Annuals sprouting adventitiously from the hypocotyl: their compensatory growth and implications for weed management

Habitats, disturbed severely at least once a year, are often dominated by annual plants, which avoid disturbance by means of a short life span and massive production of seeds. Contrary to perennials, they lack pools of reserve meristems on and storage carbon in below-ground organs necessary for vegetative regeneration after disturbance. However, some annuals are able to initiate a bud bank on the hypocotyl after loss of their shoot. In three experiments, we investigated how the timing of disturbance or population origin affects adventitious bud formation on the hypocotyl for regeneration and compensatory growth in some annual weeds. The best regenerative abilities were observed in Kickxia spuria and K. elatine, with 87% and 80% of individuals regenerating, respectively, followed by Microrrhinum minus with almost 70%. Less than 30% of individuals regenerated in Euphorbia peplus and Anagallis arvensis. The time of injury did not affect the regeneration capacity of species for which the timing was examined, nor their consequent compensatory growth. The best compensation for biomass and fruit production was observed in M. minus, albeit two populations differed in this respect. The injured plants were shorter and produced more shoots than intact plants. Mechanical control of weeds capable of forming adventitious buds on hypocotyl by harrowing, brushing, or cutting may not be sufficient in organically farmed lands.