Fecha de publicación: 01/04/2016 Fuente: ecent issues American Journal Of Enology and Viticulture Grapevine defoliation is common, as are reports of its effect on post-budburst reproductive parameters (inflorescences), but little is known about the underlying mechanisms of these defoliation effects. We propose that low carbohydrate reserves from defoliation reduce the number of inflorescence primordia (IP) initiated and, during development, limit size in latent buds. From early in Season 1 (December in the southern hemisphere), Chardonnay grapevines were completely defoliated, progressively as new leaves appeared, throughout Season 1 until leaf fall, with the fruit remaining intact. Defoliation treatment resulted in low carbohydrate reserves in the dormant wood at season end and consequently, in smaller IP by the start of dormancy and at pre-budburst in Season 2. Treatment and control grapevines had similar numbers of IP at winter dormancy and by pre-budburst in Season 2. However, post-budburst treatment inflorescences likely underwent necrosis, resulting in inflorescence abortion and fewer clusters in Season 2. Low reserves during spring of Season 2 resulted in reduced IP initiation and delayed development with fewer, smaller inflorescences at post-budburst in Season 3. Thus, defoliation effects were due to low carbohydrate reserves that reduced IP initiation numbers and size in latent buds and also to abortion of mature inflorescences immediately after budburst.