AN INVESTIGATION INTO THE PHOTOEFFICIENCY, PHOTOPROTECTION, AND CARBON & NITROGEN ALLOCATION IN SWITCHGRASS

Andrew M. Gonzalez

doi:10.7273/000007374

As global interest in renewable energy intensifies, biofuels derived from resilient perennial grasses offer a promising alternative to fossil fuels, especially on low-input, non-arable lands. Switchgrass (Panicum virgatum) is a perennial C4 grass with strong potential as a sustainable biofuel feedstock, particularly for marginal lands where environmental stressors reduce the success of traditional crops. To identify trait combinations associated with superior biomass production, this study investigates physiological, morphological, and metabolic traits across ten switchgrass genotypes (seven lowland and three upland) under simulated marginal conditions, consisting of sandy growth matrix with low nutrient application. We examined photosynthetic efficiency (ΦII, qL), photoprotective capacity (qE, xanthophyll cycle engagement), root and leaf respiration, and carbon-to-nitrogen (C:N) allocation, integrating these traits through correlation analysis and principal component analysis (PCA). Results revealed that while photochemical parameters such as ΦII and qL varied across genotypes, they were not strong predictors of shoot biomass. Instead, respiratory efficiency particularly low root respiration relative to shoot mass, was more strongly associated with higher yield. Switchgrass genotypes such as DVR3 and FLT1 exhibited moderate photosynthetic performance but achieved greater biomass through reduced respiratory costs and efficient nutrient use, which suggests a more resource-conservative strategy. PCA further supported this paradigm, with principal component 1 (PC1) delineating a trade-off between carbon investment in biomass and respiratory carbon loss. Additionally, ecotypic distinctions were observed along PC1, but some upland genotypes displayed trait profiles overlapping with lowlands, blurring traditional ecological boundaries. Collectively, these findings underscore that maximal photosynthetic output is not the sole determinant of productivity under stress. Rather, metabolic efficiency, reflected in the coordination of carbon acquisition, photoprotection, and respiratory cost, appears to be a key factor influencing switchgrass performance under marginal land. These findings contribute to a deeper understanding of genotype-specific strategies and may help guide genetic improvement efforts for biofuel crops suited to low-input, marginal-quality systems.

AN INVESTIGATION INTO THE PHOTOEFFICIENCY, PHOTOPROTECTION, AND CARBON & NITROGEN ALLOCATION IN SWITCHGRASS

Files and links (1)

Abstract

Metrics

Details