Wide- versus specific-adaptation strategy for lucerne breeding in northern Italy |
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Authors: | P Annicchiarico |
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Institution: | (1) CRA - Istituto Sperimentale per le Colture Foraggere, 29 viale Piacenza, 26900 Lodi, Italy |
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Abstract: | This study is aimed at comparing wide- versus specific-adaptation strategies for lucerne in northern Italy on the basis of
actual dry matter yield gains over 12 harvests from phenotypic selection, assessing the value of specific genetic bases and
selecting environments for the contrasting subregion A (no drought stress/sandy-loam soil) and subregion C (summer drought
stress/silty-clay soil). A second aim is to investigate the adaptive responses of five sets of 18 half-sib progenies. The
following selected populations were evaluated along with five cultivars: GW–SW, GA–SA, GA–SC, GC–SC and GC–SA (where GW, GA
and GC are the genetic bases for wide adaptation, subregions A and C; SW, SA and SC are the selection environments for wide
adaptation, subregions A and C). The selection and test environments were four artificial environments created by the factorial
combination of two drought stress levels by two soil types. Two environments represented the subregions A and C whereas the
combination of the other two environments represented the intermediate subregion B. Genotype × environment interaction (P ≤ 0.001) due to both environmental factors and implying cross-over interaction between the contrasting subregions occurred
for the populations and the five selections. Specific genetic bases (GA and GC) implied gains in their target subregions of
5.2% for subregion A and 2.9% for subregion C compared with the widely adapted one (GW). The gain of SA (‘no stress/sandy-loam
soil’) over SC (‘stress/silty-clay soil’) decreased from subregion A (10.6%) through subregion C (1.7%) but exhibited an advantage
per se across environments of 5.4%. The best specific selections (GA–SA for subregions A and B; GC–SA for subregion C) implied
higher yields of 9.8% in subregion A and 6.5% in subregion C, and over twofold greater selection efficiency across the region,
relative to GW–SW. Half-sib progeny × artificial environment interaction (P ≤ 0.05) occurred in three sets of progenies whose parents belonged to cultivars with different or similar adaptation. |
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Keywords: | Adaptation Breeding strategy Drought stress Genotype × environment interaction Medicago sativa Selection environment |
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