Biologia de Anofelinos Amazônicos. VI. Variabilidade Enzimática em ANOPHELES DARLINGI Root. (DIPTERA, CULICIDAE)

São relatados resultados preliminares sobre o polimorfismo protético de populuções naturais de Anopheles darlingi, procedentes de duas localidades da região amazônica-Ariquemes (Rondônia) e Rodovia PA-422 (Pará). Pata as esterases, foi detectada variação para o locus Est-2na população de Ariquemes, enquanto foi monomórfico na população da PA-422, sendo verificados nesta última, apenas indivíduos com o genótipo Est2*F/Est2*F. A freqüência do alelo Est2*F foi estimada em 0,80 na população de Ariquemes, valor este muito maior do que o observado na população da BR-174 (Manaus/Boa Vista), em estudos anteriores, que foi de 0,48. Os resultados para o sistema da leucina aminopeptidase (LAP) sugerem que a enzima é controlada por três loci, aparentemente monomórficos em ambas as populações.

Análise química e perfil farmacológico do Erythroxylum argentinum

Foram efetuados estudos químicos e farmacológicos dos extratos brutos hidroalcóolicos obtidos das folhas ou das raízes de E. argentinum ou de frações semi-purificadas desta planta. Os testes químicos revelaram a existência de alcalóides, fitoesteróides, leucoantocianidinas, glicosídeos flavonóides, cumarinas e taninos. A análise farmacológica in vivo demonstrou que o extrato das folhas é menos tóxico que o da raiz. Tanto o extrato bruto como as frações semi-purificadas obtidas das folhas reduziram a locomoção e pressão arterial de rato e potenciaram o sono barbiturico em camundongos. O extrato bruto, principalmente o da raiz, reduziu o edema induzido por carragenina na pata de rato. Testes in vitro demonstraram que o extrato bruto ou as frações semi-purificadas das folhas produziram uma ação semelhante à cocaína avaliada no canal deferente de rato. Além disso, o extrato bruto produziu relaxamento inespecífico no útero de rata e contração do íleo de cobaia. Os resultados obtidos sugerem que esta planta possui constituintes ativos dotados de distintas propriedades farmacológicas, destacando-se o efeito anti-inflamatório, além de uma ação tipo cocaína, merecendo, portanto, estudos químicos e farmacológicos complementares.

Produtos e subprodutos da medicina popular comercializados na cidade de Boa Vista, Roraima

O objetivo deste estudo foi identificar produtos e subprodutos de origem animal e vegetal utilizados na medicina popular que são comercializados na cidade de Boa Vista, Estado de Roraima, traçando um perfil preliminar de sua forma de comercialização. Foram identificados 117 produtos : 100 (85,5 %) de origem vegetal e 17 (14,5 %) de origem animal. Os produtos de origem vegetal de maior destaque foram o Jatobá (Hymenaea courbaril), o Barbatimão (Stryphnodendron adstrinfens), a Sucuba (Himatanthus articulatus), o Xixuá (Maytenus guianesis), a Copaíba (Copaifera officinalis) e a Pata-de-vaca (Bauhinia ungulata). A banha de Pirarara (Phractocephalus hemioliopterus) foi o produto de origem animal mais procurado pelos usuários. A maioria dos produtos identificados são originários da região Nordeste do Brasil, embora Roraima possua uma rica flora medicinal , porém, pouco explorada de forma comercial.

