Grain-filling of Diploid and Tetraploid Tartary Buckwheat

  Objective  Grain-filling of Tartary buckwheat (Fagopyrum tataricum) was studied to determine the cause of inferior crop yield of tetraploid variety.

  Method  Diploid Tartary buckwheat varieties, Xiaohuang and Liuku 2081, were compared with the tetraploid TB193 and TB198 on grain-filling, starch biosynthesis, root morphology and physiology, agronomic characteristics, and grain yield for the analysis.

  Result  Although both Tartary buckwheat varieties stopped the 100-grain weight increase 25 d after anthesis, the diploid was higher than the tetraploid in that respect. In addition, compared to the tetraploid varieties, the diploid Tartary buckwheat started earlier on the filling initiation; achieved higher peak and average filling rates; reached the maximum grain-filling in a shorter time; showed greater AGPase and SSS activities in grains at early grain-filling stage but lower in the middle and late filling stages; had significantly lower length, surface area, volume, activity, and fluid on the roots, height on the plant, number of branches on the main stem, node count on the main stem, girth between the 1^st and 2^nd nodes, and 1-2 internode thickness. On average, the diploid Tartary buckwheat was 2.97 times higher on plumpness and 1.23 times higher on yield than the tetraploid counterpart.

  Conclusion  The lower grain filling initiation, filling rate, and starch synthase activity at early filling stage appeared to be the key physiological indicators of the inferior performance of the tetraploid Tartary buckwheat on grain production.