Standardization and Comparative Evaluation of quick Inoculation Techniques for Screening Pigeonpea genotype...

Phytophthora stem blight (PSB), caused by Phytophthora cajani, is a destructive disease of pigeonpea (Cajanus cajan L.) that can lead to complete crop loss under favorable conditions. Effective resistance breeding is constrained by the lack of reliable and reproducible screening methods. The present study aimed to standardize and compare artificial inoculation techniques for consistent induction of Phytophthora blight under controlled conditions. Ten inoculation methods targeting different infection pathways were evaluated in greenhouse pot experiments over two consecutive seasons (2023-24 and 2024-25) using susceptible (UPAS-120, ICP-7119, ICP-2376) and moderately resistant (KPBR-80-2-1, IPAC-79, IPAB-7-2-1-7) pigeonpea cultivars. Disease incidence was recorded to assess the efficiency and reproducibility of each technique. All methods successfully established infection; however, disease severity varied significantly among techniques and genotypes. The leaf-lamina inoculation method consistently produced the highest and most uniform disease incidence, recording 97.7% and 96.6% in the susceptible cultivar UPAS-120 and 83.3% and 86.6% in the moderately resistant cultivar KPBR-80-2-1 across the two seasons. Node inoculation emerged as the second most reliable method. The study identifies most efficient and quick, reproducible inoculation techniques that enable rapid and high-throughput resistance screening, providing a robust methodological framework to support pigeonpea breeding and Phytophthora blight management.