Compensation studies on the tomato landrace 'Tomataki Santorinis'

- Variance (σ) partitioning in σg and σe for yield and yield components.
- The G × E interactions were qualitative (G-line) and quantitative (T-line).
- The type of G × E propose direct selection for G-line, indirect one for T-line.
- High homozygosity of T-line revealed by zero to low σg.

The attributes of yield and yield stability of two coexisting lines within the old landrace of small-sized tomatoes 'Tomataki Santorinis', i.e., 'Genuine Santorinis' ('G'-line) and 'Traditional Santorinis' ('T'-line) were defined, quantifying the interaction of the lines with the environment. The experiments were conducted in parallel at two environments: (a) two-year intra-selection experiments in situ (island of Santorini) under traditional agronomic management, (b) two-year evaluation experiments ex situ (Agricultural Research Center of Northern Greece) under the usual 'farmer's technique', and (c) final comparative trials of selected entries of each line with the source material in situ and ex situ. Especially, for the attributes of yield, the number and the weight of early and total fruits were measured. Additionally, descriptive (fruit ribbing and shape) and qualitative (total soluble solids, total solids and pH) characteristics were recorded. In the in situ environment, genetic variance for yield components was medium to high for 'G'-line and zero to low for 'T'-line. In the ex situ environment, the genetic variance was high for 'G'-line and low for 'T'-line. Ranking of yield components, between the two environments, showed significant correlations of 'G'-line and 'T'-line in situ. Ex situ, the 'T'-line performed similarly, while the 'G'-line showed reduced association between phenotypic and genotypic performance. The comparative trials showed significant difference between selected entries and source material solely for the 'G'-line, revealing different compensation profiles of the lines' adaptive ability. The 'G'-line profile revealed productivity, efficiency to direct selection and specific adaptability. The 'T'-line profile revealed lower productivity, high homogeneity and broad adaptation. These profiles permit breeders to develop two distinctive types of the landrace, either as a Protected Designation of Origin (PDO) cultivar or as a line.