بررسی تنوع ژنتیکی صفات ریشه در عدس ( (Lens culinaris Medik

Introduction
Lentils are one of the most important legumes. Many researches have been done about the aerial parts of plants. Stresses are the most important cause that cause problems in agricultural production in different ways, and drought stress is one of these stresses. The main limiting factor for plant growth is the available water, the maximum yield in terms of growth and production is achieved when the limited water in the soil is absorbed to the maximum. Considering that more than 80% of lentil cultivation in the country is in the dry season, dryness and lack of water in the soil have the greatest effect on reducing the yield of this plant in different stages of plant growth and development.However, less attention has been paid to aspects of root growth on which the whole plant structure depends. This issue is caused by the problems related to root study due to its underground condition. Efficient absorption of water by roots is an important characteristic for drought resistance. The absorption of water by the plant depends on the size of the root (length or weight), its activity and distribution in the soil. Studies have shown that root characteristics such as depth, volume, xylem diameter and dry weight have a high diversity. Water absorption by the plant depends on the morphological characteristics of the root, its activity and distribution in the plant. Therefore, it seems that to better understand the mechanisms of plant resistance to drought and to obtain the genetic resources needed in breeding programs. It is necessary to understand the morphological traits related to drought resistance, especially the traits related to plant roots. Considering that limited information is available about the diversity of lentil root traits, in the present study, the diversity of root morphological traits among a number of lentil genotypes is studied.

Methodology
Considering the importance of root characteristics in lentils and their effect on plant performance and avoiding drought stress. In order to find the genetic diversity between root traits in 23 lentil genotypes, an experiment was conducted in the form of a completely randomized design with four replications in the research greenhouse of Ilam University. In this experiment, PVC pipes with a diameter of 10 cm and a length of 60 cm, which were filled with 75% of air sand and 25% of soil, were used for cultivation. Irrigation was done twice a week. Seedlings were thinned at the stage of 2 to 3 leaves. 30 days after the germination of the seeds, the aerial parts were separated and then the roots were separated from the airy sand bed by pressurized water. Root dry weight, root length, root volume, root freshness, root surface, root specific length, root diameter, root specific volume, root water content, root tissue density, root volume density, root length density, root density, root surface density and dry weight were measured. A ruler measured the length of the roots with high precision. After, roots were placed in the water to float them. After the aerial parts of the plant were separated, the roots were washed and transferred to the laboratory, and then a digital scale measured the wet weight of the roots with an accuracy of one thousandth. Root volume was measured using a graduated cylinder.Then the roots were placed in the oven at 70 degrees Celsius for 48 hours and after the desired time, they were weighed by a digital scale with an accuracy of one thousandth. Also, the aerial parts of the studied genotypes were placed inside an electric oven with a temperature of 70 degrees Celsius for 48 hours, and after the desired period of time, the dry weight of the aerial parts was calculated by a digital scale with an accuracy of 1,000 grams. The rest of the traits were measured by the parameters and calculated with the help of the formula.At the end, variance analysis of completely random block design and average comparison between traits by Duncan's method at a statistical level of 5% was done using SAS V.9.4 software.

Conclusion
According to the results of variance analysis of the data of this experiment, it was found that there is a significant difference between the genotypes in most of the root traits at the 1% level. Sepehr genotype has the highest amount of shoot dry weight (0.056) and the highest amount of root tissue density (108. 0); FILIP2012-2L genotype had the highest root density (0.21 cm3). ILL8006 genotype also had the highest root surface density (4.63), root diameter (0.035), root specific volume (0.00025) and root fresh weight (1.15). The highest amount of root vigor (459.30 and root length (55.71 cm) belongs to FILIP2014-02IL genotype. The highest root volume density (0.00027) was observed in FILIP2014-72L genotype. FILIP2014-103L genotype has the highest value of root length density was (0.032) and root surface (313.46). The highest value of specific root length (1645.8) and root volume (2.49 cm3) belonged to the genotype FILIP2007-95L. The amount of root water content (33.71) was observed in genotype 316-6.Genotype FILIP97-10L had the highest amount of root dry weight (0.053).Considering the existence of genetic diversity between root traits in the studied genotypes. Root length is one of the most important physiological and morphological characteristics of drought resistance. Cultivars with longer root length germinate usuallyfaster than cultivars with shorter root length and are more resistant to drought. Root volume is one of the most important traits in terms of water and food absorption. Therefore, it is a good measurement unit for the relationship between roots and aerial organs.The absorption of water by the plant depends on the size of the root such as the weight and length of the root and the distribution and activity of the root in the soil. Therefore, to understand more the concepts of resistance mechanisms and to find the genetic resources needed for breeding programs, it is necessary to understand root traits that are related to drought resistance, such as root water, content.the existing diversity can be used to improve varieties resistant to drought stress in lentil.