Relationship between chlorophyll meter readings and total N in crambe leaves as affected by nitrogen topdressing

Abstract

Crambe is a crop winter, with high oil content, function as a source of raw material for the biodiesel production. This crop deserves attention agriculture because the short cycle ranging from 90 to 100 days. A portable chlorophyll-content meter for proportional estimate determinations (SPAD-502 indices) allows instant readings, and may be ideal to predict N requirements, since the method used in the laboratory is time-consuming and destructive. Consequently, this work's objective was to evaluate the relationship between chlorophyll meter readings and total N contents in leaves of crambe plants, at the stage prior to flowering, as affected by topdressing N levels. This work was conducted in Umuarama Municipal District – Paraná State, Brazil. Variables analyzed were SPAD index values (chlorophyll) in leaves, as measured with the chlorophyll meter, and total N content. The data were submitted to analysis of variance, means comparison, polynomial regression, and simple linear correlation analyses. The results showed that: nitrogen topdressing applied did not affect the chlorophyll and nitrogen in crambe leaves. There was no significant correlation between chlorophyll and leaf nitrogen meaning on crambe crop, during the full flowering.