Evaluation and calibration of noninvasive leaf chlorophyll meters for wheat

Abstract

Nondestructive and fast chlorophyll assessment can be made with portable chlorophyll meters. The meters measure the transmittance of red and near infrared radiation through the leaf and estimates the chlorophyll in non-dimensional index values by defined arithmetic operations.These metes required to calibrate for conversion of index values to the actual chlorophyll content in desired units. Calibration of widely used TYS-A (SPAD meter) and CCM-200 (Chlorophyll content index (CCI) meter) chlorophyll meters wasattempted for chlorophyll estimation in bread wheat (Triticum aestivum L.) leaves.The chlorophyll values for the wheat leaves were measured with chlorophyll meters and same samples were used in standard photometric measurements in laboratory. The SPAD values showed statistically significant linear relationship with chlorophyll content (R2=0.92). The functional relationships represented with regression models can be used to convert the SPAD value to actual chlorophyll content for wheat. The relation between SPAD and CCI was studied using independent leaf samples (n=159). The relationship was found curvilinear and fitted with statistically significant quadratic polynomial (R2=0.86).So, the fitted quadratic model can be used for inter-conversion between SPAD and CCI. The model was used to convert the values from SPAD to CCI. The derived CCI values were used to fit establish the relationship between CCI and actual chlorophyll content of wheat.

Keywords

• SPAD
• CCI,
• Chlorophyll meter
• wheat,
• calibration