Hierarchical Analysis of Switchgrass Morphology

Boe, Arvid; Casler, Michael D.

Hierarchical Analysis of Switchgrass Morphology

2005

Boe, Arvid | Casler, Michael D.

Switchgrass (Panicum virgatum L.) has potential as a biomass crop in North America. Our objective was to determine effects of cultivar and location on morphological traits that influence biomass in switchgrass. Six cultivars with origins from 37° N, 88° W (Cave-In-Rock and Shawnee) to 46° N, 100° W (Dacotah) were evaluated in 1-yr-old swards at Bristol and South Shore, SD; in 3-yr-old swards at Brookings, SD, and Arlington, WI; and in 15-yr-old swards at Pierre, SD, for biomass; tillers m⁻²; reproductive tiller proportions by count and weight; weight tiller⁻¹; phytomers tiller⁻¹; leaf, stem, and inflorescence components of tiller weight; and sheath and stem components of phytomer weight. Biomass production was related to region of cultivar origin [e.g., Shawnee produced two times more than Dacotah (6.2 Mg ha⁻¹)]. Tiller density was highest for Dacotah (1090 tillers m⁻²) and lowest for Cave-In-Rock (520 tillers m⁻²). Reproductive tiller fractions by count were plastic and higher at Arlington (0.81) than Brookings (0.08). Weights per reproductive tiller ranged from 0.7 g (Dacotah) to 3.4 g (Cave-In-Rock). Phytomers per tiller was not plastic (5.2 for Dacotah to 7.4 for Cave-In-Rock). Internode weight exhibited a basipetal increase and was highly plastic. Cultivars responded similarly to location effects on tillers m⁻², weight tiller⁻¹, and biomass production. Cultivar differences for biomass production were attributed to variation at tiller (phytomers tiller⁻¹) and phytomer (weight phytomer⁻¹) levels.

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