Tải bản đầy đủ - 0trang
V. Deleterious Rhizobacteria for Weed Control
L. E ELLIOT AND D. E. STOTT
chamber, three isolates were suitable for field testing. Plots were established at
three sites and after the winter wheat was seeded in the fall the isolates were applied at lo8cfu m-*. At the Washtucna and Eureka sites, the isolates D7 and 2VI 9
significantly reduced the downy brome pouplation. At harvest, downy brome control by isolates D7 and 2V19 significantly increased winter wheat yield at the
Washtucna and Eureka sites (Table IV).Yields were increased 3.5 and 18%, respectively, and the winter wheat population was unaffected (Kennedy ef d.,
Weed density, biomass, and seed production were reduced. Downy brome reduction is shown by the plot treated with D7 (Fig. 9a) and the untreated check (Fig.
9b). There was no benefit from the application of the organisms at the Dayton site.
The wheat was well established at the Dayton site before downy brome growth began so the weed was not as competitive as it was at the other two sites. Also, the
Dayton site was conventionally tilled and seeded, whereas the Washtucna and Eureka sites were no-till seeded. There was no surface crop residue at the Dayton site.
Downy brome control in Kentucky bluegrass by D7 is shown in the foreground
compared with the background (Fig. 10).
Current research efforts on the use of DRB for weed control were summarized
by Kremer and Kennedy (199.5). They stated that weeds cause greater economic
losses on agricultural lands than all other pests combined. They summarized the use
of DRB for weed biocontrol as follows: The DRB strategy is to regulate or suppress
weed growth, the mode of action of DRB is primarily through the production of
phytotoxins, and the DRB should have adequate specificity and efficacy so the weed
is inhibited and the crop is not harmed. DRB have been obtained that are effective
against both narrow- and broad-leaf weed species, and there has been some suc-
Winter Wheat Population and Yield from Fields Inoculated withRhizobacteria
and Planted inwinter Wheat at Three Locations in Eastern Washington
4 I OO'*
Nore. From Kennedy el a / . (1991) with permission.
"NI, noninoculated (Kennedy et al., 1991).
*Statistically different from the noninoculated control from the Same location at the 0.05 level
using Dunnett's LSD.
INFLUENCE OF NO-TILL CROPPING SYSTEMS
Figure 9 (a) No-till seeded winter wheat with downy brome in the interrow retarded and inhibited by the application of D7. (b) lnterrow growth of untreated downy brome in no-till seeded winter
wheat (from Kennedy CI a / . , 1991).
L. F. ELLIOT AND D. E. STOTT
Figure 10 Inhibition of the weed downy brome in Kentucky bluegrass seed stand by the application of 1 X lo8 deleterious rhizobacteria organisms per square meter (foreground) compared with the
untreated, check background.
cessful application in the field. Currently, there are several projects under way in
Canada and the United States. They discussed some studies that indicate DRB may
be more effective when combined with low rates of herbicides. The potential use
of DRB with other biocontrol agents was also mentioned. The successful use of
DRB for biological weed control still suffers from unpredictability. However, this
is the case for many biological control agents (Elliott and Lynch, 1995).
The development of successful weed biocontrol approaches using DRB will require additional knowledge in several areas, including (1) establishment of guidelines and procedures for isolating and selecting organisms; (ii) determination of root
colonization mechanisms; (iii) design of effective carriers including the possibility
of using crop residues previous studies have shown strong competitive ability of
winter wheat DRB growing on crop residues-this may be a useful approach for
the use of DRB for weed control; (iv) determination of the mechanism of growth
inhibition (current information strongly implicates phytotoxins but the evidence is
not conclusive); (v) the mechanism regulating specificity must be determined; (vi)
the role of DRB with herbicide use must be explored more thoroughly; and (vii) the
effect of field management practices such as seeding method (till versus no-till),
fertilizer management, etc., on DRB biocontrol strategy requires more investigation. For example, as mentioned previously, preliminary data indicated that NO;
INFLUENCE OF NO-TILL CROPPING SYSTEMS
and incubation at 5°C increased the number of TOX+ DRB isolated from the rhizoplane of winter wheat roots. The potential for the use of DRB for weed biocontrol appears good. The approach is environmentally friendly and, if successful,
should be beneficial to the development of sustainable cropping systems.
