What was it all about?

In response to drought conditions and reduced water availability in the Murray Darling Basin, this project was undertaken to investigate the impact and management of deficit irrigation in tree crops, including citrus.

Data was gathered over five years from 2007 to 2012, on citrus and other crops to provide information on how to best manage future drought events.

Effective strategies for coping with reduced water availability included…

• Reducing the size of citrus tree canopies by hedging
  
  
• Skeletonising trees (very severe cutting back), although recovery time was extended
  
  
• Reworking citrus trees (cutting back to bud in a new variety), which gave added benefits of variety renewal
  
  
• Hedging immediately following a sustained period (at least a full season) of deficit irrigation, to assist in tree recovery
  
  
• Purchasing water, where the cost of water was less than the value of produce lost by withholding that volume of water.

Strategies that proved less effective included…

• Cultural management techniques including mulching, sunscreen films applied to the canopy, and soil polymers
  
  
• Reducing the proportion of the ground wetted by irrigation, which negatively impacted recovery once normal irrigation was reinstated.

Other factors that affected crop response to deficit irrigation included:

• Irrigation system type and coverage
  
  
• Duration and severity of irrigation reduction, for example more than one season of deficit increases the time required for recovery
  
  
• Rootstock, for example the citrus rootstock Cleopatra Mandarin was superior to Sweet Orange, and Troyer Citrange and Swingle Citrumelo also performed well in other trial work conducted by the researchers.

As a result of the work, researchers found…

• Current recommendations for the use of Swingle Citrumelo and Citrange rootstocks in citrus replant situations are appropriate
  
  
• Canopy reduction is an appropriate tool for managing reduced water availability in tree crops, with severity of reductions being proportional to severity of water shortage
  
  
• The water market can be a valuable management tool, especially where crop returns are high, making water purchase economically viable.

ACT NOW

Download the project's Citrus Drought Information Package fact sheet, which provides an overview of citrus-specific drought management options