ISHS Acta Horticulturae 640: XXVI International Horticultural Congress: Viticulture - Living with Limitations
INVESTIGATIONS ON LATERAL BUDS AND STARCH GRANULES OF DORMANT VITIS VINES BY SCANNING ELECTRON MICROSCOPY |
| Authors: | S. Gu, P.E. Read |
| Keywords: | grape, bud dormancy, starch granules, SEM |
| Abstract:
One-year old dormant canes of Vitis spp. Lacrosse (own-rooted) and Chambourcin (own-rooted and grafted to 3309 Couderc) in southeast Nebraska, USA, were sampled in January, February and March 2001 and 2002. The lateral buds excised at the 5th and 6th nodes from the proximal end and the internode between the 5th and 6th nodes were dissected or sectioned for investigations of bud meristems or starch granules under scanning electron microscopy. The “dormant” lateral buds were actually growing as illustrated by the expanding bud size, increased number of primordia and number of bud structures, all of which indicated that the vines were at ecodormancy. For all the buds observed, the primary and secondary buds in a lateral bud were readily observed in January and February; the tertiary bud, however, did not appear until buds were examined in samples taken in March 2001 although most 2002 samples included it. There were some significant differences between the cultivars and among months tested in terms of primordia number, bud size, and number of bud structures. Rootstock effects were minor in 2001, but a significant influence of rootstock was found in 2002. The grafted vines were more advanced than those of own-rooted vines. Observations of cross, tangential and longitudinal sections of dormant stems showed that starch granules were mainly located in ray parenchyma cells. For all the varieties and sampling dates investigated, no major differences in the distribution and content of starch granules were observed, which indicated that the growth of lateral buds in the dormant season may consume little reserves stored in the stems or only used those reserves stored in the bud itself. | |
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