Mycorrhizal dependence and growth habit of warm-season and cool-season tallgrass prairie plants

1988 ◽  
Vol 66 (7) ◽  
pp. 1376-1380 ◽  
Author(s):  
B. A. Daniels Hetrick ◽  
D. Gerschefske Kitt ◽  
G. Thompson Wilson

Warm-season (C4) and cool-season (C3) mycorrhizal grasses were 63–215 and 0.12–4.1 times larger in dry weight than non-inoculated controls, respectively. Nonmycorrhizal warm-season plants did not grow and frequently died, while cool-season plants grew moderately well in the absence of mycorrhizal symbiosis. Like warm-season grasses, tallgrass prairie forbs were highly dependent on mycorrhizal symbiosis, even though they are not known to employ the C4 photosynthetic pathway. Thus, phenology may be more critical than photosynthetic pathway in determining mycorrhizal dependence. Warm-season grasses and forbs had coarser, less frequently branched root systems than cool-season grasses, supporting the hypothesis that mycorrhizal dependence is related to root morphology. Cool-season grasses may have developed more fibrous root systems because mycorrhizal nutrient uptake was not effective in the colder temperate environment in which they evolved. In contrast, warm-season plants and dependence on mycorrhizal fungi may have coevolved, because both symbionts are of tropical origin.

1992 ◽  
Vol 70 (8) ◽  
pp. 1596-1602 ◽  
Author(s):  
S. P. Bentivenga ◽  
B. A. D. Hetrick

Previous research on North American tallgrass prairie grasses has shown that warm-season grasses rely heavily on vesicular–arbuscular mycorrhizal symbiosis, while cool-season grasses are less dependent on the symbiosis (i.e., receive less benefit). This led to the hypothesis that cool-season grasses are less dependent on the symbiosis, because the growth of these plants occurs when mycorrhizal fungi are inactive. Field studies were performed to assess the effect of phenology of cool- and warm-season grasses on mycorrhizal fungal activity and fungal species composition. Mycorrhizal fungal activity in field samples was assessed using the vital stain nitro blue tetrazolium in addition to traditional staining techniques. Mycorrhizal activity was greater in cool-season grasses than in warm-season grasses early (April and May) and late (December) in the growing season, while mycorrhizal activity in roots of the warm-season grasses was greater (compared with cool-season grasses) in midseason (July and August). Active mycorrhizal colonization was relatively high in both groups of grasses late in the growing season, suggesting that mycorrhizal fungi may proliferate internally or may be parasitic at this time. Total Glomales sporulation was generally greater in the rhizosphere of cool-season grasses in June and in the rhizosphere of the warm-season grasses in October. A growth chamber experiment was conducted to examine the effect of temperature on mycorrhizal dependence of cool- and warm-season grasses. For both groups of grasses, mycorrhizal dependence was greatest at the temperature that favored growth of the host. The results suggest that mycorrhizal fungi are active in roots when cool-season grasses are growing and that cool-season grasses may receive benefit from the symbiosis under relatively cool temperature regimes. Key words: cool-season grasses, tallgrass prairie, vesicular–arbuscular mycorrhizae, warm-season grasses.


1989 ◽  
Vol 67 (9) ◽  
pp. 2608-2615 ◽  
Author(s):  
B. A. D. Hetrick ◽  
G. W. T. Wilson ◽  
D. C. Hartnett

The impact of mycorrhizal symbiosis on growth of Andropogon gerardii (big bluestem) and Koeleria pyranidata (junegrass) was compared. Andropogon gerardii was 98% dependent on the symbiosis, whereas K. pyranidata displayed less than 0.02% dependence. Mycorrhizal fungus inoculation resulted in 50 times larger A. gerardii plants but did not alter growth of K. pyranidata. When competing in pairs, A. gerardii dominated when the mycorrhizal symbiosis was present and K. pyranidata dominated when it was not present. Dry weight of mycorrhizal A. gerardii was altered, whether grown alone or with K. pyranidata, but mycorrhizal K. pyranidata grew well only in the absence of competition and failed to grow appreciably if A. gerardii was present. Without mycorrhizal fungus inoculation, A. gerardii did not grow and had no deleterious effects on K. pyranidata. When P fertilization was substituted for mycorrhizal fungus inoculation, A. gerardii grew better alone than in competition with K. pyranidata at low P levels but was not affected by competition at high P levels. Koeleria pyranidata was not affected by competition at low P levels, but high P fertilization resulted in reduced dry weight of K. pyranidata plants when in competition with A. gerardii. Phenologic separation of growing seasons avoids interspecific competition between these two grasses and may be one mechanism contributing toward their coexistence. Since low temperatures limit mycorrhizal nutrient uptake, phenologic separation of growing seasons could also avoid the competitive advantage of warm-season grasses conferred by their mycorrhizal dependence.


