Altering Grapevine Crop-load and Canopy Architecture Through Cultural and Genetic Methods

North Dakota's extremely short growing season leads to premature harvest of unripe, high acid grapes with atypical fruit chemistry. To combat the short growing season, grape growers utilize labor intensive grapevine canopy management practices to expose grape clusters to sunshine for enhanced ripening potential. This research examined leaf removal and shoot-thinning, two widely utilized canopy management practices, for their effect on fruit chemistry of two regionally important, cold-hardy grapevines, ?Frontenac? and ?Marquette?. These management techniques were effective at altering fruit chemistry as measured by sugar; however, they are costly to employ commercially due to yield reduction and labor requirements. Furthermore, they rarely impacted the targeted fruit component, acidity of grape must. Ultimately, we sought to mitigate labor expenses associated with on-farm canopy management practices by breeding cold-hardy grapevines with reduced single leaf area. To accomplish this goal, we utilized a novel mutant grapevine with highly dissected, technically compound leaves, ?Chasselas Cioutat?. After crossing ?Chasselas Cioutat? with native, North Dakota isolated, wild riverbank grapes (V. riparia) and two interspecific breeding parents (?Frontenac gris? and ?E.S. 5-8-17?), we observed developmental transitions within leaf shape of young seedling grapevines. Newly emerged leaves became progressively more lobed between main veins as seedlings exited juvenility. However, the targeted compound leaf form was not observed in outcrossed progeny, with one rare exception. For these reasons, grapevines were maintained under greenhouse conditions and advanced to the next generation. Within the first generation of inbreeding, segregation was observed for the distinct compound leaf trait. On-going work to isolate quantitative trait loci is merging genetic maps from multiple sequencing technologies with image analysis to create the first high-resolution understanding of genetic control of compound leaf shape in grapevines. Overall, these efforts have provided the foundation for future breeding aimed at incorporating functional leaf shapes (compound leaf morphology) in the vineyard. Future work in North Dakota grapevine management may need to focus on techniques that promote winter survival and early ripening. Future breeding efforts should continue to focus on the use of novel germplasm material to overcome biotic stresses, improve fruit quality, and increase environmental resistance