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which might interfere with the conducting tissues;
(3) An epicotyl with terminal bud;
(4) Both cotyledons (thin leal-like structures) present and intact, plus an intact epicotyl;
(5) Less than two cotyledons present; bearing organ (fleshy food storage organs resembling cotyledons); or
(6) Slight infection by fungi or bacteria, provided the essential seedling parts have not been seriously damaged and appear to be able to carry on their normal functions at the time of evaluation.
(b) Abnormal seedlings include those that have:
(1) No primary root or well-developed adventitious or secondary roots;
(2) A malformed stem, which may be characterized by severe open splits, and curled, shortened or thickened hypocotyl;
(3) No epicotyl, or an epicotyl without the terminal bud;
(4) No attached endosperm-bearing organ;
(5) Less than two cotyledons present;
(6) Decay caused by micro-organisms carried by the individual seed or seedling being evaluated; or
(7) Various combinations of the abnormalities described in this subparagraph. (20 F.R. 7935, Oct. 21, 1955, as amended at 25 F.R. 8772, Sept. 13, 1960) $201.56-11 Miscellaneous plant fami
lies. Kinds of seed by families: Benne family (Pedaliaceae)-Sesame. Carrot family (Umbelliferae) --carrot, celery,
celeriac, parsley, parsnip. Dichondra family (Dichondracea e) -
Dichondra. Knotweed family (Polygonaceae)-Buck
wheat, sorrel, rhubarb. Nightshade family (Solanaceae)-Eggplant,
pepper, tomato, husk tomato, tobacco. Geranium family (Geraniaceae)---Alfleria. Hemp family (Cannabinaceae)--Hemp. Rose family (Rosaceae)-Little burnet. Valerian family (Valerianaceae)-Cornsalad.
(a) In this group of plant families, normal seedlings include those that have: (1) A well-developed primary root, usually with root hairs; (2) a stubby root or no primary root, provided the secondary root development is strong and the hypocotyl is near normal length as is frequently encountered in tomato
seedlings; (3) a long, well-formed hypocotyl with no prominent breaks or lesions extending into the conducting tissues; (4) at least one attached cotyledon, provided the epicotyl is intact and the seedling is otherwise normal (a tiny epicotyl may be observed in seedlings left in test for final evaluation); or (5) slight infection by fungi, provided none of the essential seedling structures have been damaged (infection is likely to occur in rhubarb in which case retests may be advisable).
(b) Abnormal seedlings include those that have: (1) A stubby root or no primary root, provided there is weak secondary root development; (2) a malformed hypocotyl, which may be twisted, thickened, or shortened; (3) deep cracks or lesions on the hypocotyl extending into the conducting tissues; (4) both cotyledons, or one cotyledon and epicotyl, broken off; (5) two enlarged cotyledons, but hypocotyl short and usually malformed; (6) watery hypocotyl or root; (7) grainy hypocotyl or root; (8) decayed cotyledons or hypocotyl, provided they are not the result of improper test conditions; or (9) various combinations of the abnormalities described in this paragraph. [20 FR. 7935, Oct. 21, 1955, as amended at 25 F.R. 8772, Sept. 13, 1960) 8 201.57 Hard seeds.
Seeds which remain hard at the end of the prescribed test because they have not absorbed water, due to an impermeable seed coat, are to be counted as “hard seed.” If at the end of the germination period provided for legumes, okra, cotton and dichondra in these rules and regulations there are still present swollen seeds or seeds of these kinds which have just started to germinate, all seeds or seedlings except the above-stated shall be removed and the test continued for 5 additional days and the normal seedlings included in the percentage of germination. (5 F.R. 33, Jan. 4, 1940, as amended at 10 F.R. 9952, Aug. 11, 1945; 20 F.R. 7936, Oct. 21, 1955) 8 201.57a Dormant seeds.
Dormant seeds are viable seeds, (excluding hard seeds) which fail to germinate when provided the specified germination conditions for the kind of seed in question. Viability of ungerminated seeds may be determined by a cutting or tetrazolium test, application of germination promoting chemical, or any other appropriate method or combination of methods. (38 FR 12731, May 16, 1973) & 201.58 Substrata, temperature, dura
tion of test, and certain other specific directions for testing for germina
tion 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 8 201.57.)
(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 essentlal 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 germi. nated 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 (KNO3). 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 blotters TB= top of blotters T= paper toweling, used either as folded
towel tests or as roll towel tests in
horizontal or vertical position S sand or soll 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 soll C= creped cellulose paper wadding (0.8.
inch thick Kimpak or equivalent) covered with a single thickness of blotter through which holes are punched for the seed that pressed for about one-hall their
thickness into the paper wadding RB: blotters with raisod covers, prepared
by folding up the edges of the blotter to form a good support for the upper fold which serves as & 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 indi. cate 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. Sugar beets may require 16 hours soaking in water at 25° C., followed by rinsing and then drying for 2 hours at room temperature.
(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 ni
trate 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 lint is thoroughly wet. The excess moisture should then be blotted off.
(6) Endive (Cichorium endivia); dormant samples. Add about 13 inch of tap water at the beginning of the test and remove excess water after 24 hours.
(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. If there are over 75 percent normal fluorescent seedlings present at the time of the first count, break the contact of the roots of the nonfluorescent seedlings from the substratum and reread the fluorescence at the time of the final count.
(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.
(c) Table 2; germination requirements for indicated kinds.
TABLE 2-GERMINATION REQUIREMENTS FOR INDICATED KINDS
17 Photos 2481, 2486; see par. (b)(11).-
Remove seeds from bur; see par. (b)
Prechill 6 days a 5° or 10° C. or
Broomcorn-Sorghum oulgare var. technicum..
28 Light; KNO...
Prechill at 5°C. for 8 weeks; test 14
packed soil and prechill at 6° C.
Prechill at 5° or 10° C. or 7 days.
Burclover, California-Medicago hispida.
Pop-Zea mays var. werta.
See footnotes at end of table.