|Authors: ||E. Van Zyl, P.M. Myburgh, W.J.H. Eigenhuis|
|Keywords: ||Leucadendron, Leucospermum, Protea, evapotranspiration, irrigation requirements, soil water depletion, vegetative growth, water stress|
Currently irrigation guidelines for Proteaceae, a rapid expanding cut flower industry, are drawn from information obtained for other horticultural crops.
Water consumption of young Leucadendron cv. "Inca Gold" (L. laureolum x L. salignum), Leucospermum cv. "Succession II" (L. lineare x L. cordifolium) and Protea cv. "Cardinal" (P. eximia x P. susannae) plants under drip irrigation was determined in a field trial in the Western Cape region of South Africa during the 1996/97 and 1997/98 seasons.
The control treatment was dryland cultivation, whereas three other treatments were irrigated at 60%, 40% and 20% depletion of plant available water (PAW), respectively.
Leaf water potential values showed that plants under dryland cultivation and irrigation at 60% depletion of PAW were subjected to higher water stress from January until March.
Irrigation of Protea at 20% depletion of PAW resulted in significantly longer shoots compared to drier treatments.
Furthermore, irrigation at 20% PAW depletion resulted in the highest Protea establishment percentage.
In the case of Leucospermum, irrigation at 20% PAW depletion also resulted in the longest shoots, although they were not significantly longer than those obtained with irrigation at 40% depletion.
Different soil water depletion levels did not have a significant effect on the shoot growth of young Leucadendron plants.
Based on a third of the total surface area, water consumption of three year old Leucadendron, Leucospermum and Protea plants was approximately 845 mm, 852 mm and 982 mm, respectively, during the 1997/98 season.
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