Use of the chlorophyll meter and interpretation of readings performed in real time as an indication of nitrogen sufficiency for onion culture

Abstract

The work aims to guide technicians and farmers on the use of the chlorophyll meter and interpretation of the results obtained from the readings in real time as an indication of nitrogen sufficiency for the onion crop. The guidelines were obtained based on field experiments carried out at Epagri – Estação Experimental de Ituporanga, over a period of eight years, for four plant populations (300, 400, 500 and 600 thousand plants ha^-1), five doses of nitrogen (2011 to 2014) and three forms of payment in installments (2017 to 2020). The use of a chlorophyll meter to indicate nitrogen sufficiency in onion crops is an important tool in the decision-making process when applying or not topdressing nitrogen fertilization to maximize productivity. However, the interpretation of values and decision-making must consider, in addition to the calibration curves for each population and sufficiency limits, the conditions of climate, management and development of the crop.