Breeding Amaranth for Biomass: Evaluating Dry Matter Content and Biomass Potential in Early and Late Maturing Genotypes

Ali Baturaygil,Markus G Stetter,Karl Schmid

doi:10.3390/agronomy11050970

Abstract

Amaranth (Amaranthus spp.) is a promising biomass crop for silage and biogas production. Under long-day conditions, it exhibits prolonged vegetative growth. To evaluate the breeding potential of amaranth for biomass production, we characterized phenotypic variation in biomass yield components, quantitative genetic parameters, and the relationships between traits. We conducted field trials of 10 biomass-type genotypes exhibiting a ‘giant’ growth habit derived from spontaneous hybridization between genetically diverse parents, and used the variety “Bärnkrafft” as check. We observed two contrasting growth patterns: Bärnkrafft is a variety for grain production and was characterized by a short vegetative growth followed by a long seed ripening. In contrast, the biomass genotypes displayed a long vegetative growth followed by a short seed ripening. We observed strong correlations between dry matter content and stem diameter (r =−0.78, p < 0.01) and between plant height and biomass score (r = 0.95, p < 0.001). High values for broad-sense heritability of stem diameter (H2 = 0.88) and plant height (H2 = 0.92) suggest that the dry matter content and yield can be improved by indirect phenotypic selection. We hypothesize that selection for dry matter content and yield implies a trade-off between earliness and photoperiod sensitivity. Hence, dry matter content should be improved first by recurrent selection, which can be then combined with short-day genes to improve dry matter yield. Overall, this work provides an avenue to the breeding of biomass amaranth.

Highlights

The production of bioenergy is an important component in efforts to reduce dependence on fossil fuels
We evaluate the potential of breeding for biomass amaranth by: (1) characterizing phenotypic variation in biomass yield components, (2) determining the components of phenotypic variation and detecting correlations between traits, and (3) proposing a breeding strategy for amaranth with high dry matter yield
We focused on ten genotypes from our biomass amaranth breeding pool, whose ancestors include putative F1 generation hybrids derived from spontaneous outcrossing events between Bärnkrafft, Puerto Moutt (A. cruentus), C6 (A. caudatus) and Pastewny (A. hybridus) that occurred during field trials in 2012, as well as multiple genebank accessions cultivated with these four genotypes

Summary

Introduction

The production of bioenergy is an important component in efforts to reduce dependence on fossil fuels. One way to produce bioenergy is the anaerobic digestion of plant material in bioreactors and a consecutive conversion of the resulting biogas into electricity and heat through a generator [1]. In Germany, biogas production from energy crops has grown rapidly with 9200 biogas plants that produce 4.2 GigaWatts as of 2016 [2]. Maize silage is the most popular biogas substrate in Germany, with a mass-based contribution of about 70% among energy crops [3]. Given that methane yield is mainly determined by dry matter yield, high dry matter yield is the primary breeding objective in biogas crops [4,5]. Maize has become the predominant biogas crop because it combines high dry matter yield and content [6]. Potential negative impacts of maize monoculture, such as increased risk of soil erosion and a decrease in agrobiodiversity, create a demand for alternative energy crops [7,8]

Methods

Results

Conclusion