Allelopathic Pollen Extract from Phleum pratense L. (Poaceae) Reduces Seed Set in Sympatric Species

1995 ◽  
Vol 156 (4) ◽  
pp. 435-444 ◽  
Author(s):  
Stephen D. Murphy ◽  
Lonnie W. Aarssen
Keyword(s):  
Seed Set ◽  
Sympatric Species ◽  
Phleum Pratense ◽  
Pollen Extract ◽  
Phleum Pratense L

Reduced seed set in Elytrigia repens caused by allelopathic pollen from Phleum pratense

1995 ◽  
Vol 73 (9) ◽  
pp. 1417-1422 ◽  
Author(s):  
Stephen D. Murphy ◽  
Lonnie W. Aarssen
Keyword(s):  
Seed Set ◽  
Pollen Dispersal ◽  
Pollen Grains ◽  
Phleum Pratense ◽  
Pollen Extract ◽  
Old Field ◽  
Heterospecific Pollen ◽  
Elytrigia Repens ◽  
The Mean

Earlier studies have shown that extracts from pollen of Phleum pratense reduce pollen germination and seed set in Elytrigia repens (L.) Nevski (Poaceae), but the effect of in situ pollen from P. pratense on seed set in E. repens in the field has not been previously demonstrated. By clipping the inflorescences of P. pratense just prior to flowering, we reduced pollen dispersal in fields at three old-field sites. In adjacent fields at all three sites, P. pratense was allowed to flower unimpeded. In the clipped fields, the mean number of pollen grains of P. pratense per stigma of E. repens was reduced to less than 1 versus 9–10 grains in the unmanipulated fields. Mean percent seed set of E. repens in the clipped fields was approximately 65–70%, whereas in the unmanipulated fields it was approximately 15–20%. In the following year, when no treatments were applied (i.e., P. pratense was allowed to disperse naturally in all fields), mean percent seed set in the same plants of E. repens was uniformly reduced to less than 15% in all fields. Several lines of evidence suggest that this reduction in seed set in E. repens was caused by allelopathic pollen of P. pratense, rather than by physical occlusion: (i) previous studies using extracts of P. pratense pollen elicited similar decreases in seed set in E. repens, and the seed set decreases were nonlinear (i.e., not indicative of displacement); (ii) the number of P. pratense pollen grains on E. repens stigmas needed to cause pollen allelopathy (based on previous pollen extract studies) existed in the unmanipulated fields but not in the clipped fields; and (iii) E. repens pollen outnumbered P. pratense pollen on E. repens stigmas by at least 5:1 (even when P. pratense inflorescences were not clipped). Key words: competition, Elytrigia repens, heterospecific pollen transfer, Phleum pratense, pollen allelopathy, reproductive success.

NITROGENASE ACTIVITY OF ALFALFA GROWN ALONE AND IN MIXTURE WITH GRASS UNDER GREENHOUSE CONDITIONS

1985 ◽  
Vol 65 (3) ◽  
pp. 787-791
Author(s):  
H. A. BURITY ◽  
B. E. COULMAN ◽  
M. A. FARIS
Keyword(s):  
Medicago Sativa ◽  
Nitrogenase Activity ◽  
Dactylis Glomerata ◽  
Phleum Pratense ◽  
Bromus Inermis ◽  
Smooth Bromegrass ◽  
Medicago Sativa L ◽  
Dactylis Glomerata L ◽  
Phleum Pratense L ◽  
Nodule Tissue

A greenhouse experiment has shown that total nitrogenase activity of alfalfa (Medicago sativa L.) is not significantly affected when grown in association with timothy (Phleum pratense L.), smooth bromegrass (Bromus inermis Leyss) or orchardgrass (Dactylis glomerata L.) except after initial harvest when decreased alfalfa activity was associated with smooth bromegrass or orchardgrass. It was concluded that mixed cultures of alfalfa with timothy, smooth bromegrass or orchardgrass have no effect on alfalfa N2 fixation. The results also suggest the occurrence of N transference from alfalfa to associated grasses. It is speculated that this transfer is not primarily due to the death of roots and nodule tissue (after harvest), but involves some degree of N excretion during the period before initial harvest.Key words: Alfalfa-grass mixtures, N2-fixation, nodule activity, N-transference

