Bragantia
URI permanente para esta coleçãohttps://thoth.dti.ufv.br/handle/123456789/9887
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Item Sintomas de deficiências minerais no cafeeiro(Instituto Agronômico (IAC), 1949) Franco, C. M.; Mendes, H. C.Coffee plants (Coffea arabica L.) were grown in nutrient solutions for the purpose of studying deficiency symptoms of the following elements : nitrogen, phosphorus, potassium, magnesium, calcium, sulphur and iron. The methods employed in the growing of coffee plants in the nutrient solutions are described. After preliminary tests with several nutrient solutions Hoagland's formula was selected as most suitable for the present tests. However, the quantity of phosphate employed in the basic nutrient solution was reduced to one third of that given in Hoagland's formula. This reduction in phosphate was made because of the previous results obtained by Jacob which seemed to indicate that the coffee plant requires only very small amounts of phosphorus. In the present tests phosphorus deficiency symptoms were obtained and these results suggest that Jacob's failure to obtain phosphorus deficiency symptoms may be ascribed to use of Shive's solution, which has a very high phosphate content. While growing in this complete nutrient solution his plants may have stored enough phosphorus to supply their needs later when they were transferred to the solution lacking this element. In the course of the present investigation it was found that in the nutrient solutions containing KH2PO4 and having a pH higher than 5.5, the coffee plant absorbs insufficient iron. This difficulty of iron absorption by the coffee plants grown in nutrient solution was overcome by a technique previously described that is, when iron deficiency symptoms appeared on plants being tested for other deficiencies the nutrient solution was changed and the new solution used contained no phosphate. The plants were allowed to grow in this solution for two to four days and then the phosphate was added. In this way the plants absorbed sufficient iron for their requirements. The present paper describes and the color plates illustrate the symptoms on coffee plants that were associated, in the present studies, with nutrient solutions deficient in the various elements listed.Item Sistema radicular das principais leguminosas empregadas como adubo verde em cafezal(Instituto Agronômico (IAC), 1952-07) Scaranari, H . J .; Infobzato, R .Root .systems of the following leguminous plants used for green manure in coffee plantations were studied :- Canavalia ensiformins D. C., Crotalaria juncea L., Styzolobium sp (Mucuna anã) and Glycine max (L). Merrill var. Otootan.. It was noted that the depth of the root system' of each one of the four, espécies is related id the height attained by the; plants. The deepest, root system was found to be thatf of Crotálaria juncea, followed by Canavalia esiformis, soybeans and mucuna anã. For coffee green manure purposes it is concluded that the four studied leguminous espécies can be used safely even having .most of their root system located in the first 30 cm of the soilItem Possível causa do insucesso de se cultivar cafeeiros adultos em soluções nutritivas do tipo Hoagland(Instituto Agronômico (IAC), 1956-04) Mendes, Heli CamargoSince 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.Item Clorose das folhas do cafeeiro excelsa(Instituto Agronômico (IAC), 1951-07) Costa, A. S.; Mendes, J. E. TeixeiraA type of leaf chlorosis is shown by plants of excelsa coffee growing in nursery beds in a lath house at the Instituto Agronômico, Campinas. Tests made with various elements showed that this type of chlorosis is due to iron deficiency. Seedling plants of arabica coffee growing in the same beds do not show chlorosis, but these symptoms are exhibited by arabica scions grafted on some excelsa rootstocks. Scions from chlorotic excelsa plants recover the normal color when grafted on arabica rootstock. Likewise, arabica scions that had become chlorotic after being grafted on excelsa rootstock recovered when transferred onto an arabica rootstock. Other grafting tests indicated that no pathological cause seems to be associated with this type of chlorosis, and that it is probably due to genetical characteristics of the excelsa root system that prevents the plants from absorbing enough iron from the soil imder marginal conditions.