Cool-climate alfalfa could be a dry-land winner

Posted by Nicole Eckersley on 16th September 2010

The genes that enable some lucernes, or alfalfa plants, to adapt to freezing temperatures could also help them endure dry spells, according to new Dairy Australia-backed research.

The surprise findings from Tasmanian research could see some cold-climate lucernes being introduced to drier dairy regions of Australia.

Lucerne is grown in Australia for its seed, livestock pasture, hay, chaff and silage, can also be processed into pellets for livestock feed, and even used as garden mulch.  Australia produces significant amounts of both lucerne hay and seed.

Glasshouse and field experiments on the plants highlighted that the same genes which allow cold-acclimation also allow winter-dormant lucerne cultivars to adapt to dry conditions.

Keith Pembleton of the Tasmanian Institute of Agricultural Research (TIAR) Dairy Centre said the results were surprising and contrary to what was initially expected.

“Winter-active cultivars might be expected to be higher yielding under dry-land conditions in southern Australia, because they are able to grow over the winter period when soil moisture is readily available,” Mr Pembleton said.

“However the field experiments showed that this was not the case, even in the high rainfall environment at Elliott in north-west Tasmania. The semi-winter dormant cultivar outyielded the winter-active and highly-winter active cultivars.”

Pembleton said it appeared that lucerne cultivars which have the capability to become dormant in cold weather can also activate this capability in dry times.

“We identified that the genes that cause winter dormancy and freezing tolerance are expressed in the semi-winter dormant, but not the highly winter-active cultivar, during dry times,” he said.

“It suggests these genes would also help the plant to adapt the drought as well as freezing temperature. As these genes are only found in the more winter-dormant cultivars of lucerne, we are recommending those cultivars for environments where the plant is likely to be exposed to a water deficit at some point during the year.”

The four-year study was a collaboration between TIAR and American scientists. Mr Pembleton undertook a year of research in the US as a Fulbright Scholar.

The researchers studied plots of lucerne cultivars at Cambridge and Elliott in Tasmania and found that the plants’ genetic makeup interacted with the environment to affect growth, development and, ultimately, crop yield.

Irrigation was a major factor in determining yield potential, Mr Pembleton added. Why was the research undertaken?

“Lucerne is a very genetically diverse crop,” Mr Pembleton said.

“We wanted to study how the different lucerne cultivars responded to environmental conditions, to identify the most appropriate management practice for lucerne grown on dairy farms.”

Dairy Australia said the next step was to identify how lucerne best fits within the dairy farming system.

As part of TIAR’s Beyond 20.12 project the results of the study will be combined with on-farm crop monitoring, and biophysical, farm system and market risk modelling, to identify the best way to use forage crops (including lucerne) in the dairy feedbase of southern Australia.