Technique for Wide Cross between Cultivated Rice (Oryza sativa) and Wild Rice (O.minuta)

Abstract

Wide crosses between cultivated rice (O. sativa, AA, 2n = 24) as the female and wild rice (O. minuta, BBCC, 2n = 48) as the male had been made for introgression of some agronomic characters from wild rice into three cultivated rices. Gibberelin 75 ppm was sprayed onto pollinated panicles immediately after pollination to delaying dehiscent. Rate of seed sets was ranged from 14.52-25.30%. Embryo rescue of F₁ seed was made at 9-14 days after pollination. Embryos were cultured on ¼ macronutrient strength Murashige and Skoog (MS) medium supplemented with 2.0% sucrose and 0.6% agar at the pH of 5.8 and allowed to germinate in the dark. The rate of embryo rescue was ranged from 42.86-95.00% depending on the cultivars used. Embryos with the age of 13 days had high rate of rescue. The morphology of the F₁ hybrids from the three crosses were intermediate between the two parents but showed a preponderance of the traits of wild rice. They were robust and extremely vigorous. All of them had 36 chromosomes (2n=36) but completely sterile.