[5 F.R. 33, Jan. 4, 1940, as amended at 10 F.R. 9952, Aug. 11, 1945; 20 F.R. 7936, Oct. 21, 1955] § 201.57a Dormant seeds: firm ungerminated seeds. Dormant seeds means seeds, other than hard seeds, which are alive and fail to germinate when provided the specific germination conditions for the kind of seed in question. Firm ungerminated seeds means seeds, other than hard seeds, which neither germinate nor decay during the prescribed test period and under the prescribed test conditions. Firm ungerminated seeds may be either alive or dead. [26 F.R. 10035, Oct. 26, 1961] § 201.58 Substrata, temperature, duration of test, and certain other specific directions for testing for germination and hard seed. Specific germination requirements are set forth in table 2 in paragraph (c) to which the following paragraphs (a) and (b) are applicable: (a) Definitions and explanations applicable to table 2—(1) Duration of tests. The following deviations are permitted from the specified duration of tests: Any test may be terminated prior to the number of days listed under "Final count” if the maximum germination of the sample has then been determined. The number of days stated for the first count is approximate and a deviation of 1 to 3 days is permitted. If at the time of the prescribed test period the seedlings are not sufficiently developed for positive evaluation, it is possible to extend the time of the test period two additional days. (Also, see subparagraph (5) of this paragraph and § 201.57.) (2) Light. Cool white fluorescent light shall be provided where light is required in table 2. The light intensity shall be 75 to 125 foot-candles (750-1,250 lux). (The light intensity for nondormant seed and during seedling development may be as low as 25 footcandles to enable the essential structures to be evaluated with greater certainty.) The seeds shall be illuminated for at least 8 hours every 24 hours except when transferred to a low temperature germinator during the weekend. When seeds are germinated at alternating temperatures they shall be illuminated during high temperature periods. Seeds for which light is prescribed shall be germinated on top of the substratum except for ryegrass fluorescence tests. (3) Moisture-on-dry-side. This term means that the moistened substratum should be pressed against a dry absorbent surface such as a dry paper towel or blotter to remove excess moisture. The moisture content thus obtained should be maintained throughout the germination test period. (4) Potassium nitrate (KNO1). These terms mean a two-tenths (0.2) percent solution of potassium nitrate (KNO;) shall be used in moistening the substratum. Such solution is prepared by dissolving 2 grams of KNO, in 1,000 ml. of distilled water. The grade of the potassium nitrate shall meet A. C. S. specifications. (5) Prechill. The term "prechill" means to place the seed on, or in, a moist substratum at a specified low temperature for a designated period of time. The prechilling period is not included in the duration of tests given in table 2, unless otherwise specified. (6) Predry. The term "predry” means to place the seed in a shallow layer at a temperature of 35° to 40° C. for a period of 5 to 7 days, with provisions for circulation of the air. (7) Substrata (Kinds). The symbols used for substrata are: B= between blotterь TB= top of blotters T= paper toweling, used either as folded towel tests or as roll towel tests in horizontal or vertical position 8= sand or soil TS= top of sand or soil P= covered Petri dishes: with two layers of blotters; with one layer of absorbent cotton; with five layers of paper toweling; with three thicknesses of filter paper; or with sand or soil C= creped cellulose paper wadding (0.3inch thick Kimpak or equivalent) covered with a single thickness of blotter through which holes are punched for the seed that are pressed for about one-half their thickness into the paper wadding RB blotters with raised covers, prepared by folding up the edges of the blotter to form a good support for the upper fold which serves as a cover, preventing the top from making direct contact with the seeds. (8) Temperature. A single numeral indicates a constant temperature. Two numerals separated by a dash indicate an alternation of temperature, the test to be held at the first temperature for approximately 16 hours and at the second temperature for approximately 8 hours per day. The temperature