Afroughsadat Baniaghil *1, Hemmatollah Pirdashti1, Mohammad Ali Esmaeili1, Mitra Ramezani2, Yasser Yaghoubian1
1- Sari Agricultural Sciences and Natural Resources University
2- Mazandaran Oilseeds Development Company
2- Mazandaran Oilseeds Development Company
Abstract: (22 Views)
Introduction: Germination is a sensitive process for plant growth and achieving optimal performance. Environmental stresses, including salinity, are the most important limiting factors of plant production, and humans are forced to deal with these stresses through various management practices. Rapeseed (Brassica napus L.), one of the most important oil plants, is relatively tolerant to salinity and is the best choice for saline and sodium soils. So that its resistance to salinity is equal to that of the barley. Rapeseed cultivars tolerate salinity of slightly more than seven dS/meter. However, this plant, like most other crops, is sensitive to salinity in the initial stage of seedling establishment. Althought, the seeds of canola genotypes show different abilities to maintain their metabolic activities under saline conditions, the germination and certain stages of growth are more susceptible to damage due to salt stress. Therefore, the evaluation of salinity tolerance in the early stages of growth, especially germination, is very important. In this regard, the present study was carried out to evaluate and select salinity-tolerant genotypes of different Brassica species (Brassica spp.) in the germination stage.
Materials and methods: In the present study, the salinity tolerance of 100 genotypes of five Brassica species was evaluated using a factorial experiment based on a completely randomized design in three replications. The first factor includes Brassica genotypes (60 genotypes of B. napus L., 15 genotypes of B. nigra L., 15 genotypes of B. juncea L., 5 genotypes of B. rapa L. and 5 genotypes of B. carinata L.) and the second factor was five levels of salinity with sodium chloride including zero (control), 5, 10, 15 and 20 dS/m. For this purpose, after disinfection with 1.5% sodium hypochlorite, the healthy seeds were transferred to sterile Petri dishes with a layer of filter paper Whatman No. 1. The diameter of the Petri dishes used in this experiment was 8 cm and the number of seeds in each petri dish was 25. After placing the seeds in Petri dishes, depending on the desired treatments, five milliliters of distilled water or sodium chloride solutions with a potential of 5, 10, 15, and 20 dS/m were placed in the germinator at a temperature of 22 ̊Cand the number of germinated seeds was counted at 12-hour intervals until the number of germinated seeds was fixed. After germination, traits such as length, weight, and dry weight of root, stem, and plant were measured. Finally, the beginning, end, and uniformity of germination, germination percentage, germination speed, germination index, seedling length index, and allometric coefficient were calculated in different treatments. After the experiment and data collection, cluster analysis was done at different salinity levels using SPSS software (version 22) and the Ward’s method. Then, by analyzing the variance and comparing the mean between the groups using the least significant difference (LSD) test at the five percent probability level, the best group of genotypes was selected at each salinity level.
Results: During the experiment, due to the low potential of some genotypes, 20 genotypes were removed and data analysis was done for 80 genotypes. Based on the dendrograms obtained from cluster analysis at salinity levels of zero, 5, and 15 dS/m, the studied genotypes were divided into three groups, and at salinity levels of 10 and 20 dS/m were placed into four groups. In general, based on the comparison of the average between the groups resulting from the cluster analysis, at the salinity levels of 0, 5 and 15 dS/m the first group and at the salinity levels of 10 and 20 dS/m the fourth group was selected as the best one and then variance analysis and mean comparison were performed between genotypes in the mentioned groups. Based on the results of cluster analysis, comparing the average of the groups as well as the analysis of the genotypes of the top groups, there was a significant difference between the genotypes in most of the measured traits. So that 15 genotypes (including codes 141, 306, 328, 336, 346, 367, 446, 483, 509, 517, 693, 767, 831, 850, and 860) in all investigated salinity levels, always placed in the top group and therefore they were selected as the superior genotypes of brassicas.
Conclusion: In total, the results of this experiment showed that among the investigated genotypes, 15 genotypes were always placed in the top groups at all levels of salinity stress. Among the selected genotypes, 7 genotypes of B. napus L., 6 genotypes of B. juncea L. and 2 genotypes of B. rapa L. were present. There were any genotypes of B. nigra L. The results indicated that these genotypes had a high ability to germinate and produce strong seedlings in both normal and saline conditions and can be used for further researches and breeding programs.
Materials and methods: In the present study, the salinity tolerance of 100 genotypes of five Brassica species was evaluated using a factorial experiment based on a completely randomized design in three replications. The first factor includes Brassica genotypes (60 genotypes of B. napus L., 15 genotypes of B. nigra L., 15 genotypes of B. juncea L., 5 genotypes of B. rapa L. and 5 genotypes of B. carinata L.) and the second factor was five levels of salinity with sodium chloride including zero (control), 5, 10, 15 and 20 dS/m. For this purpose, after disinfection with 1.5% sodium hypochlorite, the healthy seeds were transferred to sterile Petri dishes with a layer of filter paper Whatman No. 1. The diameter of the Petri dishes used in this experiment was 8 cm and the number of seeds in each petri dish was 25. After placing the seeds in Petri dishes, depending on the desired treatments, five milliliters of distilled water or sodium chloride solutions with a potential of 5, 10, 15, and 20 dS/m were placed in the germinator at a temperature of 22 ̊Cand the number of germinated seeds was counted at 12-hour intervals until the number of germinated seeds was fixed. After germination, traits such as length, weight, and dry weight of root, stem, and plant were measured. Finally, the beginning, end, and uniformity of germination, germination percentage, germination speed, germination index, seedling length index, and allometric coefficient were calculated in different treatments. After the experiment and data collection, cluster analysis was done at different salinity levels using SPSS software (version 22) and the Ward’s method. Then, by analyzing the variance and comparing the mean between the groups using the least significant difference (LSD) test at the five percent probability level, the best group of genotypes was selected at each salinity level.
Results: During the experiment, due to the low potential of some genotypes, 20 genotypes were removed and data analysis was done for 80 genotypes. Based on the dendrograms obtained from cluster analysis at salinity levels of zero, 5, and 15 dS/m, the studied genotypes were divided into three groups, and at salinity levels of 10 and 20 dS/m were placed into four groups. In general, based on the comparison of the average between the groups resulting from the cluster analysis, at the salinity levels of 0, 5 and 15 dS/m the first group and at the salinity levels of 10 and 20 dS/m the fourth group was selected as the best one and then variance analysis and mean comparison were performed between genotypes in the mentioned groups. Based on the results of cluster analysis, comparing the average of the groups as well as the analysis of the genotypes of the top groups, there was a significant difference between the genotypes in most of the measured traits. So that 15 genotypes (including codes 141, 306, 328, 336, 346, 367, 446, 483, 509, 517, 693, 767, 831, 850, and 860) in all investigated salinity levels, always placed in the top group and therefore they were selected as the superior genotypes of brassicas.
Conclusion: In total, the results of this experiment showed that among the investigated genotypes, 15 genotypes were always placed in the top groups at all levels of salinity stress. Among the selected genotypes, 7 genotypes of B. napus L., 6 genotypes of B. juncea L. and 2 genotypes of B. rapa L. were present. There were any genotypes of B. nigra L. The results indicated that these genotypes had a high ability to germinate and produce strong seedlings in both normal and saline conditions and can be used for further researches and breeding programs.
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