A new description and the rate of development of inflorescence primordia over a full season in Vitis vinifera L. cv. chardonnay

There are gaps in the scientific literature of grapevine physiology concerning inflorescence primordia (IP) formation in the compound latent buds throughout the first season. Thus we sought to describe, in detail, the developmental stages, initiation times and the fate of all primordia in primary buds in relation to dates and phenological stages, and to quantify IP size in secondary and tertiary buds. Using a dissecting microscope, latent buds of Chardonnay grapevines were dissected throughout Season 1, during dormancy, and prior to budburst in Season 2. At least four IP were initiated early in Season 1, from mid-October to late-November, with no further initiation in Season 1 or 2. These IP developed quickly with two developing to differentiated primordia (Stage 5a) by December. Stage 7 was not reached until the last month of Season 1 and IP growth continued over dormancy. At least two IP remained as undifferentiated primordia (Stage 4) throughout Season 1 and formed tendrils by budburst of Season 2. Secondary buds had smaller and fewer IP and tertiary buds none. This is the first report of IP development and the contents and fate of the latent bud growing points throughout the first season, advancing grapevine physiology knowledge and aiding future research on the compound latent bud.