RICE RATOONING - IRRI books - International Rice Research Institute

240 RICE RATOONINGthe yield of the ratoon rice. Accordingly, some breeding programs started to screenfor higher ratooning ability among current commercial varieties, as a prelude toplanned breeding for a new variety with better ratooning ability and other elitesynthetic traits.It is urged that the inheritance of ratooning ability of rice be explored to helpproduce a new variety with higher ratooning ability. This paper reports on researchin this field from 1980 to 1984 in China.MATERIALS AND METHODSFrom short-duration Xian varieties, Ai-Nan-Zao, a short-duration variety withoutratooning ability, and Shu-Fong No. 1 (11), a medium-duration one with higherratooning ability, were used as the testers.Tai-Guao-Dao-Xuan, medium-Xian medium-duration variety, was tested in1980-1981; Shong-Zao-Xian No. 26, medium-Xian early-duration, in 1983; andHon-Mei-Zao, early Xian medium-duration, in 1984.Because ratooning ability appears to be a quantitative trait, a crossing designbased on genetic analysis of the generation means was made (2, 3). The sixgenerations consist of parents, F 1 , F 2 , BC 1 , and BC 2 in normal or reciprocal crosses.Each tester variety (P 1 ) was crossed with each testing variety (P 2 ) ' P 1 /P 2 = F 1 ,(P 1 /P 2 ) ' F 1 (x = F 2 , (P 1 × P 2 ) F 1 × P 1 = BC 1 , and (P 1 × P 2 ) F 1 × P 2 = BC 2 .Reciprocal crosses were also made: P 2 × P 1 = F 1 ' , (P 2 × P 1 ) F 1 ' = F 2 ' , (P 2 × P 1 ) F 1 '× P 1 = BC 1 ' , (P 2 × P 1 ) F 1 ' × P 2 = BC 2 ' (Table 1).The experiments were made at the Sichuan Agricultural University; the cropseeded in April was transplanted in May, 23.1 × 16.5 cm equidistant, 14 or 9hills/row. The plants were investigated, measured, and recorded individually,leaving 4 border plants in each row. The fields were managed according to normalratoon rice production.A randomized complete block design with two replications with Ai-Nan-Zaogroup and Shu-Fong No. 1 (11) was adopted. The arrangement follows the order ofgeneration in the group. Unequal plots were used for different generations. In eachreplication, data were taken from 24-30 plants of the generations P 1 , P 2 , and F 1 andF 1 ' , 150 plants of F 2 ' , F 2 ' , and 80 plants of BC l ' , BC 2 , and BC 1 ' , BC 2 ' .Table 1. Rice varieties tested for inheritance of ratooning ability.Year 1980,1981 1983 1984Parents Tal-Guao-Dao Shong-Zao-Xian Hon-Mei-ZaoXuan (P 2 ) No. 26 (P 2 ) (P 2 )Normal Normal NormalAi-Nan-Zao (P 1 )Shu-Fong No. 1 (11)F 1 , F 2 , BC 1 , BC 2reciprocalF 1 ', F 2 ', BC 1 ', BC 2 'normalF 1 , F 2 , B 1 , B 2reciprocalF 1 ', F 2 ', BC 1 ', BC 2 'F 1 , F 2 , BC 1 , BC 2reciprocalF 1 ' , F 2 ' , BC 1 ' , BC 2 'normalF 1 , F 2 , BC 1 , BC 2reciprocalF 1 ' , F 2 ' , BC 1 ' , BC 2 'F 1 , F 2 , BC 1 , BC 2reciprocalF 1 ' , F 2 ' , BC 1 ' , BC 2 'normalF 1 , F 2 , BC 1 , BC 2reciprocalF 1 ' , F 2 ' , BC 1 ' , BC 2 '