VI. LOW-INPUT, ON-FARM COMPOSTING
Crop yields often suffer when conservation tillage systems are implemented
(McCalla and Army, 1961; Papendick and Miller, 1977). These yield reductions
have been attributed to a variety of problems. These include short-chain fatty acids
produced during residue decomposition (Cochran et al., 1977; Lynch et al., 1981),
infection by plant pathogens such as Pythium sp. (Cook et al., 1980); and colonization of roots by deleterious rhizobacteria (Alstrom, 1987; Fredrickson and Elliott, 1985b; Schippers et al., 1987; Suslow and Schroth, 1982). Hairpinning of the
residues around the seed can result in poor seedling growth because of poor seed
zone environmental conditions (Elliott et al., 1984). No-till seeding into heavy crop
residues can cause high crown set when the residues fall back onto the seed row
(Fig. 11). This is very undesirable because the exposed roots are subject to drying,
herbicide effects, and inhibitory substances produced during straw decomposition.
Many of these problems are more severe as residue production becomes heavier.
The solution has been to bum the residues. Burning of residues is causing increased
public concern because of air pollution. Various options such as using the residues
for heat or power production have been explored but are not economically feasible
at this juncture. The management of heavy residues for conservation tillage systems
has been an unyielding problem in many cases. Heavy specialized no-till drills that
can seed through the heavy crop residues and manage them effectively have been
developed. However, the drills are too expensive for many farmers. The development of low-input, on-farm composting of high C/N ratio residues is providing an
innovative residue management option and the potential for assisting the development of sustainable farming systems. Composting of crop residues will overcome
the negative aspects of crop growth using conservation tillage systems where crops
are seeded back into heavy crop residues and will provide added benefits when put
back onto the field. The potential benefits of crop residues to soil structure have
been demonstrated (Elliott and Lynch 1984a).The possible benefits of compost for
alleviating some soil-borne diseases has also been shown (Hoitink et al., 1991).
Compost additions may alleviate problems associated with DRB. These possibilities have not been explored thoroughly. The benefits of compost applications also
include fertilizer content, soil conditioning value, and benefits to soil quality (Bangar er al., 1989; Nelson and Craft, 1992; Thomsen, 1993; Zaccheo e? al., 1993).
Compost applications have shown large benefits for land reclamation (Dick and
McCoy, 1993). Optimum use of crop residues for conservation tillage systems was
L. F. ELLIOT AND D. E. STOTT
Figure 11 High crown set in winter wheat caused by seeding into heavy crop residues and by not
keeping the residues out of the seedling row.
not feasible until the development of low input, on-farm composing of high C/N ratio crop residues. Churchill etal. (1995) have developed the approach for grass seed
straw. Our laboratory studies show the process will work as well with wheat and
rice (Oryzasativa L.) straw. Studies by Honvath and Elliott (1995a,b) and Horwath
et al. (1 995) have explained the mechanisms of the process, which appears to be
rapid delignification. Previously, it was thought that successful composting required a combined substrate C/N ratio of 30/1 or less (Biddlestone et al., 1987). If
the C/N ratio was higher than 30/1, it would have to be cocomposted with an organic material such as manure or sludge to reduce the C/N ratio. Cocomposting
greatly complicates the process for on-farm application.
The low-input, on-farm composting method consists of gathering the straw into
large piles at the side of the field. When rainfall occurs the stacks are turned to allow maximum water intake. The turning with a front-end loader also compacts the
straw, which helps the stack to retain heat. Over winter and early spring the straw
is turned when temperatures cool. The compost is ready for field application after
about three turns in as little as 16-weeks time (Churchill et al., 1995). Even with
two turns with a commercial compost turner, after 16 weeks less than 20% of the
original volume of straw remained (Fig. 12). Studies on the economics of the
process and the value of the compost additions to succeeding crops are incomplete.
INFLUENCE OF NO-TILL CROPPING SYSTEMS
Figure 12 Percentage of original volume remaining in grass straw wind rows with zero to six turns
(from Churchill e t a / . . 1995, with permission).
