No presente trabalho foram estudadas as variações nos teores dos nutrientes nas folhas de mudas de cafeeiro (Coffea arabica L. cv. catuai) em função das quantidades de cloreto e de sulfato de potássio aplicadas, acompanhadas de observações sobre os sintomas de toxicidade e sobre o desenvolvimento das plantas. O ensaio foi instalado em vasos, em casa de vegetação, constando de 12 tratamentos com cinco repetições, e o solo utilizado procedeu do grande grupo Latos-solo Vermelho-amarelo, Orto. Foram determinados nas folhas, os teores de macro e micronutrientes. Altos teores de Cl foram relacionados com sintomas de redução no crescimento, necrose e desfolhação. Foi estabelecido um limite de toxicidade para o cultivar estudado. Em função dos tratamentos, houve alteração nos teores de K, Ca, P, S e Cu, principalmente.

An experiment was carried out in order to study the quantitative changes in the nutrient content of plants (Coffea arabica L. cv. catuai), as function of the amounts of KC1 and K2SO4 applied to the soil. Throughout the experiment, the plants were observed for toxicity effects upon growth and development. Chlorine in the leaves increased with increasing amounts of KC1 applied to the soil. There was a relationship between high concentrations of Cl in the leaves and reduced growth, necrosis and defoliation. No injurious effects of Cl were observed for levels up to 7600 ppm for all the leaves or for levels up to 9400 ppm in the leaves from the lower third of the plant. The antagonism between K and Ca was confirmed and plants receiving KC1 had less P in the leaves than the ones which received K2SO4. In these, however, P decreased with increasing applied K2SO4. Plants receiving KCl had greater concentrations of Cu in the leaves than K2SO4 - fertilized plants. In all treatments, Cu and Zn accumulated more in the stems than in the leaves.

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.

It has been noticed in the greenhouse of the "Instituto Agronômico de Campinas" that many species of plants developed poorly when planted in seed beds that have been repeatedly used without change of soil. In many cases even the seeds would not germinate in such seed beds. Experiments have showed that the; lack of normal plant development in these beds is the result of the increase in soil salinity. This salinity may be due to additions of fertilizers or to salts introduced in the ordinary applications of water. It was found that the soil solution had an osmotic pressure of 13.5 athmospheres at the wilting point. The tests showed that common bean (Phaseolus vulgaris L.) plants were more susceptible to the soil salinity than were the soybean and the corn plants. Floading of those seed beds several times resulted in the leaching of salts and the restoring of conditions favorable for normal plant growth.

Moderate amounts of KH2PO4 (0.5 to 0.7 millimols) caused iron chlorosis of seedlings in solutions less acid than pH 5.5-6.0. The trouble could be avoided by omitting the phosphorus entirely and adding it separately after 2-4 days. Even with this modification the Knop type of solution (Hoagland, 2) caused persistent chlorosis in soybeans and broccoli. In the commonly used Shive solution (R5-C2) a large excess of KH2PO4 holds the pH of the solution between 4.5 and 5.0 and chlorosis is moderate to slight. The Shive solution contains 36 times as much phosphorus as the Hoagland and 6-week-old plants growing in it absorbed 15 times as much to make a slightly poorer growth. The addition of as little as 0.125 g per liter of NH4NO3 resulted in decidedly acid solutions in every experiment with nine plant species representing seven families. Initial pH's of 5.25 in an unbuffered solution fell to minimums of 3.9 to 2.9 and then rose, to pH 5.0 or 6.0 with large plants. The low pH's were shown to be due to a preferential absorption of NH+4 ion and the later rise to the slower absorption of the NO-3 ion. The use of NH4NO3 prevented iron chlorosis with some plants, notably soybeans, but resulted in acidities which were injurious to young corn and to cotton. In work done in this series but not described above, the "X" solution containing NH4NO3 gave exceptional growth of young coffee (Coffea arabica), but was toxic to older plants. It is probable that iron chlorosis has more effect on solution culture results than any other single factor, and frequently than all other factors. Iron absorption from cultures is reduced by phosphorus, probably by H2PO-4 ions especially, at pH's of about 6.0 or higher. The use of Ca3(PO4)2 reduces the trouble as does the use of enough KH2PO4 to maintain a pH below 5.5. In tank culture H2SO4 may be used more cheaply to accomplish the same result. In miscellaneous work with the Knop type of solution chlorosis can be reduced or prevented by omitting phosphorus from the solution and adding it separately 2-4 days later after iron has been absorbed.