Evaluation of yield and quality of some air-cured tobacco cultivars as affected by root-knot nematode M. incognita race 2 in Golestan province

This experiment was performed to study the reaction of some air-cured tobacco varieties (including Burley 1, Burley 151, Burley 7, BB16 A and Burley 21) to root-knot nematode during growing season of 2015. The experimental design was randomized complete block with 3 replications of 8 × 5 m2 plots in the village of Valshabad (Gorgan) with natural soil infestation. At the end of growing season, the plants were pulled out of soil. Nematodes in the soil and root samples were extracted by Jenkins and Coolen extraction methods, respectively. Disease severity was evaluated based on gall index, reproduction factor, and the number of nematodes in 500 g of soil and its root content. The plant agronomic traits such as leaf length, leaf width, number of leaves, plant height, green and dry leaves (cured leaf) yields, and sugar and nicotine content were recorded and the price per kilogram of dry weight and net income were calculated accordingly. Statistical analysis was performed using MSTATC software. The results showed that Burley 21 with gall index and sensitivity index as 8 was the most sensitive variety to M. incognita (race 2). Burley 1 and Burley151 varieties with sensitivity index as 4.5 and gall index as 3; and BB16 A and Burley 7 varieties with sensitivity index as 4 and gall index as 2 were accommodated under moderately resistant group to M. incognita.