Heterosis for biomass yield and other traits in alamo x kanlow switchgrass populations

Authors: SHRESTHA, SURYA - University Of Tennessee; BHANDARI, HEM - University Of Tennessee; ALLEN, FRED - University Of Tennessee; Tobias, Christian; SANTOSH, NAYAK - University Of Tennessee; GODDARD, KEN - University Of Tennessee; SENSEMAN, SCOTT - University Of Tennessee

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/11/2021
Publication Date: 8/11/2021
Citation: Shrestha, S.L., Bhandari, H.S., Allen, F., Tobias, C.M., Santosh, N., Goddard, K., Senseman, S.A. 2021. Heterosis for biomass yield and other traits in alamo x kanlow switchgrass populations. Crop Science. https://doi.org/10.1002/csc2.20618.
DOI: https://doi.org/10.1002/csc2.20618

Interpretive Summary: Switchgrass is a native grass of the North American Tallgrass Prairie. It is being developed as a bioenergy crop because of its high yields, adaptability, stress tolerance, and low input requirements once established. Hybrid vigor has been demonstrated in crosses between lowland and upland switchgrass ecotypes. This work describes crosses that display hybrid vigor within the lowland switchgrass ecotype. Exploiting hybrid vigor among lowland individuals with can be a useful strategy for increasing biomass production in regions where extreme cold hardiness is not required. It was also demonstrated that visual ratings of shoot density and thickness were highly correlated with biomass yield at two different locations and two years. This may be a rapid and effective indirect selection technique in switchgrass breeding programs.

Technical Abstract: Heterosis plays important role in switchgrass breeding. To identify seasonal single-cut biomass yield heterosis, ten ‘Alamo’ x ‘Kanlow’ biparental crosses along with their parents were evaluated in this study. The experiment was planted in 2018 in a randomized complete block design with two replications at two locations, the East Tennessee Research and Education Center (ETREC), Knoxville, and the Plateau Research and Education Center (PREC), Crossville, TN. The crosses and their parents were evaluated for biomass yield, plant height and clonal mass in the Fall of 2019 and 2020. The crosses were significantly different in biomass yield within and across the environments (P<0.05). Average biomass yield of the crosses ranged from 7.08 to 8.85 Mg ha-1 at ETREC and 9.96 to 11.14 Mg ha-1 at PREC. The crosses demonstrated an average of 125, 12 and 43% mid-parent heterosis and 108, 4 and 23% high-parent heterosis for biomass yield, plant height and clonal mass respectively, across the environments. Significant positive association was found between clonal mass scores and biomass yield at individual locations across years, and across locations and years (r = 0.35 to 0.79, P<0.05). However, the association between biomass yield and plant height was inconsistent (r = -0.22 to 0.67, P<0.05). The findings of biomass yield heterosis in these crosses derived from two lowland cultivars has important implications for future breeding strategies with switchgrass. Furthermore, the information may be helpful in identifying genomic regions associated with biomass yield.