Journal of Taiwan Agricultural Research

Author:Dong-Hong Wu and Kae-Kang Hwu*

Abstract:

    The objective of this study was to determine the genetic composition of 40 off-type plants of rice (Oryza sativa) from 29 sampling locations in the three-step propagation nursery. Twenty-three simple sequence repeat (SSR) markers capable of identifying the 22 superior rice varieties produced in Taiwan in 2004 and 2005 were used in this study. Foundation seeds from the second crop of 2004 were used to establish standard genetic profile of the 22 rice varieties. Results of allelic composition analyses showed that, among the 40 rice off-type plants tested, 8 cases were identical to the standard genotype profile, 8 cases were other genotypes within variety, 6 cases were variety mixture, 13 cases were hybrid progeny and 5 cases were unknown variety. These results suggest that the off-type plants of rice were mostly originated from natural hybridization, mixture of varieties and low genetic uniformity within variety. In order to improve efficiency of the three-step propagation nursery for production of superior rice varieties with genetic purity, it is necessary to establish guard rows in the field to prevent outcrossing by foreign pollen, conduct one more generation for single plant selection during breeding programe and rogue out off-type plants and foreign variety from seed producing nurseries.

Key words:Rice, Oryza sativa, Three-step propagation nursery, Off-type plant, Simple sequence repeat

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