Screening of Leaf Mustard ( Brassica Juncea L.) Cultivars for Salinity Tolerance

Leaf mustard (Brassica juncea L.) is a variety of mustard; however, a thorough evaluation of its salt tolerance and screening the reliable traits for evaluating salt tolerance is required. This study was designed to evaluate the responses of five leaf mustard cultivars which were selected from 146 varieties to 0, 50, 100, 150, and 200 mmol L−1 NaCl at the germination and seedling stages. Compared with the control, NaCl treatments significantly decreased hypocotyl length, radicle length, fresh weight, and chlorophyll content in a few cultivars, while low NaCl concentration triggered slight increase in the three germination indexes. The relative water content was not significantly different among the control and treatments. Compared with the control, NaCl treatments, especially 200 mmol L−1 NaCl, significantly increased root/shoot, chlorophyll a/b (Chl.a/b), electrical conductivity (EC), proline content, and malondialdehyde content (MDA). Principal component analysis (PCA) identified root length, hypocotyl length, and shoot weight as the most significant traits for screening inter-accession variability of leaf mustard in the future. Based on the membership function values (MFV) of 16 traits, cultivar C (Big Leaf Oil Mustard 381) exhibited stronger salt tolerance than other cultivars. In contrast, cultivars B (Lilong Kejia Mustard) and D (Lace Sweet Mustard 353) were sensitive to salt stress among the five mustard varieties.