Breeding of commercially acceptable allelopathic rice cultivars in China.

BACKGROUND One promising area of paddy weed control is the potential for exploiting the weed-suppressing ability of rice. This study was conducted to develop commercially acceptable allelopathic rice cultivars using crosses between allelopathic rice variety PI312777 and commercial Chinese cultivars (N2S, N9S, Huahui354, Peiai64S and Tehuazhan35), and to assess their weed suppression and grain yield in paddy fields in relation to their parents. RESULTS There was a positive dominance in the crosses Huahui354 × PI312777 and N2S × PI312777 but recessive or negative dominance in N9S × PI312777, Peiai64S × PI312777 and Tehuazhan35 × PI312777. Huahui354 × PI312777 and N2S × PI312777 showed stronger weed suppression than their parents and other crosses. Finally, an F8 line with an appearance close to Huahui354 and a magnitude of weed suppression close to PI312777 was obtained from Huahui354 × PI312777. This line, named Huagan-3, was released as a first commercially acceptable allelopathic rice cultivar in China. The grain yield and quality of Huagan-3 met the commercial standard of the local rice industry. Huagan-3 greatly suppressed paddy weeds, although suppression was influenced by year-to-year variation and plant density. There was no certain yield reduction in Huagan-3 even under a slight infestation of barnyard grass in paddy fields. CONCLUSION The successful breeding of Huagan-3 with high yield and strong weed suppression may be incorporated into present rice production systems to minimise the amount of herbicide used.

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