Portable chlorophyll meter for the quantification of photosynthetic pigments, nitrogen and the possible use for assessment of the photochemical process in Carica papaya L.

Abstract

The techniques utilized to extract chlorophyll from plant materials are destructive and based on methods that use organic solvents. This study proposes the non-destructive quantification of chlorophyll and nitrogen concentration using a portable chlorophyll meter (SPAD-502). Further, was possible to establish relationships between chlorophyll fluorescence and SPAD-502 values. This methodology could save time, space and resources, and could be used for analysis of the photosynthetic processes. Papaya leaves (Solo and Formosa groups) of different ages were collected from 15-month-old plants cultivated in a commercial field in São Francisco de Itabapoana, Rio de Janeiro State (410:15W; 210:27S). Correlations were established between the chlorophyll content and carotenoids extracted in DMSO, nitrogen content, a chlorophyll a fluorescence (Fφ Fmax, Fv/Fmax, qN, qP, NPQ) with readings from SPAD-502 taken on papaya leaves of different ages. The results show that while the qp and the Fv/Fmax increased with SPAD-502 readings of up to 40, the qN and NPQ variables decreased. The Fmax presented a direct linear correlation with the SPAD-502 values while the Fφ variable did not correlate with the SPAD-502 values. The portable chlorophyll meter was shown to be useful for nondestructive determination of photosynthetic pigments (chlorophyll and carotenoids) and can be used indirectly in interpretation of the photochemical process in Carica papaya L. leaves.