PRELIMINARY ASSESSMENT OF A RAPID LEAF NITROGEN TEST IN MANGO
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.
Still, L.A. and Bally, I.S.E. (2013). PRELIMINARY ASSESSMENT OF A RAPID LEAF NITROGEN TEST IN MANGO. Acta Hortic. 975, 385-392
Cardy nitrate meter, chlorophyll, 'Kensington Pride', mango, Merck RQflex10 nitrate meter, nitrogen, rapid test, SPAD-502 meter