Screening of Onion (Allium cepa L.) Genotypes for Waterlogging Tolerance.

Pranjali A Gedam,Vijay Mahajan,Suresh J Gawande,Major Singh,Dhananjay V Shirsat,Sourav Ghosh,Thangasamy Arunachalam,Amar Jeet Gupta

doi:10.3389/fpls.2021.727262

Pranjali A Gedam, Vijay Mahajan + Show 6 more

Open Access

https://doi.org/10.3389/fpls.2021.727262

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Abstract

Onion production is severely affected by waterlogging conditions, which are created due to heavy rainfall. Hence, the identification of waterlogging-tolerant onion genotypes is crucial for increasing onion production. In the present study, 100 distinct onion genotypes were screened for waterlogging tolerance under artificial conditions by using the phenotypic approach in the monsoon season of 2017. Based on plant survival and recovery and changes in bulb weight, we identified 19 tolerant, 27 intermediate tolerant, and 54 highly sensitive onion genotypes. The tolerant genotypes exhibited higher plant survival and better recovery and bulb size, whereas sensitive genotypes exhibited higher plant mortality, poor recovery, and small bulb size under waterlogging conditions. Furthermore, a subset of 12 contrasting genotypes was selected for field trials during monsoon seasons 2018 and 2019. Results revealed that considerable variation in the morphological, physiological, and yield characteristics were observed across the genotypes under stress conditions. Waterlogging-tolerant genotypes, namely, Acc. 1666, Acc. 1622, W-355, W-208, KH-M-2, and RGP-5, exhibited higher plant height, leaf number, leaf area, leaf length, chlorophyll content, membrane stability index (MSI), pyruvic acid, antioxidant content, and bulb yield than sensitive genotypes under stress conditions. Furthermore, the principal component analysis biplot revealed a strong association of leaf number, leaf area, chlorophyll content, MSI, and bulb yield with tolerant genotypes under stress conditions. The study indicates that the waterlogging-tolerant onion genotypes with promising stress-adaptive traits can be used in plant breeding programs for developing waterlogging-tolerant onion varieties.

Highlights

Onion (Allium cepa L.) is an important vegetable crop cultivated across 4.3 million hectares of land globally with a total production of 98 million tons (Food and Agriculture Organization of the United Nations, 2019)
The genotypes Acc. 1656, Acc. 1624, Acc. 1617, Acc. 1640, and W-504 exhibited less than 50% survival with high plant mortality
75 genotypes exhibited more than 80% bulb weight reduction due to waterlogging stress, whereas 14 genotypes exhibited 70– 80% reduction in bulb weight

Summary

Introduction

Onion (Allium cepa L.) is an important vegetable crop cultivated across 4.3 million hectares of land globally with a total production of 98 million tons (Food and Agriculture Organization of the United Nations, 2019). More than a half of the onion production in India occurs in the Deccan Plateau. In this region, onion is cultivated as a rain-fed and irrigated crop during monsoon and post-monsoon seasons, respectively (Wakchaure et al, 2021). Flooding affects approximately 17 million km of land annually (Kaur et al, 2020). Estimation indicates that 14 million hectares of agricultural land in India are frequently flooded every year due to heavy rainfall (Kumar and Sharma, 2020). The yield losses due to waterlogging vary with the rainfall intensity and its duration, the growth stage at which rainfall occurs, and sensitivity of genotypes for waterlogging (Pasley et al, 2020)

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