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<p>Alfalfa (<i>Medicago sativa</i> L.) improvement under arid conditions increasingly requires integrating biotic stress tolerance with forage quality. This study evaluated six alfalfa genotypes—comprising native, exotic, and synthetic origins—for their response to infestation by the alfalfa weevil (<i>Hypera postica</i>), the primary insect pest affecting alfalfa productivity worldwide, under open-field conditions. Five genotypes consisted of half-sib progenies derived from either native (GAB) or exotic parental sources (AME, ABT, SAR, ETS), whereas the synthetic genotype (SYN) corresponded to a Syn-1 population obtained by mixing seeds of superior S₁ progenies selected from a polycross, with 60% originating from the native GAB background and the remaining 40% equally contributed by the four exotic families (10% each). Genotypic differences in infestation severity were substantial, ranging from 3.03% in the synthetic line SYN to 9.00% in AME and SAR, both half-sib progenies of exotic parents. The native-derived GAB exhibited intermediate infestation (6.58%) but maintained high crude protein − CP (23.65%) and moderate resilience in plant structure, marking it as a valuable contributor from local germplasm. The synthetic line SYN displayed the best integrated performance, combining the lowest infestation with sustained growth (internode length − LEN = 2.62 cm), pigment retention (SPAD = 44.1), and thermal stability (leaf temperature = 15.9&#xa0;°C). In contrast, exotic-derived ABT, ETS, AME, and SAR showed sharper declines in structural and physiological traits under pest pressure. Across genotypes, infestation significantly increased fiber fractions (Neutral Detergent Fiber − NDF: + 7.2%; Acid Detergent Lignin − ADL: + 0.85%) while reducing digestibility (Dry Matter Digestibility − DMD declined to 62.3% in ETS) and SPAD index. Multivariate analysis (81.8% variance explained) revealed strong integration of morpho-physiological and nutritional traits. These findings underscore the breeding potential of native-derived progeny (GAB) and the synthetic line (SYN) for generating cultivars that jointly express pest resilience and forage value, offering strategic assets for sustainable alfalfa production in arid, pest-prone systems.</p>

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Integrating pest tolerance and forage quality in a breeding-focused evaluation of alfalfa genotypes under Hypera postica infestation for synthetic variety development in arid environments

  • 期刊论文

  • 发表日期：

    2026年3月9日

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  • Samir Tlahig,
  • Sabrine Chouikhi,
  • Walid Elfalleh,
  • Mohamed Loumerem

摘要

Alfalfa (Medicago sativa L.) improvement under arid conditions increasingly requires integrating biotic stress tolerance with forage quality. This study evaluated six alfalfa genotypes—comprising native, exotic, and synthetic origins—for their response to infestation by the alfalfa weevil (Hypera postica), the primary insect pest affecting alfalfa productivity worldwide, under open-field conditions. Five genotypes consisted of half-sib progenies derived from either native (GAB) or exotic parental sources (AME, ABT, SAR, ETS), whereas the synthetic genotype (SYN) corresponded to a Syn-1 population obtained by mixing seeds of superior S₁ progenies selected from a polycross, with 60% originating from the native GAB background and the remaining 40% equally contributed by the four exotic families (10% each). Genotypic differences in infestation severity were substantial, ranging from 3.03% in the synthetic line SYN to 9.00% in AME and SAR, both half-sib progenies of exotic parents. The native-derived GAB exhibited intermediate infestation (6.58%) but maintained high crude protein − CP (23.65%) and moderate resilience in plant structure, marking it as a valuable contributor from local germplasm. The synthetic line SYN displayed the best integrated performance, combining the lowest infestation with sustained growth (internode length − LEN = 2.62 cm), pigment retention (SPAD = 44.1), and thermal stability (leaf temperature = 15.9 °C). In contrast, exotic-derived ABT, ETS, AME, and SAR showed sharper declines in structural and physiological traits under pest pressure. Across genotypes, infestation significantly increased fiber fractions (Neutral Detergent Fiber − NDF: + 7.2%; Acid Detergent Lignin − ADL: + 0.85%) while reducing digestibility (Dry Matter Digestibility − DMD declined to 62.3% in ETS) and SPAD index. Multivariate analysis (81.8% variance explained) revealed strong integration of morpho-physiological and nutritional traits. These findings underscore the breeding potential of native-derived progeny (GAB) and the synthetic line (SYN) for generating cultivars that jointly express pest resilience and forage value, offering strategic assets for sustainable alfalfa production in arid, pest-prone systems.