|Authors: ||L.A. Still, I.S.E. Bally|
|Keywords: ||Cardy nitrate meter, chlorophyll, 'Kensington Pride', mango, Merck RQflex10 nitrate meter, nitrogen, rapid test, SPAD-502 meter|
Nitrogen (N) is an essential nutrient in mango, influencing both productivity and fruit quality.
In Australia, tree N is traditionally assessed once a year in the dormant pre-flowering stage by laboratory analysis of leaf N. This single assessment is insufficient to determine tree N status at all stages of the annual phenological cycle.
Development of a field-based rapid N test would allow more frequent monitoring of tree N status and improved fertiliser management.
This experiment examined the accuracy and useability of several devices used in other horticultural crops to rapidly assess mango leaf N in the field; the Konica Minolta ‘SPAD-502 chlorophyll meter’, Horiba ‘Cardy Meter’ and the Merck ‘RQflex 10’. Regression and correlation analyses were used to determine the relationship between total leaf N and the measurements from the rapid test devices.
The relationship between the chlorophyll index measured by the SPAD-502 meter and leaf N is highly significant at late fruit set (R2=0.72, n=40) and post-harvest (R2=0.81, n=40) stages in the mango cultivar ‘Kensington Pride’ and significant (R2=0.51, n=40) at the flowering stage, indicating the device can be used to rapidly assess mango leaf N in the field.
Correlation analysis indicated the relationship between petiole sap measured with the Cardy or Merck devices and leaf N is non-significant.
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