Humphreys, M. O., Feuerstein, U., Vandewalle, M., Baert, J. (2010). Ryegrasses, In: Handbook of Plant Breeding: Fodder Crops and Amenity Grasses, Volume 5, Springer New York, pp. 211-260, 2010In the temperate regions of the world ryegrasses comprise the main sown forage grasses of which the outbreeding perennial, Italian and Westerwolths ryegrasses are the most economically important. This chapter presents information on the origin and systematics of these forage grasses which share a high degree of genome ancestry with the cereals originating in the eastern Mediterranean basin. It considers how plant breeding has enhanced natural genetic resources to produce valuable new varieties with improved production and livestock nutrition characteristics together with increased tolerance of environmental stresses caused by biotic (pests and diseases) and abiotic (temperature, water and mineral extremes) pressures. The challenge of maintaining the optimum balance between vegetative growth and seed production is also addressed. Breeding methodologies based on traditional techniques are discussed and the integration of new biotechnologies into breeding programmes is reviewed. Breeding achievements are evaluated and future goals considered in relation to the increasingly diverse demands placed on grassland to provide ecosystem services, amenity value and systematic breeding as well as providing feed for ruminants

Eighty-three third backcross lines whieh comprise a set of near isogenic lines (NIL's) of the barley cultivar 'Glipper' but each carrying a different chromosomal segment from Hordeum spontaneum, marked with a distinct isozyme, were tested for resistance to three races of the barley leaf rust pathogen (Puccinia bordei). Fourteen lines showed resistance to at least one race and three showed resistance to all three races. The resistance in two of these lines was controlled by separate, single partially dominant genes. In one case the resistance gene named RpblO was on chromosome 3 and linked (r = 0.15 ± 0.05) with the isozyme locus Est2. In the second case, the gene {Rphll) was on barley chromosome 6 and linked (r = 0.07 + 0.02) with the isozyme locus Acp3 and (r = 0.11 ± 0.02) with Dip2.

The potential of a plant species to acquire nutrients depends on its ability to explore the soil by its root system. Co-cultivation of different species is anticipated to lead to vertical root niche differentiation and thus to higher soil nutrient depletion. Using a qPCR-based method we quantified root biomass distribution of four catch crop species in vertical soil profiles in pure vs. mixed stands. Pure stands of mustard and phacelia robustly reached 70 cm soil depth, while oat preferably colonized upper soil layers, and clover developed the shallowest and smallest root system. Analysis of residual nitrate pools in different soil depths and correlation with root biomass showed that, besides rooting depth also root biomass determines soil nitrogen depletion. While occupying the same vertical niches as in pure stands, mustard and phacelia dominated total root biomass of the mix. In contrast, root biomass of clover and oat was severely suppressed in presence of the other species. Below-ground biomass profiling indicated low niche complementarity among the root systems of the examined species. Nonetheless, the mixture mostly overyielded root biomass of the pure stands and thus shows higher potential for efficient soil exploration by roots.

BackgroundLolium perenne L. is the most important forage grass species in temperate regions. It is also considered as a sustainable source of biomass for energy production. However, improvement in biomass yield has been limited by comparison with other major crops. More efficient utilisation of genetic resources and improved breeding schemes are required to advance L. perenne breeding. In an attempt to elucidate the extent of genetic diversity in L. perenne, 1384 DArT, 182 SNP and 48 SSR markers were applied to 297 accessions (Set I) contributed by three German breeding companies and the IPK Genebank. Due to the heterogeneous nature of Lolium accessions, bulk samples were used. Apart from germplasm set I, additional set II and set III was used to determine the reproducibility of marker system and judge the feasibility of bulk strategy in this study.ResultsBy assessing different bulk sizes, 24 individuals per sample were shown to be a representative number of plants to discriminate different accessions. Among the 297 accessions, all marker types revealed a high polymorphism rate; 1.99, 2.00 and 8.19 alleles, were obtained per locus on average using DArTs, SNPs and SSRs, respectively. The Jaccard distance for DArT markers ranged from 0.00 to 0.73, the Modified Roger’s distance (MRD) for SNP markers ranged from 0.03 to 0.52, and for SSR markers from 0.26 to 0.76. Gene diversity for dominant DArT and co-dominant SNP and SSR markers was found to be 0.26, 0.32 and 0.45, respectively. DArT markers showed the highest consistency and reproducibility.ConclusionThe resulting data were evaluated using a number of different classification methods, but none of the methods showed a clear differentiation into distinct genetic pools. With regard to hybrid breeding, this will possibly impede substantial progress towards increased biomass yields of L. perenne by utilising heterosis.Electronic supplementary materialThe online version of this article (10.1186/s12863-017-0589-0) contains supplementary material, which is available to authorized users.

Catch crops increase plant species richness in crop rotations, but are most often grown as pure stands. Here, we investigate the impacts of increasing plant diversity in catch crop rotations on rhizosphere C input and microbial utilization. Mustard (Sinapis alba L.) planted as a single cultivar was compared to diversified catch crop mixtures of four (Mix4) or 12 species (Mix12). We traced the C transfer from shoots to roots towards the soil microbial community and the soil respiration in a 13C pulse labelling field experiment. Net CO2-C uptake from the atmosphere increased by two times in mix 4 and more than three times in mix 12. Higher net ecosystem C production was linked to increasing catch crop diversity and increased belowground transfer rates of recently fixed photoassimilates. The higher rhizosphere C input stimulated the growth and activity of the soil microbiome, which was investigated by phospholipid fatty acid (PLFA) analyses. Total microbial biomass increased from 14 to 22 g m−2 as compared to the fallow and was 18 and 8% higher for mix 12 and mix 4 as compared to mustard. In particular, the fungal and actinobacterial communities profited the most from the higher belowground C input and their biomass increased by 3.4 and 1.3 times as compared to the fallow. The residence time of the 13C pulse, traced in the CO2 flux from the soil environment, increased with plant diversity by up to 1.8 times. The results of this study suggest positive impacts of plant diversity on C cycling by higher atmospheric C uptake, higher transport rates towards the rhizosphere, higher microbial incorporation and prolonged residence time in the soil environment. We conclude that diversified catch crop mixtures improve the efficiency of C cycling in cropping systems and provide a promising tool for sustainable soil management.