Histological Peculiarities of the Abscission Layers of African Rice, Oryza glaberrima Steud. and Its Relation with Degree of Grain Shedding

[摘要] Using 30 floating and 12 ordinary rice varieties of African rice (Oryza glaberrima Steud.), breaking tensile and breaking bending strengths required to detach a rice grain from its pedicel were measured using an unbonded gauge type transducer, and abscission layers between rachilla and pedicel were investigated anatomically. Both breaking tensile and breaking bending strengths of floating rice were smaller than those of non-floating rice. In each of floating and non-floating rice, strongly positive correlations were observed between both the breaking strengths, whereas linear regression differed between the two rices. In most varieties of both floating and non-floating rices, abscission layers were formed and were found to be cracked at maturity, similar to that observed in Asian rice (O. sativa L.) varieties. In the rest of the varieties, incompletely developed abscission layers, which have not been observed in the Asian rice were observed. However, no varieties without an abscission layer were observed in this study. In the varieties with an incompletely developed abscission layer, both the breaking strengths, diameter of supporting zone and thickness of sclerenchyma around the central vascular bundle at the supporting zone were larger than those of the varieties having a normally developed abscission layer. The results suggested that the easily shedding habit of the floating varieties of African rice might be due to normally developed abscission layers, which were small in both diameter of supporting zone and the thickness of sclerenchyma tissue around the central vascular tissue at the supporting zone.

[学科分类] 农业科学（综合）

[关键词] Abscission layer;アフリカ稲;African rice;浮稲;Floating rice;グラベリマ稲;Grain shedding;脱粒性;Oryza glaberrima Steud.;離層