THE PRINCIPLES OF SEED-TESTING 491 



(5) Light. — Most seeds seem indifferent to sunlight, i.e. the 

 seeds germinate equally well in darkness or light. It is a 

 popular saying that a seed in nature germinates best when 

 covered by a layer of soil equal in depth to the diameter of the 

 seed. Exposure to direct sunlight brings with it difficulties in 

 regulating the temperature of the incubator. In a few cases — 

 e.g. the Poas — exposure to light has been shown to be distinctly 

 beneficial, expediting the germination of the seed by one to three 

 or four days, or increasing its percentage of germination. 



Where the seed is of good average quality — i.e. such as a 

 seedsman should sell and a farmer sow — the foregoing con- 

 ditions can be kept so generally constant that the test will be 

 quite reliable, and may be safely taken as an indication for 

 sowing purposes of the quality of the seed. 



Objections Raised against Seed-testing 



(a) Unreliability. — Occasionally objectors to seed-testing quote 

 cases — 



(1) In which several Stations have given widely different 



reports on the same seed. 



(2) In which the same seed tested by the same person under 



different methods has given different results. 

 The particulars as to the quality of the seed, the number of 

 seeds tested, the use or not of a " control " seed, the temperature 

 of the incubator, the degree of familiarity with the incubator, 

 and the experience of the tester are all omitted. 



The difficulty with the Poas is the usual case quoted. They 

 are delicate seeds, but not beyond reliable testing, and, further, 

 they form an infinitesimal part of the seed trade. A few 

 years ago an Irish landowner sent independently to a seed 

 firm, strongly opposed to seed-testing, and to me, samples 

 of " tussock " grass seed. The fact that the firm identified 

 this seed of a valuable fodder grass Poa Jlabellata, or Dactylis 

 ccespitosa, as a worthless grass, Aira ccespitosa, cannot be quoted 

 as proof of their general unreliability as seedsmen. The Com- 

 mittee was further told that only skilled hands could prepare a 

 uniform mixture of seeds of grasses and clovers. The mixture 

 made in the seed warehouse rearranges itself in the journey to 

 the farm, and needs remixing before being sown. The purchase 

 of mixtures is being, for obvious reasons, more and more 

 discouraged by the farmers' advisers. 



