Non-destructive analysis of photosynthetic pigments in cotton plants

Abstract

Analytical techniques used to extract chlorophyll from plant leaves are destructive and based on the use of organic solvents. This study proposes a non-destructive quantification of the photosynthetic pigment concentration in cotton leaves using two portable chlorophyll meters, the SPAD-502 and the CLOROFILOG 1030. After obtaining 200 leaf discs, each with an area of 113 mm 2, the greening rate in each disc was determined by the average of five readings from both meters. Immediately after measurement, 5 mL of dimethyl sulfoxide (DMSO) was added, and the samples were kept in a water bath at 70°C for 30 min. After cooling, 3 mL of the liquid extract was used for analyses by spectrophotometry at 470, 646 and 663 nm. Mathematical models were adjusted from analytical results using the reading index obtained from both devices to predict the contents of chlorophyll a, chlorophyll b, total chlorophyll and carotenoids. Based on these results, it was concluded that both portable chlorophyll meters are an effective way to estimate the concentration of photosynthetic pigments in cotton leaves, thus saving time, space and the resources that are often required for these analyses.