COTTON COMPENSATORY GROWTH AFTER LOSS OF REPRODUCTIVE-ORGANS AS AFFECTED BY AVAILABILITY OF RESOURCES AND DURATION OF RECOVERY PERIOD

Damaged cotton plants in which reproductive organs were manually remov ed to simulate shedding induced by Helicoverpa spp. (Lepidoptera) were compared with undamaged controls grown under contrasting availability of resources. Plant growth and partitioning were analysed and fruit m ass was taken as a measure of compensation. Under high availability of resources (low plant density, high fertility) damaged plants had a la rge potential compensatory capacity due to increased vegetative growth that enhanced their ability to assimilate carbon and nitrogen with re spect to undamaged controls. These plants shifted from vegetative to r eproductive growth when they were allowed to set fruit in the recovery period. Actual compensation was complete, however, only when the dura tion and conditions of the recovery period were favourable. Under mult iple stresses (high plant density, low fertility, low temperature), da mage triggered a marked increase in the allocation of biomass to roots which was not reversed when plants were allowed to set fruit. The app arent shift in the allocation pattern of damaged plants under stress - which matches well the survival strategy described for many perennial s - probably restricted compensatory fruit growth.