# Natural Genetic Variation for Grapevine Phenology as a Tool for Climate Change Adaptation
## 3 Results and Discussion
### 'Malbec' Clones Show Significant Variation for Phenology and Berry Traits  
We found significant intra-varietal variation for three out of the five analyzed traits (i.e., cluster weight, berry number, and days from flowering to veraison; Table 2). Cluster weight (CW) showed significant differences between the different clones, (Table 2 and Figure 2a). This trait presented a mean of 21.3 g and a range between 11.1 g and 32.1 g (Table S1).  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Clone** & **Start (\(n\))** & **Rooting (\(n\))** & **(\%)** & **Fruit Set (\(n\))** & **(\%)** & **Harvest (\(n\))** & **(\%)** \\ \hline  
\hline mean & 49 & 29 & 59 & 13 & 46 & 12 & 89 \\ sdt & 6 & 8 & 13 & 5 & 13 & 5 & 10 \\ max & 58 & 43 & 80 & 25 & 78 & 22 & 100 \\ min & 39 & 14 & 28 & 7 & 27 & 5 & 63 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Clone names, number of cuttings at the start, rotting, fruit-set, and harvest stages of the experiment.  
Similarly, berry number (BN) also differed significantly within the evaluated clones (Table 2 and Figure 2b), with a mean of 27.0 berries/cluster and a ranging from 42 to 15 berries/cluster (Table S1). Considering the components of CW analyzed here (i.e., BN and BW), BN emerged as the main determinant of CW. While CW and BN were strongly correlated (R = 0.81, \(p\) < 0.001; Figure 3a), the correlation of CW and BW was clearly lower (R = 0.37, \(p\) < 0.001; Figure 3b). The trait showing the more extreme differences between the clones was days from flowering to veraison (DFV). As described in Table 2, this trait presented an \(H\) value of 87 for the Kruskal-Wallis rank-sum test with a \(p\)-value < 0.0001. DFV showed a mean of 85.5 days with a range between 76.9 and 93.3 days. The higher differences were observed between clones 598 and 501, more than 16 days on average (Figure 2c; Table S1).  
Intra-cultivar variation for agricultural and phenology traits was largely analyzed using field clones [30; 31; 32; 33; 34]. However, despite the proven usefulness of fruiting cuttings for study developmental and physiological traits [2; 4; 15; 19; 20; 21; 22; 23; 24], just one work utilized this tool to compare clones of the same cultivar [15]. Particularly, significant differences for phenology traits were also observed in cultivar 'Tempranillo', where the authors analyzed cuttings from 13 clones, finding significant differences in  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Trait** & \(p\)**-Value** & \(H\) & **df** \\ \hline DFV & **<0.001** & 81 & 20 \\ CW & **<0.001** & 40 & 20 \\ BN & **<0.001** & 48 & 20 \\ BW & 0.03 & 33 & 20 \\ Brix & 0.01 & 37 & 20 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Kruskal-Wallis rank-sum (\(H\)) test for phenology and berry traits. The \(p\)-value, \(H\) statistic, and degrees of freedom (df) for the five analyzed characters are presented. DFV: days from flowering to veraison; CW: cluster weight; BN: berry number; BW: berry weight; Brix: degrees Brix. Significant \(p\)-values after the multiple comparison test are highlighted in bold.  
Figure 3: Pearson correlation of cluster weight (CW) and its determinants: (**a**) berry number (BN) and (**b**) berry weight (BW).  
Figure 2: Mean values for phenology and agronomical traits between 21 ‘Malbec’ clones. (**a**) Cluster weight; (**b**) Berry number; (**c**) Days from flowering to veraison. Error bars represent standard error of the calculated means.  
the number of days that elapsed fruit set and mid-veraison [15]. The results of the present study and those reported in 'Tempranillo' [15] demonstrated the usefulness of grapevine fruit-bearing cuttings for comparing the phenological behavior of different clones from the same cultivar.