A double-sigmoid model for grapevine bunch compactness development

Abstract

AimBunch compactness is the result of a complex dynamic process in which many bunch, berry and rachis features interact during the whole grapevine reproductive cycle. The aim of this work is to identify the different developmental stages involved in bunch compactness determination during the second growing season, from full-flowering to harvest time.Methods and Results In this work, bunch features from ten wine grapevine cultivars with diverse bunch compactness (including very loose and very compact bunches) have been periodically described. Experimental data allowed us to quantify changes in bunch compactness from berry set until harvest time in an objective manner. Our results indicate that bunch compactness development follows a double-sigmoid model, characterized by two consecutive cycles, each one with a growing stage followed by a latent one. Differences in the slope factor of the growing stages and in the duration of each developmental phase can explain part of the bunch compactness variation observed in our set of cultivars.ConclusionsTwo consecutive sigmoid cycles with four different stages can be observed in the determination of grapevine bunch compactness. Bunch architecture before véraison plays an important role in the final compactness of the bunch at harvest time.Significance and impact of the studyThe double-sigmoid model for bunch compactness development, and the four different stages identified will aid in future analyses aimed to unravel the underlying mechanisms affecting this complex trait.

VviUCC1 Nucleotide Diversity, Linkage Disequilibrium and Association with Rachis Architecture Traits in Grapevine

“…During the second season of the grapevine reproductive cycle, rachis experiences two main phases that determine its final dimensions. First, rachis elongates rapidly after budbreak and thickens until mid-flowering, almost reaching its final length and 75% of its final cross-sectional area at that time [ 18 , 70 , 71 ]. After flowering, minor changes in rachis length occurs, and the rachis diameter reaches its final diameter [ 70 ].…”

“…Following these works, a differential expression of an Uclacyanin I -like gene ( VviUCC1 ) between Garnacha Tinta clones with loose and compact clusters was observed during the rapid inflorescence growth occurring prior flowering [ 30 ]. Likewise, several works also indicate that this gene is highly expressed during the elongation [ 18 , 71 ] and stiffening [ 72 , 73 ] processes happening during grapevine inflorescences growth before anthesis [ 42 , 43 ]. Altogether, these findings led to the selection of VviUCC1 as a candidate gene to test its association with the variation observed for cluster compactness and multiple rachis architecture traits in a diverse collection of grapevine cultivars.…”

“…Cluster compactness is the result of a two-year course in which berry number, berry traits, and rachis traits interact in a complex and dynamic process [ 8 , 18 ]. These three major components are determined at different stages of the grapevine reproductive cycle, so they are affected by many external factors such as temperature, rainfall, and wind [ 19 , 20 ].…”

Deep learning image segmentation and extraction of blueberry fruit traits associated with harvestability and yield

“…Furthermore, blueberry harvestability and yield traits (berry number, maturity, and compactness) were extracted directly. Existing methods cannot extract all of these traits, particularly compactness for blueberries 7,8,35,41 . Although the traits were extracted from 2D images, the analyses were performed with five different views of clusters on a branch.…”

“…There are also many objective methods to quantify compactness. Tello et al 7 used a quantitative grape compactness index (CI13), which is calculated as the ratio of the berry volume over the square of rachis length. Cubero et al 8 defined the ratio of the square of the berry perimeter over the berry area of the grape bunch for bunch compactness and found that a smaller perimeter with the same area would be more compact.…”