Grain Size Distribution and Head Rice Yield of Some Rice Breeding Lines using Flat-Bed Scanning and Digital Image Analysis

Abstract

Rice grain quality evaluation is crucial in rice breeding and production of selected varieties. Characterization of rice grain fractions after milling is important; these include brown rice, milled rice, and head rice yield (HRY). The latter is the main determinant for the market price of rice. The present study aims to utilize image analysis as a tool for assessing HRY. Digital image analysis (DIA) was used to quantitatively determine HRY for eight selected rice breeding lines and the results were compared with those obtained by the conventional method of manual inspection (MI). Digital images of the rice grains were taken with a flat-bed scanner (FBS) and analyzed using free-access software (ImageJ). Areas of individual grains were determined, and percent grain area was calculated in terms of the ratio of actual-to-whole grain areas (AWGA). Size grain distribution plots were generated per breeding line, and those grains with values of the AWGA ratio greater than or equal to 75% were classified as head rice. The HRY value was calculated in percent-by-mass basis using the mass of 100 whole rice grains. Values of HRY obtained using DIA showed no significant difference compared to those obtained using the conventional method. This was done according to the paired samples t-test at 95% confidence interval, which showed a high correlation coefficient (R2 = 0.99). The DIA method showed good repeatability and reproducibility based on different precision parameters indicating its potential as a practical, inexpensive, and quantitative method for determining HRY of rice breeding lines.