12 Designing Dual-purpose Sorghum Ideotypes for High Grain and Biomass Yields Su
12 Designing Dual-purpose Sorghum Ideotypes for High Grain and Biomass Yields Suitable for Various Target Environments in Senegal
Abstract
Sorghum is a water-efficient crop and an important cereal in semiarid and arid environments where water availability limits production. Providing farmers with sorghum genotypes with specific agro-morphological characteristics of high double production (grains and biomass) would help to maintain or obtain high yields in these environments. The SAMARA model was used to define dual-purpose sorghum ideotypes for different target environments. Model calibration and evaluation were carried out with experimental data collected in Nioro du Rip in 2015 and Sinthiou Malem from 2013 to 2016 on 10 contrasting sorghum genotypes. Daily weather conditions from 1950 to 2016 were used for the simulations. Also considered were the different environmental (soil and climate) conditions of Bambey, Nioro du Rip, and Sinthiou Malem (Senegal). Simulations for the identification of optimal genotypic parameters in these target environments highlighted three ideotypes showing performances for a dual-purpose (grain and fodder) production superior to the reference genotype Nieleni. This was thanks to their strong capacity to colonize the soil (long roots) and to maintain green leaves (stay-green) throughout the cycle. Hence, long roots and stay-green trait should be strongly considered while selecting or developing dual-purpose genotypes of sorghum for the target environments, especially in less-watered areas like Bambey.
Keywords: Sorghum, dual-purpose, SAMARA, ideotype, target environment, Senegal
Introduction
Food security has become a major issue given the need to increase the global food supply by about 70% in 2050 (FAO, 2009). However, given the increasing limits to the expansion of cultivated areas in developing countries (land saturation linked to demographic changes), a significant increase in crop productivity seems necessary to achieve this objective. Sorghum is the fifth most important cereal crop in the world and is the staple food of more than 500 million people in more than 30 countries (ICRISAT, 2009). It is a water-efficient crop, making it an important cereal in semiarid and arid environments where water is the main limiting factor in production. Despite its high-yield potential in terms of grains and biomass, sorghum production is very sensitive to environmental conditions. In Senegal, the average yield of sorghum, the third most important rainfed cereal after millet and maize, remains low (1020 Kg.ha-1; ANSD, 2018) with an estimated total area of more than 221,329 ha for a national production of 225,865 tons. Indeed, its cultivation faces several constraints including low soil fertility (Vanlauwe et al., 2010) and the lack of or low use of agricultural inputs (i.e., fertilizers, seeds of improved varieties; Gerstenmier & Choho, 2015). In addition, rainfall has inter- and intra-annual variabilities (Hansen, 2002).
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