ASSOCIATION BETWEEN GRAIN SHATTERING HABIT AND FORMATION OF ABSCISSION LAYER CONTROLLED BY GRAIN SHATTERING GENE SH-2 IN RICE (ORYZA-SATIVAL)

Rice garin shattering habit is closely associated with the abscission layer formed at the base of sterile lemmas (empty glumes). In the curr ent study, the character expression of sh-2, one of the representative shattering genes, was investigated by comparing some agronomic parame ters among Norin 29, a Japanese non-shattering cultivar, and its shatt ering near-isogenic line SH-AJNT, as well as Dee-geo-woo-gen, a shatte ring indica cultivar. After observation of longitudinal sections of st erile lemmas bases, the abscission layer was not found at the spikelet differentiation stage. However, at the reproductive cell formation st age, SH-AJNT faintly formed the abscission layer. No abscission layer, on the other hand, appeared in Norin 29 throughout the stage of panic le development. The breaking strength at the base of sterile lemmas wa s measured to compare the threshability among materials. Until 19 days after heading, both threshability on Norin 29 and SH-AJNT exhibited s imilarly high values, indicating non-shattering conditions. At 21 days after heading, the garin of SH-AJNT dropped more easily than those of previou stages, while Norin 29 kept its persistent character. This di fference is important for the evaluation of SH-AJNT and Norin 29, shat tering and non-shattering cultivars, respectively. The progressive dec line in the breaking strength of SH-AJNT was thought to be associated with the ripening of the grain.