Effect of water stress on root growth of Opuntia ficus-indica and O. robusta

Author: H.A. Snyman
Year: 2004
Issue: 6
Volume: 34
Page: 101 - 103

Due to the regular occurrence of drought in southern Africa, there is a need for more research on drought tolerant plants such as Opuntia species. This study aimed at quantifying the effects of water stress on the growth of tap roots, side roots and rain roots of Opuntia ficus-indica (cultivar, Morado) and O. robusta (cultivar, Monterey). Cladodes were planted in root boxes that were kept in the greenhouse at day/night temperatures of 25-30/15-18 °C. The highest daily tap root growth was 42.12 and 36.23 mm for O. ficus-indica and O. robusta, respectively. Tap root growth increased in the morning with water stress for both species but decreased in the afternoon. Side root growth increased with water stress. Rain roots developed within the first two hours after rewetting the soil and grew only for three days. The quick reaction to water is an adaptation that allows the plants to survive under very low rainfall conditions.

Keywords: Rain roots, root boxes, side roots, tap roots
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