2013 Annual Report
1a.Objectives (from AD-416):
Determine the potential of Amaranthus species germplasm accessions as an alternative lignocellulosic biomass crop for bioenergy.
1b.Approach (from AD-416):
An annual herbaceous crop with C4 type photosynthesis with an upright growth habit, the genus Amaranthus grows in both temperate and tropical climates. The U.S. National Plant Germplasm System's (NPGS) amaranth holdings include grain, vegetable, ornamental and weedy types. High-yielding weedy amaranths are known to continue vegetative growth following grain harvest, and offer potential as an alternative, lignocellulosic bioenergy source (Brenner et al., 2000). It produces a large amount of biomass in a short period of time and can grow in marginal production areas and tolerates water deficient conditions. Because it has a C4 photosynthetic pathway, it is able to maintain relatively high rates of carbon dioxide fixation. Amaranth cell wall biochemical composition analyses indicate it is an equally viable candidate as maize, switchgrass and miscanthus for biomass feedstock production. Currently, the Germplasm Resource Information Network (GRIN) does not contain evaluation information for amaranthus biomass. Evaluation for biomass and chemical constituents can provide basic information for the breeding of alternative biofuel feedstock. Germplasm evaluation will identify promising germplasms as potential commercial cultivars and/or parental lines for future molecular breeding applications. High-biomass and low-lignin fermentation candidates, identified via this research, will serve as an alternative next-generation biofuel (non-food) crop for small stakeholders and growers to support the biofuel industry. Grain and stem dry matter (DM) samples will be evaluated for forty amaranth accessions of 20 diverse species, supplied by the NPGS Amaranth curator, for biomass and cell wall biochemical composition. A complete random design experiment with three replicates will be conducted in each of two growth environments (greenhouse and field). Entries were seeded in 18-well trays in late-April 2012 and transferred into 3-gallon containers in the greenhouse, subjected to 18 hour daylength and high fertility for 60 days. Another set of seeds will be sown in one row plots, 6 m long and 1 m apart, planted in mid- or late-May 2012. Biomass yield (wet and dry matter): Grain and stem sections will be harvested from fully mature plants, dried at 80F for 48 hours or until completely dry, ground for further cell wall composition analysis, and data on grain and stem biomass yield (wet and dry matter) will be collected. Cellulose, hemi-cellulose, and lignin content will be measured using the methods of Fu et al (2011) in the laboratory of Iowa State University, Ash, carbon, and sulphur contents will be analyzed using the methods of Viglasky et al. (2009) in the laboratory of University of Arkansas. Growth habit, plant height, adult stem color and diameter, leaf size, flowering time and color, seed color and size, and maturity will be recorded during the growing season, using standard GRIN Amaranthus phenotypic descriptors, at the Texas AgriLife Research Center at Dallas, TX. All data will be returned for loading in the GRIN database by NPGS Curator.
A total of 81 Amanranthus accessions from the National Plant Germplasm System collection were sown in a greenhouse in Dallas Research Center on April 8, 2013. Individual plants of each genotype were transplanted into 5 gallon pots with three replicates. Some plants were damaged by rabbits. Only 35 genotypes (31 Amaranthus and 4 Celosia accessions) matured but no seeds were harvested because our greenhouse cooling system failed and caused heat stress. We harvested above ground plant biomass of these 35 genotypes for biomass yield (no grains). We collected fresh and dry matter weights (samples dried at 80°C in an oven for 72 hours). We also collected agronomic traits such as plant height, leaf size (area), leaf number, and stem diameter which are related to biomass yield.
A. australis accessions had the greatest fresh and dry biomass yield. This species grows fast and tall (330 cm when flowering). Several genotypes have good biomass yield, such as accessions from A. cruentus (PI 606799, PI 606797, PI 477913 and Ames 13887) and A. hypochondriacus (PI 604794 and PI 619249).
The trial will be repeated to successfully obtain results.