure based on the parameters of brix value and nutrient content in each internode (IN) of the whole stalk, biomass, and soil properties. The results showed that the peak sugar content of sweet sorghum was located in the middle INs but decreased at both the lower and upper INs along with the normal distribution; therefore, the middle INs had a higher brix value that should be prioritized. The combined application of K and P, rather than P alone, as topdressing promoted brix value and contents of N and P in the INs. The application of P as either basal or topdressing fertilizer had no positive effect on brix value, despite the soil being deficient in phosphorus. In contrast, application of P combined with manure stimulated sugar accumulation rapidly as sweet sorghum approached maturity, improved Na content in INs, inhibited Na transfer to grains, shortened internode length, increased both the content of SOM and Ca in the 0–60 cm soil layer, and decreased the pH of the 0–30 cm soil layer. Fertilization rates per hectare were recommended as follows: 80–120 kg P2O5 combined with 213 kg organic matter, together with 90 kg N as basal, 52 kg K2O as topdressing during the jointing stage. In addition, the stalks can be cut at 138 d after seeding to obtain higher sugar and nutrient content, improve soil fertility, and reduce salinity. The above results provide a basis for the subsequent planting of sweet sorghum in saline soil. This important bioenergy crop will significantly facilitate the development of phytoremediation for both phosphorus-deficient and potassium-rich saline soils.

     

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