RAPID MONITORING OF NITROGEN IN MANGO TREES
Nitrogen (N) is an essential nutrient in mango, influencing both productivity and fruit quality. In Australian mango orchards, tree N is traditionally assessed once a year at the dormant pre-flowering stage using 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. These experiments 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 was highly significant at late fruit set (R2=0.72, n=40) and post-harvest (R2=0.81, n=40) stages and significant at the flowering stage (R2=0.51, n=40) in the cultivar Kensington Pride, 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 was non-significant.
Bally, I.S.E. and Still, L.A. (2013). RAPID MONITORING OF NITROGEN IN MANGO TREES. Acta Hortic. 992, 107-113
rapid test, 'Kensington Pride', chlorophyll index