An APSIM-powered framework for post-rainy sorghum-system design in India

Abstract

Sorghum contributes to the livelihoods of millions of food-insecure households in semi-arid agri-systems. Annual production widely fluctuates throughout India due to erratic rainfall and suboptimal agronomic practices. Our novel approach utilizes the digital reflection of post-rainy (rabi) sorghum production systems in India to help better understand its spatio-temporal variations and enable the designing of geography-specific, climate-responsive system interventions (Genotype × Management; GxM). For this, we evaluated a range of farmer-relevant agronomic management practices across three soil types (shallow, medium, and deep vertisols) in combination with observed ranges of biological variability in sorghum cultivar characteristics. We used the crop growth simulation model Agricultural Production Systems sIMulator (APSIM) to identify GxM combinations that can support the enhancement/ stability of post-rainy sorghum production systems in India. In general, we found the post-rainy sorghum systems would benefit from early-season sowing (16th - 23rd September), short crop duration (compared to Maldandi (M35–1), commonly grown crop type), and medium fertilizer inputs (70–70 kg urea ha −1 as basal and top-dress application). In addition, site-specific crop management (M) and crop characters (G) optimizations would further enhance/ stabilize sorghum production. Simulations highlighted that in the poorly-endowed environmental context (i.e. shallow soils and low-rainfall areas), optimal G×M targets might involve water conservation GxM combinations, such as low plant populations and low fertilization along with low crop vigor and limited transpiration responsiveness. Details on site-specific optimum GxM are available in a web application at https://ls40.pef.czu.cz/maps/. To enable the use of the study outputs for certain applications (e.g. breeding), we separated the examined geographies based on similarities in optimum production characteristics and similarities in system response to GxM interventions into four “homogeneous system units” (HSU; i.e. geographical units within which reduced GxM interactions are expected). These HSUs intended to offer geography-specific targets to prioritize, test, and introduce distinct G×M interventions. We conclude that the APSIM-powered framework presented provides region-specific Genotype × Management options that could become a blueprint for defining quantitative breeding targets that achieve enhanced productivity/ stability of dry-season sorghum cultivation throughout India. • APSIM-driven framework to capture the spatio-temporal variations in sorghum production was established. • This framework quantified the effects of sorghum genetics and management (GxM) on crop production. • Site-specific GxM optimization would increase stover and grain production over the current practices. • GxM options to optimize sorghum production in targets geographies were defined. • The APSIM-framework is available on-line at https://ls40.pef.czu.cz/maps/.