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Intensification of an irrigated rice system in Senegal: Crop rotations, climate risks, sowing dates and varietal adaptation options

Van Oort P.A.J., Balde A., Diagne M., Dingkuhn M., Manneh B., Muller B., Sow A., Stuerz S.. 2016. European Journal of Agronomy, 80 : p. 168-181.

Feeding the future world population requires increased crop production. Here, we investigate the intensification option of increasing production by increasing cropping intensity and choice of varieties with different crop duration. We developed a model to generate, compare and visualise opportunities for single/double/triple cropping systems consisting of irrigated rice and optionally a vegetable. The model was applied in a case study in the Senegal River valley. Results showed that with appropriate choice of sowing dates, severe cold sterility in rice can be avoided, also in rice¿rice crop rotations. At optimal sowing dates, simulated total long term average potential yields of single, double and triple cropping yields were 10.3, 19.0 and 18.9 t/ha respectively (total of 1,2 and 3 yields). With a hypothetical completely cold tolerant variety, yields could increase to 11.2, 20.2 and 20.9 respectively. Simulated Triple crop yields are hardly any higher than those of a double crop with two medium duration varieties. Delay in sowing due to late availability of resources (machinery, irrigation water allocation within a scheme, credits for pump fuel) is a known problem in the region. Therefore we also simulated how much delay was possible (width of the sowing windows) whilst still allowing for double cropping. We found enough delay was possible to allow for a rice¿rice or a rice-vegetable crop. A rice-rice-vegetable triple cropping system would only be possible without delays and with a very short duration vegetable of 2 months. Most promising options to increase production are through shifting the sowing date to facilitate double cropping, adoption of medium duration varieties and breeding for cold tolerant varieties. (Résumé d'auteur)

Mots-clés : système de culture; rotation culturale; facteur climatique; date de semis; tolérance au froid; infertilité; rendement des cultures; modèle mathématique; modèle de simulation; modélisation des cultures; intensification; riz irrigué; oryza sativa; sénégal; idéotype

Thématique : Systèmes et modes de culture; Méthodes mathématiques et statistiques; Physiologie et biochimie végétales

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