Genetic analysis of tolerance to transient waterlogging stress in pigeonpea (Cajanus cajan L. Millspaugh)

Abstract

Pigeonpea (Cajanus cajan L. Millspaugh) is mainly grown in the rainfed ecosystem during the monsoon season on deep vertisols, and it often faces transient waterlogging problems due to continuous and heavy downpours during early monsoon seasons. Thus, waterlogging has become a significant issue in most of the pigeonpea growing areas of the semi-arid tropics due to heavy rain during the initial crop growth stage, which causes 30 to 40% economic yield loss in India and around the world. Only a few sources of waterlogging tolerant genotypes are available in pigeonpea but are not in the required duration. Hence, the present investigation was carried out to identify waterlogging tolerant pigeonpea genotypes in different durations suitable for different agroecologies of India and to find ideal selection indices as appropriate strategies to identify waterlogging tolerant genotypes. In this study, 162 genotypes were screened under in vitro conditions for 2, 4, 6, and 8 days by submerging seeds. Of these, 33 genotypes could survive for eight days. Further, following a standard screening protocol; these 33 pigeonpea genotypes were screened under pot culture for two years (2020 and 2021). Based on different morpho-physiological parameters and waterlogging tolerant coefficient, genotypes ICP-10397, ICP-7507, ICP-7869, ICP-7148, ICP-4903 ICP-16309, ICP-7375, ICP-6815, ICP-7507, and ICP-6128 were identified as tolerant to transient waterlogging. In addition, this study reports the existence of substantial genetic variation for waterlogging tolerant traits in pigeonpea. Stress indices, such as stress tolerance index) (STI), mean relative performance (MRP) and relative efficiency index (REI) were identified as the ideal selection index. Therefore, identified genotypes are further validated and can be deployed in waterlogging tolerance pigeonpea breeding programs