Predicting nitrogen, magnesium and iron nutritional status in some perennial crops using a portable chlorophyll meter

A field study was conducted through the years 1996 and 1997 in Ismailia and Sharkia governorates, Egypt, with the horticultural crops: mango, mandarin, guava and grapevine. The study aimed at predicting nitrogen, magnesium and iron-status under field conditions using the pocket apparatus Hydro N-Tester (Minolta, Japan). The data showed that the apparatus can be used as an easy and fast tool to predict both chlorophyll and N-status in the leaves of fruit trees. The N-Tester readings in the range of 110-610 for mango, 735-820 for mandarin, 249-332 for guava and 285-345 for grapevine were considered to be in the range for nitrogen sufficiency at the recommended growth stages for each crop. Lower readings were considered to be in the deficiency range and higher ones in the excess range. The N-Tester can also be used to assess Mg-status for some fruit trees. Measurement of Fe-status using the N-Tester chlorophyll meter under field conditions was not possible. (C) 1999 Elsevier Science B.V. All rights reserved.