Reference "Genetic improvement of rice in aerobic systems: Progress from yield to genes."

Reference ID

7773

Title

Genetic improvement of rice in aerobic systems: Progress from yield to genes.

Source

Field-Crops-Research, 2002, vol. 75, pp. 171-190

Authors (3)

Lafitte-H-R	Courtois-B
Arraudeau-M

Abstract

Genetic improvement of rice for aerobic (non-flooded) environments has received
less attention than breeding for lowland production systems. Aerobic rice has
traditionally been grown in low-input systems, but as fresh water for irrigation
becomes increasingly scarce, aerobic rice cultivation is expected to expand into
regions with more intensive cropping. The primary yield constraints for the low-
input aerobic crop include water deficit, acid and infertile soils, weed
competition, and disease. Yield potential has been improved through traditional
breeding approaches, and some improved upland rice cultivars show a similar
pattern of interactions with environments as traditional cultivars. Critical
environmental factors that interact with genotype are the distribution of
rainfall during the season, the amount of solar radiation received in the period
just prior to flowering, and disease pressure. In systems where adequate inputs
are applied, aerobic rice tends to yield less than lowland rice, and yield
reductions are dramatic when water deficit occurs. The poor adaptation of the
lowland cultivar IR72 to aerobic soils is associated with reduced height and
harvest index in aerobic conditions, but IR72 had similar biomass production by
anthesis as better-adapted upland cultivars. The best-yielding upland lines had
very stable pre-anthesis biomass production across five contrasting
environments. The physiological and molecular dissection of aerobic rice yield
is expected to identify opportunities to accelerate progress in the areas of
aerobic adaptation, tolerance to water deficit, and improved weed
competitiveness. QTLs have been reported for a number of traits potentially
related to performance under water deficit, such as improved root morphology and
osmotic adjustment. In an upland-by-lowland mapping population, alleles from the
lowland cultivar contributed significantly to improved yield in aerobic
environments.