Reza Darvishzadeh *1 
, Mona Bordbar1 , Hamid Hatami Maleki2 , Maryam Tahmasbali1 , Amir Fayaz Moghaddam1
, Mona Bordbar1 , Hamid Hatami Maleki2 , Maryam Tahmasbali1 , Amir Fayaz Moghaddam1
1- Urmia University
2- University of Maragheh
2- University of Maragheh
Abstract: (88 Views)
Abstract
Introduction and Objectives: Tobacco (Nicotiana tabacum L.) with 2n = 4x = 48 chromosomes is one of the most important industrial and economic plants in many countries of the world, which is mainly cultivated for harvesting and collecting its leaves. The performance of tobacco, due to its polygenic nature, is significantly affected by both abiotic and biotic stresses including the weed Orobanche. In this context, the response of varieties to the environment varies depending on the genotype of the cultivar, which is referred to as the genotype × environment interaction. By studying the genotype × environment interaction and analyzing stability, it is possible to select genotypes that have satisfactory performance in various environmental conditions. Although there are many reports on the use of stability methods in assessing the response of plants to the environment, there are no reports on the stability of dry leaf yield of tobacco across environments contaminated with weeds. This project aims to evaluate the response of existing oriental tobacco genotypes in the country's tobacco germplasm in two environments: one with Orobanche weeds and one without, in order to identify and select compatible and stable genotypes in the studied environments.
Materials and methods: In this experiment, 92 oriental type tobacco genotypes were evaluated in terms of tolerance to Orobanche stress based on randomized complete block design with three replications. The tobacco genotypes were prepared from the genetic and biological resources bank of Urmia Tobacco Research Center and Tirtash Tobacco Research Institute (Mazandaran). The experiment was conducted in the form of a randomized complete block design with three replications. For cultivation, 10-liter clay pots were selected and filled with soil prepared from the alfalfa field, and the pots were arranged according to the experimental design plan in an open area space in the Urmia Tobacco Research Center. Alfalfa is not the host of Orobanche, and its long-term establishment in the field (usually six years), do not results in any Orobanche seeds dispersion in the soil; therefore, the soil should be almost free of Orobanche seed. In the experiment with Orobanche infection, the soil of the pots before being filling, mixed with 0.06 grams of Orobanche cernua seeds (containing approximately 12,000 seeds) which was collected from the field of Urmia Tobacco Research Center one year before the experiment was carried out. In the north-west regions and especially in West Azerbaijan, this type of Orobanche is predominant on the tobacco and is seen more often in the fields. The seedlings of each tobacco genotypes were prepared in the bed and when the tobacco seedlings reached a height of 12 cm, they were transferred to the pots. All agricultural operations such as transplanting, irrigation, adding soil at the base of the plant and protecting against pests and diseases during the tobacco growing period were carried out according to the existing standards for oriental tobacco. The leaves of tobacco genotypes were harvested at the time of industrial ripening (about 45-50 days after transplanting) in three times, dried in front of the sun and weighed using a digital scale with an accuracy of 0.001 grams. After a simple and combined analysis of variance, the univariate parameters of stability were calculated.
Results: The results of the analysis of variance showed that there was a significant difference between the genotypes of tobacco in terms of all the traits studied, and the interaction effect of genotype x environment was significant for all the traits, which indicates the existence of diversity between genotypes and their different reactions into Orobanche stressed and non-stressed conditions. Mean comparisons showed that the stress of Orobanche reduces the average of all morphological traits. Using stability analysis methods based on variance and regression analysis, genotypes 45, 33, and 78, respectively, had the highest value of the coefficient of variation and, in other words, the lowest amount of stability, while genotype 45 had a higher average than the total average and also, genotypes 75, 53 and 41 are considered stable genotypes due to having the lowest value of stability variance. According to the Plastid and Peterson method (θi), genotypes 75, 55, 53, and 41 have the lowest value of θi, among which genotype 53 is a with average performance higher than the overall average.
