RESPONSE OF WAXFLOWERS (CHAMELAUCIUM SPECIES) TO SOIL MOISTURE DEFICIT
In the Southwest of Western Australia, with a predominantly dry Mediterranean climate, native flowers including Geraldton waxflower (Chamelaucium spp.) have adapted to survive in short wet winters followed by long dry summers. These are low water use plants that are naturally drought tolerant surviving and flowering on winter rainfall (750 to 350 mm). Field trials showed that waxflowers were opportunistic plants in that they respond to applied irrigation over summer. With increasing irrigation water applied plants responded by increasing stem growth and dry matter. The water requirements of irrigated plantations depended on evaporative demand, with water used increasing from 5 litres per day per plant in the Perth region to 15 litres per day per plant in regions north of Perth which experience higher evaporative demand. Glasshouse trails showed that waxflower varieties could survive on as little as 12.5% of soil water availability (SWA), however there was a cost in terms of reduced production. For Crystal Pearl, a hybrid Geraldton wax flower variety, stem growth and dry matter production were approximately linearly related to the amount of water applied and flowering was delayed by 4 weeks compare to well watered plants (100% SWA). For a number of Geraldton wax flower varieties of different genetic parentage plants were up to 36% shorter and dry mater production was reduced by up to 49% when watered with 12.5% SWA compared to 100% SWA. This response was associate with a reduced leaf relative water content on average of 12.7% or a RWC of 80% drought plants compared to 93% for plants subject to 100% soil water availability, and may indicated that a loss of turgor at this RWC is restricting extension growth.
Seaton, K.A. (2013). RESPONSE OF WAXFLOWERS (CHAMELAUCIUM SPECIES) TO SOIL MOISTURE DEFICIT. Acta Hortic. 990, 345-350
soil water availability, dry matter production, plant height, water content