In laboratory studies to determine the mechanisms of high C/N ratio substrate
composting, grass straw was incubated under mesophilic and thermophilic conditions. After 45 days of incubation, the loss of lignin C in the Klason lignin fraction
was 25 and 39% under mesophilic and thermophilic conditions, respectively.
Changes in elemental composition indicated that 94% of the lignin fraction had
been altered under both incubation conditions. These data showed that changes in
the lignin fraction were much more extensive than measured by the Klason
method. C mineralization from the straw was 46 and 52% under mesophilic and
thermophilic conditions, respectively. The addition of N decreased the rate of C
mineralization. C mineralization per unit of microbial biomass under thermophilic
conditions was twice that under mesophilic conditions. These data indicate that the
microbial biomass was less efficient under thermophilic conditions, which lead to
greater C mineralization per unit of microbial biomass. These data also established
that the C and N pathways were largely independent. Plate counts of bacteria, fungi, and actinomycetes did not show any definite patterns between the two incubation conditions. These studies indicate that there is the possibility for regulating
the quality of the compost end-product (Horwath and Elliott 1995a,b; Horwath el
1995). Low-input, on-farm composting could be a valuable asset to developing sustainable cropping systems.
Low-input, on-farm composting will allow no-till seeding or shallow conservation tillage on fields that have contained heavy residues. These cropping techniques will be possible without the risk of severe yield reductions of the succeed-
L. E ELLIOT AND D. E. STOTT
ing crop if the heavy residues can be removed before seeding and composted. It is
also likely that weed control problems will be expedited in the absence of the heavy
residues. Finally, the lack of extensive tillage and return of the residues should enhance soil quality over systems using conventional tillage practices.
Alstrom, S. (1987). Factors associated with detrimental effects of rhizobacteria on plant growth. Plum
Bangar, K. C., Shanker, S., Kapoor, K. K., Kukreja, K.,and Mishra, M. M. (1989). Preparation of nitrogen and phosphorus-enriched paddy straw compost and its effect on yield and nutrient uptake
by wheat (Triricum uestivurn L.). Biol. Fertil. Soils 8,339-342.
Biddleston, A. J., Gray, K. R., and Day, C. A. (1987). Composting and straw decomposition. In “Environmental Biotechnology” (C. F. Forster and D. A. Wase, Eds.), pp. 135-175. Wiley, New York.
Bolton, H., Jr., Elliott, L. F., Gurusiddiah, S., and Fredrickson, J. K. (1989). Characterization of a toxin produced by a rhizobacterial Pseudomonus sp. that inhibits wheat growth. Plant Soil 114,
Brian, P. W., Wright, J. M., Stubbs, J., and Way, A. W. (1951). Uptake of antibiotic metabolites of soil
microorganisms by plants. Nurure 167,347-349.
Bristow, K. L., Campbell, G. S., Papendick, R. I., and Elliott, L. F. (1986). Simulation of heat and moisture transfer through a surface residue-soil system. Agric. FOEMeterol. 36, 193-2 14.
Brown, P. L., and Dickey, D. D. (1970). Losses of wheat straw residue under simulated field conditions. SoilSci. Soc.Am. Proc. 34, 118-121.
Cherrington, C. A., and Elliott, L. F. (1987).Incidence of inhibitory pseudomonads in the Pacific Northwest. Plunr Soil 101, 159-165.
Churchill, D. B., Bilsland, D. M., and Elliott, L. F. ( I 995). Method for composting grass seed straw
residue. Appl. Eng. Agric. 11(2), 215-279.
Cochran, V. L., Elliott, L. F., and Papendick, R. 1. (1977). The production of phytotoxins from surface
crop residues. Soil. Sci. SOC.Am. J . 41,903-908.
Collins, H. P., Elliott, L. F., and Papendick, R. 1. (1990a). Wheat straw decomposition and changes in
decomposability during field exposure. Soil Sci. SOC.Am. J. 54, 1013-1016.
Collins, H. P., Elliott, L. F., Rickman, R. W., Bezdicek, D. F., and Papendick, R. I. (1990b). Decomposition and interactions among wheat residue components. Soil Sci. SOC.Am. J. 54,780-785.
Cook, R. J., Sitton, J. W., and Waldher, J. T. (1980). Evidence for Pyrhium as a pathogen of direct drilled
wheat in the Pacific Northwest. Plunr Dis. 64, 102-103.
