Abstract:

【Objective】Plant height and panicle traits are key yield-dependent traits in foxtail millet. The objective was to probe into inheritance patterns of plant height and panicle traits and provide a reference basis for genetically improving related traits and mapping their genes. 【Method】Yugu 18, a high performing foxtail millet variety, was arranged as the male parent to cross two foxtail millet varieties, Huangruangu and Hongjiugu, and thus two F₇ populations of which each was composed of recombinant inbred lines involving 250 family lines（YYRIL and YRRIL）were established. Phenotypic data of Five agronomic traits of the two populations, plant height, panicle length, internode length under panicle, spikelet number per panicle and grain weight per panicle, were genetically examined in two different environments using the mixed inheritance model of major gene plus polygene. 【Result】In these two environments, all the five agronomic traits showed continuous variations with their kurtosis and skewness values standing at the absolute value of less than 1 and thus presenting a distribution close to a normal distribution, were characterized by typical inheritance of quantitative traits; some of these traits saw super-parent separation phenomena. The correlation analysis among the traits showed that the plant height appeared significantly and positively correlated with the panicle length, and an extremely significantly positive correlation between spikelet number per panicle and grain weight per panicle was also found in the two environments. The analysis by the inheritance model showed that the best inheritance models for the plant height of the YYRIL and YRRIL population were the PG-AI and PG-A polygene models, and the heritability of the polygenes standing at 95.15% and 91.27%, respectively. The best inheritance models for the spikelet number per panicle of the two populations were the PG-AI, with the heritability of the polygenes standing at 70.07%-71.58%. The best inheritance models for the internode length under panicle of the two populations were the 4MG-CEA and 3MG-CEA of which both were models for equally additive major genes. In YYRIL, the heritability of the major genes for the internode length under panicle stood at 9.69%, and the four pairs of major genes had an equal additive effect value of -0.34, taking negative effect; and in the YYRIL, the heritability of the major genes for the internode length under panicle stood at 45.78%, and the 3 major gene pairs in question had an equal additive effect value of 1.17, taking positive effect. In the YYRIL, the best inheritance model for the panicle length was the MX2-ED-A, a model for two pairs of dominant epistatic major genes and additive polygenes, with the heritability of the major genes and polygenes standing at 43.56% and 50.56%, respectively. the two pairs of panicle length-dependent major genes separately had the additive effect values of -1.21 and 1.68 and the polygenes had a lower additive effect value of -0.0017; in the YRRIL, the best inheritance model for the panicle length was the MX2-AE-A, a mixed inheritance model for two pairs of accumulative effect major genes and additive polygenes; the major genes and polygenes for the panicle length had heritability values standing at 46.40% and 46.91%, respectively. The first pair of panicle length-dependent major genes had an additive effect value of 1.53, taking positive effect; The additive and epistatic interactions effect value of the first×the second pairs of major genes were 0.60. The polygenes had an additive effect value of -0.47, taking the lower negative inheritance effect. In the YYRIL, the best inheritance model for the grain weight per panicle was the MX2-ED-A; the grain weight per panicle followed the inheritance model for two pairs of dominant epistatic major genes + additive polygenes with the heritability of the major genes and polygenes standing at 69.09% and 12.08%; the additive effect values of the two pairs of grain-weight per panicle-dependent major genes were separately 0.58 and 5.82, with the additive effect of the second pair of major genes dominating, and the additive effect value of polygenes stood at a value of -3.81. In the YRRIL, the best inheritance model for the grain weight per panicle was the 3MG-PEA, an inheritance model for three pairs of partially equal additive major genes; the heritability of the grain weight per panicle-dependent major genes stood at 81.10% and the additive effect values of the three pairs of major genes separately were -2.68, -2.68and 2.66, all taking negative effect. 【Conclusion】In foxtail millet, the plant height and spikelet number per panicle had similar inheritance models, were all under polygenic control with a higher heritability and environmentally affected to a slight content; the inheritance of the internode length under panicle was genetically controlled by major genes, which had a lower heritability and were environmentally affected to a great extent, and thus environmental factors should be taken into full account in production; the panicle length was genetically controlled jointly by major genes and polygenes; the grain weight per panicle was genetically controlled by major genes with a high heritability in both of the two population and probably carried major QTL.

Key words: foxtail millet, RIL, plant height, panicle traits, major gene+polygene