Rootstock-driven variation in early-season vegetative development of Pinot Noir grapevines: A sustainable solution to water limitations in New Zealand cool climate regions : A dissertation submitted in partial fulfilment of the requirements for the Degree of Master of Wine and Viticulture

Abstract

Grapevine rootstock selection is a key factor contributing to overall vineyard performance. Extensive breeding efforts have been made in recent years to develop rootstocks that tolerate increasing environmental pressures, of which drought is a primary concern. This study focused on investigating the influence of eight commercially available rootstocks on early-season vegetative development of Pinot Noir in the cool-climate region of Canterbury, New Zealand (NZ). The experimental procedure explored canopy vigour (shoot elongation and leaf area), phenological development (rate of leaf appearance), leaf gas exchange (photosynthesis, transpiration and conductance), and hydraulic relations (stem water potential) to assess rootstock influence on early-season vegetative development. Research was conducted over four weeks (November 18th to December 18th), spanning the developmental stages of pre-bloom, flowering, and fruit set. Based on experimental results, no statistically significant differences (p>0.05) were observed, indicating no differences in overall canopy development between rootstocks during early-season growth. An absence of significant differences between the eight rootstocks could be attributed to confounding factors, including high rainfall during data collection, coupled with the need for methodology refinements to strengthen statistical rigour. The obtained findings provide a basis for future research to build on and gain a more comprehensive understanding of Pinot Noir production in Canterbury, NZ, under water-limited conditions.