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-INTRODUÇÃOO estudo da transpiração das plantas interessa à agronomia sob diversos aspectos. O conhecimento, pelo menos aproximado, da quantidade de água retirada do solo, pela transpiração da planta, é uma necessidade básica na elaboração de projetos de irrigação. No caso do cafeeiro (Coíjea arábica L.), este Instituto já iniciou estudos agronômicos sobre a irrigação desta cultura. Pelos resultados preliminares e pela situação atual da lavoura, tudo indica que a irrigação dos cafezais se desenvolverá grandemente em futuro próximo. Há, pois, interesse em estudos visando a determinação da quantidade de água transpirada pelo cafeeiro, em condições de cultura. Além disto, para o prosseguimento dos trabalhos sobre o sombreamento dos cafezais em andamento na Secção de Fisiologia é de grande valor o conhecimento aproximado da quantidade de água retirada do solo pelo cafeeiro e pela árvore de sombra.Convém lembrar que nenhum dos métodos existentes para a medida da transpiração das plantas satisfaz plenamente, quando se trata de medir a transpiração in loco, nas condições de cultura. Todos são mais ou menos falhos e sujeitos à crítica. Devido a isso e também ao fato de serem tantos e tão variáveis os fatores que influem sobre a quantidade de água retirada do solo por uma cultura, os resultados obtidos de estudos desta natureza não devem ser tomados como exatos, mas, apenas, como indicadores da ordem de grandeza do fenômeno.Neste trabalho tratamos da medida da quantidade de água transpirada pelo cafeeiro cultivado ao sol, em todos os meses do ano. -MÉTODOS 2.1-PESAGEM RÁPIDA DAS FOLHASInicialmente, tentamos empregar o método de pesagem rápida das folhas, idealizado por Pfaff (3) e melhorado por Hüber (5) e que Rawitscher (4) iá empregou em folhas de cafeeiro. Este método baseia-se no fato consta-

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Two of the more popular solutions for experimental culture of plants show a striking yariation in the amounts of phosphorus used. Shive's socalled best solution, R5-C2 (4) contains 2.45 gm. per liter or 0.018 mols of KH2PO4, partly as a source of phosphorus, but more perhaps as an acid buffer tending to maintain the solution at pH 4.5-5.0. Hoagland's 1940 solution (2) on the other hand contains only 0.068 gm. per liter or 0.0005 mols of the same salt. The Shive solution thus contains 36 times as much phosphorus as the equally successful Hoagland solution. As a portion of a general study of ion balance in nutrient solutions we have compared the growth, color and phosphorus absorption of several plants in these mixtures and in two experimental solutions; the first ("X") somewhat resembling the Hoagland solution, but carrying more than half of its nitrogen as NH4NO3, and the second ("P") being a modification of Zinzadze's buffered solution (6) carrying a moderately high concentration of phosphorus as a colloidal precipitate of the tricalcium salt and with the nitrogen again added as NH4NO3. Methods Plants were grown in quart mason jars with cork stoppers (3). Four seedlings in each jar were thinned to two to obtain maximum uniformity. Five replicates were used for each treatment and some of the experiments were repeated as many as five times. Corn (Zea mays), broccoli (Brassica oleracea var. italica), soybeans (Glycine max), tomatoes (Lycopersicon esculentum), sunflowers (Helianthus annuus), cotton (Gossypium hirsutum), and rice (Oryza sativa) were used in a main test of growth rates in April and May of 1945; corn, soybeans, and rice were used in June and July of the same year for studies of phosphorus absorption. Some of the plants were grown to fruiting, but, because of the small size of the culture jars, most of the work, including the phosphorus analyses, was done with plants 4 to 6 weeks old. Concentrations of the salts used in grams per liter and of the various ions in millimols are shown in table I. Iron was furnished by 10 ml. of a 0.1% solution of ferric tartrate at each change of solutions and by 1.0 ml. additions of the same solution one to three times a week as required. All solutions received 1.0 p.p.m. of boric acid and 0.5 p.p.m. of ZnSO4 at each change. After the seedling period of 2-3 weeks, solutions were changed at

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

O presente estudo foi executado com o objetivo de pesquisar a possibilidade de aumentar a produtividade de cafèzais velhos, sem emprêgo de matéria orgânica trazida de fora. Foram estudados N, P, K, micronutrientes (zinco, cobre e boro) e adubação verde. Utilizou-se um delineamento fatorial 3² X 2², em blocos de 18 canteiros com nove plantas cada um, com bordadura de uma planta entre os canteiros. O ensaio foi instalado na Estação Experimental de Ribeirão Prêto, em um cafèzal com mais de 40 anos de idade, em terra-roxa-legítima, e cuja produção média nos quatro anos anteriores foi de 24 sacos de café em côco por mil pés. Obteve-se grande aumento de produção com o emprêgo de nitrogênio, devido não só às quantidades aplicados, mais elevadas do que as até então recomendadas, mas principalmente à sua aplicação parcelada. Os aumentos devidos ao nitrogênio na dose de 360 g de N por planta, na forma de sulfato de amônio, corresponderam a 6, 11, 13, 16 e 34 sacos de café em côco por mil pés, nos anos de 1954 a 1958. A dose mínima de potássio empregada foi de 120 g de K(2)0 por planta. A dose de 240 g de K(2)0 por planta ainda proporcionou um aumento de produção de 9% em relação à anterior. Não houve reação ao fósforo nem à adubação verde. A aplicação de micronutrientes (zinco, boro e cobre) fêz desaparecer os sintomas de deficiência de zinco, mas resultou em decréscimo significativo da produção. A aplicação do nitrogênio melhorou a coloração e o desenvolvimento da folhagem. Não houve influência dos outros fatôres sôbre o aspecto vegetativo das plantas.

The coffee plant does not thrive well under shade in most of the coffee areas of the State of São Paulo, Brazil. It has been shown that water competition from the shade trees during the dry season is the factor responsible for the failure in growing coffee under shade in São Paulo. In all cases where the coffee plants were not thriving well under shade, the soil moisture after two to three months of drought was at the wilting point at the depths most utilised by the root systems of shade trees and coffee plants. In open plantations this was never observed. All commercial coffee plantations of Central America are shaded. Most of them are located in areas with a dry season as long as in São Paulo and some times even longer. A comparative study of the climatological factors, methods of cultivation and most common species of shade trees was made. No one of these factors explained the different behavior of the coffee plant under shade in Central America and in São Paulo. The available soil water was measured in many coffee plantations in Costa Rica and El Salvador after four months without apreeiable rainfall. In all cases it was' found that, the actual moisture percentage was considerably higher than the wilting point. The amount of available water held by soils in São Paulo and Central America does not seem to be significantly different, although this was not carefully determined. It is suggested that a comparative study of the moisture-tension curves of soils of São Paulo and Central America might explain the different behavior of the coffee plant with shade under these two different conditions. It is possible that, as a consequence of a much steeper moisture-tension curve, the plants in São Paulo soils transpire freely until the soil moisture reaches the wilting point. This would result in a rapid soil water consumption. If the Central American soils have a smoother moisture-tension curve, the Avater absorption and transpiration rate by plants may be slower and as a consequence the available water may last longer in the soil. The ratio of the moisture equivalent to the wilting point was found to be around 1.29 for the soils studied in the Meseta Central of Costa Rica, around 1.44 for those in El Salvador and 1.94 for the ashy soils in the vicinity of San Salvador volcano