Living turf grass library – reference plots of warm-season turf grass cultivars

Background and objectives

Many of the newer warm-season turf grasses, particularly those developed within the last decade or so, have not been tested under Queensland conditions. Even those that have been grown in Queensland often have not been evaluated against a comprehensive range of other varieties.

Our long-term strategy in planting and growing plots of virtually all the available turf grass varieties at the Redlands Research Station is to develop a more detailed understanding of their growth characteristics, together with their relative strengths and weaknesses under local conditions. This has the following benefits:

• Initial impressions of the adaptation, performance and management (including preliminary herbicide tolerance observations) of different cultivars can be gained through close observation of these plots. These observations can later be critically evaluated against results obtained in replicated trials elsewhere.
• Assembling a comprehensive reference collection of turf grass varieties enables us to choose appropriate genetic material for use in other projects that look more deeply at turf grass management and physiology.
• A ready source of material is available from which appropriate varieties of common knowledge can be drawn for Distinctness-Uniformity-Stability (DUS) comparisons. These are used by the Centralised Test Centre as comparators in formal growing trials used to describe new varieties for Plant Breeder’s Rights registration.

Field layout and management

Vegetative and seeded varieties of warm-season turf grasses from around the world are established from rooted plugs or sprigs in unreplicated field plots. Each plot measures 3 m x 2.5 m. Plot borders were defined by laying 20 cm x 8 cm sleepers onto the red volcanic soil. The profile within each plot was then built up with 8 cm of greens-grade sand.

The first varieties were planted in May 2000. Because of difficulties in sourcing planting material of some varieties, plots have been established progressively as varieties become available. As well as released cultivars, the collection also includes a number of experimental lines approaching release.

With the 138 available plots fully used by 137 different cultivars or experimental lines and only one duplicate, we have to rationalise entries in our plots, removing some under-performing and non-commercial lines in favour of long-term vegetative germplasm maintenance in large tubs. These are being replaced progressively by new varieties as they are released from quarantine. In general, our aim is to maintain released cultivars in permanent plots, while eventually phasing out experimental lines not developed commercially. Any plots badly contaminated by other grasses that cannot be selectively controlled with herbicides are also removed and replanted to the original variety.

All plots are irrigated and receive the same rate of slow-release fertiliser at regular intervals of two months during the growing season. Species and varieties have been arranged in four mowing groups, for which the height of cut (5, 10, 20 or 40 mm twice weekly through the warmer months) is increased moving from south to north through the experimental site.

Varietal attributes

To date, the growth of each variety has not been formally monitored by regular visual observations. In future, however, we plan to make formal ratings and measurements (e.g. turf quality, colour, seed head production, pest and disease incidence, sod strength) at regular intervals.

Varieties represented

The reference plots currently contain cultivars of 20 different species and 3 types of interspecific hybrids from 13 different genera:

• Axonopus compressus (broadleaf carpetgrass)
• Axonopus fissifolius (formerly A. affinis) (narrowleaf carpetgrass)
• Bothriochloa pertusa (Indian bluegrass)
• Buchloe dactyloides (American buffalograss)
• Cynodon dactylon (green couch)
• Cynodon transvaalensis (Transvaal couch)
• Cynodon hybrid – C. dactylon x C. transvaalensis (hybrid green couch)
• Dactyloctenium australe (sweet smothergrass)
• Digitaria didactyla (blue couch/Swazigrass)
• Eremochloa ophiuroides (centipedegrass)
• Panicum laxum
• Paspalum nicorae (Brunswickgrass)
• Paspalum notatum (bahiagrass)
• Paspalum vaginatum (seashore paspalum)
• Pennisetum clandestinum (kikuyugrass)
• Sporobolus virginicus (marine couch)
• Stenotaphrum secundatum (buffalograss/St Augustinegrass)
• Zoysia hybrids (Z. matrella x Z. japonica and Z. japonica x tenuifolia)
• Zoysia japonica (Japanese lawngrass)
• Zoysia macrantha (dune couch)
• Zoysia matrella (Manilagrass)
• Zoysia tenuifolia (Koreangrass)

This collection is probably the largest of its type in the southern hemisphere.

Funding Support

Between 2009 and 2012, funding was made available by Horticulture Australia (HAL), using the turf industry levy and matched funds from the Australian Government, to pay for maintenance of the turf demonstration plots under project TU09002. The second stage of the project, TU12001, further provides for the improvement and maintenance of the turf demonstration plots. This work will be continued with further HAL funding through until the end of May 2015.

Further information

• Warm season turf grasses
• Order Horticulture Australia report Improvement and maintenance of turfgrass demonstration plots for national research and extension (TU 09002)