XVI International Botanical Congess

Grass leaves are often inhabited by endophytes that enhance growth and may improve host resistance to drought. We determined growth of 13 genotypes of perennial ryegrass as modified by endophytes during recovery from drought. Sixteen infected and 16 uninfected ramets per genotype were planted in tubular pots in a glasshouse. Half were watered regularly, while half were exposed to a 2-wk drought (on two occasions) and permitted to recover for 3 wk. After the first drought, endophyte effects on tillering depended on host genotype, host size depended on genotype and treatment. After the second drought and recovery period, live leaf area was reduced by drought and dependent on host genotype but endophytes showed no consistent effect. Perennial ryegrass harbors substantial genetic variation in the ability to withstand, and recover from, drought.