Response of Cactus Pear (Opuntia spp.) Biomass Production to Fruit Load

A balance between cladode and fruit production is important for optimal fodder production. The aim of this study was to investigate the response of biomass production of 42 cactus pear cultivars to fruit load. The cactus pear orchard was laid out as a complete randomized block design with two replications of five plants each. Plants were pruned and fruits were thinned according to the South African Cactus Pear Growers guidelines from planting up to season 6. From season 7 and onwards, no fruit was removed from plants anymore. Number and fresh mass of pruned cladodes and harvested fruit were recorded from season 6 up to season 9. Total cladode (t ha(-1)), fruit (t ha(-1)) and biomass production (t ha(-1)) were then calculated. Cultivars responded differently in each of the four seasons. In the first season after no fruit thinning was done (season 7) a significantly lower total cladode production (24.67 t ha(-1)) and higher total fruit production (17.79 t ha(-1)) were recorded. However, the higher number of fruits produced did not compensated for the loss in cladode production. A significant lower total biomass production was recorded for season 7 (44.57 t ha(-1)) and season 8 (35.29 t ha(-1)) than for season 6 (48.15 t ha(-1)). Total biomass production increased again during season 9, but this was not significant. Only 'Turpin' produced a high cladode and fruit yield in almost all the seasons. Biomass production of cactus pear plants significantly decreased as fruit load emphasized the importance of a balance that needs to be established between cladode and fruit production through plant manipulation such as pruning and fruit thinning.