STARCH AND SUGARS OF VITIS VINIFERA

Abstract

were cut between 7 and 8 A.A. and taken directlv to the laboratory. The leaves w-ere promptly stripped off, and comparatively large samples of young anid of mature leaves were taken. Then 4-to 6-incll sections were removed from the base, middle, and tip of each shoot. The base and middle sections were divided into wood and bark. All samples were quickly cut into small pieces, weighed, and rapidlv dried in a small fruit dlehvdrater with a verv strong air blast at 600 to 630 C. The vines were cane pruned so that mature shoots (canes) could be sampled in the same mannier, except that there were 414PLANT PHYSIOLOGY no tip samples. Two 3-inch sections were sawed or cut from each trunk, the bark was removed, and the wood was separated according to annual rings: one-year-old wood and the subsequent growth during the sampling period, two-year-old wood, and wood three years old and older (two years' growth, including the pith). As soon as the trunk was removed, the root.s in the vicinity of the vine were dug up. After washing and drying of the external moisture, three types of root samples were taken: small rootlets (3/32-inch and less), one-year-old roots (3/16-to 1/4-inch), and two-year+ roots (1/2-to 3/4-inch). The one-and two-year root sections were divided into wood and bark samples. The dried samples were ground in a Wiley mill.Analytical procedure To obtain the sugars, the samples were continuously extracted with 95 per cent. ethyl alcohol for 6 hours by letting the condensed alcohol fall directly from the condenser onto the sample contained in alundum thimbles, the liquid level being kept above the material to help prevent channeling. The alcohol extract was evaporated to a small volume. The residue, taken up in warm water, was subsequently treated with an excess of neutral lead acetate, and the precipitated material was centrifuged off. The excess lead was removed with oxalate. Invertase was used for the sucrose inversion. The alcohol-extracted residue served as the sample for determining starch. The sample, plus 50 cc. water, was placed in an enclosed steam bath for one hour. Subsequently, 10 cc. of a phosphate buffer of pH 5 (4) and 10 cc. of the Taka diastase solution (2.5 per cent.) were added. Taka diastase utilized was purified, to remove most of the blank, by precipitation from a saturated water solution through the addition of 2.5 times its volume of 95 per cent. ethyl alcohol. The precipitate was centrifuged off and redissolved.The sample was then transferred to a porcelain jar, several flint pebbles were added, and the whole was rotated on its axis for 16 hours at 250 r.p.m.This procedure reduced the material to a very fine state of division, facilitating complete hydrolysis. If starch was revealed by a microscopical examination, the samples were re-treated. The extract was clarified, using lead acetate, and brought to a definite volume; and sufficient hydrochloric acid was added to make 2.5 per cent. by volume. The samples were then hydrolyzed in an enclosed st.eam bath for 2.5 hours. To determine th...

Use of Carbohydrate Reserves During Growth from Cuttings of Grape Vine

“…The initial starch content of 12% is, on the one hand, similar to the late autumn maximum contents of canes reported for example by Winkler and Williams (1945) and Eifert, Panczel, and Eifert (1961). These authors and others have found a marked fall in starch and a corresponding rise in sugars during winter under natural conditions, followed by a partial reversal to give a second starch peak in early spring.…”

“…A value of roughly 0·09 mg CO 2 /g fresh weight/hr was obtained, corresponding to some 0·37 g CO 2 for two-node cuttings for the period between the two harvests. This value is considered very high for woody tissue, and Winkler and Williams (1945) have pointed out that misleading results may be obtained in measuring cane respiration by means of CO 2 evolution, but it appears that respiratory needs of the cane may be of the same order as reserves utilized between harvests 2 and 3. However, the mention of two other possible reasons for the greater (absolute) reserve loss by two-node canes at this time is considered warranted.…”

“…No knowledge of this nature has been found documented in the literature, although several workers (notably Winkler and Williams 1945;Eifert, Panczel, and Eifert 1961) have studied carbohydrate changes in field plants or dormant cuttings. For the experiment reported in this paper it was postulated that carbohydrate status of the whole plant arising from a cutting would be reflected in changes occurring in the parent cane portion, and it is these changes which have been measured.…”

Effect of Postharvest Defoliation on Carbon and Nitrogen Resources of High-Yielding Sauvignon blanc Grapevines

“…The storage of non-structural CHO is generally greatest in the root tissue of grapevines (Bates et al 2002, Uys andOrffer 1983), and root-derived CHO was found to be the principal reserve source for the annual resumption of growth in grapevines (Bates et al 2002, Loescher et al 1990, Zapata et al 2004. Reserve CHOs accumulate to their greatest concentrations in all plant organs by leaf fall in autumn (Bennett et al 2005, Williams 1996, Winkler and Williams 1945 and are mostly retained during ectodormancy (abbreviated to 'dormancy' throughout this work), apart from small respiratory losses. During leaf senescence in autumn, hydrolytic enzymes break down leaf proteins, CHO, and nucleic acids that are transported in the phloem back into the permanent plant structure, where they are stored during dormancy and remobilized in spring for early growth.…”

Distribution of 14C-Photosynthetate in the Shoot of Vitis vinifera L. cv Cabernet Sauvignon I. The Effect of Leaf Position and Developmental Stage of the Vine

“…Although the roots are considered the most important sites of accumulation of carbohydrates as regards vine reserves (Winkler & Williams, 1945;Scholefield, Neales & May, 1978), the primary goal of the viticulturist is to divert carbohydrates to the grapes in order to obtain high quality. Sugar accumulation in the fruit can either be directed from photosynthesis or mobilized from stored carbohydrate reserves in the roots, canes and trunk (Mansfield & Howell, 1981).…”