Non-Thermal Atmospheric Pressure Plasma Treatment to Improve Seed Germination and Seedling Growth of Two Okra (Abelmoschus esculentus (L.) Moench) Varieties

This study explores the application of non-thermal atmospheric plasma treatment to improve seed germination and seedling characteristics of two varieties of Okra (Abelmoschus esculentus var. ‘Smooth Green’ and ‘Red Ruby’) seeds. Two variants of Okra were obtained, with 660 seeds each. Seeds were directly treated with atmospheric pressure plasma (APP) and subjected to germination testing and seedling characterization and compared with untreated seeds. Both germination testing and seedling characterization were done in split-plot design in Completely Randomized Design (CRD) with APP treatment as the main factor and the variety as the subplot with 3 replicates per treatment and 2 subsample of 30 seeds each. Germination was observed daily for 14 days, and sowing commence thereafter for 2 wks. Characteristics such as germination index, germination percentage, time spread of germination, mean germination time, were determined. Further, seedling shoot and root length and total plant length and vigor index II were also determined after sowing the seedlings in pots with moist coir dust. Data was analyzed using two-way Analysis of variance. In all parameters observed, significant differences were observed for both germination and seedling characteristics. Higher germination percentage, more uniform and earlier germination with shorter germination time were observed on APP treated seeds. Generally, longer plants as indicated by longer shoot and root lengths were observed on APP treated seeds across varieties. In terms of germination index, APP treated seeds also had higher germination and more vigorous seedlings compared to untreated seeds across varieties. These findings suggest that direct non-thermal atmospheric plasma exposure may be effective at stimulating rapid germination and seedling growth for both ‘Red Ruby’ and ‘Green Smooth’ varieties.