Seedling Growth Responses of Buffelgrass (Pennisetum ciliare) to Tebuthiuron and Honey Mesquite (Prosopis glandulosa)

Weed Science ◽  
1986 ◽  
Vol 34 (1) ◽  
pp. 88-93 ◽  
Author(s):  
G. Allen Rasmussen ◽  
Roger P. Smith ◽  
Charles J. Scifres

Tebuthiuron {N-[5-(1,1-dimethylethyl)-1,3,4-thiadiazol-2-yl]-N,N′-dimethylurea} at 2 or 4 ppmw placed 0 to 3, 8 to 11, or 15 to 18 cm deep in soil columns reduced root and shoot weights of buffelgrass [Pennisetum ciliare(L.) Link # PESCI] 30 days after emergence. Plains bristlegrass (Setaria macrostachyaH.B.K.) seedling shoot weights were not reduced when 2 ppmw tebuthiuron was placed 8 to 11 cm deep or deeper. Effects of tebuthiuron at 0.13 to 0.50 ppmw on buffelgrass shoot and net tiller production were not moderated by the presence of honey mesquite (Prosopis glandulosa# PRCJG) in the pots. However, regardless of tebuthiuron dosage, average height and shoot weight of buffelgrass seedlings were greater when seedlings were grown in soil collected from beneath honey mesquite canopies compared to growth in soil from interspaces. Therefore, spatial variations in buffelgrass response to applications of tebuthiuron for control of invading shrubs may largely be attributed to soil changes induced by woody plants rather than to presence of shrubs.

Weed Science ◽  
1987 ◽  
Vol 35 (3) ◽  
pp. 444-448 ◽  
Author(s):  
Herman S. Mayeux

Herbicide solutions of known concentration were applied to honey mesquite (Prosopis glandulosaTorr. # PROJG) with a tractor-mounted carpeted roller. The volume of solution applied was measured, and average height and density of the honey mesquite stands were also determined. The volume of solution applied ranged from about 3 to 20 L/ha and was positively correlated with stand density (r2= 0.71). Height of the stand had no influence on volume of solution applied. Amounts of herbicide applied at concentrations of 30, 60, and 120 g/L averaged about 0.2, 0.6, and 1.25 kg ae/ha, respectively. Calculated amounts of active ingredient of herbicide applied to individual plants (dosage) ranged from 0.3 to more than 3 g/shrub and decreased curvilinearly with increasing stand density, suggesting that the carpeted roller is most efficient in treating sparse stands.


Weed Science ◽  
1988 ◽  
Vol 36 (3) ◽  
pp. 373-378 ◽  
Author(s):  
Robert E. Meyer ◽  
Rodney W. Bovey

Tebuthiuron {N-[5-(1,1-dimethylethyl)-1,3,4-thiadiazol-2-yl]-N,N′-dimethylurea} in various formulations and placements was applied to honey mesquite (Prosopis glandulosaTorr. # PRCJG), huisache [Acacia farnesiana(L.) Willd. # ACAFA], live oak (Quercus virginianaMill.#QUEVI), Macartney rose (Rosa bracteataJ. C. Wendl. # ROSBC), and Texas whitebrush [Aloysia gratissima(Gillies & Hook.) Troncoso # ALYLY]. There was little difference in a species response to the various tebuthiuron formulations. Pellets (20%) at 2 g ai/tree base reduced the canopy 85% and killed 50% of the honey mesquite. At 1 g ai/plant, two briquettes at 0.5 g ai each or pellets (5.14 g, 20%) killed 37 and 80% of the huisache, respectively. Pellets were no more effective at 2 g than at 1 g ai on huisache. Basal treatments of 0.25, 0.5, 0.5, 1, and 2 g ai tebuthiuron/tree killed from 8 to 22, 48 to 62, 62 to 85, and 92% of the live oak, respectively. Pellets at 2 g ai placed at the base reduced the canopy 83% and killed 59% of the Macartney rose. On Texas whitebrush, 0.25, 0.5, 1, and 2 g ai tebuthiuron/tree killed from 68 to 85, 75 to 100, 90, and 100% of the plants, respectively. Tebuthiuron persisted mainly in the upper 30 cm of soil for at least 15 months.


