Does physiological integration among intraclonal ramets of Iris pumila enhance stress tolerance in heterogeneous environments?
Abstract:
We tested the hypothesis that sharing essential resources through
interconnected ramets increases stress tolerance of a clonal plant in
patchy environments. A number of circle-shaped clones of Iris pumila
naturally growing in a sun-exposed habitat were selected and cut into
two equal halves with different integration status: one with intact and
the other with disconnected rhizomes. One-half of each clone was then
shaded with a neutral screen to provide 50\% of ambient irradiance, so
that one-half of both clones consisted of connected and disconnected
halves (referred to as ``clone quarters{''}). Leaves collected from each
clone quarter were analyzed for malondialdehyde (MDA) content (a stress
indicator) and the values of three functional traits, specific leaf area
(SLA), leaf dry matter content (LDMC) and leaf water content (LWC). MDA
content was greater in unshaded (more stressed) than in shaded (less
stressed) leaves. All three morphological traits changed with light
gradient, but only SLA was impacted by the ramet integration status. SLA
and MDA tended to be inversely related in each clone quarter, indicating
a (compensatory) mechanism utilized by I. pumila plants in coping with
environmental stress. SLA and LDMC were highly negatively correlated in
general, but less strongly in interconnected ramets compared to those
with a disrupted connection. The results suggest that intraclonal
physiological integration confers a fitness benefit to I. pumila plants
in heterogeneous environments, likely by balancing two fundamental plant
activities rapid biomass production and nutrient conservation.
Keywords:
Physiological integration; functional leaf traits; stress tolerance; Iris pumilaSource:
Archives of Biological Sciences, 2014, 66, 2, 713-720
DOI: 10.2298/ABS1402713J
ISSN: 1821-4339