The role of allelopathy in legume decline in pastures. I. Effects of pasture and crop residues on germination and survival of subterranean clover in the field and nursery

1995 ◽  
Vol 46 (1) ◽  
pp. 179 ◽  
Author(s):  
JH Leigh ◽  
DM Halsall ◽  
MD Holgate

In a series of five trials, three conducted in the field and two in seed-flats in the nursery, it was shown that mulched residues from Phalaris aquatica and Triticum aestivum reduced the germination and production of Trifolium subterraneum. The deleterious effects observed with the mulched residues were not evident when the residues were incorporated into the upper soil layer. It is suggested that a reduction of the residues in pastures before the opening rains in autumn would be an essential requirement to ensure good germination and early seedling vigour from the annual legume component in mixed legume/grass pastures, especially those based on P. aquatica.


1980 ◽  
Vol 20 (106) ◽  
pp. 568 ◽  
Author(s):  
KD McLachlan

A study was made of the role of superphosphate and lime on subterranean clover (Trifolium subterraneum) production on an infertile acid soil in pot culture. Both fertilizers increased the exchangeable calcium in this deficient soil. Lime and superphosphate were involved in nodulation of the clover plants. There was no evidence of the direct involvement of either of them in the nitrogen fixation process, but they did increase nitrogen uptake by the plants. Once the legume functioned adequately, full expression of the yield response to phosphorus on this deficient soil followed. Most efficient phosphorus use occurred at the lime 1255, superphosphate 2000 kg ha-1 level (lime 1/2, P 16). Heavy lime dressing reduced exchangeable magnesium and the phosphorus available to the plant. Aluminium and pH were involved in the effects observed. Lime reduced CaCl2-extractable aluminium and the titratable acidity in the soil. Phosphate increased the CaCl2-extractable aluminium and apparently reduced the titratable aluminium. The combined treatments reduced these three attributes and promoted increased plant growth. Increased plant growth was associated with increased aluminium uptake by the plants, which suggests that the real effect of aluminium may have been on the calcium and phosphorus uptake by the plants, rather than on the toxic nature of the element itself.



2017 ◽  
Vol 246 ◽  
pp. 144-156 ◽  
Author(s):  
Timothy I. McLaren ◽  
Therese M. McBeath ◽  
Richard J. Simpson ◽  
Alan E. Richardson ◽  
Adam Stefanski ◽  
...  


2002 ◽  
Vol 42 (5) ◽  
pp. 557 ◽  
Author(s):  
E. Piano ◽  
L. Riccioni ◽  
L. Pecetti ◽  
A. M. Carroni ◽  
A. Porta-Puglia

Breeding programs of subterranean clover in southern Europe have traditionally set low priority on selection against major pathogens, in part because there have been no major disease outbreaks in this region. However, root-rot causing fungi, such as Fusarium spp., occur frequently on other crops and can therefore also represent a threat to clover. Thus, the breeding program carried out in Sardinia, Italy, took note of this disease. This study reports the results of 2 trials carried out in 2 consecutive years following artificial infestation with Fusarium spp. The first trial included 45 genotypes, of which 37 were Sardinian lines under advanced breeding and 8 were commercial varieties. To validate the variation observed in disease response, a subset of 27 genotypes was further evaluated in the second trial. In both trials, 3 pathogen treatments were applied, in addition to a control, uninoculated treatment - F. avenaceum, F. oxysporum, and an equal mixture of both fungi. One-month-old clover seedlings were scored in all treatments for shoot-growth vigour (1-9 scale), then excavated for scoring root-rot symptoms (1-5�scale), and finally weighed after oven drying. Analysis of variance tested differences among treatments, among genotypes, and between subsp. subterraneum and brachycalycinum of Trifolium subterraneum. On the common set of genotypes to both trials, a cluster analysis was applied using, as original variables, the average disease score across the 3 inoculated treatments in the 2 trials. Confirming previous evidence, F. avenaceum proved more pathogenic than F. oxysporum. The results suggested that high seedling vigour may play a role in limiting root-rot effects, and this may also contribute to the relatively better tolerance of subsp. brachycalycinum over subsp. subterraneum observed. Despite some inconsistency of response in the 2 trials both at the treatment and genotype level, some Sardinian genotypes demonstrated a consistent level of tolerance especially in relation to the performance of the commercial varieties tested. Among them were the lines `125 brachy C', `56 sub D', `22 brachy G', `56 sub B' (=Campeda), and `19 brachy E' (=Antas).



