IN INOCULANTS Nodulaid - 17th International Nitrogen Fixation ...

17 th International Congress on Nitrogen Fixation
Fremantle, Western Australia
27 November – 1 December 2011
Session Details: Monday 28 November 2011
Concurrent Session 1 – Field Applications 1
1530 - 1650
Authors: Felipe A. Burgos 1 , Ron Yates 1,3 , Graham O‟Hara 1 , Halina Kobryn 2 & John Howieson 1
1 Centre for Rhizobium Studies, Murdoch University, Murdoch, 6150, Western Australia.
2 School of Environmental Science, Murdoch University, Murdoch, 6150, Western Australia.
3 Department of Agriculture and Food of Western Australia
Presentation Title: Use of remote sensing to assess the symbiotic performance of Rhizobium leguminosarum
var. vicieae strains and field pea.
Presentation Time: 1610 - 1630
The symbiotic performance between legumes and rhizobia relies on the plant-bacteria genetic compatibility and
on the symbiotic partner‟s capacity to overcome environmental stresses. Symbiosis contributes nitrogen to the
plants, which, among other things, increases the number of chloroplasts, and the number and size of cells per
leaf. Hyperspectral imagery can detect vegetation changes combining information stored in the image. The
symbiotic performance is affected by some abiotic stress factors such as low clay content and low soil water
holding capacity. These soil features can be estimated using ground penetrating radar (GPR), a geophysics
instrument based on energy pulses interacting with soil layers. The aim of this work was to investigate whether
integrated remote sensing techniques are able to estimate the interaction of field pea inoculated separately with
five strains of Rhizobium leguminosarum bv. viceae with different nitrogen fixation effectiveness levels. The
experiment was carried out firstly in a glasshouse to assess the pure symbiotic performance and then in an
agricultural area to assess the interaction with abiotic factors. Hyperspectral images and GPR measurements
were captured to cover the glasshouse and field site experiments. The plant sample analyses consisted of plant
dry weight, nitrogen content and nodulation score.
The plant samples showed significant differences in nitrogen levels, nodule score and dry weight across strains.
The analyses of the spectral band combinations confirmed the presence of outstanding indices sensitive to the
differential symbiotic performance and were correlated with plant analyses. The GPR data also revealed a mixed
composition of soil properties associated with variable water availability that affected root and plant growth. It is
concluded that remote sensing can be a valuable tool for estimating legume nitrogen fixation in fields, and GPR
for estimating below ground properties that affect plant growth in field experiments.
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