How drought tolerant are the different types of Buffalo Grasses and Turf? Matilda Turf scores very highly in this test.
Drought Tolerance
This chapter details the results of experiments on water use (i.e. evapotranspiration, ET), responses to declining irrigation and performance on a soil of moderately high pH (7.5-7.9) conducted in field plots and lysimeters in Perth, Western Australia, a Mediterranean-type climate. The first objective was to determine the rates of water use (i.e. evapotranspiration, ET) and responses to declining irrigation of soft-leaf buffalo grass cultivars.
The study was conducted at The University of Western Australia, Faculty of Natural and Agricultural Sciences, Field Station in Shenton Park (31o 56.91S, 115o 47.57E), Australia. The soil is Spearwood sand (McArthur & Bettenay, 1960); a deep brown sand classified as a Basic Arenic Bleached-Orthic Tenosol (Isbell, 1996)
The experiment used a randomised split-plot design, with irrigation treatments applied to main plots and genotypes as sub-plots: 3 irrigation treatments x 12 genotypes x 3 replicates (12 x 9 m2 plots in 9 blocks (main plots) in a randomised design) under a travelling-boom irrigator at the UWA Turf Research Facility, Shenton Park Field Station. The variable-speed lateral boom irrigator was used to apply highly uniform and reproducible treatments to plots arranged in a completely randomised block design (see Short & Colmer, 2007), based on evaporation data inputs from a weather station (WeatherMaster 200, Environdata, Australia).
Rooted stolons were propagated from verified stock of the cultivars, transported to Western Australia, passed quarantine inspection, and planted on 30/11/05 and 1/12/05. The plots were managed under current industry practices for the first 12 months, so that irrigation studies were conducted on “mature” plots. The irrigation regime at planting was: (i) first 28 days, 100% daily replacement of evaporation (split into 3 applications), (ii) next 21 days, 70% daily replacement of evaporation (split into 2 applications), (iii) followed by 70% replacement of evaporation in one daily application. Fertiliser at planting was 2 t/ha of pelletised fowl manure (“Turf Start”, Organic 2000, Carrabooda, WA), followed by 30 kg N/ha (in the form of “CRESCO Lawn”, CSBP, Kwinana, WA every 21 days until 15 weeks after planting. Following establishment, plots received “Turf Special” (contains N, P, K, S, Ca, Fe, Cu and Mn; CSBP, Kwinana, WA) at 15 kg N/ha every 4 weeks, and were mown weekly at a 20 mm cutting height.
During the 2006/07 summer, three irrigation treatments were imposed for 16 weeks and then turfgrass recovery assessed for the following 4 weeks, by re-watering all plots. The 16 weeks of treatments commenced on 23/11/06 and the recovery period was 15/3/07 to 12/4/07. The irrigation treatments were: (1) 80% daily replacement of net evaporation; (2) replacement of 50% net evaporation summed over 2 days and applied every 2nd day; (3) replacement of 33% net evaporation summed over 3 days and applied every 3rd day. The recovery period involved re-watering all plots daily at 80% replacement of net evaporation. All plots received “Turf Special” at 15 kg N/ha every 4 weeks, and were mown weekly at 20 mm cutting height.
Growth (weekly dry mass of clippings) was measured by collecting clippings from each plot in the catcher of a cylinder mower (26 inch cylinder mower, ALROH), placing these in labelled paper bagsfor oven-drying at 65oC for 24 hrs. Dry mass was then recorded. Colour was measured weekly, or every two weeks, using a CR-310 Chromameter (Minolta, Japan). The measuring head (50 mm diameter) was pressed firmly onto each turf plot, in 3 random positions. As recommended by Landschoot & Mancino (2000), turf greenness can be assessed using the hue angle for the CIELAB colour space; the greater the value the greener the turfgrass.
Leaf water content was measured as the difference between fresh mass determined immediately for a sub-sample of fresh clippings and dry mass determined after drying in an oven at 65oC for 24 hrs. Sap osmotic potential was measured on sub-samples immediately sealed into cryovials and frozen in the field in dry ice. Sap was expressed from freeze/thawed tissues using a simple press, and analysed with a freezing-point depression osmometer (model one-ten, Fiske Associates, Massachusetts).
Results
The Table below show the total clippings obtained over 98 days of drought treatments and the percentage difference from the control sample which was kept watered during the process. the growth figures are an average across 3 plots of each cultivar. A higher % indicates more growth of that cultivar under the specified drought conditions.
| Cultivar | CONTROL (80% of evaporated water replaced) Grams (dry mass) / m2 |
50% water replacement test % of control | 33% replacement test % of control |
|---|---|---|---|
| Sapphire | 149g | 82% (122g) | 47% (70g) |
| Shademaster | 145g | 104% (150g) | 45% (65g) |
| Sir Walter | 203g | 91% (185g) | 54% (109g) |
| Matilda | 195g | 104% (202g) | 72% (140g) |
| Palmetto | 148g | 82% (121g) | 17% (25g) |
Total clippings produced (g/m2) by cultivars irrigated at 80%, 50% or 33% replacement of net evaporation, for 98 days in plots at Shenton Park, Western Australia (Summer of 2007/08). Plots were mown weekly at 25 mm.
The table below shows the recovery period of each cultivar, after the 98 day drought treatment the plots were watered at 80% of net evaporation for 28 days and the clippings were measured. this test shows how quickly a cultivar will recover after severe drought
| Cultivar | CONTROL (80% of evaporated water replaced) Grams (dry mass) / m2 |
50% water replacement test % of control | 33% replacement test % of control |
|---|---|---|---|
| Sapphire | 17.5g | 112% (19.6g) | 49% (8.6g) |
| Shademaster | 12.3g | 88% (10.8g) | 63% (7.7g) |
| Sir Walter | 23.2g | 106% (124.7g) | 39% (9.1g) |
| Matilda | 18.9g | 110% (20.8g) | 102% (19.3g) |
| Palmetto | 11.0g | 97% (10.7g) | 142% (15.6g) |
Total clippings produced (g/m2) by 12 buffalo grass genotypes during 28 days of recovery (irrigated daily at 80% replacement of net evaporation) following 98 days of irrigation at 80%, 50% or 33% replacement of net evaporation
From the information above it can be seen that the top performer was Matilda, Matilda maintained 72% growth at only 33% of the evaporated water being replaced and was unaffected at the 50% test, results showing more growth for Matilda at 50% water than the test where 80% of water was replaced. Matilda also produced over 100% growth rates during the recovery period where each plot was watered at 80% replacement for 28 days. Shademaster showed good growth at 50% replacement as did the other cultivars, with minimal loss in growth for the 50% test. Sir Walter was also a good performer in the 33% test maintaining just over 50% growth, followed by Sapphire and Shademaster. Palmetto struggled in the 33% test producing only 17% of the control clippings. Palmetto did recover very well however returning to 142% of the control during the recovery period. Palmetto can be seen to not perform in drought but when water is applied it come back very quickly.