VARIATION IN RESPONSE TO DEFOLIATION BETWEEN POPULATIONS OF BOUTELOUA-CURTIPENDULA VAR. CAESPITOSA (POACEAE) WITH DIFFERENT LIVESTOCK GRAZING HISTORIES

Authors
Citation
Se. Smith, VARIATION IN RESPONSE TO DEFOLIATION BETWEEN POPULATIONS OF BOUTELOUA-CURTIPENDULA VAR. CAESPITOSA (POACEAE) WITH DIFFERENT LIVESTOCK GRAZING HISTORIES, American journal of botany, 85(9), 1998, pp. 1266-1272
Citations number
38
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Plant Sciences
Journal title
ISSN journal
0002-9122
Volume
85
Issue
9
Year of publication
1998
Pages
1266 - 1272
Database
ISI
SICI code
0002-9122(1998)85:9<1266:VIRTDB>2.0.ZU;2-3
Abstract
Distinctive plant growth and development have been associated with res istance to defoliation by herbivores. Descriptions of resistance (tole rance/avoidance) strategies are common, although little is known about genetic variation affecting their expression in natural plant communi ties. This research compared response to three frequencies of defoliat ion in populations of Bouteloua curtipendula var, caespitosa from Ariz ona with different histories of exposure to domestic herbivores. One p opulation occurs on a site that has likely been unaffected by large he rbivores including cattle, while the other has been regularly grazed b y cattle, Mixed-model analysis of variance was used to examine variati on in traits associated with defoliation resistance. Data were collect ed in a 168-d greenhouse experiment using ramets of 15 genets from eac h population. Mortality was lower in the cattle-impacted population, s uggesting improved defoliation resistance. This was associated with in creased production of tillers with lower mass following defoliation. P lasticity was observed for all traits in response to different defolia tion frequencies. The cattle-free population exhibited significant gen etic variation for plasticity affecting leaf blade angle, while little variation was noted for this trait in the cattle-impacted population. Evidence of reduced genetic variation within the cattle-impacted popu lation was noted for traits associated with defoliation resistance. In general, these observations are consistent with expectations followin g selection for resistance to defoliation.