In a study of factors responsible for variation in the results of barley germination tests, the effects of varying the amount of water available to the corns during such tests have been examined. It has been found that this factor profoundly influences the final percentage germination, because an early stage in germination involves a process which in some samples takes place slowly and which in these barleys can be inhibited by rapid absorption of an excess of water. It follows that the amount of water applied to the seeds in germination tests must be carefully controlled if reproducible results are to be obtained.
Conditions have been defined by which the husks may be rapidly and conveniently removed from barley so that the treated corns are able to germinate readily and completely. As a result of detailed study, a technique for determining germinative capacity which gives accurate and reproducible results has been evolved, requiring 3‐hr. treatment with 50% (v/v) sulphuric acid, removal of acid and husk, and germination in petri dishes on paper under standard conditions of temperature and water supply.
A simple and reliable technique for germination tests is described, giving maxi mum germination and satisfactory reproducibility with non-dormant barleys, and involving growth (72 hrM 18-21°C) on filter paper under standard conditions with standard addition of water. A slight modification of the method also permits the assessment of the water-sensitivity of the barley as a guide to its suitability for normal malting procedures; the technique is exactly as in the germination test, except that an excess of water is used.
During malting, the phytase activity of barley increases markedly, attaining in the green malt approximately eight times its original value; despite considerable inactivation on the kiln, especially in the early stages of drying, the finished malt shows a higher activity than was present in the barley. The inorganic phosphate content of barley is small, but increases sharply to the green malt stage and less sharply thereafter; phytate, however, shows in general no parallel decrease and cannot represent the sole, or even the major source, of inorganic phosphate. In normal brewery malts, the recovery of phytate phosphate is approximately 90% of that originally present in the barley.
The rate of improvement of germinative energy in dormant barley samples increases with increasing temperature of storage. The rate of disappearance of water‐sensitivity during storage is inversely related to the moisture‐content after drying.
The removal of the husk of barley by means of sulphuric acid as previously described provides the basis of a method for determining husk‐content and permits mealiness to be estimated by direct examination of the endosperm. Husk is determined from the difference in dry 1,000‐corn weight between the original and treated barley. Mealiness is determined from visual assessment of corns of different degrees of steeliness in the sample.
It has been shown that storing barley at 40°C. for 3 days brings about an increase in germinative energy irrespective of whether drying takes place. On the other hand the stimulatory effect of desiccation alone is small. Heating, either with or without drying, has no regular immediate effect on water-sensitivity.It is well known that kiln drying of dormant barley improves its germination. Recently it has been shown8 that the degree of desicca tion of a barley is an important factor governing the subsequent rate of recovery from water-sensitivity, the driest samples recovering most rapidly. It has also been shown that, when germinative energy is low, raising the temperature during storage accelerates the increase in germinative energy which then takes place.8 An investigation of the effects of heat and desiccation, taken separately and together, on the germination characteristics of dormant barley has there fore been carried out. This was of particular interest because of a claim that drying dor mant barley at 40°C. so that its moisture content falls to 7-8% is fully effective in removing dormancy.* Eight samples of dormant barley of several varieties from the crop of 1956 were kept at 40°C. for three days in open containers, and duplicate samples were similarly treated in closed vessels so that drying occurred only in the samples heated in the open containers. The heated barleys were then allowed to germinate under the conditions of the germinative energy and water-sensitivity tests previously described.1 The tests were in this instance also extended for two-days longer than the three days usually allowed.The results obtained (Table I) show clearly that the stimulation of germination resulting from these treatments is due primarily to the increased temperature, for the germinative energies of the portions which had been heated in closed containers were generally equal to or definitely greater than those of samples heated in open dishes. The moisture contents of the former group were in many cases more than double those of the latter, so that any effect of desiccation alone must be a minor one. It will be seen that the effect TABLE I Effect of Heat on the Germination of • G = germinative energy (%); S = germination (%) in water-sensitivity test; M = moisture content (%).
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