Possível causa do insucesso de se cultivar cafeeiros adultos em soluções nutritivas do tipo Hoagland

Abstract

Since 1946 several attempts have been made to grow coffee plants (Coffea arabica L. var. bourbon (B. Rodr.) Choussy) in Hoagland's nutrient solution. Growth of the plants is quite satisfactory in the early stages, but a rather sudden decline followed by death usually occurs when they start flowering at the age of 3 or 4 years. Preliminary observations made following the addition and withdrawal of NH4NO3 and KCl (0,125 g/l each salt) to nutrient solutions in which coffee trees at the critical age were growing showred a correlation between the addition of these salts and a satis-factory growth of the plants. These observations suggested that the decline of coffee plants growing in Hoagland's nutrient solution when they begin to flower might result from an insufficiency in the reducing power of the roots during this period. In this case the roots would be unable to use the nitrates and nitrites that would thus become toxic to them. This possibility is being further investigated.