Ann. Tabac, 1986, Sect. 2-20, p. 5-57., ISSN.0399-0354

A partial study of nitrate reductase activity in Virginia tobacco

IBRAHEEM S.M.
Institut Expérimental du Tabac, Bergerac, France
After initially defining the parameters for measuring nitrate reduction ïn vivo", the author studied the influence of different factors in nutritive mediums, on nitrate reduction using very young tobacco seedlings of the Virgin D variety. Nitrate reduction and evolution throughout the vegetative plant life of tobacco in fields cultivated in the traditional french manner are also described. In young seedlings, the type of nitrogen fed had little influence on NaRA, molybdenum, a cofactor of the enzyme, does not appear to intervene except at very weak doses : its suppression in the nutritive solutions had little effect. Triadimenol, a fungicide, and tungsten had an important inhibitor effect. In field tobacco of the Virginie D cultivar, NaRA was at a maximum when the transplanted seedlings took roots. Afterwards, it steadily decreased until the leaves were harvested with two slower stages, one when floral buds appear and the other after topping. Towards the end of vegetative life NaRA potential remained relatively high and seemed capable of assuring a late assimilation of nitrogen.