1990 ◽  
Vol 68 (3) ◽  
pp. 461-467 ◽  
Author(s):  
B. A. D. Hetrick ◽  
G. W. T. Wilson ◽  
T. C. Todd

The responses of five C4, warm-season and five C3, cool-season tallgrass prairie grasses to phosphorus (P) fertilization, mycorrhizae, and soil microorganisms were compared in greenhouse studies. The warm-season grasses responded positively to mycorrhizae or to P fertilization, but mycorrhizal plants did not respond to P. The soil microflora reduced mycorrhizal plant dry weight and root colonization. In contrast, cool-season grasses did not respond to mycorrhizae or P fertilization. Soil microorganisms did not suppress cool-season plant growth, but root colonization was reduced in nonsterile soil. For the warm-season grasses there was an inverse relationship between mycorrhizal root colonization and P fertilization and a positive relationship between root colonization and plant dry weight. For the cool-season grasses there was also an inverse relationship between root colonization and P fertilization, but the relationship between root colonization and plant dry weight was negative. In both the warm-season and cool-season grasses, low levels of mycorrhizal root colonization persisted even when P fertilization was sufficient to eliminate mycorrhizal effects on plant growth. Thus, warm- and cool-season grasses display profoundly different strategies for nutrient acquisition. Key words: cool-season grasses, warm-season grasses, vesicular–arbuscular mycorrhizae.


Weed Science ◽  
1989 ◽  
Vol 37 (3) ◽  
pp. 375-379 ◽  
Author(s):  
Thomas J. Peters ◽  
Russell S. Moomaw ◽  
Alex R. Martin

The control of three summer annual grass weeds with herbicides during establishment of forage grasses was studied near Concord and Mead, NE, in 1984, 1985, and 1986. Three cool-season forage grasses, intermediate wheatgrass, tall fescue, and smooth bromegrass, and two warm-season grasses, big bluestem and switchgrass, were included. The control of three major summer annual grasses, green foxtail, barnyardgrass, and large crabgrass, was excellent with fenoxaprop at 0.22 kg ai/ha. Slight to moderate injury to cool-season forage grasses and severe injury to warm-season grasses were evident. Sethoxydim at 0.22 kg ai/ha and haloxyfop at 0.11 kg ai/ha controlled green foxtail and large crabgrass, but not barnyardgrass. Sulfometuron-treated big bluestem and switchgrass plots had the best forage stand frequencies and yields and, at the rate used, sulfometuron satisfactorily controlled green foxtail but only marginally controlled barnyardgrass and large crabgrass.


1998 ◽  
Vol 28 (1) ◽  
pp. 150-153
Author(s):  
J N Gemma ◽  
R E Koske ◽  
E M Roberts ◽  
S Hester

Rooted cuttings of Taxus times media var. densiformis Rehd. were inoculated with the arbuscular mycorrhizal fungi Gigaspora gigantea (Nicol. & Gerd.) Gerd. & Trappe or Glomus intraradices Schenck and Smith and grown for 9-15 months in a greenhouse. At the completion of the experiments, leaves of inoculated plants contained significantly more chlorophyll (1.3-4.1 times as much) than did noninoculated plants. In addition, mycorrhizal plants had root systems that were significantly larger (1.3-1.4 times) and longer (1.7-2.1 times) than nonmycorrhizal plants, and they possessed significantly more branch roots (1.3-2.9 times). No differences in stem diameter and height or shoot dry weight were evident at the end of the experiments, although the number of buds was significantly greater in the cuttings inoculated with G. intraradices after 15 months.


2010 ◽  
Vol 28 (1) ◽  
pp. 40-45 ◽  
Author(s):  
E. L. Bouressa ◽  
J. E. Doll ◽  
R. L. Cates ◽  
R. D. Jackson

2014 ◽  
Vol 94 (7) ◽  
pp. 1139-1148 ◽  
Author(s):  
B. Biligetu ◽  
P. G. Jefferson ◽  
R. Muri ◽  
M. P. Schellenberg