Genetika ◽  
2012 ◽  
Vol 44 (2) ◽  
pp. 235-250 ◽  
Author(s):  
Ahmad Dadashpour

The effects of different salt sources (C Cl2, NaCl, and KCl) and concentrations, as measured by electrical conductivity, (0, "control", 1, 3, 5, 7 and 9 dS m-1) on seed germination and seedling growth of ?Ferro?, ?Obez?, ?RS 841? and ?Strong Tosa F1? pumpkin varieties used as rootstock were investigated in this study. The results showed that germination rate, root length, shoot length, fresh root weight, dry root weight, fresh shoot weight and dry shoot weights tend to decrease when the electrical conductivity of the solution is higher than 5 dS m-1, independent of salt sources and in all of the varieties. Three days after seeding, a germination ratio of 5 % was obtained from RS 841 variety in all salt source and concentrations, while a germination ratio over 50 % was obtained in ?Strong Tosa? variety for the same conditions except CaCl2 salt source. Nevertheless, seeds germinated in medium having high concentrations of CaCl2 had lower germination rate and poor seedling growth, compared to media having the same concentrations of NaCl and KCl. It was concluded that all of the varieties studied were more sensitive to the concentrations prepared using CaCl2 than that of the KCl, and NaCl.


1997 ◽  
Vol 12 (3) ◽  
pp. 81-88 ◽  
Author(s):  
Deborah S. Page-Dumroese ◽  
Martin F. Jurgensen ◽  
Alan E. Harvey ◽  
Russell T. Graham ◽  
Jonalea R. Tonn

Abstract Conifer regeneration in western North America is often hampered by low soil moisture, poor soil nutrient status, and competing vegetation. Three site preparation techniques were evaluated at two different elevations in northern Idaho as potential remedies for these problems: (1) soil mounds without control of competing vegetation, (2) soil mounds with herbicidal control of competing vegetation, and (3) scalping (removal of soil surface organic horizons and mineral topsoil). Treatments were evaluated for effects on soil nutrient levels, soil physical properties, and the growth of Douglas-fir (Pseudotsuga menziesii var. glauca) and western white pine (Pinus monticola) seedlings. Both species generally grew best when planted in the mounded treatment with competing vegetation removed and worst after scalping. Mounding with herbicide application resulted in the lowest bulk density, best seedling growth, and increased water availability. Mounding may be a viable site preparation method in the Inland Northwest on less productive sites that have severe competition. Scalping, especially when competition was not a problem, generally did not produce favorable seedling growth responses. Scalping may also reduce longer term seedling growth by removing surface organic matter. West. J. Appl. For. 12(3):81-88.


Weed Science ◽  
1980 ◽  
Vol 28 (3) ◽  
pp. 358-362 ◽  
Author(s):  
R. E. Meyer ◽  
R. W. Bovey

Hexazinone [3-cyclohexyl-6-(dimethylamino)-1-methyl-1,3,5-triazine-2,4(1H,3H)-dione] was applied to honeylocust (Gleditsia triacanthosL.), honey mesquite [Prosopis juliflora(Swartz) DC. var.glandulosa(Torr.) Cockerell], huisache [Acacia farnesiana(L.) Willd.], live oak (Quercus virginianaMill.), Macartney rose (Rosa bracteataWendl.), post oak (Quercus stellataWangenh.), saw greenbrier (Smilax bona-noxL.), whitebrush (Aloysia lycioidesCham.), and yaupon (Ilex vomitoriaAit.). Bromacil (5-bromo-3-sec-butyl-6-methyluracil) and tebuthiuron {N-[5-(1,1-dimethylethyl)-1,3,4-thiadiazol-2-yl]-N,N′-dimethylurea} were used for comparison in some experiments. Hexazinone was required at the following rates to kill at least 75% of the following species: 1.1 kg/ha for live oak, 2.2 kg/ha for post oak, 4.5 kg/ha for huisache (at Bryan, Texas) and whitebrush, and 9 kg/ha for honeylocust. Hexazinone was ineffective at 9 kg/ha for control of honey mesquite, huisache (at Washington, Texas), Macartney rose, saw greenbrier, and yaupon. Tebuthiuron at 1.1 kg/ha killed 80% of the live oak, and as a subsurface spray at 4.5 kg/ha, killed huisache (at Washington, Texas). Bromacil was effective on huisache at 9 kg/ha.