Efeitos do arsênico sôbre a cultura do algodoeiro em terra arenosa

The authors studied the action of arsenic, in the form of lead arsenate and sodium arsenite, on cotton in white sandy soil of Piracicaba, State of S. Paulo, Brazil. The experiment was carried out in Mitscherlich pots, applying increasing quantities of the above mentioned compounds. The following conclusions were reached: sodium arsenite is more toxic than lead arsenate. 48 pounds per acre of lead arsenate and 16 pounds per acre of sodium arsenite reduced the vegetative development and the production of cotton. The roots were more seriously affected than the aerial parts. Sandy soils were sensitive to arsenic toxicity. The arsenic mobilization in the soil seems to depend upon factors such as, the a- cidity, the concentration of Fe2O3, CaO, P2O5 and soil colloids, both clay and humus components. The authors suggest, based on their own experiment and after a detailed study of the literature, the use of organic insecticids which may not leave toxic residues, rotation of crops, application of lime and reduction of arsenical sprays to a mini mum. Arsenic compounds should not be used in soils destined to the cultivation of food plants. Rice should not be planted in soils contaminated by arsenic compounds during several years of cotton cultivation. Future experiments are planed, using other soils such as "terra roxa", in Mitscherlich pots and in field plots.

O tratamento de pré-emergência com o 2, 4-D no milho

In order to study the action of herbicides - sodium salt, amine salt and ester of 2,4-D, TCA and 2,4,5-T a preliminary experiment for pre-emergence weed control was corried out, and the corresponding results are given in table I and II. The corn used in the experiments was of the flint type 1A 3531. The loam soil on which the experiment has been carried out is called "terra roxa". All treatments were highly significant when compared with the check plots, except the 2B one in the control of broad leaf weeds, and 4B in the control of grass weeds. Among these treatments there are no significant differences. But we note the following: (table I). a) treatments of higher concentrations were superior to lower ones. b) the treatments which gave the best control for broad leaf weeds were in the following decreasing order: 1A, 5A and 3A. For grass weeds, they were 5A, 1A and 3A. c) the amine 2,4-D (600 grs. per hectare) supplied very good control when we get into consideration that on the acid basis, it was in very low concentration. d) TCA in high concentration affected the germination, growth and yield, in the lower one it did not show good control of weeds, especially of grasses. It is not suitable for pre-emergence control in corn. e) 2,4,5-T was not better than the 2,4-D products. As it is much more expensive than the others, economically its use in pre-emergence weed control in corn is not praticable. f) all the products used controled grass weeds as well as broad leaf ones; this show the superiority of the pre-emergence treatment method over that of post-emergence. g) Even a dose as strong as the treatment 1A (3.400g. of 2,4-D acid per hectare) did not damage corn production (table II). h) the superiority noted in the production of all the treatments with the exception of 2A, which damaged the plants, we atribute to the lack of competion between corn and weeds; all chek-plots suffered this competition, because they were not Probably, there was, also, hormonial effect of 2,4-D on the corn plant. Not withstanding the fact that the present experiment has been successful, we think that new researches are necessary, especially with the purpose of studying factors as climate and soil which in other countries, interferred with the success of the pre-emergence weed control.

