Cultivated Grapevine Displays a Great Diversity for Reproductive Performance Variables

Abstract

Background: There are thousands of grapevine varieties that display a wide range of variation for traits like grape use (wine, table grape or both), color or ripening time, but little is known about their reproductive performance, especially flowering and fruitset (conversion from flower to fruit). Works focused at the study of these traits in grapevine evaluated one or few varieties and used different methodologies making comparisons difficult. This study aimed to characterize the reproductive performance of 120 varieties and its stability over two seasons using a precise methodology. Methods: Reproductive performance was determined through counting flowers and berries in the same inflorescences/bunches (10 per variety), for which a new methodology of image analysis of scanned calyptras was developed. Varieties were classified according to their reproductive performance. Results: A great diversity was found for most variables including fruitset and number of flowers. Large differences between varieties were observed both in values and in stability among seasons. The varieties clustered in three main classes that displayed significant differences not only for the reproductive performance variables used for the clustering but for most the variables studied. Varieties in these classes showed a non-random distribution regarding the grape use and the genetic structure based on molecular markers. Conclusions: This is the largest study of reproductive performance variables such as fruitset ever done in grapevine. It provides specific values for many varieties for the first time, useful for breeding programs. The clustering based on these variables is related with those based on use and geographical origin.