THE INFLUENCE OF FROST AND DROUGHT ON YOUNG CACTUS PEAR PLANTS - P. L. Avenant 1, H. J. Fouché 1 & H. A. Snyman 2

1 Agricultural Research Council, University of the Free State,  Bloemfontein 9300, South Africa
2 Department of Animal, Wildlife & Grassland Sciences, University of the Free State, Bloemfontein 9300, South Africa

There is a lack of information on the adaptability of different spineless cactus pear cultivars under a range of environmental conditions. A study was conducted to evaluate the cold/frost tolerance of 10 cultivars of Opuntia ficus-indica (L.) Miller and one cultivar of O. robusta Wendl. over three growing seasons in a semi-arid climate. The cultivars of O. ficus-indica included Algerian, Gymno Carpo, Morado, Nudosa, Roedtan, Sicillian Indian Fig, Tormentosa, Van As, X28 and Zastron. The species O. robusta was represented by the cultivar Monterey. The percentage frost damage observed was indicated as 25%, 50%, 75% or 100% damage to the cladodes. It was evident from this study that young cactus pear plants could be killed by a combination of frequent successive nights of temperatures below freezing point (as low as -9°C) and water stress conditions. Algerian, Sicillian Indian Fig, Van As and X28 suffered 100% frost damage in the winter preceding the third growing season. The damage to Tormentosa and Roedtan was 98%, Nudosa 97%, Morado 96% and Gymno Carpo 95%. The remaining two cultivars also suffered frost damage but to a lesser degree (Monterey 40% and Zastron 85%). From the results of this study it is believed that extreme low temperatures (below -6°C), together with water stress, increases the risk of killing young cactus pear plants.