ISHS Acta Horticulturae 814: XII EUCARPIA Symposium on Fruit Breeding and Genetics
STABILITY OF MAIN APPLE CULTIVARS GROWN IN TRANSYLVANIA DETERMINED BY MEANS OF NONPARAMETRIC ANALYSES |
| Authors: | L. Lukacs, M. Ardelean, V. Mitre, C. Botez, R. Pop, M. Cordea |
| Keywords: | fruit yield, fruit weight, phenotypic stability, nonparametric analysis |
| Abstract:
Most often, when choosing promising genitors for apple breeding programs, their performance stability stands as a major criterion. This means that an increase in speed, accessibility and accuracy of performance stability evaluation will translate into more efficient crossing programs. Five apple cultivars, widely grown in Transylvania (‘Golden Delicious’, ‘Jonathan’, ‘Starkrimson’, ‘Idared’, and ‘Florina’) were analyzed in five commercial orchards located in areas with obvious different environments, during 2004 and 2005. Fruit yield as well as tree (height, crown diameter) and fruit (weight, size) characteristics were registered, the resulting data being evaluated by means of Hühn (1990a, b) nonparametric stability indices: Si(1) = mean of the absolute rank differences of a genotype over environments and Si(2) = variance among the ranks over environments. For a genotype with maximum stability Si(1) = 0 and Si(2) = 0. The results obtained show that there is a fairly good correspondence between the two stability indices at the phenotypic level not only for fruit yield but also for fruit characteristics. The fact that the highest stability of fruit yield both in 2004 and 2005 was found in ‘Florina’ and ‘Idared’ must be emphasized. Varieties showing the smallest values of Si(1) (1.70-1.85; 1.45-1.65) and Si(2) (1,03-2,03; 1,81-2,87). ‘Florina’ is the only domestic variety tested in this experiment and, quite expectedly, one of the best adapted to the studied environments. Plots portrayed by mean yields (t/ha) vs. Si(1), in 2004 and 2005, showed that it is quite difficult to find high yielding cultivars with a similarly high index of stability. Therefore selection of genitors or of cultivars to be recommended for commercial purposes should be extended to cultivars with high yielding potential and an index of stability as near as possible to the mean computed Si(1) for that specific set of cultivars and environments. | |
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