Estudos químico-agrícolas sôbre o enxofre

1. Analyses of soluble sulphates in 2 N ammonium chloride extracts of 24 samples of soils of the state of São Paulo, Brazil, S. A., showed a sulphur content varying from 0,0013 g per 100 g (found in the b layer of a genuine "terra roxa") to 0,007 g per 100 g of soil (b layer of a soil of depression without definite characteristics). (The results are expressed as elemental sulphur). Determinations of total sulphur in 56 samples of soils of the same state using the method of fusion with sodium carbonate and sodium nitrate revealed 0.007 g of elemental S per 100 g of soil as the lowest value (found in several soil types) and 0.096 g as the highest one (found in the b layer of an ar-quean soil). Apparently soluble sulphates accumulate in the upper layers and total sulphur does the opposite. It was found a strong correlation between total S and carbon content. 2. Under laboratory conditions, in a compost of fresh soil, powdered sulphur and apatite, it was verified after a three months period of incubation that the pH value lowered from 6.30 to 3.23; the citric acid solubility of apatite increased to 271.1 per cent of the original one. Lupinus sp. grown in soil manured with sulphur and apatite has showed fresh and dry weights higher than the plants in control pots; the results are significant at 5% level of probability; phosphorus content is also higher in the manured plants. It was observed a net influence of the apatite plus sulphur treatment on the weight of root nodosities that was four times greater than in the control plants. 3. Nearly five hundred determinations of S, N and P were carried out in 35 species of plants cultivated in the state of São Paulo. A great variation in the amounts of these elements was observed. As a general rule, the leaves contain more sulphur than the stems and roots show the lowest percentages. The conjunct roots and stem of guar (Cyamopsis psoraloides) revealed only 0.019 per cent sulphur; the leaves of kale showed the highest sulphur content, i. e., 2.114%. Apparently there is no correlation between the amounts of S, N and P. The ratio S/N increases from 0.006 (guar) to 0.485 (kale). The ratio S/P, always higher than the corresponding S/N, increases from 0.082 (guar) to 6.381 (older leaves of tomato plants). It is interesting to mention that several among the most important crops in the state of São Paulo namely, cotton, rice, coffee and sugar cane contain more sulphur than phosphorus. 4. Tomato plants cultivated in nutrient solution lacking sulphur showed the following visual symptons of deficiency : chlorosis first in the younger leaves and afterwards in all the leaves; anthocyanin pigments in the petioles and stems; absence of fruits; primary roots stunted and secondary ones longer than in the control plants; stems slender, hard, woody. The histological study of petioles suffering from sulphur deficiency revealed anthocyanin in the parenchyme layer instead of clo-rophyll pigments observed in normal petioles; in the chlorotic leaves the large chloroplasts present only the stroma but the small ones have a little amount of green pigments. Chemical analysis revealed in the abnormal plants : less sulphur and an increased proportion of phosphorus; older leaves contain more sulphur and less phosphorus than the younger ones probably due to physiological difficulties in translocation of sulphur bearing material; increased amount of total N attributed to accumulation of nitrates; marked decrease in ash, sugars and starch; increased proportion of crude fiber and dry material. In the plants suffering from sulphur deficiency photosyntetic rate decreased 34 per cent. 5. Tomato plants were succesfully cultivated in nutrient solution in absence of mineral sulphur but in presence of cysteine. The plants absorbed sulphur, under that form and were able to grow up quite well; the fruiting was normal. In this way rested cleary demonstrated the possibility of absorption of organic sulphur without previous mineralization and its utilization in the building up of protein molecules.

Efeitos do enxofre e do boro e da inoculação em alfafa (Medicago sativa L.)

This paper deals with the results of a pot and plot experiment which was carried out to determine the influence of sulphur and boron and the effect seed inoculation with Rhizobium meliloti in the yield of alfafa. Sulphur was applied as flower of sulphur at the rates of 1,000 and 2,000 kg por hectare; boron was employed in the proportion of 15 kg of borax per hectare; both sulphur and boron were distributed broadcast before planting; the experimental design chosen for the field trial was a latin square of 6 x 6 with the following treatments: Number Treatment 1 Control 2 One dosis S + inoculation 3 Two dosis S +inoculation 4 One dosis S + B + inoculation 5 B + inoculation 6 inoculation The crop supplied four cuttings in an eleven months period. The pot experiment nearly confirmed the plot one. The following conclusions can be drawn: 1. The classification of treatments in a decrescent order was: l.o - two doses S + inoculation; 2.o - one dosis S +inoculation, S + B + inoculation, and B + inoculation (these treatmente were not statistically different); 3.o - control; 4.o - inoculation; 2 The vield due to the treatment two dosis S + inoculation was 22 per cent higher than the control one, a fact that suggests that the S supply in the soil studied ("terra roxa misturada") is not sufficient for the total requirements of alfafa; 3. From an economical point of view the best treatment was: one dosis B + inoculation which permits a net gain of Cr$ 12.527,30 per hectare per year; 4. Based on the mentioned results we recommend in soils of same type the following fertilization for alfafa. 5 tons limestone/hectare 300 kg serranafosfato and 600 kg hiperfosfato/ha 300 kg muriate of potash/ha 15 kg borax/ha and a medium organic manuring if the soil is very poor in organic matter.

