In Vitro Regeneration of Onion (Allium cepa L.) Genotypes under Salt Stress Condition

Abstract

Salinity is a major problem affecting crop production all over the world. Excessive soil salinity can reduce the productivity of many agricultural crops including many vegetables and spices. Onion is one of the most important spices in the Asiatic region which is now in high demand. The experiment was conducted to observe in vitro regeneration of onion (Allium cepa L.) under salt stress condition from September 2016 to July 2017. The experiment was conducted as two factorial (genotype and treatment) Completely Randomized Design (CRD) with 3 replications for each treatment. Shoot tip segments of three genotypes namely Faridpuri, Taherpuri and Pusa red (Indian) were cultured in MS (Murashige and skoog, 1962) media supplemented with 25, 50, 75 and 100 mM NaCl. The genotype Faridpuri gave maximum salt tolerance upto 100 mM salinity level with 10.60 cm shoot length and 1.94 cm root length having the highest relative shoot and root growth. Pusa red was found to be salinity sensitive genotype which showing lowest shoot length of 7.03 cm and root length of 0.96 cm at 100 mM NaCl treatment. However, Taherpuri was tolerant up to 100 mM salinity level with 8.14 cm shoot length and 1.25 cm root length. Both the highest fresh weight of root (54.77 mg) and dry weight of root (41.36 mg) was from the genotype Faridpuri with 25 mM NaCl treatment. However, a convenient in vitro regeneration protocol of onion genotypes under different salinity level has been developed and the genotype Faridpuri can be used for further investigation in field condition to evaluate its performance at various salinity levels.