Grain Zinc (Zn) and Iron (Fe) content in wheat is majorly influenced by environmental conditions like soil nutrients content, soil pH, temperature and other factors. However, only little information known about effect of drought and spot blotch on grain Zn and Fe contents. In the present study, we determined Genotype × Environment (G × E) interaction and effect of spot blotch and drought on grain Zn and Fe content. Nine homozygous (M6) gamma mutagenized wheat mutants and the parent (HD2967) were grown at Banaras Hindu University, Varanasi, India in 2021-22, in different environments/locations, Irrigated (IY-1, I-2, I-3), Drought (D-1, D-2) and Spot Blotch infection (SB-1). All genotypes were sown in 3 rows of 1m length in environments I-2, I-3, D-1, D-2 and SB-1, while in IY-1 (Irrigated yield trial), they were grown in plot size of 3 m x 1.5 m consisiting of 6 rows. Drought treatment was initiated 12 days before heading and artificial spot blotch inoculation with two virulent isolates (HD3069 and PUSA2) of Bipolaris sorokiniana was done at Zadok-55 growth stage.

Grain Zn and Fe content were analysed in ED-XRF (Energy Dispersive X-ray Fluorescence) machine and additionally test weight (TW, grain weight in fixed volume) were also recorded. Mean Zn and Fe content across all environments ranged from 23 ppm (TAW97) to 28.8 ppm (TAW122); and 29 ppm (TAW122) to 38 ppm (TAW98), respectively. However, mean environments Zn and Fe of all genotypes ranged from 23.9 ppm (IY-1) to 30.5 ppm (I-2); and 28 ppm (SB-1) to 39.8 ppm (I-2) respectively. G × E interaction ANOVA showed that 16% of variation in Zn content was due to genotypes, 40% due to environment and 32% due to G × E, and for Fe content, 14.8% of variation was due to genotype, 49.3% due to environment and 17% due to G × E. Means comparison (Tukeys) considering all environments showed that the Zn content in TAW122 (higher), TAW15 and TAW 97 (lower) were significantly different from parent HD2967 (26.1 ppm). Similarly for Fe content, TAW19, TAW132, TAW95, TAW98 significantly higher than parent (33 ppm).  Fe content significantly reduced in SB-1 (28 ppm) compared to all other environments, while Zn content was significantly increased in SB-1 as compared to IY-1 and D-2, and decreased from I-2. Further, drought significantly reduced Zn in D-1 (26 ppm) and D-2 (23.6 ppm) from their respective control I-2 (30.7 ppm) and I-3 (28 ppm). Drought also decreased Fe [D-1 (35.5 ppm) and D-5 (36 ppm)], compared to their respective control [I-2 (38 ppm) and I-3 (39.8 ppm)]. There was good positive association with Zn and Fe in IY-1 (r=0.5), I-3 (r=0.5) and SB-1 (r=0.4). In addition, there was positive association with Fe and TW in IY-1 (r=0.59), I-2 (r=0.27), I-3 (r=0.46), D-1 (r=0.25) & D-5 (r=0.4); however, negative in SB-1 (r= -0.4). There was no clear association pattern with Zn and TW. Further TW in SB-1 significantly reduced from other environments. Overall, our results clearly showed negative impacts of spot blotch and drought on Zn and Fe contents of wheat grain.