Testing for Seed Quality
Laboratory tests are used to determine basic measure of seed viability of the species. Field (wild) collections of native species typically have variable seed quality, and many collections are essentially non-viable, and are thus removed from the evaluation. Other accessions with extremely high seed germination at this stage are identified.
Early information on the influence of origin on seed fill can also be gained from these tests. Other useful information gained from these initial tests includes speed of germination, indications of seed dormancy, and assessment of region wide potential for agronomic production. Species that show extremely low natural seed set or viability are identified at this point, and evaluation may be discontinued.
Growing Transplants for Field Evaluation
Transplants are grown for initial evaluation plots, and established at multiple locations throughout south Texas. Typical evaluation plots consist of two replications of ten plants per accession. Plants are established in a spaced plant design, on 1-2 ft spacing between plants.
Most species are evaluated at a minimum of three locations. Species with limited distributions (such as sand sheet or coastal plants) are evaluated at the appropriate locations only. The transplant evaluation plots are irrigated to insure establishment for the first year after planting. After one year plots are not irrigated.
Evaluation of Field Performance
Field performance data and seed production potential is assessed for 2-3 years, under irrigation and natural conditions. For the first year of evaluation, monthly ratings of survival,vigor,uniformity,development stage, seed production, biomass production, plant height and agronomic production potential are taken.
For the second and subsequent years, bi-monthly ratings are taken. Throughout the evaluation, seed is collected whenever produced. This seed is cleaned, and laboratory tests are conducted to document the seed production potential of each accession from each location.
At the completion of evaluation, STN, TARS and PMC personnel meet to discuss the release potential of each evaluated species. Criteria such as seed production potential, seed quality, accession variability, commercial demand, and ease of production are assessed.