EFFECTS OF THE METHOD OF DESICCATION ON THE CARBOHYDRATES OF PLANT TISSUE¹

Abstract

The iron division precipitate is treated directly with nitric acid and potassium chlorate to remove the manganese. (At this point phosphates may be removed if present.) Iron is removed by adding a large excess of ammonium hydroxide. The filtrate from the iron precipitate is evaporated until Only a faint odor of ammonia remains and nickel is tested for by adding dimethyl glyoxime directly to V6 of this solution, no adjustment of hydrogen ion being necessary.The remainder of the solution is further evaporated to a sirup and transferred to a test-tube; enough water is then added to dissolve the precipitated salts, and cobalt is tested for by a modified Vogel's test; 3 cc. of 10% potassium thiocyanate solution is added, followed by 3 cc. of a mixture of amyl alcohol and ether (1 vol. : 3 vol.) and the tube gently shaken, Cobalt causes the ether layer to become blue-green. If the color is not distinct, the careful addition of a few drops of 12 N hydrochloric acid to the ether layer will give the blue-green color if cobalt is present, or a straw-colored or colorless layer, if it is absent. This test is extremely sensitive and can be applied to the original solution if iron is absent.The writer wishes to thank Professor J. H. Reedy of the University of Illinois and Professor J. F. G. Hicks of the University of Nevada for testing the above method with their students.

Influence of Drying and Storage Conditions on Nonstructural Carbohydrate Analysis of Herbage Tissue—a Review

“…The literature on heat-drying substantiates the early 1920 observations of Link and Tottingham (18) and Link (17) that no one method can be relied on for all plant parts and species. This also may be the case with the form of tissue used since it has been shown that method of drying does not equally affect fresh and ensiled herbage (7,27).…”

“…Link and Tottingham (18) and Link (17) found few heat-drying treatments that were suitable for all kinds of tissues. Drying at 60°t o 80°C in forced-draft ovens was satisfactory for some tissues.…”

The Laboratory Drying of Herbage and Faeces, and Dry Matter Losses Possible During Drying

“…However, slow low-temperature drying is not to be recommended in these cases. Not only will the associated dry matter losses alter the proportions of the remaining constituents, but these themselves may be changed during the drying process (16). While r.f.…”

“…Thus LINK (16) has shown considerable changes in the free and reducing sugar content of plant material during drying. This means that an estimation of, say, reducing sugar content of similar plant material before and after drying cannot be taken as a measure of the loss of reducing sugars during drying.…”

Errors in Measuring Nitrogen and Dry–matter Content of Plant and Faeces Material

“…On the other hand, the discolouration of oven-dried material would suggest that these determinations should be made on fresh herbage or freeze-dried material (15,23).…”