WORTH A MILLION

Manawatu Standard, Volume LVI, Issue 168, 17 June 1936, Page 17

WORTH A MILLION

DOMINION’S SEED TRADE PURITY ANALYSIS WORK AN IMPORTANT INSTITUTION New Zealand’s seed trade is estimated to have a value of over £1,000,000 per annum. Practically the whole of this is based on the certificates, of analysis issued by the Seed Testing Station at Palmerston North for samples submitted voluntarily by seed merchants and on officially drawn samples in the case of certified seed. This important institution,, which, works unostentatiously on the fourth floor of a large building at this centre, is maintained by the Department of Agriculture for the purpose of testing agricultural seeds of commerce in New Zealand. Under the direction of Mr Nelson 11. Foy, Government Seed Analyst, fihe work has steadily expanded and, apart from its monetary value, is of great indirect economic importance. Testing on behalf of the seed trade alone requires the working of some 16,0U0 samples per annum, and necessitates the carrying out of over 25,0U0 duplicate purity analyses and triplicate germination tests, besides other special examinations.

PROBING THE SAMPLE. The position of New Zealand in this respect is unique, because in no other country docs the trade operate to sued high standards, entirely without ttie pressure of legislation requiring the testing and true description oi seed sold on retail markets. With admirable perception, the New Zealand seed inercnant has realised the advantages of using the official seed testing service for his business. Likewise, the department has had the vision to see the wisdom and appraise the value of this work. Very little agricultural seed is quite pure, and contains large or small quantities, depending on the variety of seed, of impurities of various kinds. It is under the purity analyses that these are probed, tne seed sample being divided into its component parts oi pure seeu', and impurities such as other crop seeds, weed seeds, and inert material. The sample is put through a mixingmachine repeatedly until it is reduced to a workable size. A proportion is then weighed and placed in an electrically operated blower, where an a:r blast lifts away all lighter seed, empty glumes and foreign matter. Next

both the pure seed and inert matter are examined over a reflected light with a diathanoscope, which is a check on the blower. It is then weighed on scales so super-sensitive that they will reveal the weight of a signature. An efficient young lady—one of some twelve on the staff—uses a pair of forceps on a sheet of plate glass under the glare of a powerful electric lamp to separate the impurities from the genuine seed. This calls for skilful work in identification. Magnifying goggles are used when conducting the purity analysis of minute seeds. The proportion of impurities by weight determines the purity of the sample, and an index record is kept of each phase of the examination. GERMINATION POWERS.

Although the sample may contain a high proportion of pure seed, it must also be ascertained whether this will grow, and consequently a germination test has to be made. Three lots of 100 seeds are counted by hand and each lot is placed on a chemically-pure absorbent paper disc. These discs are placed on sheets of non-absorbent material, on which have been folded several layers of sterile towelling, moistened to full capacity with water. Over each test is placed a concave glass. The germinating room has twelve germinators and eight Copenhagen tanks. The germinators are water jacketed cabinets. heated by gas under thermostatic control. The seed is held there for a defined period and examined tour times. An interim report is made on the energy or vitality of tlio soocl aftor the second count. Copenhagen tanks are used for the germination of seeds which require a longer penod of incubation than most types. Finally, test results are entered on the purity and germination certificate.

The most recent phase of seed testing work is the development of laboratory methods for the determination of plant type from a seed sample. Differences in type or strain ar ® ~ rarel s shown by the appearance of theseed itself, and it has been necessary to investigate the practicability of differentia! responses of artificially raised idlings to physical and chemica treatments. It has been discovered that seedlings of superior hl S h P ducing plants react differently to inferior ones, and that the value of a sample for the establishment of high producing pasture may be assessed. Probablv the most outstanding o these methods is the use of screened ultra-violet light in the d ‘ a gnosis of strain perennial ryegrass. Practically the whole of the. inferior types o perennial ryegrass in New Zeafand have become degenerate through hy bridisatiom with the annual Italia" ryecrass With the use of the ultra-violet fi„ht the degree of contamination can

