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Phenological responses of upland rice grown along an altitude gradient

Shrestha S.P., Asch F., Brueck H., Ramanantsoanirina A., Dusserre J.. 2011. In : International Conference on Crop improvement, Ideotyping, and Modelling for African Cropping Systems under Climate Change - CIMAC, University of Hohenheim, 7-9 February 2011 : Book of abstracts. Stuttgart : Hohenheim University, p. 40-40. International Conference on Crop Improvement, Ideotyping and Modelling for African Cropping Systems under Climate Change, 2011-02-07/2011-02-09, Hohenheim (Allemagne).

Crop adaptation strategies are required in terms of varietal development and crop management to avoid negative impacts of climate change. In order to characterize the agronomie fit of a potential upland rice ideotype, the phenological response of ten selected upland rice varieties were studied on three different altitude gradient locations (Iow altitude 25 m asl, mid altitude 965 m asl and high altitude 1625 ma asl) in Madagascar, ranging from hotequatorial conditions to the lower limit of the crop's thermal adaptation. Genotypic phenological responses were studied by closely observing the time required to panicle initiation, booting, heading, flowering, and physiological maturity. Above ground biomass, grain yield and yield components, and spikelet sterility were recorded for each genotype and planting dates from ail the three locations for two years. Depending on genotypes, the duration from germination to flowering stage ranged between 100 and 146 days in the high altitude condition, whereas in the mid altitude it ranged between 73 and 97 days, and between 56 and 80 days in the low altitude as the mean air temperature gradually increases to the lower altitude. The local landrace genotype Botramaintso has the longest crop duration in ail the three locations, however the duration reduced in the lower altitudes. Ali genotypes yielded better in the lower altitudes as the total sterility due to heat and/or cold is minimum during cropping period. In the high altitude, genotypes such as Chomrong, and FOFIFA 161, FOFIFA 167 and FOFIFA 172 produced more grain yield. These coId tolerant genotypes have above average yield stability. Variation in cold tolerance can be used to adapt genotype to different environments. Morpho-physiological traits contributing to cold tolerance need to be identified for further breeding. Phenological responses, photo-thermal effects and sterility will be discussed and presented for an altitude gradient upland rice cropping system. (Texte intégral)

Mots-clés : riz pluvial; oryza sativa; changement climatique; madagascar

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