THE PRODUCTION OF CONTRASTING GENOTYPES OF PERENNIAL RYEGRASS (<i>LOLIUM PERENNE</i> L.) IN MONOCULTURES AND MIXED CULTURES OF VARYING COMPLEXITY

Rhodes, I.

doi:10.1111/j.1365-2494.1970.tb01205.x

Cited by 18 publications

(9 citation statements)

References 13 publications

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“…(i) The increase in cover with increasing species diversity itself shows that additional plant species occupy ‘empty’ niches in space or in time, if the phenology of individual species does not allow full cover for a monospecific stand of this species. (ii) A more complete utilization of canopy space and greater light interception in closed stands suggest that diverse communities are also more productive because of complementary shoot architecture (Rhodes 1970; Tremmel & Bazzaz 1993; Trenbath 1974). We therefore analysed diversity effects on a subset of plots that reached a closed canopy and compared them with those of all plots (Table 4).…”

Section: Discussionmentioning

confidence: 99%

Above‐ground resource use increases with plant species richness in experimental grassland ecosystems

et al. 2000

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1. Diversity effects on canopy structure and the use of space and light were investigated in experimental grassland communities of one, two, four, eight or 32 species and of one, two or three functional groups (grasses, legumes and non‐leguminous forbs) in north‐western Switzerland. 2. Plant species and functional group richness improved the establishment of grassland assemblages and increased mean vegetation cover from 64% in monocultures to 100% in 32‐species mixtures. 3. Above‐ground biomass and leaf area index increased linearly with the logarithm of plant species number in all 3 years of the experiment. The most species‐rich communities produced 143% more biomass than the mean of all monocultures and 25% more biomass than the most productive monoculture in the third year of the experiment. 4. Plant light absorbance per unit ground area increased by 44% with diversity (32‐species mixtures compared with monocultures) for two reasons. (i) The lack of species complementarity in terms of success of seedling establishment and plant size in vegetation with low species diversity increased the gap area in the canopy, and consequently more light reached bare ground. (ii) Diverse ecosystems absorbed more light within their closed canopies (+20%) than did less diverse ecosystems, because of better three‐dimensional space filling and greater biomass density due to complementarity in plant architecture, particularly between grasses and dicots. 5. The overall canopy height was increased by 46% and the centre of gravity of the canopy was raised by up to 10 cm over the range of experimental diversity treatments from one to 32 species. 6. These results cannot be explained solely by a higher likelihood of the inclusion of more productive dominant species in the more diverse communities (sampling effect), which suggests that biomass production may be determined by the most productive species present in a community. For all important canopy characteristics of multispecies communities, we show that with increasing diversity, mixtures perform better than the best monoculture. This is a strong indication that part of the positive effect of diversity on biomass production is driven by complementary resource use.

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Section: Discussionmentioning

confidence: 99%

Above‐ground resource use increases with plant species richness in experimental grassland ecosystems

et al. 2000

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“…Trenbath (1974) describes a few exceptions (Rhodes, 1968(Rhodes, , 1970 . Such yield advantages of genotypes in binary mixtures may occur when the components are of contrasting growth habit (Rhodes, 1970) or have different seasonal growth patterns (Zannone et al ., 1983) . Most of these studies have been short-term (usually single generation) and made with random pairs of cultivars or genotypes.…”

Section: The Theoretical Outcome Of Intergenotypic Interactionsmentioning

confidence: 99%

Intergenotypic interactions in plant mixtures

Turkington

1996

Euphytica

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Pastures provide a good model system to study intergenotypic plant interactions because most pastures are mixtures of several sown genotypes and species and the conditions necessary for genetic change are present : (i) an extremely variable biotic and abiotic environment at the local scale, (ii) wide genetic variation, (iii) intense competition so that strong selection is likely, and (iv) long term continuity enables selection to be continuous and cumulative . These together provide a system in which (v) the theoretical outcome of intergenotypic interactions may be readily tested and maximizes the probability of detecting patterns . Interactions between the species will have both ecological and evolutionary consequences, both of which may be of interest to plant breeders . These patterns are detectable at different scales but particular attention will be focused at the level of the individual genotype and especially with mixtures of the grass Lolium perenne and the legume Trifolium repens . Competition experiments between L . perenne and T repens are plentiful, but where specific hypotheses about adaptation at the genotype level have been tested, in all cases T. repens grows best when planted with its natural L . perenne neighbor -a reciprocal effect in the L . perenne has only been reported once . This specific T. repens -L . perenne neighbor recognition may be mediated through soil microorganisms, particularly Rhizobium leguminosarum biovar trifolii and Bacillus polymyxa .

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“…A synergistic effect occurred in mixtures as the 90% LL mixture outyielded monocultures. Mixtures of perennial ryegrass have already been found to perform better than monocultures (Rhodes, 1970;Rhodes and Stem, 1977), Since nutrients and water were not limiting, these mixtures were Bs.sumed to utilize light more effectively because of the optimum architecture of the canopy relative to that of the higher yielding component grown In monoculture.…”

Section: Infrequent Cuttingmentioning

confidence: 99%

Evidence from the use of isozyme markers of competition in swards between short‐leaved and long‐leaved perennial ryegrass

Hazard

Ghesquière

1995

Grass and Forage Science

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Intraspecific competition in Lolium perenne was studied using a replacement series of a short‐leaved and a long‐leaved genotype that was managed under different cutting frequencies and nitrogen supplies. Leaf length, tiller density and yield were recorded 6 months after sowing. Since the two competitors were labelled at the PG1/2 locus, it was possible to identify unambiguously the origin of tillers in the mixtures and to estimate the average length of lamina of each genotype. The difference in leaf length between the two competitors was maintained under particular types of management and generated contrasting competitive abilities leading to evolution of the genotypic composition of the mixtures. Thus, under infrequent cutting, competition for light resulted in the domination of the long‐leaved genotype and in a concomitant intragenotypic selection for leaf length. Supplying nitrogen fertilizer emphasized the phenotypic plasticity of the genotypes, particularly of the dominated one. Frequent cutting reduced competition for light and the change towards the short‐leaved genotype was far less rapid. The yielding and competitive abilities of ryegrass genotypes and the implications for breeding are briefly discussed.

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THE PRODUCTION OF CONTRASTING GENOTYPES OF PERENNIAL RYEGRASS (LOLIUM PERENNE L.) IN MONOCULTURES AND MIXED CULTURES OF VARYING COMPLEXITY

Cited by 18 publications

References 13 publications

Above‐ground resource use increases with plant species richness in experimental grassland ecosystems

Above‐ground resource use increases with plant species richness in experimental grassland ecosystems

Intergenotypic interactions in plant mixtures

Evidence from the use of isozyme markers of competition in swards between short‐leaved and long‐leaved perennial ryegrass

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