Effects of fruiting on vegetative growth and development dynamics of grapevines (Vitis vinifera cv. Semillon) can be traced back to events at or before budbreak

Leaf and shoot growth and development patterns in Vitis vinifera L. cv. Semillon were analysed dynamically. Potted fruiting and vegetative vines were grown in controlled conditions and budbreak, leaf and internode (metamers) appearance and expansion were measured. Buds were also dissected microscopically. Metamer appearance occurred in three zones; the first 5–6 metamers emerged as a cluster with fastest expansion and largest size. Marked differences in sizes and dynamics of growth occurred between fruiting and vegetative vines because flowers were absent. The next 13–14 preformed metamers appeared at a constant rate and metamer size declined along the shoot. Timing of maximum expansion and duration of growth of the metamers in this cohort was increasingly delayed in fruiting compared with vegetative vines. Beyond node 20, neoformed metamers emerged at a slow constant rate and were smallest overall. Throughout development, extension of the internode occurred before expansion of the subtending leaf, consistent with the liana habit of grapevines. Differences between fruiting and vegetative vines in metamer development were observed just after budbreak and these differences generally appreciated over time. The impact of reproduction on vegetative growth can, therefore, likely be attributed to competition for carbohydrate between floral and leaf primordia in the dormant or breaking bud, accounting for the smaller leaves and internodes.