Relationship between tolerance to aphid (Myzus nicotianae Blackman) of oriental tobacco genotypes and some chemical and morphological traits of tobacco

In this study tolerance of 36 oriental tobacco genotypes to aphid was evaluated under field conditions at Tirtash Research & Education Center Tirtash,Iran during 2006. The evaluation method consisted of natural infestation of host plant and abundance of aphids on the tip of leaf. Based on the means of abundance in peak of aphid population, genotypes Basma 12-2 and Basma Mahalades were ranked as moderately. To study the relationship between tolerance of tobacco genotypes and morphological and chemical traits, percent of sugar, nicotine, total nitrogen, resin, height of plant, length, width, number, colour and thickness of leaves were measured. Results showed significant differences among the genotypes regarding these traits. Analysis of correlations revealed that genotypes having more percent of sugar in leaves and less thickness leaf were relatively more tolerant