Rice crop duration and leaf appearance rate in a variable thermal environment : III. Heretability of photothermal traits

In arid, irrigated, rice environments, crop duration is highly variable, resulting in uncertain crop calendars for double cropping. The main causes of this variability are varying temperature and daylength. Breeding for stable crop duration in such environments might make a major contribution to rice production. A previous study established genetic differences in phenological responses to temperature and photoperiod, based on a field study with sequential planting dates in Senegal. The present study applied this experimental approach to a five-parent complete dialled scheme. The five parents and 20 F1 progeny populations were sown on 14 dates at 2-week intervals at Ndiaye, Senegal (16°14' N) during the cold-dry, hot-dry and wet seasons in 1996. The model LAP (Leaf Appearance) described previously was used to disaggregate photoperiodic and thermal traits, which gave reproducible results for the thermal component, but not for the photoperiodic responses. Responses to photoperiod were therefore measured using a subset of environments in the Wet season (stable temperatures and 12.6-13.1 h daylength). Cross involving IR29725-40-3-2-3 (IR29725; short duration) and IR4630-22-2 (IR4630; medium duration), in combination with any of the other lines in the diallel, gave consistent patterns of heritability for earliness of flowering in the different seasons, the sensitivity of panicle induction to low temperatures, and photoperiod-sensitivity in the range of 12.613.1 h daylength. The results permitted three conclusions: (1) short duration in the wet season was a dominant trait, and in the cold-dry season, a super-dominant trait. IR29725 is a promising donor for this trait. (2) Despite its moderate to high phenological sensitivity to low temperatures, IR29725 acted as donor for low sensitivity of panicle initiation to temperature. This trait was dominant. (3) At least under the thermally stable conditions of the wet season, IR4630 acted as donor of a dominant trait for photopetiod-sensitivity, whereas IR29725 acted as donor for photoperiod-insensitivity. In summary, IR29725 is a promising donor of traits, such as short duration, low photoperiod-sensitivity and low sensitivity of phenological processes to temperature.

Bibliographic Details

Main Authors:	Sié, M., Dingkuhn, Michaël, Wopereis, Marco, Miézan, K.M.
Format:	article biblioteca
Language:	eng
Online Access:	http://agritrop.cirad.fr/264309/ http://agritrop.cirad.fr/264309/1/264309.pdf
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