MODERN SEED-TESTING.

New Zealand Journal of Agriculture, Volume XXVI, Issue 2, 20 February 1923, Page 65

MODERN SEED-TESTING.

THE NEW ZEALAND OFFICIAL SEED-STATION.

NELSON R. FOY,

Biological Laboratory, Wellington,

THE idea of testing seeds before they are sown is not by any means a recent one, for in writings of the eighteenth century there is reference to the examination' of seed. In 1869 the first seed-control station was initiated by Dr. ' Nobbe,. in Saxony, and gradually seed-stations ’ were instituted all over Europe. Among the most notable are those at Zurich (Switzerland) and at Copenhagen. These two stations may be termed the leaders of the world's seedtesting, and much valuable research work has been done there. In the British Isles Ireland has had a seed-testing station for twenty years, Scotland for about ten, and England for five years past. The United States of America and Canada have been testing seeds for many years ; in the former country there is at least one station in every State, with the main station at Washington, while in Canada there are several, large stations. Australia is also well provided in this respect. All these countries have some form of seed legislation, under which it is . compulsory to have all seed tested, and necessary that it shall be of a certain standard of purity and germination before it is placed on the market. ' -

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For the ten months ended .January, 1923, 7,500 samples have been tested, making an aggregate of nearly 61,500 samples dealt with since the establishment of the system.

METHODS ’OF SEED-TESTING. ' The two methods of seed-testing—the Continental and the Irish have been described previously in the Journal; in the former method only mature seeds are germinated, and in the latter both mature and immature seeds. There has been much ( discussion over the relative advantages of the two methods, the trend of opinion being towards the Continental. In New Zealand all testing is carried out. on the Irish method, but the time may not be far off when, with one. or two other countries, we shall have to fall into line and adopt the Continental system, in order that tests from all parts of the world may be uniform. Theoretically the Continental method is the more correct, its great disadvantage being the laborious and complicated methods of executing the tests, requiring more , than double the operating force. The only case in which the Irish method is at present departed from at the New Zealand station is that of Waipu brown-top, which, as the lin.es usually contain a large percentage of empty glumes, is dressed until only full mature seed remains. The report on such a sample is given, for example, thus: Empty glumes, 40 per cent.; kernel, 50 per cent.; extraneous seeds, 10 per cent. ; germination, 85 per cent. THE NEW ZEALAND SYSTEM IN DETAIL. As each sample is received it is given a number, and all the particulars concerning it are entered upon a special record card, one for each sample. Upon the card also is entered the dates on which the test is to be counted, and a space for the record of the purity analysis. Process of Germination. Germination tests are carried out in specially constructed germinators, of which there are three —the all-metal water-bath germinator, which is enclosed at the sides, top, and bottom by a water-jacket ; the glass, wooden-framed type ; ■ and the small water-bath type. All the more difficult testing, such as rye-grass, cocksfoot, dogstail, arid fescue, is carried out in the first type, owing to its uniformity of temperature, correct degree of humidity, and the ease with which temperatures can be controlled. With the exception of the germinator for cereals, all the germinators are gas-heated. All the clovers, crucifers (swedes, turnips, &c.), cereals, peas, and vegetable seeds generally are germinated in the second type. It is proposed to gradually replace these with the first type. The small germinators are used for paspalum, Poa species, and any other seeds with which a high temperature is required. The sample is well mixed and poured on to a sheet of stiff paper. From different portions of it are counted two lots of 100 seeds, which are placed on separate trays, these trays being placed in separate germinators. Thus all tests are made in duplicate, while four tests are made of Chewings fescue, cocksfoot, and Poas. The germinatingmedium itself is simply coarse felt saturated, with water and covered with two thicknesses of blotting-paper, the whole being placed on an asbestos tray. Each sample is covered by a 3 in. watch-glass raised at one side to allow of ventilation. With the exception of paspalum, Poa species, cereals, and peas all seeds are germinated at a temperature alternating from 85° to 65° F. —■ 85° for eight hours, and then allowed to fall to 65° for the remaining

sixteen hours. Paspalum and the Poas are germinated at 95 0 to 65°, peas at 75 0 to 6o°, and cereals at ordinary room-temperatures. Peas and beans are soaked in water for sixteen hours before being placed to germinate, the latter being then germinated in damp sawdust. Four counts are made of each sample,' but the interval between the counts varies according to the class of seed under test, thus : —

