Multi-location evaluation of mungbean (Vigna radiata L.) in Indian climates: Ecophenological dynamics, yield relation, and characterization of locations

Multi-location evaluation of field pea in Indian climates: eco-phenological dynamics, crop-environment relationships, and identification of mega-environments

Characterization of crop-growing environments in relation to crop's genotypic performance is crucial to harness positive genotype-by-environment interactions (GEI) in systematic breeding programs. Given that, the study aimed to delineate the impact of diverse environments on crop phenology and yield traits of dwarf-statured field pea, pinpointing location(s) favoring higher yield and distinctiveness within breeding lines. We tested twelve field pea breeding lines across twenty locations in India, covering Central Zone (CZ), North Western Plain Zone (NWPZ), North Eastern Plain Zone (NEPZ), and Northern Hill Zone (NHZ). Across these locations, maximum and minimum temperatures during flowering (TMAXF, TMINF) and reproductive period (TMAXRP, TMINRP) ranged 18.9-28.3, 3.3-18.0, 15.0-30.8, and 7.9-22.1oC, respectively. Meanwhile, notable variations in phenological and agronomic traits (coefficient of variation) were observed: flowering (31%), days to maturity (21%), reproductive period (18%), grain yield (48%), and 100-seed weight (18%). Combined ANOVA demonstrated an oversized impact of environment (81%) on yield, while genotype and GEI effects were 2% and 14%, respectively. The variables TMINF, TMINRP, and cumulative growing degree-day showed positive correlations with yield, while extended vegetative and maturity durations negatively influenced yield (p < 0.05). Additionally, linear mixed-models and PCA results explained that instability in crop phenology had significant influence on field pea yield. Seed weight was markedly varied within the locations (9.9-20.8 g) and both higher and lower seed weights were associated with lower yields (Optimal = 17.1 g). HA-GGE biplot-based on environment focus-scaling demonstrated three mega-environments and specific locations viz. Kota (CZ), SK Nagar (CZ), Raipur (CZ), Sehore (CZ), and Pantnagar (NWPZ) as the ideal testing-environments with high efficiency in selecting new genotypes with wider adaptability. The study findings highlight distinct impact of environments on crop phenology and agronomic traits of field pea (dwarf-type), hold substantial value in designing efficient field pea (dwarf-type) breeding program at mega-environment scale.

Exogenous application of antagonistic Streptomyces sp. SND-2 triggers defense response in Vigna radiata (L.) R. Wilczek (mung bean) against anthracnose infection

Anthracnose is a devastating disease caused by the fungus Colletotrichum lindemuthianum (CL) in Vigna radiata (L.) R. Wilczek (mung bean). In the present study, an eco-friendly approach to control anthracnose infection, growth promotion and enhancement of defense response in mung bean plants using endophytic actinomycetes was performed. Among the 24 actinomycetes isolates from the Cleome rutidosperma plant, the isolate SND-2 exhibited a broad spectrum of antagonistic activity with 63.27% of inhibition against CL in the dual culture method. Further, the isolate SND-2 was identified as Streptomyces sp. strain SND-2 (SND-2) through the 16S rRNA gene sequence. In-vitro screening of plant growth trials confirmed that SND-2 has the potential to produce indole acetic acid, hydrogen cyanide, ammonia, phosphate solubilization, and siderophore. The in-vivo biocontrol study was performed with exogenous application of wettable talcum-based formulation of SND-2 strain to mitigate CL infection in mung bean seedlings. The results displayed maximum seed germination, vigor index, increased growth parameters, and lowest disease severity (43.63 ± 0.73) in formulation treated and pathogen challenged mung bean plants. Further, the application of SND-2 formulation with pathogen witnessed increased cellular defense through the maximum accumulation of lignin, hydrogen peroxide and phenol deposition in mung bean leaves compared with control treatments. Biochemical defense response exhibited upregulation of antioxidant enzymes such as phenylalanine ammonia-lyase, β-1,-3-Glucanase, and peroxidase enzymes activities with increased phenolic (3.64 ± 0.11 mg/g fresh weight) and flavonoid (1.14 ± 0.05 mg/g fresh weight) contents in comparison with other treatments at 0, 4, 12, 24, 36, and 72 h post pathogen inoculation. This study demonstrated that formulation of Streptomyces sp. strain SND-2 is a potential source as a suppressive agent and plant growth promoter in mung bean plants upon C. lindemuthianum infestation and witnesses the elevation in cellular and biochemical defense against anthracnose disease.