CMS (cytoplasmic male sterile) line is one of the most important hybrid parents in hybrid rice production technology using Three-Line systems. Test-crosses for selection of candidate local maintainer lines were conducted using 24 rice varieties and two CMS-WA (wild abortive) lines IR78374A/B and 1A/B. The F1 of the two combinations, namely IR78374A/P519 and 1A/MR243 had less than 10% spikelet fertility (6.4 and 7.2%, respectively), indicated that P519 and MR243 are partially maintainers and could be used for the development of new locally adapted CMS lines. As a results, two CMS lines, namely 0025A/B and 0047A/B were generated after 5 to 6 successive backcrossing of IR78374A with P519 and 1A with MR243. The CMS 0025A/B and 0047A/B lines had maturation age which is comparable to other commonly grown inbred varieties. The percentage of stigma exertion rate for CMS 0025A/B and 0047A/B were 17.9 and 21.3%, respectively, lower than that of IR78374A/B (43.2%). Both showed poor out-crossing rate. CMS 0025A/B and 0047A/B are classified as long and slender grain. They had intermediate amylose content. Their gel consistency was hard, comparable to that of MR263 (medium). CMS 0025A/B and 0047A/B lines were also moderately resistant to foliar blast disease and brown planthopper infestation.
Artificial selection of biotypes of green rice leafhopper, Nephotettix cincticeps Uhler (Homoptera: Cidadellidae), and virulence to resistant rice varieties
