RESUMO
Sorghum production system in the semi-arid region of Africa is characterized by low yields which are generally attributed to high rainfall variability, poor soil fertility, and biotic factors. Production constraints must be well understood and quantified to design effective sorghum-system improvements. This study uses the state-of-the-art in silico methods and focuses on characterizing the sorghum production regions in Mali for drought occurrence and its effects on sorghum productivity. For this purpose, we adapted the APSIM-sorghum module to reproduce two cultivated photoperiod-sensitive sorghum types across a latitude of major sorghum production regions in Western Africa. We used the simulation outputs to characterize drought stress scenarios. We identified three main drought scenarios: (i) no-stress; (ii) early pre-flowering drought stress; and (iii) drought stress onset around flowering. The frequency of drought stress scenarios experienced by the two sorghum types across rainfall zones and soil types differed. As expected, the early pre-flowering and flowering drought stress occurred more frequently in isohyets < 600 mm, for the photoperiod-sensitive, late-flowering sorghum type. In isohyets above 600 mm, the frequency of drought stress was very low for both cultivars. We quantified the consequences of these drought scenarios on grain and biomass productivity. The yields of the highly-photoperiod-sensitive sorghum type were quite stable across the higher rainfall zones > 600 mm, but was affected by the drought stress in the lower rainfall zones < 600 mm. Comparatively, the less photoperiod-sensitive cultivar had notable yield gain in the driest regions < 600 mm. The results suggest that, at least for the tested crop types, drought stress might not be the major constraint to sorghum production in isohyets > 600 mm. The findings from this study provide the entry point for further quantitative testing of the Genotype × Environment × Management options required to optimize sorghum production in Mali. Supplementary Information: The online version contains supplementary material available at 10.1007/s13593-023-00909-5.
RESUMO
Sorghum is an important cereal crop cultivated by smallholder farmers of Mali, contributing significantly to their food demand and security. The study evaluated different fertilization strategies that combined organic and inorganic fertilizer applications with three sorghum varieties. The experiments were conducted over three cropping seasons (2017-2019) in three sites (Bamako, Bougouni, and Koutiala respectively) within the Sudanian region of Mali. Our results showed a significant effect of season, variety, and fertilization strategies on grain and stalk yields. Grain yield increased by 8-40% in Koutiala, 11-53% in Bougouni, and 44-110% in Bamako while the average stalk yield was above 5000 kg ha-1 with fertilized treatment compared to unfertilized treatment in the three sites. Fadda performed the best variety, mean grain yield was 23% and 42% higher than that of Soumba and Tieble, respectively. Similarly, there was a progressive increase in grain yield with an increasing level of poultry manure (PM) from 0 to 150 g/hill and cattle manure (CM) from 0 to 100 g/hill. However, the application of 100 g/hill of CM and PM plus 3 g/hill of Di-ammonium Phosphate (DAP) increased yield by 8% and 12% respectively compared to only CM or PM treatments. The results further revealed higher yield gain by 51% (Bamako), 57% (Koutiala), and 42% (Bougouni) for T10-[PM (100 g/hill) + Micro-D_DAP (3 g/hill)] equivalent to 73 kgNha-1 than others (T2-T9), but not proportionate to the highest value-cost ratio (VCR). Radar charts used to visualize sustainable intensification (SI) performance in the three domains (productivity, profitability, and environment) showed that the environmental variable has a direct influence on productivity, meanwhile profitability across the strategies ranged from low to moderate value across sites and different fertilizer strategies. Our study, therefore, recommends the use of multiple-choice fertilizer strategies includingT2-CM (50 g/hill)+PM(50 g/hill), T5-DAP-Micro-D (3 g/hill), T6-DAP41:46:00 and T9-PM(50 g/hill) alongside with improved sorghum varieties tested, for higher productivity and profitability across the region.