The choice of cultivar for your plantation is one of the most important decisions you make when planting coffee. These Coffee Cultivator articles discuss the main factors to consider when choosing cultivars, including growth habit, yield, harvestability, ripening period, bean size and liquoring quality.
Arabica coffee has been grown in Australia for well over a century. The original cultivars grown commercially from the 1880s to the 1920s have persisted as self-sown seedlings in backyards in tropical and subtropical areas along the east coast. When coffee again became a commercial prospect in the early 1980s as a result of high world coffee prices and the development of a machine-harvester in Brazil, a search began for the best cultivars to suit Australian conditions.
In 1982-83, Queensland DPI researcher Ted Winston planted more than 70 overseas cultivars (arabica and robusta) along with promising local lines at Kamerunga Research Station near Cairns in North Queensland. A second trial was planted in 1983 in the shallow granitic soils of the dry Mareeba area and a third in 1987 on the heavier volcanic soils of the Atherton Tablelands at Walkamin. In the mid-1980s this evaluation program was extendedinto northern New South Wales where 18 of the most promising cultivars from North Queensland and locally adapted selections were planted. The program in both states was designed to evaluate the cultivars in a range of microclimates and on differing soil types.
The trials in both North Queensland and northern New South Wales were designed to simulate a machine-harvest planting, with trees one metre apart and rows four metres apart forming hedgerows (2500 plants/ha), with grass cover in the inter-rows. All plants were grown in full sun and trained to a single stem.
The Queensland trials were irrigated. Cultivars were assessed on their commercial yield over three to five years, including total cherry yield, cherry to dry green bean ratio, bean size and appearance, cupping quality, and suitability for machine-harvesting. Time of maturity, ripening pattern on the tree, resistance to pests and diseases, plant adaptability and growth rates were also evaluated.
All trials were harvested by hand every three to four weeks to determine yield progress and the maturity pattern or profile, information vital for machine-harvesting. In later years the trials were machine-harvested. As early results became available, seed of promising cultivars was distributed to interested landholders for wider evaluation of their commercial potential.
Robusta coffee was quickly discarded as a commercial prospect due to its lower bean quality, low market value and, most importantly, difficulty with machine-harvesting.
Cultivars were classified as either tall, semi-dwarf or dwarf. Under hot humid conditions at Kamerunga, the tails quickly became too tall for effective machine-harvest, and required some form of pruning. Initial harvest of the semi-dwarf types proved difficult as much of the initial crop was borne on branches too low for the harvester. This became less of a problem after the first harvest. In areas such as northern New South Wales or more elevated areas on the Atherton Tablelands where growth is slower this may preclude the use of semi-dwarf types. The dwarf cultivars performed poorly at all sites when planted at similar populations to tall and semi-dwarf cultivars.
Yields from the more promising cultivars in the initial North Queensland trial are shown in the Informed Farmers article ‘Other Factors in Coffee Cultivar Selection for Australia.’ Marked yield variations between the different trial sites are evident. Yields from the 19 cultivars evaluated in northern New South Wales are shown in the article. Site differences are less pronounced.
All arabica cultivars were successfully machine-harvested, but cherry on some cultivars were more difficult to remove than others (see Informed Farmers Coffee Harvesting article.)
David Peasley and Ted Winston