Present study was aimed to develop an efficient microbial consortium for combating Alternaria blight disease in cumin. The research involved isolating biocontrol agents against Alternaria burnsii, characterizing their biocontrol and growth promotion traits, and assessing compatibility. A pot experiment was conducted during rabi season of 2022-2023 to evaluate the bioefficacy of four biocontrol agents (1F, 16B, 31B, and 223B) individually and in consortium, focusing on disease severity, plant growth promotion, and defense responses in cumin challenged with A. burnsii. Microbial isolates 1F, 16B, 31B, and 223B significantly inhibited A. burnsii growth in dual plate assays (~ 86%), displaying promising biocontrol and plant growth promotion activities. They were identified as Trichoderma afroharzianum 1F, Aneurinibacillus aneurinilyticus 16B, Pseudomonas lalkuanensis 31B, and Bacillus licheniformis 223B, respectively. The excellent compatibility was observed among all selected biocontrol agents. Cumin plants treated with consortia of 1F + 16B + 31B + 223B showed least percent disease index (32.47%) and highest percent disease control (64.87%). Consortia of biocontrol agents significantly enhanced production of secondary metabolites (total phenol, flavonoids, antioxidant, and tannin) and activation of antioxidant-defense enzymes (POX, PPOX, CAT, SOD, PAL, and TAL) compared to individual biocontrol treatment and infected control. Moreover, consortium treatments effectively reduced electrolyte leakage over the individual biocontrol agent and infected control treatment. The four-microbe consortium significantly enhanced chlorophyll (154%), carotenoid content (88%), plant height (78.77%), dry weight (72.81%), and seed yield (104%) compared to infected control. Based on these findings, this environmentally friendly four-microbe consortium may be recommended for managing Alternaria blight in cumin.

• Keywords
• Alternaria burnsii, Antioxidant-defense enzymes, Consortia of biocontrol agents, Electrolyte leakage, Secondary metabolites,
• MeSH
• Alternaria * growth & development   physiology   MeSH
• Biological Control Agents MeSH
• Cuminum * microbiology   immunology   growth & development   MeSH
• Microbial Consortia * MeSH
• Plant Diseases * microbiology   prevention & control   immunology   MeSH
• Disease Resistance MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Biological Control Agents MeSH

To clarify the effect of leaf scorch on walnut leaf photosynthesis, photosynthetic parameters were measured in Juglans regia 'Wen185' and 'Xinxin2' symptom trees (WS, XS) and symptomless trees (WH, XH). At the early stage of infection and under the low-grade leaf scorch, WS showed significantly lower net photosynthetic rate (P N), stomatal limitation (Ls), and higher intercellular CO2 concentration (C i) than those of WH. However, at the mid to late stage of infection and under the high-grade leaf scorch, WS showed significantly lower P N, C i, the maximal quantum yield of PSII photochemistry and higher Ls, minimal fluorescence yield of the dark-adapted state, nonphotochemical quenching than those of WH, which would occur once Juglans regia 'Xinxin2' was infected. The above results indicated the effect of leaf scorch on walnut leaf photosynthesis was related to the walnut varieties and the duration and severity of the disease. Under the influence of leaf scorch, the decline in photosynthesis of Juglans regia 'Wen185' leaves changed from stomatal to nonstomatal restriction, while Juglans regia 'Xinxin2' leaves showed always nonstomatal restriction.

• Keywords
• chlorophyll fluorescence, daily variation, gas exchange, seasonal changes, stomatal regulation,
• Publication type
• Journal Article MeSH