be measured and the sample classified. The Hanovia quartz mercury vapom lamp is used for this test, its value having been discovered at the State Seed Control Station, Munich (Germany) some years ago. Italian ryegrass becomes fluorescent under this light, as do seedlings of the false perennial type, but true perennial ryegrass, under similar conditions, does not react. UNDER THE ANAESTHETIC. White clover is another important species in New Zealand grasslands, and a technique has been evolved lor its type diagnosis. The test- is a chemical one, and depends upon the fact that superior strains contain complex glucosides absent in the inferior ones, this is known as the picric acid test, and is used to determine the amount of the glucoside present when it is liberated ill the form of hyciro-cyan.t acid gas. For the purpose of thi test seed is germinated on filter pad; in full light and, on the eighth day. when the exposed cotyledons are ; dark green, fifty seedlings are taken |at random and firmly packed at jh i base of a three-inch test tube. Two

or three drops of toluene' are then added. This has the effect of anaesthetising the seedlings, in which condition tne enzymes which liberate hy-dro-cyanic acid from the cyanogenetic glueosides become active. A small slip of p'icrate paper (filter paper immersed in a solution of picric acid and sodium carbonate and stored only partially drv) is then inserted along the full ‘length of the tube, four of which are prepared and then incubated for 48 hours at 30 degrees Centigrade. Upon the completion ol this period, the HCN gas liberated is shown by the changes in the originally coloured lemon paper, and the tubes are then classified into groups according to the degree of colour change from dark orange to the unchanged lemon. Colour classifications have been correlated with the plot classifications reported by the agrostologist. DETECTION OF DISEASE. Research activities include the discovery and measuring of low germination* of perennial ryegrass grown in certain districts of New Zealand, including the Manawatu, in certain seasons. a fungus parasite which attacks the seed head soon flowering destroys the devetoping germ, and although the seed itself develops, it is quite weak in its powers of germination. With a widely distributed crop such as ryegrass, a system of control is practically impossible, and the success of seed crops of ryegrass is dependent on the presence or absence of climatic conditions under which the disease is able to perpetuate itself in seed. A method has been evolved at the station for the detection of diseased seed beads in the early stages, and bv this means it is possible to indicate* to a grower whether or not the germination capacity of his crop, after harvest, will l>e high or low through disease contamination. The failure of many lines of newly harvested' Algerian oats to germinate led to an investigation which showed that it was due to the fact that, like some other seeds, Algerian oats ripen or mature for some weeks or months after harvesting, and are incapable of growth under normal conditions until maturity is complete. Experiments showed that incompletely ripened oats could be induced to germinate at very low temperatures, and, in fact, have been grown successfully when tested on a block of ice. Speed of maturity is dependent on seasonal conditions up ro harvesting, and on subsequent stoiage conditions, which phase of the matter is at present under investigation. Brown top is in very general demand for the laying down of fine lawns, and it is essential that the seed used be free from that closely related coarse grown species, red-top. Broun-top certified free from red-top is available,

but the buyer of small quantities cannot always ascertain the source of the seed. A method pf distinguishing between artificially grown seedlings of the two species has been evolved, and consists .or microscopic examination of the seedling leaf. REACTIONS IN STORAGE. Other investigations cover the ability of certain seeds to store satisfactorily under certain conditions of temperature and humidity, and experiments have been designed to duplicate the conditions to which seeds are subject during shipment from New Zealand to Hie Northern Hemisphere. This is important work, as heavy losses have been experienced through deterioration of the germination of some species of glass seed during sh.pmeut. Constant endeavours uqe being made to extend the Dominion’s seed export trade, worth at present nearly £250,000, and it is essential that seed exported be delivered with a high germination capacity, the stations findings in respect of the use of cold storage and seed drying have resulted in the use of special methods of shipment and paciring, particularly tor seeds susceptible to the influence of unfavourable conditions, The whole of the State’s requirements of agricultural seed, amounting annually to between 000 and 400 tons, Is also purchased 1 y the station on behalf of other Government departments.

Time required for type identification ,in field or plot trials is very considerably reduced by the Seed Testing Station’s technique. Specific nmrpuo.ogical differences are exhibited by the seeds of most genera, but in some instances they become apparent only by critical examination. On the other hand, morphological and physiological differences within species are not usually associated with structural differences in the seed, or with form or growth behaviour of the seedling. The absence of morphological differences in seed or seedlings has resulted in a concentration on the physiological and bio-chemical fields. Besides the methods outlined there are many other phases of seed-testing activity which can be carried out, such as the use of phenol tnd chloral hydrate in specific and varietal differences in seed of the Brassica family (confined almost entirely to Europe and Russia), ol the "easurement by the speed of germination, of the absorption bv seed of standard sugar cane solutions (termed “suction force”), and of the differentiition between seed samples representative of early and late flowering red lovers, by the respective photoperiodic eactions in the seedling stages.