EVALUATION OF TIMOTHY CULTIVARS FOR VOLUNTARY INTAKE AND NUTRIENT COMPONENTS

1988 ◽  
Vol 68 (4) ◽  
pp. 1121-1129 ◽  
Author(s):  
W. N. MASON ◽  
P. M. FLIPOT
Keyword(s):  
Key Words ◽  
Dry Matter ◽  
Phleum Pratense ◽  
Dry Matter Intake ◽  
Dry Matter Yield ◽  
Dry Matter Digestibility ◽  
Flower Stage ◽  
Voluntary Intake ◽  
Phleum Pratense L

Five timothy (Phleum pratense L.) cultivars, Clair, Champ, Milton, Climax and Bounty, were harvested at first flower stage during 2 consecutive years and in the regrowth for 1 yr. The forages were each offered as hay to 15 young rams to evaluate voluntary intake. Five animals were used to determine initial harvest dry matter digestibility. The cultivars varied significantly in voluntary intake at first flower stage. The highest intake (g kg−0.75 d−1) averaged for the years was obtained in the early cultivar Champ (65.9), which was 10% more than that of the medium-late cultivar Climax. The cultivars did not differ significantly in dry matter digestibility. In the regrowth, the relative intakes of the cultivars were essentially reversed from that of the initial harvest. The voluntary intake was substantially higher but the differences among forages were less marked. Climax regrowth voluntary intake was higher (P < 0.05) than all cultivars, except Bounty. A 15% range in digestible dry matter intake was present among cultivars. The ranking of the culivars for digestible dry matter was different than for dry matter yield. Key words: Timothy, Phleum pratense L., voluntary intake, dry matter digestibility

COPPER, MOLYBDENUM AND SULFUR CONTENTS OF FORAGE CROPS AT KAPUSKASING, ONTARIO

1970 ◽  
Vol 50 (6) ◽  
pp. 685-691 ◽  
Author(s):  
J. R. LESSARD ◽  
M. HIDIROGLOU ◽  
R. B. CARSON ◽  
J. M. WAUTHY
Keyword(s):  
Dactylis Glomerata ◽  
Phleum Pratense ◽  
Birdsfoot Trefoil ◽  
Festuca Rubra ◽  
Forage Crops ◽  
Reed Canarygrass ◽  
Red Fescue ◽  
Cu Content ◽  
Dactylis Glomerata L ◽  
Phleum Pratense L

Each of the species birdsfoot trefoil (Lotus corniculatus L.), timothy (Phleum pratense L.), bromegrass (Bromus inermis Leyss.), orchardgrass (Dactylis glomerata L.), reed canarygrass (Phalaris arundinacea L.) and creeping red fescue (Festuca rubra L.) was grown in the field on 10 plots sampled at weekly intervals in rotation from June 13. Each plot was resampled after 6 weeks and all samples were analyzed for copper, molybdenum and sulfur. In most species, levels of Cu and Mo were highest in the early samplings and decreased with advancing maturity. Second-cut samples tended to be higher in Cu, Mo and S than first-cut samples. The S content was more uniform in the first cycle but increased considerably in the second cycle, especially in reed canarygrass. The ranges in Cu content were 7.4 to 14.1 ppm for birdsfoot trefoil and 3.7 to 11.4 ppm for the grasses. Mo ranged from 1.9 to 8.1 ppm in birdsfoot trefoil and from 1.0 to 6.5 ppm in the grasses. The overall range in S content was from 0.14 to 0.95%. The mineral composition of the crops is discussed in relation to the requirement of ruminants for these three elements.

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