The effect of light intensity on seed production and quality in a number of Australian wild oat (Avena fatua L.) lines.

Freshly harvested seeds of three genetically nondormant populations of wild oat (Avena fatua L.) germinated readily in the dark at optimum temperatures. Direct or diffused light caused germination inhibition in seeds of all these populations. This light-induced germination inhibition was intensity dependent; the higher the light intensity, the greater the inhibition. Germination inhibition by light was accentuated by higher incubation temperatures, indicating an interaction between these two factors on the induction of secondary seed dormancy in genetically nondormant populations. This interaction may be of adaptive significance to the survival of nondormant populations, and reconciles some apparently conflicting reports in the literature.

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Effect of light intensity and photoperiod on Nile tilapia Oreochromis niloticus L. seed production

Aquaculture Research ◽

10.1046/j.1365-2109.2000.00481.x ◽

2000 ◽

Vol 31 (7) ◽

pp. 609-617 ◽

Cited By ~ 24

Author(s):

M T Ridha ◽

E M Cruz

Keyword(s):

Light Intensity ◽

Seed Production ◽

Oreochromis Niloticus ◽

Nile Tilapia ◽

Nile Tilapia Oreochromis Niloticus ◽

Effect Of Light

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Wild oat (Avena fatua) seed production in spring barley (Hordeum vulgare) is affected by the interaction of wild oat density and herbicide rate

Weed Science ◽

10.1017/s0043174500089517 ◽

1998 ◽

Vol 46 (3) ◽

pp. 336-343 ◽

Cited By ~ 24

Author(s):

Michael J. Wille ◽

Donald C. Thill ◽

William J. Price

Keyword(s):

Hordeum Vulgare ◽

Seed Production ◽

Spring Barley ◽

General Pattern ◽

Logistic Function ◽

Avena Fatua ◽

Initial Population ◽

Wild Oat ◽

Population Densities ◽

Initial Population Density

The efficacy of current wild oat herbicides and their high cost have resulted in use rates that are less than those recommended. While acceptable weed control may be attained at less cost, this practice does not consider the potential for increased wild oat seed production. The objective of this experiment was to determine the interaction of wild oat density and reduced imazamethabenz rates on wild oat seed production in spring barley. As wild oat densities increased from 8 to 1,100 plants m−2, wild oat seed production increased from 180 to 9,950 seed m−2without herbicide, and from 0 to 2,810 seed m−2using 0.53 kg ai ha−1imazamethabenz. This general pattern was modeled using a cumulative logistic function. Estimates from this model indicated that < 1 wild oat seed m−2was produced at population densities of ≤ 20 plants at any imazamethabenz rate. Imazamethabenz rates of 0.26 kg ha−1or greater at wild oat densities of less than approximately 190 plants m−2did not result in wild oat seed production above the initial population density. As wild oat density increased, however, imazamethabenz rates below 0.40 kg ha−1resulted in substantially greater wild oat seed production compared to the recommended rate.

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Influence of wild oat (Avena fatua) relative time of emergence and density on cultivated oat yield, wild oat seed production, and wild oat contamination

Weed Science ◽

10.1614/ws-04-124r1 ◽

2005 ◽

Vol 53 (3) ◽

pp. 342-352 ◽

Cited By ~ 18

Author(s):

Christian J. Willenborg ◽

William E. May ◽

Robert H. Gulden ◽

Guy P. Lafond ◽

Steven J. Shirtliffe

Keyword(s):

Seed Production ◽

Avena Fatua ◽

Wild Oat ◽

Relative Time

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Effect of Shading on Activity of Imazamethabenz and Fenoxaprop in Wild Oat (Avena fatua)

Weed Science ◽

10.1017/s0043174500084174 ◽

1994 ◽

Vol 42 (1) ◽

pp. 66-69 ◽

Cited By ~ 5

Author(s):

Hai Sheng Xie ◽

Andrew I. Hsiao ◽

William A. Quick

Keyword(s):

Light Intensity ◽

Experimental Period ◽

Light Treatment ◽

Avena Fatua ◽

Herbicidal Activity ◽

Growth Stages ◽

Wild Oat ◽

Low Light ◽

Better Than

Growth chamber and greenhouse studies were conducted to evaluate effects of long-term low-light intensity on wild oat control with imazamethabenz and fenoxaprop. Seventy percent shading imposed during the entire experimental period resulted in enhanced activities for both herbicides applied at early and later growth stages. Such shading also reduced wild oat regrowth following application of imazamethabenz and fenoxaprop. When applied to plants exposed to 70 to 90% prespraying shading, both herbicides had phytotoxicity similar to, or better, than plants grown under continuous shading. Postspraying shading has less effect on herbicidal activity than prespraying shading or prolonged shading, especially with imazamethabenz. Full-light treatment more adversely affected fenoxaprop activity than imazamethabenz activity.

