Screening Blackgram (Vigna mungo (L.) Hepper) Genotypes for Salt Tolerance at Germination and Seedling Stages

Aim: Salt stress negatively affects the growth and development of plants. An effective and important strategy to develop salinity tolerant crops is to harness the genetic diversity within the crop germplasm by identification of salinity tolerant genotype. The present study was carried out with an objective to screen blackgram genotypes (A31, DPU 968, KU 7720, LBG 787, PLU 621, TMV 1, Tutiminimum, VBG 18028, VBG 18032, and VBN 2) for salt tolerance at germination and seedlings stage and identification of saline tolerant blackgram genotype based on salt stress tolerance indices.

Study Design: Factorial and arranged in a completely randomized design.

Place and Duration of Study: Department of Crop Physiology, Tamil Nadu Agricultural University, Coimbatore; May-June 2022.

Methodology: Using petriplate and roll towel techniques, blackgram seed germination indices and seedling growth indices such as germination percentage, germination index, mean germination time, seedling vigour index, shoot and root length, fresh and dry seedling weight, and stress tolerance indices were recorded. Two-way ANOVA, Principle Component Analysis (PCA) and Cluster Heat-map Analysis were used to analyze the data.

Results: PCA indicates that salinity stress accounted for 86.2 percent of the variation, whereas the individual genotype contributes only 5.4 percent of the variation observed in germination and growth parameters that were studied in blackgram under control and 130mM NaCl salt stress conditions. Among the ten blackgram genotypes, stress tolerance index was highest for LBG 787 (0.831) followed by KU7720 (0.722). On the other side, the stress susceptible index was found to be lower for the blackgram genotype KU7720 (0.335) followed by LBG 787 (0.592), as compared to other genotypes screened. Cluster heat-map analysis for all the measured parameters revealed that blackgram genotype LBG 787 was clustered with PLU 621 and VBG 18028 and found to tolerate the salt stress level (130mM NaCl stress) compared to other blackgram genotypes.

Conclusion: Observations indicate that the blackgram genotypes KU 7720, LBG 787, PLU 621 and VBG 18028 exhibit greater tolerance towards salinity during the germination and seedling growth stages.