Biligetu, B., Jefferson, P. G., Muri, R. and Schellenberg, M. P. 2014. Late summer forage yield, nutritive value, compatibility of warm-and cool-season grasses seeded with legumes in western Canada. Can. J. Plant Sci. 94: 1139–1148. In late summer and fall, quality and quantity of forage are important for weight gain by grazing animals in western Canada. The objective of this study was to evaluate forage nutritive value, dry matter (DM) yield, and compatibility of crested wheatgrass [Agropyron cristatum (L.) Gaertn.], meadow bromegrass (Bromus riparius Rehm.), green needle grass [Nasella viridula (Trin.) Barkworth], northern wheatgrass [Elymus lanceolatus (Scribn. & J. G. Sm.) Gould], western wheatgrass [Pascopyrum smithii (Rydb.) Barkworth & D.R. Dewey], Russian wildrye [Psathyrostachys juncea (Fisch.) Nevski], big bluestem (Andropogon gerardii Vitman), or switchgrass (Panicum virgatum L.) in eight grass monocultures, and their binary mixtures with alfalfa (Medicago sativa L.), sainfoin (Onobrychis viciifolia Scop.), or cicer-milkvetch (Astragalus cicer L.) harvested once in August or September. A field study was conducted over a 7-yr period from 1998 to 2004 near Swift Current (lat. 50°25'N, long. 107°44'W, 824 m elev.), SK, Canada, using a randomized complete block design. Forage DM yield was similar between August and September harvests (P>0.05). Binary mixtures of alfalfa–grass produced highest (P<0.05) DM yield ranging from 2449 to 2758 kg ha−1. The monoculture of crested wheatgrass (2143 kg ha−1), sainfoin with crested wheatgrass (2061 kg ha−1), and cicer-milkvetch with green needle grass (1838 kg ha−1) or cicer-milkvetch with western wheatgrass (1861 kg ha−1) produced the second highest (P<0.05) DM yields in the ranking. The two warm-season grasses produced the lowest (P>0.05) DM yields over the 7-yr period. Monocultures of green needle grass or northern wheatgrass had the highest acid detergent fiber (ADF) and neutral detergent fiber (NDF), while warm-season grasses with legumes had the lowest. Alfalfa with western wheatgrass and alfalfa with Russian wildrye had the highest crude protein (CP) concentrations. Monocultures of meadow bromegrass, crested wheatgrass, green needle grass, or cicer-milkvetch with meadow bromegrass, and sainfoin with crested wheatgrass had the lowest CP concentrations. In vitro organic matter digestibility (IVOMD) was greater for mixtures than for the grass monocultures. Concentration of Ca and P was greater for warm-season grasses than cool-season grasses. Alfalfa with western wheatgrass was the best combination considering yield, quality, and compatibility for deferred grazing in late summer and fall in the semiarid prairies. Tested warm-season grasses are not recommended for seeding as binary mixtures with legumes for southwestern Saskatchewan.


2016 ◽  
Vol 9 (2) ◽  
pp. 87-95 ◽  
Author(s):  
Katie L. Wirt ◽  
Rodney G. Lym

When invasive weeds are removed with herbicides, revegetation of native species is often desirable. The extended soil activity of aminocyclopyrachlor is important for long-term weed control but could reduce recovery of native species as well. The effect of aminocyclopyrachlor applied alone or with chlorsulfuron on cool- and warm-season grass species commonly used for revegetation was evaluated. The cool-season grasses included green needlegrass, intermediate wheatgrass, and western wheatgrass, whereas the warm-season grasses were big bluestem, sideoats grama, and switchgrass. A separate experiment was conducted for each species. Aminocyclopyrachlor was applied at 91 to 329 g ha−1 alone or with chlorsulfuron from 42 to 133 g ha−1 approximately 30 d after emergence. Warm-season grasses generally were more tolerant of aminocyclopyrachlor than the cool-season grasses evaluated in this study. Switchgrass and big bluestem were the most tolerant of the warm-season species when aminocyclopyrachlor was applied at 168 g ha−1 and averaged 199 and 150% forage production, respectively, compared with the control. Green needlegrass was the most tolerant cool-season grass. Western wheatgrass was the least tolerant species evaluated because forage production only averaged 32% of the control the year after treatment and thus would not be suitable for seeding if aminocyclopyrachlor was applied. The effect of chlorsulfuron applied with aminocyclopyrachlor varied by grass species. For example, green needlegrass injury 8 wk after treatment (WAT) averaged 30 and 48% when aminocylopyrachlor was applied alone, respectively, but injury was reduced to less than 16% when aminocyclopyrachlor was applied with chlorsulfuron. However, injury on the less-tolerant intermediate wheatgrass ranged from 48 to 92% by 4 WAT when aminocyclopyrachlor was applied alone and from 60 to 86% when chlorsulfuron was included in the treatment.


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