Comparison of different chlorophylls determination methods for leafy vegetables
¹Latvia University of Agriculture, Faculty of Agriculture, Institute of Plant and Soil
Sciences, Strazdu 1, LV-3004 Jelgava, Latvia
²Latvia University of Agriculture, Faculty of Food Technology, Department of
Chemistry, Liela 2, LV-3001 Jelgava, Latvia
³Latvia University of Agriculture, Faculty of Information Technologies, Liela 2,
LV-3001 Jelgava, Latvia
Modern agricultural farming requires precise, quick and nondestructive methods for determination of basic plant physiological parameters. One of the widely used and informative parameters is chlorophyll content in plant leaves. Determination of chlorophyll content by nondestructive methods is well elaborated for main field crops, but these methods are not widely used for chlorophyll content determination in leafy vegetables. The aim of the study was to compare two nondestructive methods with a classic biochemical chlorophylls determination method. Pigment content was expressed regarding to the leaf weight and leaf area. For nondestructive chlorophyll determination were used: a low cost handheld chlorophyll meter atLEAF+ and Miniature Leaf Spectrometer CI-710 (CID- Bio-Science). Chlorophylls content was determined using one of the 21 indices incorporated in Cl-710. For comparison of methods four different plant species (lettuce, leaf mustard, radish and cabbage) were used. Plants were grown at four illumination conditions – natural light, illumination supplemented with red, blue and mixed red/blue LED light. Results showed that at the majority of the investigated wavelengths, readings of the chlorophyll meter atLEAF+ and indices used for calculation are more sensitive to chlorophyll a content calculated per unit area. The maximum sensitivity of reflectance to variation with pigment content is found at 605 nm and 696 nm and in the near infrared region (740–930 nm). Higher correlation between non-destructive methods and biochemical analyses was observed in radish and leaf mustard leaves. The highest correlation coefficient was obtained with Difference Vegetation Reflectance index (NDVI) and Simple Ratio Pigment Index (SRPI). Nondestructive chlorophyll determination with chlorophyll meter atLEAF+ and Miniature Leaf Spectrometer CI-710 can completely replace biochemical analyses.