shall be determined at the substratum level and shall be as uniform as possible throughout the germination chamber. (A sharp alternation of temperature, such as obtained by hand transfer, may be beneficial in breaking dormancy.) If tests are not subjected to alternating temperatures over weekends and on holidays, they are to be held at the firstmentioned temperature during this time. In cases where two temperatures are indicated (separated by a semicolon) the first temperature shall be regarded as the regular method and the second as an alternate method. (9) Paper substrata must be free of chemicals toxic to germinating seed and seedling growth. If root injury occurs from toxicity of a paper substratum or from the use of potassium nitrate, retests shall be made on soil or on a substratum moistened with water. (b) Special procedures and alternate methods for germination referred to in table 2-(1) Alyce clover (Alysicarpus vaginalis); Swollen seeds. At the conclusion of the 21-day test period carefully pierce the seedcoat with a sharp instrument and continue the test for 5 additional days. Alternate method: The swollen seeds may be placed at 20° C. for 48 hours and then at 35° C. for 3 additional days. (2) Bahia grass (Paspalum notatum); removal of glumes-(i) Vars. Common and Argentine. Remove the glumes with the aid of a sharp scalpel. If the seed is fresh or dormant scratch the surface of the caryopsis lightly and use potassium nitrate. (ii) Var. Pensacola. The glumes shall not be removed for the germination test. (3) Beet, Swiss chard (Beta); preparation of seed for test. Before placing the seeds on the germination substratum they shall be soaked in water for 2 hours, using at least 250 ml. of water per 100 seeds, then washed in running water and the excess water should be blotted off. The temperature of the soaking and washing water should be no lower than 20° C. Samples producing darkened radicles should be retested in soil or by washing in running water for 3 hours and tested on "Kimpak," keeping the seed covered with slightly moist blotters. (4) Buffelgrass (Pennisetum ciliare); alternate method for dormant seed. The caryopses shall be removed from the fascicles and placed on blotters moistened with a 0.2 percent potassium nitrate solution, in Petri dishes. The seeds from a fascicle should be arranged so they will not be confused with seeds from other fascicles during the test. The seeds are then prechilled at 5° C. for 7 days and tested at 30° C. in light for 21 additional days. Firm ungerminated seeds remaining at the conclusion of the test should be scratched lightly and left in test for 7 additional days. (5) Cotton (Gossypium spp.); dormant samples. Samples of cottonseed which do not respond to the usual method should be placed in a closed container with water and shaken until the excess lint is thoroughly wet. The moisture should then be blotted off. (6) Endive (Cichorium endivia); dormant samples. Add about 1 inch of tap water at the beginning of the test and remove excess water after 24 hours. (7) Lettuce (Lactuca sativa); light exposure. All samples should be given at least 2 hour of light after being placed on the moist substratum. Additional light during the test period is desirable for dormant samples and facilitates seedling interpretation for samples of low vigor. (8) Rescue grass (Bromus catharticus); dormant samples. Wash for 48 hours in running water, or soak for 48 hours, changing the water and rinsing each morning and night. (9) Rice (Oryza sativa)—Alternate method: Plant the seeds in moist sand. On the seventh day of the test add water to a depth of one-fourth inch above the sand level and leave for the remainder of the test. Only a final count is made. Dormant seeds: Presoak 24 to 48 hours in 40° C. water. For deeply dormant seeds, presoak 24 hours in 1,000 p.p.m. ethylene chlorohydrin or 5 percent solution of sodium hypochlorite (clorox at bottle strength). (10) Ryegrass (Lolium); fluorescence test. The germination test for the fluorescence of ryegrass shall be conducted in light (not to exceed 100 foot-candles) with white filter paper as a substratum. The test shall be conducted in a manner that will prevent the contact of roots of different seedlings. (11) Trifolium, Medicago, Melilotus, and Vicia faba; temperature requirements. A temperature of 18° C. is desirable for Trifolium spp., Medicago spp., Melilotus spp., and Vicia faba. |