Adaptive Ecology of Lotus corniculatus L. Genotypes: II. Crossing Ability

Abstract

Birdsfoot trefoil (Lotus corniculatus L.) is a widely distributed polymorphic Old‐World perennial forage legume found in wild and naturalized populations throughout temperate regions of Europe, Asia Minor, North Africa, and North and South America. Exotic birdsfoot trefoil germplasm has rarely been used for birdsfoot trefoil genetic enhancement, and information about its crossing ability with other exotics and commercial quality germplasm is not available. The objectives of this research were to (i) characterize the crossing ability of 27 exotic birdsfoot trefoil genotypes with two genetically diverse hybridization testers, and (ii) determine if crossing ability among genotypes was related to their genetic background measured by random amplified polymorphic DNA (RAPD) markers and their ecogeographic origins. Crossing ability was determined using reciprocal crosses with one commercial‐quality germplasm and one exotic genotype tester. All possible crossing combinations for an eight‐genotype subset were also determined. Crossing ability was measured as the percentage of pollinated flowers that set pods, F1 progeny pollen viability, pod length, and seeds per pod. Self‐genotype pod set and pollen viability were not correlated. Intermediate bridge crosses were identified that could potentially overcome specific cross incompatibilities and be used to obtain progeny for any combination of genotypes. Genotype‐crossing ability was associated with ecogeographic features of the collecting site, but not with morphologic characteristics. This differs from findings that other genotype morphologic characteristics are associated with ecogeographic origins and genetic similarities based on RAPD markers. Exotic birdsfoot trefoil genotypes can be utilized with commercial‐quality germplasm using conventional crossing methods.