Curry, J. 0. (1969). The decomposition of organic matter in soil. Part I. The role of the fauna in decaying grassland herbage. Soil Biol. Biochem. 1,235-258.
Dick, W. A.. and McCoy, E. L. (1993). Enhancing soil fertility by the addition of compost. In “Science
and Engineering of Composting: Design, Environmental, Microbiological and Utilization Aspects” (H. A. J. Hoitink and H. M. Keener, Eds.), pp. 622-644. Renaissance, Worthington, OH.
Douglas, C. L., Jr.. Allmaras, R. R., Rasmussen, P. E., Ramig, R. E., and Roager, N. C., Jr. (1980).
Wheat straw composition and placement effects on decomposition in dry land agriculture of the
Pacific Northwest. Soil Sci. SOC.Am. J. 44,833-837.
Douglas, C. L., Jr., and Rickman, R. W. (1992). Estimating crop residue decomposition from air temperature, initial nitrogen content, and residue placement. Soil Sci. SOC.Am. J. 56, 272-278.
Elliott, L. F., and Lynch, J. M. ( I 984a). The effect of available carbon and nitrogen in straw on soil and
ash aggregation and acetic acid production. Plunr Soil 78,335-343.
INFLUENCE OF NO-TILL CROPPING SYSTEMS
Elliott. L. F.. and Lynch, I. M. (1984b). Pseudomonads as a factor in the growth of winter wheat
(niticurn aestivum L.). Soil B i d . Biochem. 16,69-72.
Elliott. L. F.. and Lynch. J. M. (1985).Plant growth-inhibitory pseudomonads colonizing winter wheat
(Triticurn aestivum L.) roots. Plant Soil 84,5745.
Elliott, L. F.. and Lynch, J. M. (1995). The international workshop on establishment of microbial inocula in soils: Cooperative research project on biological resource management of the Organization for Economic Cooperation and Development (OECD). Am. J. Alt. Agric. 10,50-73.
Elliott. L. F., Papendick, R. 1.. and Cochran, V. L. (1984).Phytotoxicity and microbial effects on cereal growth. In Proceeding: Sixth Manitoba-North Dakota Zero Tillage Workshop,” pp. 40-47.January 1984.Bismarck, N. Dakota.
Fredrickson. J. K., and Elliott, L. F. (1985a). Colonization of winter wheat roots by inhibitory rhizobacteria. Soil Sci. Soc. Am. J. 49, I 172-1 177.
Fredrickson. J. K..and Elliott, L. F. (1985b). Effects on winter wheat seedling growth by toxin-producing rhizobacteria. Plant Soil 83,399409.
Fredrickson, J. K.. Elliott, L. F., and Engibous. J. C. (1987).Crop residues as substrate for host-specific inhibitory pseudomonads. Soil Biol. Biochem. 19, 127-1 34.
Gregory, J. M. ( 1982).Soil cover prediction with various amounts and types of crop residue. Trans.
Am. Soc. Agric. Eng. 25, 1333-1337.
Hendrix. P. F., Pannelee, R. W., Crossley, D. A., Coleman, D. C., Odum, E. P., and Groffman, P. M.
(1 986).Detritus food webs in conventional and no-tillage agroecosystems. Bioscience 36,374-380.
Hoitink, H. A. J., Inbar, T., and Boehm, M. J. (1991).Status of compost amended potting mixes naturally suppressive to soilborne diseases of floriculture crops. Plunr Dis. 75,869-873.
Horwath, W. R.. and Elliott, L. F. (199%). Microbial C and N dynamics during mesophilic and thermophilic incubations of ryegrass. B i d . Fertil. Soils 19,1-9.
Horwath, W.R., and Elliott, L. F. ( 1995b). Ryegrass straw component decomposition during mesophilic
and thermophilic incubations. B i d . Fertil. Soils 18, 1-6.
Horwath, W. R., Elliott, L. F., and Churchill, D. B. (19%). Mechanisms regulating composting of high
carbon to nitrogen ratio grass straw. Compost Sci. Util. 3(3),22-30.
Iritani, W.M.,and Arnold, C. Y. (1960). Nitrogen release of vegetable crop residues during incubation
as related to their chemical composition. Soil Sci. 89,74-82.
