Breeding lucerne for Australia's southern dryland cropping environments

Abstract

Lucerne is a deep-rooted perennial forage legume with an important role in preventing dryland salinity in southern Australian cropping regions. Annual cereal production has created a water-use imbalance, which is placing the industry under threat through rising saline watertables and resultant dryland salinity. Lucerne is being incorporated into cropping systems to reduce groundwater recharge and improve the sustainability of grain production. Existing lucerne varieties have been developed for the animal industries, primarily for the areas with high rainfall or irrigation. The new challenge is to develop lucernes specifically for southern Australian cropping systems. This paper provides a background literature review of the breeding challenges that are anticipated in the development of these new types of lucerne. Lucerne is intolerant of acidic soils, waterlogging, saline soils, and intensive grazing. Other important attributes covered include the ability of the plant to fix nitrogen with existing rhizobia and be resistant to diseases that affect lucerne and other crops in the rotation. Finally, this paper addresses some of the breeding strategies that will be used to screen lucerne germplasm for tolerances to these soil conditions and diseases.

Variation in seedling growth of 11 perennial legumes in response to phosphorus supply

“…The possibilities of introducing novel perennial legumes into low-P farming systems Although lucerne is increasingly being used in the wheatbelt in south-western Australia, there are areas where lucerne is not suitable and other perennial legumes need to be identified as possible alternatives (Humphries and Auricht 2001). Understanding the P requirements of plants is important in plant introduction, selection and breeding.…”

“…Lucerne (Medicago sativa L.) is an alternative to shallow-rooted annual pasture species in this region (Cocks 2001). However, lucerne is poorly adapted to acidic sandy soils, to the seasonal waterlogging encountered in many texture-contrast soils, and to salinisation (Humphries and Auricht 2001). In addition, lucerne is poorly adapted to the dry and hot conditions from November to April in areas with <350 mm average annual rainfall, and to the setstocking grazing management common in the region (Loo et al 2006).…”

Contrasting responses to drought stress in herbaceous perennial legumes

“…In recent decades, the perennial pasture legume lucerne (Medicago sativa L.) has been more widely sown in south-western Australia (Cocks 2001). However, it is poorly adapted to the dry, hot summers in areas with <350 mm average annual rainfall (Loo et al 2006) and to acidic sandy soils (Humphries and Auricht 2001). Furthermore, reliance on a small diversity of species within agricultural systems is considered inadequate to respond to the multitude of environmental conditions present .…”

Nutritional and chlorophyll fluorescence responses of lucerne (Medicago sativa) to waterlogging and subsequent recovery

“…The problem is further In Australia as in many other countries, lucerne (Medicago sativa) is the main perennial pasture legume (Humphries and Auricht, 2001). Being a deeprooted perennial, lucerne is able to reduce water table recharge (Latta et al, 2002), which is a major cause of dryland salinity (Dear et al, 2003;Kington and Pannell 2003).…”

“…This capacity has meant that lucerne is increasingly being used in agricultural phase farming systems (1-4 years of annual crops followed by 2-5 years of perennial pastures). However, lucerne is thought to be relatively sensitive to both waterlogging and salinity (Humphries and Auricht, 2001). In the south west of Western Australia and in southern regions of South Australia, relatively short (two-four weeks) periods of waterlogging in winter are common.…”