Cropping

Phosphorus use studied

By Country News

University of Western Australia research will help unlock phosphorus bound in soils, and improve crop production.

Phosphorus is an important plant macro-nutrient and its low availability in the soil is a major constraint to crop production worldwide.

Agricultural intensification and fertiliser application has led to a large amount of phosphorus being locked in the soil and contributes to environmental pollution.

Lead researcher Kadambot Siddique said phosphorus was a finite resource and the team had been working on strategies to improve phosphorus-use efficiency.

The researchers screened more than 250 chickpea genotypes with diverse genetic backgrounds from the world core collection to study the role of root morphology, physiology and bio-chemistry in acquiring phosphorus from the soil.

‘‘Chickpea can mobilise the phosphorus bound in soils by exuding carboxylates, such as malonate, from the root system which are particularly important for phosphorus acquisition in low phosphorus conditions,’’ Professor Siddique said.

However, Research Fellow Dr Jiayin Pang, from The UWA Institute of Agriculture, said measuring carboxylates from the soil was a laborious process which meant it was difficult to screen a large number of varieties that had this trait.

‘‘To make the screening process easier, we developed the world’s first tool that uses the matured leaf of crops to assess carboxylates in the rhizosheath,’’ Dr Pang said.

‘‘We have shown for the first time that manganese concentration in mature leaves can be used as an easily measurable proxy for the assessment of below-ground carboxylate-releasing processes in chickpea grown in soils with low phosphorus availability.’’

In another study, the researchers found that leaf transpiration also plays a role in phosphorus acquisition in chickpeas grown in low-phosphorus sandy soils.