Development of energy plants from hybrids between Miscanthus sacchariflorus and M. lutarioriparius grown on reclaimed mine land in the Loess Plateau of China

Abstract

Miscanthus, a promising bioenergy plant, has a high biomass yield with high cellulose content suitable for biofuel production. However, harsh climatic and poor soil conditions, such as barren lands or abandoned mines, pose a challenge to the survival and yield of Miscanthus feedstock on the marginal land. The selection from the interspecific hybrids of Miscanthus might combine high survival rates and high yield, which benefits energy crop development in multi-stressful environments. A total of 113 F₁ hybrids between Miscanthus sacchariflorus and M. lutarioriparius together with the parents were planted and evaluated for multiple morphological and physiological traits on the mine land of the Loess Plateau of China. The majority of hybrids had higher establishment rates than M. sacchariflorus while M. lutarioriparius failed to survive for the first winter. Nearly all hybrid genotypes outperformed M. lutarioriparius for yield-related traits including plant height, tiller number, tiller diameter, and leaf area. The average biomass of the hybrids was 20 times higher than that of surviving parent, M. sacchariflorus. Furthermore, the photosynthetic rates and water use efficiency of the hybrids were both significantly higher than those of the parents, which might be partly responsible for their higher yield. A total of 29 hybrids with outstanding traits related to yield and stress tolerance were identified as candidates. The study investigated for the first time the hybrids between local individuals of M. sacchariflorus and high-biomass M. lutarioriparius, suggesting that this could be an effective approach for high-yield energy crop development on vast of marginal lands.

Keywords: Miscanthus lutarioriparius; Miscanthus sacchariflorus; biomass; hybrids; photosynthetic rate; reclaimed mine land; water use efficiency.

Figure 1

Differences of (A) average plant and individual tiller’ biomass, (B) average plant and stem height between measuring hybrid and parent individuals in two consecutive growth seasons. Different capital letters A and B represent a significant difference of plant and individual tiller’ biomass, and plant and stem height between two years at P<0.05 level, respectively. Different lowercases a and b represent a significant difference between M. sacchariflorus, M. lutarioriparius and their hybrids at P<0.05 level, respectively. Error bars indicate standard error of 333 surviving hybrid individuals, 5 and 3 surviving female parent individuals in both 2018 and 2019, and 10 surviving male parent individuals in 2018, respectively.

Figure 2

Differences of average plant height between measuring hybrid and female parent individuals throughout growth months in two growing seasons, and male parent individuals throughout growth months in the 2018 growing season. Different capital letters A, B, and C represent a significant difference of plant height between growth months at P<0.05 level, respectively. Different lowercases a and b represent a significant difference of M. sacchariflorus, M. lutarioriparius and their hybrids at P<0.05 level, respectively. Error bars indicate standard error of 333 surviving hybrid individuals, 5 and 3 surviving female parent individuals in both 2018 and 2019, and 10 surviving male parent individuals in 2018, respectively.

Figure 3

Differences of (A) average photosynthetic rate, (B) the advantage in average stomatal conductance, (C) transpiration rate between measuring hybrid and female parent individuals in both 2018 and 2019 growing season, and male parent individuals in 2018. Different capital letters A, B and C represent a significant difference of photosynthetic rate, stomatal conductance, and transpiration rate between growth months at P<0.05 level, respectively. Different lowercases a and b represent a significant difference of photosynthetic rate, and stomatal conductance, and transpiration rate between M. sacchariflorus, M. lutarioriparius and their hybrids at P<0.05 level, respectively. Error bars indicate standard error of 333 surviving hybrid individuals, 5 and 3 surviving female parent individuals in both 2018 and 2019, and 10 surviving male parent individuals in 2018, respectively.

Figure 4

Differences of (A) average WUE_e, (B) WUE_i between measuring hybrid and female parent individuals during the 2018 and 2019 growing season, and male parent individuals in 2018. Different capital letters A, B, and C represent a significant difference of WUE_e and WUE_i between growth months at P<0.05 level, respectively. Different lowercases a and b represent a significant difference between M. sacchariflorus, M. lutarioriparius and their hybrids at P<0.05 level, respectively. Error bars indicate standard error of 333 surviving hybrid individuals, 5 and 3 surviving female parent individuals in both 2018 and 2019, and 10 surviving male parent individuals in 2018, respectively.

Figure 5

The distribution of the total biomass of all survival ones from 10 individuals planted in 10 m² for each hybrid genotype in November 2019.

Figure 6

Systematic cluster of hybrid genotypes based on growth traits at the end of 2019 growing season. A total of 113 hybrid genotypes are divided into three classes that are showed by using the red, blue, and black lines on the left. The blocks from the red to the green in the heat map represent the good and poor growth performance, respectively. PB, plant biomass; BIT, biomass of individual tiller; SH, stem height; PH, plant height; TN, tiller number; SD, stem diameter; NN, Node number; BN, branch number; IL, internode length; LW, leaf width; LA, leaf area; LBA, leaf basic angle.