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Influence of variable rates of imazamethabenz and difenzoquat on wild oat (Avena fatua) seed production, and wheat (Triticum aestivum) yield and profitability

Canadian Journal of Plant Science ◽

10.4141/p03-054 ◽

2003 ◽

Vol 83 (4) ◽

pp. 977-985 ◽

Cited By ~ 11

Author(s):

J. T. O’Donovan ◽

K. Neil Harker ◽

R. E. Blackshaw ◽

R. N. Stougaard

Keyword(s):

Seed Production ◽

Field Experiments ◽

Wheat Yield ◽

Economic Loss ◽

Avena Fatua ◽

Wild Oat ◽

Economic Returns ◽

Rate Reduction ◽

Full Rate ◽

Soil Seedbank

Field experiments to investigate the effects of variable imazamethabenz rates on wild oat seed production and wheat yield and profitability were conducted at Lacombe, Lethbridge and Vegreville, Alberta, and Kalispell, Montana, over several years. Similar studies with difenzoquat were conducted at Lacombe and Lethbridge. In most cases, reducing the herbicide rates below those recommended resulted in increases in wild oat seed production, but the potential for returning relatively large amounts of wild oat seed to the soil seedbank depended on the extent of the rate reduction. For example, averaged over locations and years, reducing the rate of imazamethabenz to 75% of the recommended rate resulted in wild oat seed production increasing by 25% compared with an increase of over 100% when the rate was reduced to 50%. Wheat yields and economic returns as functions of rate also varied for both herbicides. It was more economical, in most cases, to apply imazamethabenz at 50 or 75% of the recommended rate compared with the full rate. However, an economic loss occurred in four and three of the 11 location-years when the imazamethabenz rate was reduced to 50 and 75%, respectively, and losses were more severe at the 50% rate. Compared with imazamethabenz, reducing the rate of difenzoquat tended to be more risky in terms of increased wild oat seed production and reduced net economic return. Key words: Reduced herbicide rates

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Effect of light intensity on the ultrastructure of the filamentous cyanobacterium, Anabaena variabilis

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100103565 ◽

1988 ◽

Vol 46 ◽

pp. 300-301

Author(s):

C. S. Bricker ◽

S. R. Barnum ◽

B. Huang ◽

J. G. Jaworskl

Keyword(s):

Fatty Acid ◽

Light Intensity ◽

Acid Content ◽

Fatty Acid Content ◽

Anabaena Variabilis ◽

Chloroplast Envelope ◽

Major Constituent ◽

Filamentous Cyanobacterium ◽

Photosynthetic Membrane ◽

Effect Of Light

Cyanobacteria are Gram negative prokaryotes that are capable of oxygenic photosynthesis. Although there are many similarities between eukaryotes and cyanobacteria in electron transfer and phosphorylation during photosynthesis, there are two features of the photosynthetic apparatus in cyanobacteria which distinguishes them from plants. Cyanobacteria contain phycobiliproteins organized in phycobilisomes on the surface of photosynthetic membrane. Another difference is in the organization of the photosynthetic membranes. Instead of stacked thylakolds within a chloroplast envelope membrane, as seen In eukaryotes, IntracytopIasmlc membranes generally are arranged in three to six concentric layers. Environmental factors such as temperature, nutrition and light fluency can significantly affect the physiology and morphology of cells. The effect of light Intensity shifts on the ultrastructure of Internal membrane in Anabaena variabilis grown under controlled environmental conditions was examined. Since a major constituent of cyanobacterial thylakolds are lipids, the fatty acid content also was measured and correlated with uItrastructural changes. The regulation of fatty acid synthesis in cyanobacteria ultimately can be studied if the fatty acid content can be manipulated.

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