Shoot growth, radiation interception and dry matter production and partitioning during the establishment phase of Miscanthus sinensis‘Giganteus’ grown at two densities in the UK

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Abstract
SUMMARY: Photosynthetic area index (PAI), radiation interception (I) and dry matter partitioning between shoots and roots were measured for Miscanthus sinensis‘Giganteus' grown from micro‐propagated transplants on a fertile peaty loam soil in eastern England. In the establishment year, Miscanthus plants produced 35 and 70 shoots plant‐1 at densities of 4.0 and 1.8 plants m‐2 respectively. At the higher density, there were 140 shoots m‐2 with the largest reaching a height of 1.8 m; these canopies attained a maximum PAI of 5.45, intercepting 94% of incident radiation. Leaf lamina contributed c. 90% of total photosynthetic area with stems contributing the remainder. At the lower density, maximum PAI and I values were 2.88 and 86% respectively. PAI was related to I by calculating attenuation coefficients (k); these indicated that Miscanthus canopies were more effective at intercepting radiation per unit PAI at the lower density (k= ‐0.31) compared with the higher density (k= ‐0.20). Radiation interception was related to dry matter accumulated by calculating conversion efficiencies (e). At 4 plants m‐2, × for shoot dry matter production was 1.17g MJ‐1. Miscanthus partitioned a relatively large amount of total dry matter into below‐ground biomass. By plant senescence, c. 30% of total dry matter had been partitioned into root and rhizome; rhizome biomass contributed 80% of below‐ground dry matter, × increased to 1.62 g MJ‐1 when calculated on a total dry matter basis (shoot + root + rhizome). Total dry matter production was increased 68% by a 2.2‐fold increase in plant density.