Contribuição ao estudo do «vermelhão» do algodoeiro (Gossipium herbaceum)

During the years 1948, 1949 and 1951 a disease occurred in the cotton crops of the state of S. Paulo Brazil (S. Am.), which caused a severe drop in yields. The abnormality was characterized by a typical reddish - purple color of the leaves, being by this reason, called "vermelhão", that is, reddening of the cotton plant. The disease was associated with a dry season. Among the several hypotheses raised to explain the causes of the disease were: insect attack, potassium deficiency - where from the name "potash hunger" was also given -, and magnesium deficiency: In order to study the problem the Department of Agricultural Chemistry of the College of Agriculture of the University of São Paulo, at Piracicaba, carried out a series of experiments as follows: 1. pot experiments in which soil of one of the affected regions was used ("terra roxa", a red-brownish soil derived from basalt); 2. pot-soil experiments varying the moisture supplied; 3. sand culture experiments omitting certain elements from the nutrient solutions; 4. field plot experiments, conducted on a sandy soil; three different varieties were employed: Texas, Express, and I.A. 817; magnesium was applied either as sulfate or dolomitic limestone. All the experiments were completed with suitable chemical analyses. The results can be summarized as follows: 1. in the first trial, the not properly manured pots (minus Mg), symptoms were registered which were similar to the symptoms observed in the field; it was possible to establish some differences among three different types of reddening: due to lack of K in the mixed fertilizers used, the characteristic cotton rust made its appearance, the red color in the leaves of the minus Mg plants was all alike that described in the current literature as a symptom of Mg-deficiency; in all the treatments ocurred a yellow-reddish color in the leaves associated with the latest stages of maturity; 2. in the second experiment it was verified that when the plants in the pots with soil were kept 75 per cent of the water holding capacity, no symptom of deficiency showed up; was true even for the plants not receiving neither K nor Mg; however, plants supplied with only 25 per cent of the water holding capacity showed, respectively, cotton rust in the minus K treatment and the red purplish color in the minus Mg series; 3. the sand culture experiment confirmed lack of Mg as the cause of "vermelhão", being potash deficiency the responsible for cotton rust; 4. in the field experiment, variety LA. 817 revealed to be the most sensitive to "vermelhão" when Mg was omitted from the fertilizers; symptoms of K deficiency appeared when no K was supplied; both magnesium sulfate and dolomitic limestone proved to be equally effective in the control of "vermelhão"; 5. the analyses of material collected both in the field as well in the pots revealed that leaf petiole in the most reliable part to indicate the K and Mg status of the plant; the variation in Mg content suffered by the plants showing different stages of "vermelhão was, quantitatively, at least as large as that in K content, however when one deals with K deficient plants, that is, plants showing the typical rust, no variation occurred in the Mg content, whereas K in the dry mater dropped from more than 1 per cent to less than half per cent. Then, the following general conclusions can be drawn: 1. Mg deficiency is the cause of "vermelhão" of cotton crops; 2. K deficiency also occurred, but in a lesser degree; 3. the climate conditions - especially the lack of rain influenced the soil dynamic of K, and especially Mg, bringing a severe reduction in their assimilability; 4. the "vermelhão" disease can be easily controlled upon additions either of magnesium sulfate or dolomitic limestone.

Irrigação de alface

The author carried out an experiment of watering of lettuce (Lactuca sativa L.) in the vegetable garden of the Escola Superior de Agricultura "Luiz de Queiroz", with soil of the type know as "terra roxa". Eight treatments, with 4 replications, were used, divided into 3 groups, as follows: Group A - Watering once a day, late, in the afternoon, with 5, 10 and 15 liters per square meter; Group B - Watering twice a day, with 10 and 15 liters per square meter, one half in the morning, one half late in the afternoon; Group C - Watering as in group A, but with a 0.1% Chilean nitrate of soda, every 3 days. The size of plots was 2,0 x 2,0 meters. The means obtained, with their respective standard errors, were the following: Group A- (4295 ± 53 gm.) 5 lit./sq.m. 4120 ± 92 gm. 10 lit./ sq. m. 4248 ± 92 gm. 15 lit./sq.m. 4518 + 92 gm. Group B- (4091 ± 65 gm.) 10 lit./sq.m. 3960 ± 92 gm. 15 lit./ sq. m. 4223 ± 92 gm. Group C- (4490 ± 53 gm.) 5 lit./ sq. m. 4300 ± 92 gm. 10 lit./sq.m. 4480 ± 92 gm. 15 lit./sq.m. 4690 ± 92 gm. Differences between groups, as well as within them were significant, even if within groups B the 5% probability level was not quite reached.

