Document Type

Thesis - Open Access

Award Date

2023

Degree Name

Master of Science (MS)

Department / School

Agronomy, Horticulture, and Plant Science

First Advisor

E. Brent Turnipseed

Keywords

dormancy, germination, optimum temperature, river bulrush, seed testing, stiff goldenrod

Abstract

Federal and state seed laws require seed lots offered for sale to be tested and labeled with the appropriate information before they can be sold. Those tests are conducted in seed testing labs all around the world. In the United States, accredited seed testing labs follow the Association of Official Seed Analysts (AOSA) Rules for Testing Seeds to provide information for labeling. The rules lack instructions for weights and germination for many native species. Stiff goldenrod (Solidago rigida) and river bulrush (Bolboschoenus fluviatilis) are two species that lack any information required for testing. When seed testing labs use correct weights and optimum germination temperatures, they can provide customers with accurate results in a timely manner. This research evaluates the weights needed for purity and noxious weed seed testing and the optimum temperature(s) needed for germination. Multiple seed lots of each species were gathered to determine the weights required for a purity and noxious analysis. Following the steps laid out in the AOSA Rules to calculate weights, eight replications of 100 seeds were counted out from each sample and weighed. The average weights of the replications, minimum weight for a purity and noxious analysis, and the number of seeds per gram were determined for each species. The average weight for 100 stiff goldenrod pure seed units was 0.0548 grams. The weight required for a purity and noxious analysis were 1.4 and 14 grams, which provides approximately 2500 pure seed units for a purity and 25,000 seeds for a noxious exam. The number of seeds per gram was 1824.7391. River bulrush had an average weight of 0.6516 grams per 100 pure seed units. The weight needed for a purity and noxious exam were 16 and 160 grams. River bulrush contained 153.4794 seeds per gram. A thermogradient table was used to evaluate the optimum temperature for germination of the selected species. The thermogradient table allowed multiple temperatures to be tested at once. The temperatures created with the thermogradient table were 13°C, 17°C, 19°C, 22°C, 23°C, 24°C, 26°C, 27°C, 28°C, 30°C, 31°C, and 32°C. In addition, six germinators set to temperatures typically used for species in the AOSA Rules were used. These temperatures included three constant temperatures (15°C, 20°C, 25°C) and three alternating temperatures (15-25°C, 15-30°C, 20-30°C). A total of 18 temperatures were assessed. Four lots were chosen for each species. Four replications of 50 seeds from each lot were planted at every temperature evaluated. Stiff goldenrod exhibited the highest germination at a constant 25°C with an average germination 63.8%. River bulrush exhibited the highest germination of 2.5% at the alternating temperature 20-30°C.

Publisher

South Dakota State University

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Rights Statement

In Copyright