An adventure in applied science - IRRI books - International Rice ...

106 History of the International Rice Research Instituterelative amylose content of the starch. Beachell’s experience in Texas especiallyqualified him to establish and administer this laboratory, the data from whichenabled the breeders to discard breeding lines not meeting minimum qualitystandards.Another important activity that occupied both Jennings and Chang duringthe first 3 years of IRRI’s operation was basic studies of the causes of lodgingand its impact on yield. They investigated the effect of season, of spacing, andof nitrogen levels and concluded that although there was less lodging in thedry season than in the wet, in wide rather than narrow spacing, and at lownitrogen levels rather than high, the only real protection against lodging andthe consequent yield losses was to breed rice varieties with thick, sturdy, shortstems. By supporting tall varieties such as Peta and MTU-15 with bamboosticks, Jennings found that tall varieties yielded essentially as well as didlodging-resistant varieties. Moreover, the lodging-susceptible varieties whensupported responded well to nitrogen applications, whereas the unsupportedplants showed a decided negative response to the addition of nitrogenousfertilizer. This proved beyond doubt that lodging per se was the primary causeof low yields when traditional tropical varieties were subjected to modernmanagement methods.Rice breedingGermplasm collection and distribution and the fundamental studies providedfor the breeding procedures a background that was significant and, in manyinstances, critical to the success of the breeding program. But the real impactof IRRI on world rice production was a result of the distribution and testing ofthe genetic lines and varieties developed in its breeding program. Again, forthe sake of brevity, only the highlights of that program are sketched here.Because IRRI’s first variety, IR8, set new yield records for tropical rice, theprocess of its breeding and selection is covered in detail.In late 1962, Jennings and his research aides (later to be known as researchassistants) made 38 crosses, 11 of which involved as one of the parents a shortstaturedvariety from Taiwan — either Taichung Native 1, Dee-geo-woo-gen,or I-geo-tse. The other parents were mainly tall tropical indicas or ponlais. Theeighth cross among the 38 was one between Peta — a tall Indonesian varietywith high vigor, seed dormancy, resistance to several insects and diseases andwidely grown in the Philippines — and Dee-geo-woo-gen — a high-yielding,heavy-tillering, short-statured variety from Taiwan. The following descriptionof the cross is largely from an article Jennings prepared for the September1966 issue of The IRRI Reporter.As a result of the initial cross, 130 seeds were formed. These were plantedin pots in the screenhouse and produced the first generation of plants, all ofwhich were tall. Seed from those F 1 plants was sown in the field and producedabout 10,000 F 2 plants. These segregated by height according to the Mendelianratio of 3:l. All tall late-maturing plants were discarded and the short earlymaturingones were saved. Seed from these remaining plants were bulked andplanted in the rice blast nursery, where all highly susceptible plants were