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Exploiting phenotypic diversity of hybrid rice: identification of novel traits of interest for high yield : [Oral presentation abstract 614]

Lafarge T., Bueno C.S.. 2012. In : International Rice Research Institute ; Directorate of Rice Research ; Indian Council of Agricu. Public-private partnership for hybrid rice, Final program and abstract book of the 6th International hybrid Symposium, Hyderabad, India, 10-12 September 2012. s.l. : s.n., p. 43-43. International Hybrid Rice Symposium. 6, 2012-09-10/2012-09-12, Hyderabad (Inde).

Discovering traits of interest for higher yield potential in rice can be addressed by comparing high yielding genotypes of diverse genetic background and geographical origin. Overall, 32 entries developed by distinct institutions and companies, including 20 hybrids from four countries (Philippines, China, Columbia, and India) were analyzed during contrasted seasons at thë IRRI farm, Philippines. While grain yield was significantly higher in the dry (9.0 t ha-1) than in the wet (6.7 t ha-1) season, the performance of hybrids in favorable conditions (dry season) was confirmed to be significantly higher than that of inbreds, 9.2 vs 8.6 t ha-1. When looking at individuals regardless of origin and genetic background, two types of component traits supporting higher performance during both seasons were identified: those related to (i) high light interception capacity during grain filling (erect leaves and tillers, substantial green leaf area index maintained a few days before maturity) and (ii) a compact structure of the panicle (short panicle with minimal rachis and high ratio of primary to secondary spikelets, within a range of variation of panicle length from 23 to 28 cm). The abovementioned traits were confirmed as having great value to support the difference in final grain yield when comparing two by two genotypes with the same potential sink size. Interestingly, high light interception capacity and culm dry weight at around maximum tillering, and high tillering efficiency, were also favorable traits. These major findings for irrigated rice are discussed in light of previous results published on the dynamics of biomass accumulation and sink regulation.

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