2nalyses of the carbohydrates in the leaf and stem of perennial rye-grass were carried out during uninterrupted growth from May to November. Although there were individual variations in the amounts of glucose, fructose and sucrose present, no major seasonal trends in these sugars were evident. The plant accumulated in the stem a reserve of fructosan which reached a maximum of 2 1 % of the dry matter before it diminished in the autumn. There was a gradual increase in the percentages of cell-wall polysaccharides. The relation between fructosan accumulation and synthesis of cell-wall material during the growth of the plant is discussed.The autumn aftermath growth was analysed and its composition compared with that of the first growth.
Considerable enzymic breakdown of sucrose and fructosan has been found to occur during wilting and laboratory ensilage of grass. The implications of this are discussed with respect to the collection of grass samples for analysis and the preparation of grass silage.
The seasonal variations of the carbohydrates in the leaf and stem of lucerne have been studied during two successive years' growth. During growth from seed in the first year, when the crop did not flower, there was a continuous accumulation of sucrose in the plant. I n the second year, flower and seed formation influenced the soluble sugar content, which was highest when the flowers were in bloom. This substantiates field observations by other workers that the best hay and silage are obtained from material cut a t this stage. In both years there was a continuous increase in the amount of cell wall polysaccharides.
Investigations have been carried out on methods of grass-drying. Satisfactory results for the free-sugar and fructosan contents of grasses are obtainable when the analyses are performed immediately after freeze-drying and milling. I t has long been realized that the method employed for the dehydration of grasses exerts a considerable influence on the ultimate constitution of the product. Thus, Bartlett, Henry, Kon, Osborne, Thompson & Tinsley (1938) showed statistical differences in the biological value of the proteins of grasses dried a t different temperatures and Marston, Quinlan-Watson & Dewey (1943) found variations in the ascorbic acid content of lucerne (Medicago sativa) according to the conditions of drying. Here the best yield was obtained by rapid air-drying at IIOO and these authors demonstrated that, in meal stored at 37' in vacuo, the loss of ascorbic acid was less than 1oO4 in seven months, provided the moisture content was less than 3O4.A systematic investigation into methods of drying and preservation of rye-grass for 'sub. sequent analysis was undertaken by Collins & Shorland (1945), who examined the action of boiling water and ethanol, of freezing to -g? and -22O and of air-drying at 35", 70', 1 0 5~ and 120'. Phosphatide, fatty acid, ascorbic acid and sugar contents were used as criteria of the efficiency of preservation. I t was found that boiling ethanol or rapid air-drying appeared to be the most efficient method of arresting enzyme action, but that for subsequent analysis, storage in ethanol was much more satisfactory unless the dried material was kept out of contact with the air. The analytical figures for these products indicated that the free-sugar content of the ethanol-preserved grass was higher than that of the air-dried material. Furthermore, it was shown that the free-sugar content of air-dried grass increased greatly on storage, and in the course of 32 days had attained a value equal to about six times that of the original. This finding agrees with that of Archbold (1938), who demonstrated that the oven-drying of grasses did not inactivate the enzymes present. For the estimation of the sugar content, the grass was extracted with water, and after clarification with cadmium hydroxide, the reducing sugars present in the extract were determined by the use of the Somogyi reagent. A further analysis was carried out after hydrolysis with o~o~~-s u l p h u r i c acid, the value found here being taken as ' total sugar '. As pointed out by Laidlaw & Reid (I952), such methods of analysis are non-specific and do not take into account the complex nature of the mixture of carbohydrate and other material present in the aqueous extract. The results, however, show that considerable changes of composition occur on dehydration and storage. I t was decided therefore to undertake a reinvestigation of the problem, with special reference to the free-sugar and fructosan contents of grasses, using the newer methods recently developed for the estimation of these constituents. The use of the paper chroma...
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