Table I
Climatic parameters at the places of origin of the six studied populations. Trait codes and dimensions are shown in parentheses.
| Climatic parameter | Population | |||||
|---|---|---|---|---|---|---|
| 1 | 2 | 3 | 4 | 5 | 6 | |
| Mean temperature (T, °C) | 13.3 | 10.9 | 12.3 | 13.6 | 11.9 | 12.6 |
| Mean of max. temp. in month with highest mean (TMMC, °C) | 25.8 | 26.6 | 26.5 | 26.4 | 22.9 | 24.5 |
| Mean of min. temp. in month with lowest mean (TMMF, °C) | 4.4 | –0.3 | 1.1 | 4.2 | 1.2 | 2.0 |
| Absolute maximum temperature (AMT, °C) | 34.8 | 38.3 | 37.7 | 38.3 | 36.7 | 36.5 |
| Absolute minimum temperature (F, °C) | –4.2 | –12.5 | –9.3 | –0.7 | –9.8 | –9.5 |
| Min. monthly summer precipitation (PE, mm) | 19.0 | 16.0 | 3.0 | 0.0 | 42.0 | 22.0 |
| Drought index (A, month) * | 1.8 | 3.0 | 3.8 | 3.3 | 0.0 | 1.0 |
| No. days with T < 0 °C in spring (ND0S, day) | 5.0 | 16.8 | 1.4 | 0.1 | 1.8 | 3.7 |
| No. days with T < 0 °C in autumn (ND0A, day) | 4.1 | 10.8 | 0.5 | 0.3 | 1.0 | 0.7 |
Drought index (A): time span, measured in months, during which the curve of the monthly mean values lies above the monthly precipitation curve, pi, in an ombro-thermal Gaussen-type graph (months on the X -axis and temperature and precipitation on the Y -axis, so that the values of p are the same height as the expression of temperature in degrees of half their value). This factor correlates well with the actual configuration of water deficits and approximately implies the condition 2ti ≥ pi .