The seeds that have germinated are counted off and discarded, and the number entered upon the record card. Purity Analysis. . .- In the purity analysis the percentage .of extraneous seeds is given by weight. The sample is . thoroughly mixed, and a definite amount weighed by means of a special balance. The amount weighed for examination varies for different seeds, being as follows : For the larger seeds, such as rye-grass, cow-grass, &c., 2| grams ; for the smaller seeds, such as crested dogstail, white clover, &c., 1 gram ; for seeds of the Brassicas, such as rape, 5 grams ; for-oats, prairie-grass, &c., 10 grams. The weighed amount is spread evenly over a squared surface and gone , through carefully with an eyeglass. ' All extraneous seeds are picked out and weighed, and the percentage calculated. The remainder of the sample is then gone through, and any additional extraneous seeds picked out and their names entered, together with those found in the weighed amount, on ‘the record card. In the event of Californian thistle, clover dodder, or ox-eye daisy being found in a sample the number of seeds per pound is calculated and entered on the card. ■ Reports. In every case after the second germination count a report is furnished to the sender. This gives the average germination after a specified number of days, and the percentage of impurities'. The interim report is of special value f01 two reasons: Firstly, it gives the merchant (dr other sender) some idea of how the line is shaping, and enables him to judge whether it is suitable for his purpose without his having to wait the full time for the final test. For instance, a sample of crested dogstail germinating 85 per cent, in the interim report will finish up with an approximate final of 95 per cent. Again, if a sample of ryegrass shows an interim result of, say, only 25 per cent, the merchant will know-'immediately that it is worthless. Secondly, the interim report gives x a good indication of the vitality of a line. The degree of rapidity with which germination takes place is indicative of the vitality of the seed — slow germination means low vitality, a rapid one high

vitality. Thus the final reports on two separate lines of rape may both be 92 per cent., with interim reports at 90 per cent, and 80 per cent, respectively. At the expiration of the testing-period final reports are sent but. . These show the interim and final germination, each at a certain number of days, and in the case of purity tests the percentage of extraneous seeds and a complete list of the impurities. Any peculiarity noted about the sample, such as the presence of mites, &c., is also reported. In the case of clover-seeds there usually remains after the test is completed a certain number of seeds 'that have neither germinated nor rotted. These are seeds the seed-coats of which are too hard to allow the water to enter, with a result that germination does not take place. These are termed “ hard seeds,” and as they are living seeds, with the possibility of softening and germinating in the soil, half of the number- is counted as viable and included in the final result.

Year ended March. Number of Samples tested. Year ended March. Number of Samples . . tested. . IQIO ... .. 180 .' "1917 •<"•'" • • 2 , 700 ‘ 1911 .. • .. 400 1918 .'. 3,859 1912 400 1919 •• •' 6,261 • 1913 .. 650 . 1920 . . . 8,165 1914 •• 1,863 ' 1921 . . , 8800 1915 . .. . •• 2,646 . 1922 . . . ,400 1916 ... .. 3,200

First Count. Second Count (Interim Report). Third Count. Fourth Count. . (Final Report) Fourth Count (Final Report) Days. Days. Days. Days. Crucifers, clovers 2 . 4 7 IO Rye-grass, Lotus spp. ... 3 6 IO : 14 ’ Fescues, dogstail, mangolds 4 8 13 18. Cocksfoot, paspalum .,. - 5 IO lb 22 Poa spp. . . • . . .6 ■ 12 20 28 Pinus, spp. 21 42 63 up to 84