Contributions of Thousand-Kernel Weight and Grain Number to Yield Growth during Durum Wheat Breeding at the Samara Agricultural Research Institute

This study is carried out to identify the role of the thousand-kernel weight (TKW) and the grain number per 1.0 m2 (GN1.0 m2) in the process of breeding durum wheat to substantiate the directions of breeding for yield. The objects of the study are 18 genotypes of durum wheat of the fourth to sixth stages of breeding at the Samara Agricultural Research Institute. The standard is the Bezenchukskaya 139 variety. The total yield increase in the varieties of the fifth and sixth stages, relative to Bezenchukskaya 139, is 8.02–12.8% and 23.6–38.2%, respectively. At the fifth stage of breeding, it is achieved due to the prevalence of the contribution of TKW (+3.62 c/ha) over GN1.0 m2 (–0.26 c/ha). At the sixth stage, three groups of varieties are identified. The first group with the advantage of GN1.0 m2 (from +9.4 c/ha for 1429d-10 to +5.18 c/ha for Bezenchukskaya 209) over TKW (from –2.45 c/ha for 1429d-10 to +2.54 c/ha for Alazar) includes varieties with shortened straw. The second group, with the superiority of TKW over GN1.0 m2, includes the Marina (the contributions of the indicated traits to the yield are 5.17 and 0.56 c/ha, respectively) and Bezenchukskaya Yubileinaya (5.69 and 3.19 c/ha) varieties. The third group consists of varieties with similar contributions (45.0–57.0%) of the studied traits to the yield increase. The trait GN1.0 m2 is positively related to the number of ears per 1.0 m2 (r = 0.48–0.88) and negatively related to the stem length ((–0.59)–(–0.72)), the length of the upper internode ((–0.54)–(–0.78)), and the stem weight ((–0.48)–(–0.69)). The TKW positively correlates with the grain weight per ear (0.68–0.86) and stem weight (0.52–0.67). The grain yield from the aboveground mass and from the ear mass and the number of spikelets and grains per ear has no reliable correlations with the studied traits.