Jawson, M. D., and Elliott, L. F. (1986).Carbon and nitrogen transformations during wheat straw and
root decomposition. Soil B i d . Biochem. 18,15-22.
Kennedy. A. C.. Elliott. L. F., Young, F. L., and Douglas, C. L. (1991).Rhizobacteria suppressive to
the weed downy brome. Soil Sci. Soc. Am. J. 55,722-727.
Kennedy. A. C.. Bolton, H.. Jr., Stroo, H. F., Elliott, L. F., and Fredrickson, J. K. (1992).Competitive abilitiesofTn5TOX mutants ofarhizobacterium inhibitory to wheat growth. PlantSoil144,143-153.
Knapp, E. B.. Elliott, L. F., and Campbell, G. S. (1983a). Microbial respiration and growth during the
decomposition of wheat straw. Soil B i d . Biochem. 15,319-323.
Knapp, E. B., Elliott. L. F., and Campbell, G. S. (1983b). Carbon, nitrogen and microbial biomass interrelationships during the decomposition of wheat straw: A mechanistic simulation model. Soil
B i d . Biochern. 15,45.5461.
Kremer, R. J. (1987).Identity and properties of bacteria inhabiting seeds of selected broadleaf weed
species. Micmbial Erol. 14,29-37.
Kremer. R. J., and Kennedy, A. C. (1995).Rhizobacteria as biocontrol agents of weeds. Weed Techno/.,
Linn. D. M.. and Doran. J. W. (1984).Effect of water-filled pore space on carbon dioxide and nitrous
oxide production in tilled and nontilled soils. Soil Sci. Soc. Am. J. 48, 1267-1272.
Lynch, J. M.. Ellis, F. B., Harper, S. H. T., and Christian, D. G . (1981). The effect of straw on the establishment and growth of winter cereals. Agric. Environ. 5,321-328.
Martin, J. P.. and Haider. K. (1986).Influence of mineral colloids on turnover rates of soil organic car-
L. E ELLIOT AND D. E. STOTT
bon. In “Interactions of Soil Minerals with Natural Organics and Microbes” (P. M. H. M. Schnitzer,
Ed.), pp. 283-304. SSSA Spec. Publ. 17. Soil Science Society of America, Madison, WI.
McCalla, T. M., and Army, T. T.(1961). Stubble mulch farming. Adv. ARron. 13, 125-196.
McClellan, R. C., Nelson, T. L., and Sporcic, M. A. (1987). Measurements of residue to grain and relative amounts of straw, chaff, awns and grain yield of wheat and barley varieties common to eastern Washington. In “STEEP-Conservation Concepts and Accomplishments” (L. F. Elliott, Ed.).
pp. 61 7-624. 1986 STEEP Annual Review. Washington State Univ., Pullman.
Nelson, E. B., and Craft. C. M. (1992). Suppression of dollar spot on creeping bentgrass and annual
bluegrass turf with compost-amended topdressings. Plant Dis. 76,954958.
Papendick, R. I., and Miller, D. E. (1977). Conservation tillage in the Pacific Northwest. J. Soil Wufrr
Pm.J. F., and Papendick, R. 1. (1978). Factors affecting the decomposition of crop residues by microorganisms. In “Crop Residue Management Systems” (W. R. Oshwald. Ed.), pp. 101-1 29. ASA,
CSSA, SSSA, Madison, WI.
Reiners. W. A. (1968). Carbon dioxide evolution from the floor of three Minnesota forests. Ecology 44,
Reinertsen, S. A.. Elliott, L. F., Cochran, V. L., and Campbell, G.S. (1984). Role of available carbon
and nitrogen in determining the rate of wheat straw decomposition. Soil B i d . BkJChem. 16,
Rovira, A. D., and Greacen, E. L. (1957). The effect of aggregate disruption on the activity of microorganisms in the soil. Ausf. J. Agric. 8,659-673.
Rovira, A. D.. Elliott. L. F., and Cook, R. J. (1990). The impact of cropping systems on rhizosphere organisms affecting plant health. In “The Rhizosphere” (J. M. Lynch, Ed.), pp. 389-436. Wiley.
Salt, G. A. (1979). The increasing interest in minor pathogens. In “Soil Borne Plant Pathogens” (B.
