In commercially grown Miscanthus × giganteus, despite imposing a yield penalty, postwinter harvests improve quality criteria for thermal conversion and crop sustainability through remobilization of nutrients to the underground rhizome. We examined 16 Miscanthus genotypes with different flowering and senescence times for variation in N, P, K, moisture, ash, Cl and Si contents, hypothesizing that early flowering and senescence could result in improved biomass quality and/or enable an earlier harvest of biomass (in autumn at peak yield). Ideal crop characteristics at harvest are low N and P to reduce future fertilizer inputs, low K and Cl to reduce corrosion in boilers, low moisture to reduce spoilage and transportation costs, and low Si and ash to reduce slagging and consequent operational downtime. Stems and leaves were harvested during summer, autumn and then the following spring after overwinter ripening. In spring, stem contents of N were 30–60 mg kg⁻¹, P were 203–1132 mg kg⁻¹, K were 290–4098 mg kg⁻¹, Cl were 10–23 mg kg⁻¹ and moisture were 12–38%. Notably, late senescence resulted in increased N, P, K, Cl, moisture and ash contents, and should therefore be avoided for thermochemical conversion. Flowering and senescence led to overall improved combustion quality, where flowered genotypes tended towards lower P, K, Cl and moisture contents; marginally less, or similar, N, Si and ash contents; and a similar higher heating value, compared to those that had not flowered. Such genotypes could potentially be harvested in the autumn. However, one genotype that did not flower in our trial exhibited sufficiently low N and K content in autumn to meet the ENplus wood pellet standards for those traits, and some of the lowest P, moisture and ash contents in our trial, and is thus a target for future research and breeding.

中文翻译：

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迈向芒草燃烧质量改进：开花和衰老的作用。

在商业化种植的Miscanthus  ×  giganteus中，尽管会造成产量损失，但冬后收获通过将养分重新转移到地下根茎，提高了热转化和作物可持续性的质量标准。我们检查了 16株芒草因 N、P、K、水分、灰分、Cl 和 Si 含量的变化而具有不同开花和衰老时间的基因型，假设早期开花和衰老可能导致生物量质量的提高和/或使生物量的更早收获（秋季在峰值产量）。收获时理想的作物特性是低氮和低磷以减少未来的肥料投入，低钾和氯以减少锅炉腐蚀，低水分以减少腐败和运输成本，以及低硅和灰分以减少结渣和随之而来的运行停机时间。茎和叶在夏季、秋季和次年春季在越冬成熟后收获。春季，茎的N含量为30-60 mg kg ^-1，P为203-1132 mg kg ^-1，K为290-4098 mg kg ^-1, Cl 为 10–23 mg kg ^-1和水分为 12–38%。值得注意的是，晚衰老导致 N、P、K、Cl、水分和灰分含量增加，因此应避免进行热化学转化。开花和衰老导致燃烧质量总体改善，开花基因型倾向于降低 P、K、Cl 和水分含量；N、Si 和灰分含量略低或相似；与未开花的相比，具有类似的更高的热值。这样的基因型可能会在秋季收获。然而，在我们的试验中没有开花的一种基因型在秋季表现出足够低的 N 和 K 含量以满足 EN加这些特性的木屑颗粒标准，以及我们试验中一些最低的 P、水分和灰分含量，因此是未来研究和育种的目标。