2000 ◽  
Vol 77 (10) ◽  
pp. 1419-1424 ◽  
Author(s):  
Inderjit ◽  
Chikako Asakawa ◽  
KMM Dakshini

Verbesina encelioides (Cav.) Benth. & Hook. F. ex. A. Gray (Asteraceae) is a perennial weed that interferes with the growth and establishment of crop species in semiarid regions of India. The present research was designed to understand the probable involvement of allelopathy in its interference mechanism. We studied the effect of soils amended with different dilutions of V. encelioides root leachate (full strength and 1:2 and 1:4 (v/v) ratios of root leachate to water) on the growth of radish seedlings (Raphanus sativus L.). Soils that were not amended were used as controls. We also investigated the influence of different levels of N fertilization (1, 5, and 10 mM) on the modification of the allelopathic potential of amended soils, in terms of their effect on soil total phenolics and radish seedling growth. The addition of both full strength and 1:2 dilution of V. encelioides root leachate resulted in significant (P < 0.05) suppression of root (-25.7 and -17.2%, respectively) and shoot (-21.3 and -13.8%, respectively) growth of radish seedlings. The total level of phenolics in soil amended with full-strength (8.53 ± 0.55 µg/g), 1:2 dilution (5.43 ± 0.4 µg/g), and 1:4 dilution (4.17 ± 0.36 µg/g) was significantly (P < 0.05) higher compared with that of control (2.98 ± 0.47 µg/g) soil. Although the different amounts of N fertilization in soil amended with V. encelioides root leachate could not counteract the probable allelopathic interference, we observed an increase in root growth of radish seedlings in soil amended with 10 mM N fertilization plus either a 1:2 dilution (+21.2%) or a 1:4 dilution (+36.5%) of root leachate. No significant differences in NO3- and NH4+ concentration were observed between control soil and soil amended with different amounts of root leachate and N fertlization. Since allelopathic activities include both inhibitory and stimulatory growth responses, the radish seedling growth responses to V. encelioides root leachate can be explained by allelopathy. High performance liquid chromatography data indicate qualitative and quantitative differences in phenolic peaks of both control and amended soil. Our research demonstrates the allelopathic potential of V. encelioides roots and the probable involvement of allelopathy in its interference success.


2000 ◽  
Vol 30 (6) ◽  
pp. 845-854 ◽  
Author(s):  
Masahiro Shishido ◽  
Christopher P Chanway

Seeds of two hybrid spruce (Picea glauca (Moench) Voss × Picea engelmannii Parry ex Engelm.) ecotypes were inoculated with one of six plant growth-promoting rhizobacteria (PGPR) strains previously shown to be able to stimulate spruce growth in controlled environments. The resulting seedlings were grown in the greenhouse for 17 weeks before outplanting at four reforestation sites. Inoculation with five of the six strains caused significant seedling growth promotion in the greenhouse, which necessitated analysis of relative growth rates (RGR) to evaluate seedling performance in the field. Four months after outplanting, most strains enhanced spruce shoot or root RGRs in the field, but seedling growth responses were strain specific. For example, Pseudomonas strain Ss2-RN significantly increased both shoot and root RGRs by 10-234% at all sites, but increases of 28-70% were most common. In contrast, Bacillus strain S20-R was ineffective at all outplanting sites. In addition, seedlings inoculated with four of the six strains had significantly less shoot injury than control seedlings at all sites. Evaluation of root colonization by PGPR indicated that bacterial population declines were not related to spruce growth response variability in the field. Our results indicate that once plant growth promotion is induced in the greenhouse, seedling RGR can increase by more than 100% during the first growing season in the field. However RGR increases of 21-47% were more common and may be more representative of the magnitude of biomass increases that can result from PGPR inoculation.


1988 ◽  
Vol 18 (1) ◽  
pp. 75-84 ◽  
Author(s):  
Ian G.W. Corns

Soils developed on four parent materials (glaciolacustrine clay, clay loam till, coarse fluvial, and loamy eolian) in west-central Alberta were examined to determine residual effects of logging and use of site-preparation equipment upon soil bulk density. These studies were conducted on sites that were logged during the previous 24 years. Compaction was evident on all soils except those of the Summit association, which were dominantly Brunisolic Gray Luvisols developed on cobbly fluvial deposits of Tertiary age. Compaction was greatest on soils of the Marlboro association, which were dominantly Brunisolic Gray Luvisols developed on clay loam till. Soil bulk density values on the clear-cuts had recovered to those of the controls at comparable depth at ages ranging from 0 (Summit) to 17–21 years (Marlboro). Lodgepole pine and white spruce seedlings were grown on the four soils compacted in the laboratory to three bulk densities approximating the following field conditions: (1) those observed or expected immediately following logging and site preparation; (2) those observed 5–10 years after logging and site preparation; and (3) undisturbed control. In most cases, significant reduction in nine expressions of seedling growth (maximum root depth, maximum root depth in soil core, total weight, shoot weight, root weight, stem diameter, shoot height, seedling survival, and shoot weight: root weight ratio) was observed with increased bulk density.


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