Submitted to: Rice Technical Working Group Meeting Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: February 24, 2002
Publication Date: N/A
Technical Abstract: For 15 years high yielding indicas from China have been observed in the southern US. Although yield levels have been exciting, grain quality of the indicas has not been suitable for US markets. Therefore the very early, high yielding, high-amylose (25%), indica variety Zhe733, from China National Rice Research Institute, was used as a "cornerstone" variety in crosses in early 1998 with IR64 and six late maturing, intermediate amylos (20-22%) accessions from IRRI, which approach US long grain quality standards. Generations were advanced as follows: F1 in summer 1998, F2 in summer 1999, F3 and F4 in winter nursery 1999/2000, F5 in summer 2000, F6 in winter 2000/2001, and F7 in summer 2001. The initial F2 populations, totaling 30,000 plants, were reduced in stages by selection for early maturity in the summer F2 and F5 generations, followed by selection for intermediate amylose level (20-22%) in the F5, F6, and F7 generations. In the 2001 F7 generation, 68 selections which had passed the F2 and F5 maturity screens and the F5 and F6 amylose screens, plus parents and two tropical japonica long grain checks, were grown in a small-plot, three- replicate, yield test. Following the F7 amylose screening, nine lines were discarded on basis of high amylose values (= 24%), leaving 59 lines. Yields of the 59 lines ranged from 6546 to 9477 kg/ha, compared to 5025 and 5804 kg/ha for the two tropical japonica checks and 6688 kg/ha for the Zhe733 parent.