ソバ属2種の脱粒性関連形質の種・品種間差異 Comparison of some traits associated with grain shattering habit among cultivars and strains of two buckwheat (Fagopyrum spp) species
ソバ属(Fagopyrum spp.)栽培種は収穫時に脱粒しやすい。そこで本研究では,小枝強度を指標にしてソバ属2種の脱粒性を調査した。供試した材料は,日本産,ソ連産およびネパール産の普通ソバ(F. esculentum Moench.)3品種2系統とソ連ならびにネパール産のダッタンソバ(F. tataricum Gaerutner)2系統である。開花・結実後3日毎に小枝の抗張強度と抗曲強度を測定し,登熟に伴う小枝強度の変化を調べた。また,登熟程度の目安とするために,痩果の生鮮重を測定した。結実直後の抗張強度ならびに抗曲強度は,全品種・系統とも10g程度と小さく,登熟するに従い次第に増加した。しかし,登熟が終わると,日本産やソ道産の普通ソバでは抗曲強度が顕著に低下した。登熟後の普通ソバとダッタンソバの小枝強度を比較すると,ダッタンソバの強度は普通ソバの半分程度に過ぎなかった。一方,抗曲強度の最高強度を普通ソバの品種・系続開で比較すると,最も強いネパール産ソバと最も弱いソ連産ソバとの差は11gで,その差は比較的小さかった。また,ダッタンソバの場合は,系統間に有意な差はなかった。抗張強度の測定時に痩果が離脱した部位を調べたところ,痩果の基部付近から小枝の中央部にかけて離脱しやすいことがわかった。これは,イネ科植物で見られるような特定部位での脱粒とは異なっている。
Cultivated buckwheat (Fagopyrum spp ) is well known as having an easy grain shattering habit. In this study, we measured the breaking bending strength and the breaking tensile strength of pedicels, which were used as good indices of shattering habit. Materials were three Japanese cultivars and one Russian and one Nepalese strain of common buckwheat (F. esculentum Moench), as well as two strains of tartary buckwheat (F. tataricum Gertner). In addition, fresh fruits in various stage were weighed to figure the growth process of fruits. The breaking bending strength and breaking tensile strength of both buckwheat species were around 10g at three days after fruit set, and then these strengths gradually increased with the ripening at the grains. After finishing of the fruits ripening, however, increasing tendency of the breaking strength stopped and changed to decrease, especially on Japanese and Russian common buckwheat. The breaking strength of pedicels of tartary buckwheat was smaller than that of common buckwheat, and it was about half of the common buckwheat at the late stage of grain ripening. On the other hand, the differences of the breaking strengths within species were not clear, although various changing patterns of the breaking strength during grain ripening period were observed. For example, in comparison of the maximum value of breaking bending strength, the difference between the highest common buckwheat, Nepalese, and the lowest one, Russian, was only 11g, and the difference between two tartary buckwheat was almost zero g. When the fruits were pulled from pedicels to measure the breaking strength, the detached portion from pedicels were various. Some fruits were detached from maternal plants around the base of fruits and others were from mid of pedicels. This peculiarity of detached portions were different from those of gramineous plants, which shed the grains from the special portion where abscission layer was formed.
岐阜大学農学部研究報告 62, 7-13, 1997-12-26