Managing Global Resources for a Secure Future

A study on the influence of soil volume on root development and canopy growth rates of cactus pear (Opuntia ficus-indica) was undertaken at Palermo University, Italy in 2014-2015. Sixty cactus pear cladodes were planted in pots containing five different soil volumes (5, 9, 18, 33 and 50 liters). Root length, root surface area, root volume and cladode dry mass of each plant were monitored at 6, 12, 18 and 24 month intervals. Root surface area was measured using VegMeasure® image processing software. The results revealed a significant effect of soil volume, sampling dates and their interaction (P<0.01) on root surface area, root volume and canopy dry mass. Root surface area ranged between 5639 and 757 cm2. The highest value obtained was from plants grown in 50 liters of soil volume, and sampled at 24 months. A linear increase in canopy dry mass was observed with respect to soil volume increase. Root surface area, root volume, canopy dry mass and root to shoot mass ratio of the plants that were subjected to the lowest soil volume did not show significant change over time. It is concluded that the restriction of soil availability in cactus pear resulted in a major growth limitation for both root and canopy. Key words: cactus pear, soil volume, VegMeasure, CAM plants, root: shoot mass ratio