IFEVA   02662
INSTITUTO DE INVESTIGACIONES FISIOLOGICAS Y ECOLOGICAS VINCULADAS A LA AGRICULTURA
Unidad Ejecutora - UE
artículos
Título:
Italian ryegrass density responses under ozone and herbicide stress
Autor/es:
MARTINEZ-GHERSA. M.A.; RADOSEVICH, S.R.
Revista:
AUSTRAL ECOLOGY
Referencias:
Año: 2009 vol. 34
ISSN:
1442-9985
Resumen:
<!--
/* Font Definitions */
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;
mso-font-charset:0;
mso-generic-font-family:roman;
mso-font-pitch:variable;
mso-font-signature:-1610611985 1107304683 0 0 159 0;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{mso-style-unhide:no;
mso-style-qformat:yes;
mso-style-parent:"";
margin:0cm;
margin-bottom:.0001pt;
mso-pagination:widow-orphan;
font-size:12.0pt;
font-family:"Times New Roman","serif";
mso-fareast-font-family:"Times New Roman";
mso-ansi-language:EN-US;
mso-fareast-language:EN-US;}
.MsoChpDefault
{mso-style-type:export-only;
mso-default-props:yes;
font-size:10.0pt;
mso-ansi-font-size:10.0pt;
mso-bidi-font-size:10.0pt;}
@page Section1
{size:612.0pt 792.0pt;
margin:70.85pt 3.0cm 70.85pt 3.0cm;
mso-header-margin:36.0pt;
mso-footer-margin:36.0pt;
mso-paper-source:0;}
div.Section1
{page:Section1;}
-->
Adaptations to
overcrowding of individual plants result in density dependant control of growth
and development. There is little information on how anthropogenic stresses
modify these responses. We investigated
whether combinations of diclofop-methyl herbicide and tropospheric ozone alter
the pattern of expected growth compensation with density changes resulting from
intraspecific competition in Lolium
multiforum Lam (Poacea) plants. Individual plant vegetative parameters and
total seed production were assessed for plants growing under various densities
and different herbicide rates and ozone treatments. The stressors differently changed
the frequency distribution for average individual plant weight resulting from
increasing densities. Only herbicide affected seedling mortality. Plants were
able to compensate during grain filling maintaining similar seed
productiondensity relationships in all treatments. Our findings contribute to the understanding
of the impact of stress factors on the demographic changes in plant
populations. Important ecological implications arise: (i) contrasting responses
to ozone and herbicide, alone and in combination of individual plants resulted
in different biomass-density relationships, (ii) stress effects on plant
populations could not be predicted from individual responses and (iii) changes
in competitive outcome by single or combined stress factors may alter the
expected genotype frequency in a crowded population with few dominant
individuals