Gp. Cheplick et al., Effect of drought on the growth of Lolium perenne genotypes with and without fungal endophytes, FUNCT ECOL, 14(6), 2000, pp. 657-667
1. Grass leaves are often inhabited by fungal endophytes that can enhance h
ost growth. In some forage species, endophytes improve host resistance to,
and recovery from, drought.
2. Our objective was to determine if the growth of genotypes of Lolium pere
nne L. was improved by endophytes during recovery from drought.
3. Thirteen infected genotypes were cloned into ramets. Half were treated w
ith a systemic fungicide to eliminate the endophyte (E-); half were untreat
ed and retained high endophyte levels (E+). In a glasshouse, half of all E-
and E+ ramets were watered regularly, whilst half were exposed to a 2 week
drought on two occasions, each followed by a 3 week recovery period.
4. After the first drought and recovery period, endophytes significantly re
duced tiller production in the drought-stressed group.
5. After the second drought and recovery period, effects of drought on live
leaf area and dry mass were highly dependent on host genotype, but not end
ophytes. The mean tiller mass of E+ ramets after drought was significantly
less than that of watered E+ ramets, but this was not true in E- ramets. Fo
r six genotypes there was greater mass allocation to storage in the tiller
bases of E- ramets after drought.
6. This perennial ryegrass population showed marked genotypic variation in
the ability to recover from drought stress, but endophytes played little or
no role in this ability. For some host genotypes there may be a metabolic
cost of harbouring endophytes during environmentally stressful conditions.