Parasitic interactions of Orobanche with selected Nicotiana species and identification of effective resistant genotypes

Abstract

Tobacco is an important commercial crop in India and other parts of the world. Recently, Orobanche cernua Loefl. (broomrape), a total root parasite is causing considerable yield losses to tobacco crop cultivated in India. Control strategies focusing largely on agronomic practices are not successful in achieving its control. Unfortunately there is no tobacco variety having good levels of resistance to O. cernua is available for managing its menace. Due to lack of the availability of O. cernua resistance even in germplasm of cultivated tobacco species, a study was conducted with seven selected species of Nicotiana viz., N. repanda Lehm., N. benthamiana-repanda, N. nesophila, N. umbratica-nesophila, N. stocktonii, N. paniculata L. and N. tabacum L. cv Siri for identifying Orobanche resistance for further utilization in transferring resistance factors to cultivated tobacco. Emergence of higher number of Orobanche and reduction in plant height and weight in N. paniculata, N. repanda, and N. tobacum cv. Siri indicated they are susceptible. Higher reduction in plant height and weight with less number of Orobache shoots N. stocktonii proved to be a susceptible species. With relatively low reduction in plant height and weight under O. cernua treatment, N. benthamiana-repanda and N. nesophila can be considered as tolerant species. N. umbratica-nesophila with less number of Orobanche spikes, higher plant height and dry weights under both control and treated conditions can be considered as a resistant species and can be used in breeding resistant cultivars. Resistant/tolerant species either increased or maintained their nutrient uptake abilities under parasite infestation thereby maintained their growth.