Persistence of diverse lucerne (Medicago sativa sspp.) germplasm under farmer management across a range of soil types in southern Australia

Abstract

The persistence of a diverse group of lucerne (Medicago sativa sspp.) germplasm was evaluated under farmer management across a range of acidic and neutral-alkaline soils at 8 sites in South and Western Australia. Dryland field trials were sown in parallel with commercial lucerne paddocks being grown in rotation with cereal crops, remaining unfenced and under management by the farmer for the life of the stand. The combined differences in soil type, grazing management, and low rainfall contributed to large differences in average lucerne persistence between sites in South Australia and Western Australia. After 3 years, plant frequency (a measure of plant density used to monitor persistence) averaged 17% (at least 17 plants/m2) on the strongly acidic soils in Western Australia and 30% on the neutral-alkaline soils in South Australia (at least 30 plants/m2). Differences in persistence were attributed to the combined stresses of soil pH, drought conditions, and grazing management. Genetic correlation analyses between sites failed to show any clear patterns in the performance of entries at each site, except for a high correlation between 2 South Australian sites in close proximity. Highly winter-active germplasm was less persistent than other winter activity groups, but was higher yielding when assessed in an additional trial at Katanning, WA. Highly winter-active lucerne (class 9–10) should continue to be recommended for short (2–4 year) phases in rotation with cereals, and winter-active groups (6–8) should be recommend for longer (4–7 year) phases in rotations. The results of this evaluation are also being used to identify broadly adapted, elite genotypes in the breeding of new lucerne cultivars for the southern Australian cropping districts.

Lucerne and other perennial legumes provide new options for rain fed livestock production in the Mediterranean-climate region of Chile

“…SARDI Ten and Aquarius averaged 8.4 t ha -1 in 2013 and 11 t ha -1 in 2014, years that received 397 and 570 mm of annual rainfall, respectively (61% and 87% of the long-term average annual rainfall, respectively). The apparent water use efficiency of lucerne in this study (19−21 kg DM ha mm -1 of rainfall) is much greater than that reported for similar Mediterranean climates in southern Australia (Latta et al, 2002, Ward, 2006Humphries et al, 2008). This increases in efficiency likely caused by the greater root volume and the water holding capacity of the soil at this location.…”

“…Among the lucerne cultivars, the differences detected in total biomass production were not large; a large group of cultivars exceeded 8,000 kg DM ha -1 that included Genesis, SARDI Ten, SARDI Seven, WL903, Venus, Aquarius and the three genotypes of Alta Sierra. These levels of biomass production are greater than those obtained in drylands in South Australia by Humphries et al (2008). The high production of the accessions of the ancestral Alta Sierra lucerne is particularly relevant because this germplasm originates from the Illapata Valley in northern Chile.…”

“…Compared with the annual legumes currently used in the Mediterranean zone of Chile, the growth dynamics with the seasonal distribution of production is one of the most relevant aspects of incorporating perennial legumes into livestock farming systems (Humphries et al, 2008). The production obtained at the end of winter is a resource of high value because for annual pastures, this is a period of essentially no production.…”

Lucerne (Medicago sativa L.) Persistence Remains Unchanged under Variable Cutting Regimes

“…This is an interesting result primarily because it is recognised that the continuous grazing or cutting of lucerne without sufficient rest intervals can result in poor persistence [13,19]. Secondly it is known that highly winter active cultivars are more upright in their growth habit than winter dormant cultivars [16,[20][21][22] and have their crown more exposed above the soil surface, making them more susceptible to trampling [23] by sheep and this can affect persistence. The cultivars used in these experiments were winter active (winter dormancies 7 and 8) and had upright growth habits so it might be expected that persistence would be affected.…”