Conclusion: The stability indices, with evaluating the stability of genetic materials, can be beneficial to a large extent in optimal and efficient selection of parental genotypes for developing high-yielding and stress-tolerant cultivars. Based on different stability methods, genotype number 53 is introduced as a stable genotype with optimal performance.
Introduction and Objectives: Tobacco (Nicotiana tabacum L.) with 2n = 4x = 48 chromosomes is one of the most important industrial and economic plants in many countries of the world, which is mainly cultivated for harvesting and collecting its leaves. The performance of tobacco, due to its polygenic nature, is significantly affected by both abiotic and biotic stresses including the weed Orobanche. In this context, the response of varieties to the environment varies depending on the genotype of the cultivar, which is referred to as the genotype × environment interaction. By studying the genotype × environment interaction and analyzing stability, it is possible to select genotypes that have satisfactory performance in various environmental conditions. Although there are many reports on the use of stability methods in assessing the response of plants to the environment, there are no reports on the stability of dry leaf yield of tobacco across environments contaminated with weeds. This project aims to evaluate the response of existing oriental tobacco genotypes in the country's tobacco germplasm in two environments: one with Orobanche weeds and one without, in order to identify and select compatible and stable genotypes in the studied environments.
Materials and methods: In this experiment, 92 oriental type tobacco genotypes were evaluated in terms of tolerance to Orobanche stress based on randomized complete block design with three replications. The tobacco genotypes were prepared from the genetic and biological resources bank of Urmia Tobacco Research Center and Tirtash Tobacco Research Institute (Mazandaran). The experiment was conducted in the form of a randomized complete block design with three replications. For cultivation, 10-liter clay pots were selected and filled with soil prepared from the alfalfa field, and the pots were arranged according to the experimental design plan in an open area space in the Urmia Tobacco Research Center. Alfalfa is not the host of Orobanche, and its long-term establishment in the field (usually six years), do not results in any Orobanche seeds dispersion in the soil; therefore, the soil should be almost free of Orobanche seed. In the experiment with Orobanche infection, the soil of the pots before being filling, mixed with 0.06 grams of Orobanche cernua seeds (containing approximately 12,000 seeds) which was collected from the field of Urmia Tobacco Research Center one year before the experiment was carried out. In the north-west regions and especially in West Azerbaijan, this type of Orobanche is predominant on the tobacco and is seen more often in the fields. The seedlings of each tobacco genotypes were prepared in the bed and when the tobacco seedlings reached a height of 12 cm, they were transferred to the pots. All agricultural operations such as transplanting, irrigation, adding soil at the base of the plant and protecting against pests and diseases during the tobacco growing period were carried out according to the existing standards for oriental tobacco. The leaves of tobacco genotypes were harvested at the time of industrial ripening (about 45-50 days after transplanting) in three times, dried in front of the sun and weighed using a digital scale with an accuracy of 0.001 grams. After a simple and combined analysis of variance, the univariate parameters of stability were calculated.
Results: The results of the analysis of variance showed that there was a significant difference between the genotypes of tobacco in terms of all the traits studied, and the interaction effect of genotype x environment was significant for all the traits, which indicates the existence of diversity between genotypes and their different reactions into Orobanche stressed and non-stressed conditions. Mean comparisons showed that the stress of Orobanche reduces the average of all morphological traits. Using stability analysis methods based on variance and regression analysis, genotypes 45, 33, and 78, respectively, had the highest value of the coefficient of variation and, in other words, the lowest amount of stability, while genotype 45 had a higher average than the total average and also, genotypes 75, 53 and 41 are considered stable genotypes due to having the lowest value of stability variance. According to the Plastid and Peterson method (θi), genotypes 75, 55, 53, and 41 have the lowest value of θi, among which genotype 53 is a with average performance higher than the overall average.
Conclusion: The stability indices, with evaluating the stability of genetic materials, can be beneficial to a large extent in optimal and efficient selection of parental genotypes for developing high-yielding and stress-tolerant cultivars. Based on different stability methods, genotype number 53 is introduced as a stable genotype with optimal performance.
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