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The infection caused by grain mold in rainy season grown sorghum deteriorates the physical and chemical quality of the grain, which causes a reduction in grain size, blackening, and making them unfit for human consumption. Therefore, the breeding for grain mold resistance has become a necessity. Pedigree breeding has been widely used across the globe to tackle the problem of grain mold. In the present study, a population breeding approach was employed to develop genotypes resistant to grain mold. The complex genotype × environment interactions (GEIs) make the task of identifying stable grain mold-resistant lines with good grain yield (GY) challenging. In this study, the performance of the 33 population breeding derivatives selected from the four-location evaluation of 150 genotypes in 2017 was in turn evaluated over four locations during the rainy season of 2018. The Genotype plus genotype-by-environment interaction (GGE) biplot analysis was used to analyze a significant GEI observed for GY, grain mold resistance, and all other associated traits. For GY, the location explained a higher proportion of variation (51.7%) while genotype (G) × location (L) contributed to 21.9% and the genotype contributed to 11.2% of the total variation. For grain mold resistance, G × L contributed to a higher proportion of variation (30.7%). A graphical biplot approach helped in identifying promising genotypes for GY and grain mold resistance. Among the test locations, Dharwad was an ideal location for both GY and grain mold resistance. The test locations were partitioned into three clusters for GY and two clusters for grain mold resistance through a “which-won-where” study. Best genotypes in each of these clusters were selected. The breeding for a specific cluster is suggested. Genotype-by-trait biplots indicated that GY is influenced by flowering time, 100-grain weight (HGW), and plant height (PH), whereas grain mold resistance is influenced by glume coverage and PH. Because GY and grain mold score were independent of each other, there is a scope to improve both yield and resistance together.

Milk stage kernel infection frequency has substantial effects on mold development in mature sorghum grain. Field experiments were conducted with 16 sorghum genotypes at four grain mold prone locations (Akola, Hyderabad, Dharwad and Surat) in India during kharif 2014 and 2015. The genotypes included grain mold susceptible, resistant, improved germplasm, breeding lines and released cultivars. The objective was to quantify natural infection frequency of fungi in milk stage kernel and study the response of various sorghum genotypes against this infection. Results revealed that Fusarium (16.1%) and Curvularia spp. (7.9%) were predominant fungal genera at the milk stage kernel at all the locations under study. Few other fungi namely Alternaria, Bipolaris, Aspergillus, and Penicillium spp. were detected sporadically in low frequency (~0.95%). There was significant negative association between infection frequency of Fusarium and Curvularia especially when intensity of infection was moderate to high (>25%). The genotypes B58586, GMR156-1, GMR166-1, SGMRN12-3-1 and IS25070 were found promising with low intensity (average total infection<10%) of infection across environments. The information can be useful for resistant breeding program against specific fungal component of grain mold.