The growing demand for rice and the increasing pressure on irrigated land in Madagascar is strengthening efforts to developing upland rice systems. Actual yield is below its potential yield in farmers’ field due to biotic and abiotic stresses. In higher altitude, specific cold tolerant upland rice genotypes are planted due to temperature constraints. According to climate change prediction, it is easy to expect positive effects on upland rice production systems in high altitude. The rise in temperature will increase productivity mainly via reduced spikelet sterility, considering that other climatic parameters such as rainfall patterns will not have adverse effects. Climate change will increase the number of genotypes which can be cultivated in upland areas; however genotypes still will be sensitive to weather experienced during sensitive physiological and phenological periods. To avoid negative impacts, crop adaptation strategies are needed in terms of varietal development and crop management. Grain yield depends on genotype, environment and management practices and their interaction with each other (Messina et al., 2009). Under the same management conditions, variation in grain yield is principally explained by the effects of genotype and environment (Dingkuhn et al., 2006). Interaction between these two explanatory variables gives insight for identifying genotype suitable for specific environments. The objective of this study was to compare contrasting genotypes which cover a broad range of phenological and physiological traits across a temperature gradient in Madagascar in order to quantify the extent of genotype by environment interaction and to characterize yield stability and adaptability across different environments.

In the Ma dagascar highlands, increasing demand for rice combined with increasing land pressure in the lowlands led to the development of upland rice. To tackle the sustainability problem of upland crop production systems, Centre de coopération internationale en recherche agronomique pour le développement ( CIRAD , an internat ional governmental organization ) and TAFA ( an NGO) ha ve developed direct - seeding mulch - based cropping systems (DMC), which not only decrease soil erosion but also increase soil fertility. To understand the mechanisms underlying the performance of upland rice DMC , an experiment was set up in 2003. The yield c omponents of upland rice were studied under high - altitudinal conditions during six rainy season s from 2003 / 04 to 2008 / 09. Treatments compared were two soil management techniques: conventional tillage with removal of most of the crop residues , associated with plowing ( ‘ plo w ing ’ ) ; and a no - till system with direct seeding under mulch made of crop residues ( ‘ no - till ’ ). The rice yields obtained were often better from plo w ing than from no - till, except in the last season. This difference was due to blast disease , which was significantly lower in no - till with low fertilization (best percentage of full grains and better weight of grain). The differences in yields obtained between no - till and plo w ing were mainly explained by problems of crop installation. The plant densities and plant growth were lower in no - till. This was particularly linked to slower root development in no - till. Overall, the biomass production of rotations of rice seemed too low in the highland conditions (low temperature) for the no - till system to be successful in the early years (low soil protection and s lower restructuring of the soil )