A New Description and the Rate of Development of Inflorescence Primordia over a Full Season in Vitis vinifera L. cv. Chardonnay

Abstract

There are gaps in the scientific literature of grapevine physiology concerning the formation of inflorescence primordia (IP) in the compound latent buds throughout the first season. Therefore, the goal of this study was to provide a detailed description of the developmental stages, initiation times, and the fate of all primordia in primary buds relative to the time of year and to the phenological stage; we also sought to measure IP size in secondary and tertiary buds. Using a dissecting microscope, we examined latent buds of Chardonnay grapevines throughout season 1, during dormancy, and prior to budburst in season 2. At least four IP 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 IP developing into differentiated primordia (stage 5a) by December. The IP did not reach stage 7 until the last month of season 1, and IP growth continued through dormancy. At least two IP remained 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 had none. This is the first report of IP development and of the contents and fates of the latent bud growing points throughout the first season; its findings advance our knowledge of grapevine physiology and will aid future research on the compound latent bud.