Evaluation of the effect of broomrape on some morphological characteristics of oriental tobacco genotypes by REML method

Among biotic and abiotic stresses, broomrape (Orobanche cernua L.) is the most important factor in reducing the yield of tobacco plant, so it is necessary to determine the genotypes that produce relatively acceptable yield under stress conditions. In order to identify tolerant genotypes to broomrape stress, 92 tobacco genotypes were investigated based on randomized complete block design with three replications in two control (without broomrape) and stressful (along with broomrape) environments at the research farm of Urmia tobacco research Centre during two successive years in terms of flowering date, plant height, leaf number, fresh and dry weight of root, leaf area, fresh and dry weight of leaf, fresh and dry weight of plant aerial parts. Broomrape stress was applied by mixing 0.06 grams of broomrape seeds with pot soil. The results of analysis of variance in the two experimental environments during two years showed that there is not significant difference between the experimental environments for most of the studied traits. There was a significant difference between genotypes for all of the studied traits. Genotype × environment interaction was significant for all of the studied traits indicating the presence of different reaction of genotypes within each environment. Mean comparisons showed that broomrape stress reduced the mean of all morphological traits. So that the fresh weight of shoots except leaf (23.50%) and dry weight of shoots except leaf (23.70%) had the highest decrease percentage; whereas flowering date (-0.7%) and number of leaves (5.02%) had the lowest decrease percentage. In general, based on the results of the percentage reduction of mean of studied traits, it was found that C.H.T.283-8, Kharmanli, Immni 3000, F.K.40-1, Pz17, K.B, L 16a, Rustica, C.H.T.209.12e, C.H.T.283-8, Basma 181-8, SPT 413, T.K.L and Samsun 1 are among the most susceptible genotypes to broomrape stress. While Ploudive 58, Ts 8, Mutant 3, OR-379, P.D.328, Jahrom14 and Lengeh genotypes did not show any decrease in any of the traits and are tolerant genotypes to broomrape stress.