Yield stability of selected forage vetches (Vicia spp.) under rainfed conditions in west Asia

Abstract

With the current high prices for livestock, forage legumes are increasingly attractive to farmers in west Asia. There has been very little genetic improvement of the main species, of which three vetches, Vicia saliva (common vetch), V. villosa subsp. dasycarpa (woollypod vetch), and V. narbonensis (Narbon vetch), show promise. As a first step in genetic improvement 23 genotypes of common vetch and one each of woollypod vetch and Narbon vetch were grown at four sites in Syria and one in Lebanon over three seasons. Since local climatic conditions were considered to be of considerable importance, each site in each year was treated as a separate environment, to give 15 environments in all. genotype × environment (G × E) interactions were analysed using linear regression.

There was considerable variation in herbage and seed yields within both genotypes and environments, and G × E interactions were highly significant. In the case of herbage yield good environments could be defined as those receiving high rainfall and low incidence of frost. Several genotypes appeared to possess wide adaptation, in terms of both yield and stability. Climate, except for late spring rains, had little effect on seed yield, nor were any of the genotypes widely adapted. However, in the broad sense heritability was much higher for seed than for herbage yield.

There is a need to define good and bad environments for seed yield. Based on observations during the study it is likely that good environments for Narbon vetch are those where broomrape (Orobanche crenata) is absent, while root-knot nematode (Meloidogyne artiella) may affect seed yield of common vetch. In view of its high seed yield the possible role of Narbon vetch as a grain legume is briefly discussed.