Gerhard Rossouw completed his masters degree in viticulture at the University of Stellenbosch, South Africa in 2009. The focus of his study was on the effects of vineyard variability in vigour and water status on grapevine physiology, and in particular on carbon isotope discrimination. He then worked in the wine industry from 2009 until mid 2013, being involved in viticulture and wine production. This included experiences in South Africa, South Australia, California and New Zealand. In July 2013 he enrolled for his PhD studies at the NWGIC at Charles Sturt University, where he will focus his research on grapevine physiology, and mainly look at effects of water relations and grapevine balance.
Specialization: Grapevine physiology
Focus area: Carbohydrate and nitrogen reserve mobilization and partitioning during fruit ripening
Carbohydrates reserves in perennial grapevine organs are used for early season vine development. Water constraint, limited canopy leaf area and high crop load can cause the carbohydrate demand of ripening fruit to outweigh the supply through leaf photoassimilation. This alters the partitioning of carbohydrates between starch and sugars in storage tissues, and can cause starch remobilization from perennial organs to support fruit sugar accumulation, potentially depleting starch reserves. Low starch reserves at the initiation of growth in the following season causes weak vegetative and reproductive development.
Along with carbohydrates, the grapevine nitrogen reserves are also important for early season vine development. The availability of nitrogen can influence shoot and leaf development, and also impact on fruit yield. Nitrogen distribution can be affected by abiotic conditions and grapevine crop load, and the allocation to berries contributes to berry juice yeast assimilable nitrogen content.
The aim of this project is to improve the understanding of grapevine carbohydrate and nitrogen mobilization and partitioning during berry ripening.