Abstract:

【Objective】The color difference analysis for grain quality evaluation was conducted using the foxtail millet varieties participating national high-quality foxtail millet competition in recent years. The results, combined with the expert sensory evaluation, could improve high quality millet breeding.【Method】Millet varieties that participated in the past three high-quality millet competition in 2015, 2017, and 2019 were accounted, the L* values, a* values, b* values were determined by the color difference analysis, and the correlation analysis was performed with the commercial quality scores, cooking and eating quality scores and the total scores. 【Result】The number of millet varieties competed for high-quality increased by 82.3% in the last 3 sessions. summer-sowing varieties increased by 60.0% while spring-sowing was 100.0%. The number of first-class quality varieties increased by 133.3%, of which, 87.5% were bred by 7 scientific research institutes. 93.7% of the varieties were bred by cross breeding, 62.5% of which was herbicide resistant. Among all of the high-quality millets, the L* values ranged from 55.05 to 66.03 in summer-sowing region, which was from 53.12 to 68.84 in spring-sowing region. The a* values ranged from 1.63 to 8.74 in summer-sowing region, and that was from 2.13 to 8.59 in spring-sowing region. The b* values ranged from 54.50 to 75.35 in summer-sowing region, and that was from 40.07 to 71.40 in spring-sowing region. The L* values, a* values, b* values of all tested varieties and high-quality millets showed an increasing trend. Comparing with summer-sowing region, spring-sowing region had greater variation in b* value and the higher color richness. The commercial quality scores and the total scores were significantly correlated with L* values, a* values, b* values. The steamed millet scores were significantly correlated with L*, a* values. However, the millet congee scores were not significantly correlated with L* values, a* values, b* values. The correlation between commercial quality scores and total scores was the highest, with a correlation coefficient of 0.7528. The commercial quality scores were positively correlated with the steamed millet scores, but was not correlated with the millet congee scores. In the regression model of the first-grade high-quality millet, the L* values, a* values, b* values determined the 74.3% variation of the total score. The varieties with top 10 commercial quality scores and total scores in summer-sowing region were mainly divided into two types: one was the golden varieties with low a*, high L* and b * values, such as Jigu 39 and Yugu 33; the others were the light yellow varieties with high a*, low L* and b* values, such as Jigu 19 and Jigu 42. The varieties with top 10 commercial quality scores and total scores in spring-sowing region were mainly divided into three types: one was the dark yellow varieties with low L*, high a* and b * values, such as 2015KM826F7-75 and Fenghong 4 hao; one was the light yellow varieties with high L*, low a* and b* values, such as Yugukang 1 and Chihong 1 hao; one was the light yellow and red varieties with high a*, low L* and b* values, such as Zhangzagu 13 and Jinfen 106. 【Conclusion】In the last three national competitions for high-quality foxtail millet varieties, the number of millet varieties showed an increasing trend. Many scientific research institutes have focused on quality breeding. In the future, high grain quality would become an important goal for millet improvement. The commercial quality score and total score showed strong correlation, so it was important to improve the commercial quality of millet for quality breeding. It was an intuitive and convenient breeding method to select millet color by the color difference L* values, a* values, b* values. The commercial quality score correlated with L* values, a* values, b* values, so millet color selection should be based on the characteristics of the variety in quality breeding.

Key words: foxtail millet, color difference analysis, good quality, correlation analysis