Genotypic variation and trait relationships for morphological and physiological traits among new switchgrass populations

Evaluation of potential switchgrass (Panicum virgatum L.) breeding populations for biomass and underlying traits that determine high biomass are critical for further genetic improvement. Therefore, the objective of this research was to assess genetic variation for biomass, morphological, and physiological traits among 19 new synthetics. Simultaneous pot and field experiments were established to evaluate biomass, tiller, and phytomer based morphological and physiological traits. Data were analyzed with principle component analysis (PCA) and path coefficient analysis to screen the experimental populations and quantify trait interactions for target traits. The Northern lowland (NL) synthetic, NL 94 C2-3 produced 13 and 10.3 % more biomass plant⁻¹ than the check (Alamo) in pot and field experiments, respectively. The southern lowland (SL) synthetic SL 93 C2-2 had 7 % more photosynthesis capacity than Alamo and seasonal photosynthesis was higher in SL populations. The PCA was able to discriminate lowland and upland populations for morphological traits, but was unclear for physiological traits. The path analysis results showed strongest correlation between biomass and plant height (r = 0.76*** pot study in greenhouse and r = 0.82*** field experiment), also plant height had the most direct effect on biomass with path coefficients of 1.32 and 0.90 in greenhouse and field experiments, respectively. Similarly, stomatal conductance (g ₛ ) had highest correlation (r = 0.8***) and strongest direct impact with path coefficient of 1.93 on photosynthesis (P ₙ ). Ample genetic variation was evidenced among switchgrass populations for evaluated traits indicating the genetic potential to advance the switchgrass populations for performance and adaptation in a wider geographic and environmental range.