Schippers and W. Gams, Eds.), pp. 289-312. Academic Press, New York.
Schippers, R.. Bakker, A. W., and Bakker, P. A. H. M. (1987). Interactions of deleterious and beneficia1 rhizosphere microorganisms and the effect of cropping practices. Annu. Rev. Phyroparhol. 25,
Sommers, L. E., Gilmour, C. M., Wildung, R. E., and Beck, S. M. (1981). The effect of water potential on decomposition processes in soil. In “Water Potential Relations in Soil Microbiology” (J. F,
Parr, W. R. Gardner, and L. F. Elliott, Eds.), pp. 97-1 18. Soil Science Society of America, Madison, WI.
Stott, D. E. (1991). RESMAN: A tool for soil conservation education. J. Soil Wafer Consen: 46,
3 32-3 33.
Stott, D. E., and Rogers, J. B. ( 1990). RESMAN: A residue management decision support program.
Public domain software. NSERL Publ. No. 5.266 kb. USDA Agricultural Research Service National Soil Erosion Research Laboratory, West Lafayette. IN.
Stott, D. E., Elliott. L. F., Papendick, R. I., and Campbell, G. S. (1986). Low temperature or low water potential effects on the microbial decomposition of wheat residue. Soil B i d . Biochem. 18,
Stott, D. E., Stuart, B. L.. and Barrett, J. R. (1988). Residue management decision support system.
American Society of Agriculture Engineers Microfiche Collect. Paper No. 88-754 I . St. Joseph,
Stott, D. E., Stroo, H. F., Elliott, L. F., Papendick, R. 1.. and Unger, P. W. (1990). Wheat residues loss
from fields under no-till management. Soil Sci. Soc. Am. J . 54,92-98.
Stroo, H. F., Elliott, L. F., and Papendick, R. 1. (1988). Growth, survival and toxin production of rootinhibitory pseudomonads on crop residues. Siol B i d . Biochem. 20,201-207.
Stroo, H. F., Bristow, K. L., Elliott, L. F., Papendick, R. I., and Campbell, G.S. (1989). Predicting rates
of wheat residue decomposition. Soil Sci. Soc. Am. J. 53.9 1-99.
INFLUENCE OF NO-TILL CROPPING SYSTEMS
Suslow. T. V.. and Schroth, M. N. ( 1982). Role of deleterious rhizobacteria as minor pathogens in reducing crop growth. Phvropathology 72, 1 11-1 IS.
Taylor. S. E.. and Sexton. 0. J. (1972). Some implications of leaf tearing in Musaceae. Ecology 53,
Thomsen, 1. K. (1993). Nitrogen uptake in barley after spring incorporation of ISN-labeled Italian ryeg r a s into sandy soils. Planr Soil 150, 193-201.
Tisdall, J. M., and Oades, J. M. (1982).Organic matter and Water-Stdbk aggregates in soils. J. Soil Sci.
Turco. R. F.. Kennedy, A. C.. and Jawson, M. D. (1994). Microbial indicators of soil quality. In “Defining Soil Quality for a Sustainable Environment” (J. W. Doran, D. C. Coleman, D. F. Bezdicek,
and B. A. Steward. Eds.), pp. 73-90. SSSA Spec. Publ. No. 35. American Society of Agronomy,
Wiant. H. V.(1967). Influence of temperature on rate of soil respiration. J. For 65,489490.
Wieder, R. K., and Long, C. E. (1982). A critique of the analytical methods used in examining decomposition data obtained from litter bags. Ecology 63, 1636-1642.
Wiegert. R . G . . and Evans. F. C. (1964). Primary production and disappearance of dead vegetation on
an old field in southeastern Michigan. Ecology 45,49-63.
Witkamp. M..and Olson, J. S. (1963). Breakdown of confined and nonconfined oak litter. Oikos 14,
Woltz. S. S. ( 1978). Nonparasitic plant pathogens. Annu. Reu Phyropafhol. 16,403430.
Zaccheo. P., Crippa, L.. and Genevini. P. L. (1993). Nitrogen transformation in soil treated with I5N
labelled dried or composted ryegrass. Plrnt Soil 148, 193-201.
This Page Intentionally Left Blank