No abstract

Italian ryegrass (Lolium multiflorum Lam. ssp. italicum Volkart ex Schinz et Keller) thrives well in permanent grassland in mild and moist regions of Switzerland. Ecotypes of Italian ryegrass from Swiss permanent meadows have often been used successfully as the base material of breeding programmes. However, their agronomic performance per se has never been studied in detail. Therefore, field trials were conducted to assess the potential of this semi-natural genetic resource for use in breeding. Twenty ecotype populations were collected in different geographical regions in 2003 and seed was increased. Plot trials with 20 ecotype populations were conducted 2005-2007 at three locations, supplemented by row trials at two additional locations, and including four currently recommended cultivars as controls. Average performance in terms of yield, vigour and resistance to snow mould of ecotypes was superior to the cultivars. Depending on the characteristic, between three and 16 of the 20 ecotypes performed significantly better than the cultivars mean. However, resistance against crown rust of all ecotypes was significantly poorer than that of the cultivars. Correlation and regression analysis showed that more eastern and more northern collecting sites harboured better performing ecotypes. However, the most consistent site related factor favouring performance of the ecotypes in terms of yield, vigour, snow mould and Xanthomonas resistance was a low abundance of species which are typical of Arrhenatheretum type meadows. Data from the plot trials were related to results obtained with spaced plants at a single site, either in a seedling nursery or in the greenhouse. Resistance against crown rust was extremely well predicted by spaced plant observations. Xanthomonas resistance observed after artificial inoculation in the greenhouse was also significantly, but less closely correlated with field observations. An early date of ear emergence as observed on spaced plants was associated with high annual yield in the plot trials. It is concluded that in intensively managed habitats, natural selection has resulted in ecotype populations of Italian ryegrass which are highly promising for use in breeding. Individual plant selection for resistance can be expected to efficiently reduce their high susceptibility to crown rust.

Abstract:Resistance to powdery mildew of 127 spring barley varieties was evaluated in 702 official variety trials, using scores from 1 to 9. Trials with sufficient disease severity were only analysed. Varieties possessing the resistance genes Mla7 (Elgina), Ml(Kr) (BR-1519), Mla13 (Koral) and mlo (Forum) were among the most resistant ones. The varieties Diamant, HE-3527, HE-3631, II/61-FUDII and Zefir showed high susceptibility. Fifteen varieties, carrying the genes Mla1, Mla3, Mla6, Mla9, Mla13, Ml(Kr) and Ml(Sc), were in the first years of testing highly resistant, but became susceptible later. The score of the most resistant variety ranged each year from 8.05 to 9.00, only in 1987-1991 it was lower. Since the pathogen population rapidly adapted to most resistance genes in the mid eighties, no resistant variety was found in [1987][1988][1989]. From 1986 to 1995 on average only 6.6% of the tested varieties were resistant, but there was no variety with resistance score above 8.50. High resistance was typical for varieties possessing an effective major resistance gene. Since the resistance of such varieties was not durable, we recommend breeding of varieties with at least two fully effective resistance genes, using molecular markers.

Herbage yield trials are necessary to test if candidate varieties are well suited for organic conditions. In order to elucidate a particular suitability for organic conditions, we run such trials in parallel under both organic and conventional conditions. Here, we report on second and third year results of the sowings 2004 and 2005. These trials are part of a targeted breeding programme for organic conditions. Irregular colonisation of pure grass plots with adventitious plants, in particular white clover, was recognized as a major constraint to the quality of the results obtained under organic conditions. The coeYcients of variance in dry matter yield almost doubled when compared to conventional trials, and signiWcant diVerences in annual yield among varieties were rare. However, when herbage yield was corrected for the estimated fraction of adventitious plant colonization at each cut, the number of instances with statistically signiWcant diVerences for annual yield among varieties increased more than fourfold. Dry matter yields under organic and conventional conditions were signiWcantly and positively correlated. However, analysis of variance showed a signiWcant culture type by variety interaction for annual dry matter yield in 12 out of 24 trials. When diploid and tetraploid varieties of the same Lolium species were tested in one common trial, only tetraploid varieties were identiWed as being particularly well suited for organic conditions, while in these trials, the great majority of apparently poorly suited varieties were diploid. This suggests that breeding tetraploid Lolium varieties is promising when aiming at a favourable response to organic agriculture.