Retests shall be made as follows:
(a) When the range of 100-seed replicates of a given test exceeds the maximum tolerated range in the table appearing in this section. Table of Maximum Tolerated Ranges Between 100-Seed Replicates for Use in
Connection With Sec. 201.55(A)------------------------------------------------------------------------
Average percent germinations Maximum allowed between----------------------------------------------- replicates
-------------------------
4 2
replicates replicates------------------------------------------------------------------------99................................... 2 598................................... 3 697................................... 4 7 696................................... 5 8 695................................... 6 9 794................................... 7 10 893................................... 8 10 892................................... 9 11 991................................... 10 11 990................................... 11 12 989................................... 12 12 1088................................... 13 13 1087................................... 14 13 1186................................... 15 14 1185................................... 16 14 1184................................... 17 14 1183................................... 18 15 1282................................... 19 15 1281................................... 20 15 12
80................................... 21 16 1379................................... 22 16 1378................................... 23 16 1377................................... 24 17 1376................................... 25 17 1375................................... 26 17 1474................................... 27 17 1473................................... 28 17 1472................................... 29 18 1471................................... 30 18 1470................................... 31 18 1469................................... 32 18 1468................................... 33 18 1567................................... 34 18 1566................................... 35 19 1565................................... 36 19 1564................................... 37 19 1563................................... 38 19 1562................................... 38 19 1561................................... 40 19 1560................................... 41 19 1559................................... 42 19 1558................................... 43 19 1557................................... 44 19 1556................................... 45 19 1555................................... 46 20 1554................................... 47 20 1653................................... 48 20 1652................................... 48 20 1651................................... 50 20 16------------------------------------------------------------------------
(b) When at the time of the prescribed final count there are indications, such as presence of firm ungerminated seeds, that a satisfactory germination has not been obtained;
(c) When there is evidence that the results may not be reliable due to improper test conditions, errors in seedling evaluation, the presence of fungi or bacteria, or inaccuracies in counting or recording results;
(d) When a sample shows seedling injury or abnormality as a result of chemical treatment, of exposure to chemicals, or of toxicity from any source. (Retest shall be made in soil or a mixture of soil and sand);
(e) When no two satisfactory tests are within tolerance.
Note to Sec. 201.55: To find the maximum tolerated range, compute the average percentage of all 100 seed replicates of a given test, rounding off the result to the nearest whole number. The germination is found in the first two columns of the table. When the differences between highest and lowest replicates do not exceed the corresponding values found in the ``4 replicates'' column, no additional testing is required. However, if the differences exceed the values in the ``4 replicates'' column, retesting is necessary. [25 FR 8771, Sept. 13, 1960, as amended at 65 FR 1707, Jan. 11, 2000] Sec. 201.55a Moisture and aeration of substratum.
(a) The substratum must be moist enough to supply the needed moisture to the seeds at all times. Excessive moisture which will restrict aeration of the seeds should be avoided. Except as provided for those kinds of seeds requiring high moisture levels of the germination media, the substrata should never be so wet that a film of water is formed around the seeds. For most kinds of seeds blotters or other paper substrata should not be so wet that by pressing, a film of water forms around the finger.
(b) The following formula may be used as a guide in the preparation of sand for germination tests: [118.3 cc. (1 gill) sand/Its weight in grams]x20.2-8.0=The number of cc.
of water to add to each 100 grams of air-dry sand.
(c) The amount of water provided by this formula is satisfactory for seeds the size of clovers and will have to be modified slightly, depending on the kind of seed being tested and the kind of sand used. For example, slightly more moisture should be added when the larger seeds are to be tested.
(d) In preparing soil tests water should be added to the soil until it can be formed into a ball when squeezed in the palm of the hand but will break freely when pressed between two fingers. After the soil has been moistened it should be rubbed through a sieve and put in the seed containers without packing.
(e) The addition of water subsequent to placing the seed in test will depend on the evaporation from the substrata in the germination chambers. Since the rate of evaporation will depend upon the relative humidity of the air, it is desirable to keep water in the germination chambers or to provide other means of supplying a relative humidity of approximately 95 percent. Germination tests should be observed at frequent intervals to insure an adequate moisture supply of the substrata at all times. [20 FR 7931, Oct. 21, 1955]