1984 ◽  
Vol 35 (4) ◽  
pp. 539 ◽  
Author(s):  
JH Silsbury ◽  
D Zuill ◽  
PH Brown

Effects of constant temperatures of 10, 15, 20, 25 and 30�C on the germination, emergence and early vegetative growth of Trifolium subterraneum L. cv. Mt Barker grown as swards were examined in temperature-controlled glasshouses and in a growth cabinet. Seedlings were established at a density of about 2000 plants m-2 and grown for up to 70 days. Plants were either inoculated and grown without mineral nitrogen (-N), or supplied with 7.5 mM NO-3 (+ N). Percentage germination and emergence were hardly affected by temperatures of 10-20�C, but at 25�C were reduced to 50%, and at 30�C to about 10%. The rates of germination and emergence were slowest at 10�C, but showed little change with temperature over the range 15-30�C. Time to closed canopy (leaf area index 3) and time to a dry weight of 133 g m-2 were shorter where plants were supplied with NO; than where mineral nitrogen was withheld and a symbiotic system established. Rates of N2-fixation, as measured by acetylene reduction assay, were not markedly affected by temperature over the range 10-25�C. Relative efficiency ranged from about 0.55 at 10, 15, and 20�C to about 0.66 at 25�C. At 30�C nodulation still occurred, but nitrogenase activity was very slight. It is concluded that, where swards of subterranean clover are grown in the absence of any mineral N, a period of N-starvation limits growth during the time taken for symbiotic N2-fixation to become established. Such retardation of growth is small at about 20�C, but becomes more marked at lower and higher temperatures. The establishment of subterranean clover swards in soils of low N status are likely to be retarded following an early (March) or a late (July) start in the growing season. In such cases a 'starter' application of mineral nitrogen may promote the early growth of the legume.



2000 ◽  
Vol 51 (3) ◽  
pp. 377 ◽  
Author(s):  
G. M. Lodge

Seedlings of 3 perennial grasses, Danthonia linkii Kunthcv. Bunderra, D. richardsonii Cashmore cv. Taranna(wallaby grasses), and Phalaris aquatica L. cv. Sirosa,were each grown in replacement series mixtures with seedlings ofTrifolium repens L. (white clover),Trifolium subterraneum L. var. brachycalycinum (Katzn.et Morley) Zorahy & Heller cv. Clare (subterraneanclover), and Lolium rigidum L. (annual ryegrass). Plantswere sown 5 cm apart in boxes (45 by 29 by 20 cm) at a density of 307plants/m2. Maximum likelihood estimates were usedto derive parameters of a non-linear competition model using the dry matterweights of perennial grasses and competitors at 3 harvests, approximately 168,216, and 271 days after sowing. Intra-plant competition was examined inmonocultures of each species, grown at plant spacings of 2, 5, and 8 cm apartwith plants harvested at the above times.Competition occurred in all perennial grass–competitor mixtures, exceptin those of each perennial grass with white clover and thephalaris–subterranean clover mixture (Harvest 1) and those withD. richardsonii and phalaris grown with white clover(Harvest 2). For D. richardsonii (Harvests 1 and 2) andD. linkii (Harvest 1 only) grown with white clover andthe phalaris–subterranean clover (Harvest 1), the two species in themixture were not competing. In the phalaris–white clover mixture, eachspecies was equally competitive (Harvests 1 and 2). These differences incompetition and aggressiveness reflected differences in individual plantweights in monocultures where there was an effect (P < 0.05) of species ondry matter weight per box, but no significant effect of plant spacing.These data indicated that for successful establishment,D. richardsonii and D. linkiishould not be sown in swards with either subterranean clover or white clover,or where populations of annual ryegrass seedlings are likely to be high.Phalaris was more compatible with both white clover and subterranean clover,but aggressively competed with by annual ryegrass.





2004 ◽  
Vol 94 (5) ◽  
pp. 433-439 ◽  
Author(s):  
S.N. Johnson ◽  
P.J. Gregory ◽  
P.J. Murray ◽  
X Zhang ◽  
I.M. Young

AbstractThis study investigated the ability of neonatal larvae of the root-feeding weevil, Sitona lepidus Gyllenhal, to locate white clover Trifolium repens L. (Fabaceae) roots growing in soil and to distinguish them from the roots of other species of clover and a co-occurring grass species. Choice experiments used a combination of invasive techniques and the novel technique of high resolution X-ray microtomography to non-invasively track larval movement in the soil towards plant roots. Burrowing distances towards roots of different plant species were also examined. Newly hatched S. lepidus recognized T. repens roots and moved preferentially towards them when given a choice of roots of subterranean clover, Trifolium subterraneum L. (Fabaceae), strawberry clover Trifolium fragiferum L. (Fabaceae), or perennial ryegrass Lolium perenneL. (Poaceae). Larvae recognized T. repens roots, whether released in groups of five or singly, when released 25 mm (meso-scale recognition) or 60 mm (macro-scale recognition) away from plant roots. There was no statistically significant difference in movement rates of larvae.



2013 ◽  
Vol 37 ◽  
pp. 1155-1165 ◽  
Author(s):  
Farhana KAUSAR ◽  
Muhammad SHAHBAZ ◽  
Muhammad ASHRAF


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