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WATER REQUIREMENTS TRIALS

Ian Smith HortiCulture
Evaluation of the performance of landscape ornamental plants in response to reduced irrigation - Greenhouse Trial

Abstract
The objective was to determine the response of 6 ornamental plant cultivars to reducing irrigation regimes.

Experimental groups were established in a heated greenhouse at Silvan, Victoria, Australia, consisting of four 3.6 sq meter troughs providing four irrigation treatments. Ten plants of 6 cultivars were planted into 125mm pots in each irrigation treatment.
Each trough was flood irrigated with the same volume at each irrigation, the frequency of irrigation was used to provide a range of treatments designed to stress the plants and so determine the cultivars response to reducing water availability.

Objective

The primary objective was to determine whether the protocol used was an effective measure of plant water requirements

Null hypothesis

All plants will respond identically to various levels of irrigation.

Materials and Methods

The trial was conducted at Silvan, Victoria in a heated greenhouse. Diurnal temperature range was 140C to 280C during the period of trial. Environmental variables were measured during the duration of the trial.
The potting media used was selected to provide effective capillary uptake from the flooded benches. Ten plants potted in 125mm pots were randomly assigned to each treatment. Moisture sensors were used to determine the appropriate irrigation frequency to ensure the potting media was continually moist and to maximise growth rate. The range of irrigation treatments were achieved by varying the frequency, three day interval being the maximum irrigation rate, with further treatments of 6 day interval, 9 day interval and 12 day interval.

Results

Plants responded as expected to reducing irrigation treatments. The protocol used is effective in determining plant water response.

Selected ornamental ground cover cultivars - response to reducing irrigation