Nitrificação e aproveitamento de alguns adubos nitrogenados

The rate of nitrification of several nitrogenous fertilizers (ammonium sulfate, nitre-chalk, ureia, and cottonseed meal) was studied in three soils, namely, "terra roxa legítima", a red soil derived from basalt, "terra roxa misturada", a soil also derived from basalt but with a higher proportion of sand, and "areito Corumbataí", a sandy soil. The effects of the following treatments on nitrification were considered: addition of limestone of micronutrients (Fe, Cu, Zn, Mn, and Mo), and inoculation with a suspension of spores of Aspergillus wentii, a heterotrophic nitrifier. The results showed that: in "terra roxa legítima" limestone had no influence on the nitrification rate, whereas the micronutrients estimulated the oxidation of nitre-chalk, cottonseed meal and urea; inoculation with A. wentii helped only the nitrification of ammonium sulfate and of the cottonseed meal; the latter, in all the treatments employed gave use to a smaller amount of nitrates; in "terra roxa misturada", all the fertilizers depending upon the treatments they were subjected to, presented maximum values for nitrification; limestone estimulated the oxidation of ammonium sulfate as well as the mineralization of the cottonseed meal; the addition of micronutrients helped the nitrification of all the fertilizers, except that of urea; inoculation showed a benefical influence on the nitrification of ammonium sulfate and cottonseed meal; in "arenito de Corumbatai", the amounts of nitrates produced was roughly the same for all the fertilizers investigated; limestone estimulated the nitrification of nitro-chalk, ammonium sulfate and cottonseed meal whilst the addition of micronutrients benefited only the latter two; the inoculation with A. wentii helped the oxidation of all the fertilizers. In order to study the availability of the various fertilizers above discussed, two plant growing experiments were carried cut, one in pots, using the three soil types and another one in the field, with "terra roxa misturada". In "arenito de Corumbatai" there was no significant difference in the yield both of straw and rice grains for none of the fertilizers: Chilean nitrate of soda was used as a control; ho marked agreement could be detected between the data concerning nitrification and the yield results. In "terra roxa legítima", ammonium sulfate won the competition and there was a good parallelism between nitrification and yield. In "terra roxa misturada", there was no statistical difference among the various fertilizers; the agreement between nitrification and yields was reasonable. In the field (corn), Chilean nitrate, ammonium sulfate and nitro-chalk were clearly beter than urea and cottonseed meal which did not differ from the minus nitrogen plots.

Tracer studies in the coffee plant (Coffea arabica L.)

Due to the great importance of coffee to the Brazilian economy, a good deal of the work carried out in the "Laboratório de Isótopos", E. E. A. "Luiz de Queiroz", Piracicaba, S. Paulo, Brazil, was dedicated to the study of some problems involving that plant. The first one was designed to verify a few aspects of the control of zinc deficiency which is common in many types of soils in Brazil. An experiment conducted in nutrient solution showed that the leaf absorption of the radiozinc was eight times as high as the root uptake; the lower surface of the leaves is particularly suited for this kind of absorption. Among the heavy metal micronutrients, only iron did not affect the absorption of the radiozinc; manganese, copper, and molybdenum brought about a decrease of fifty per cent in total uptake. In another pot experiment in which two soils typical of the coffee growing regions were used, namely, a sandy soil called "arenito de Bauru" and a heavy one, "terra roxa", only O.l and 0.2 per cent of the activity supplied to the roots was recovered", respectively. This indicates that under field conditions the farmer should not attempt to correct zinc deficiency by applying zinc salts to the soil: leaf sprays should be used wherever necessary. In order to find out the most suitable way to supply phosphatic fertilizers to the coffee plant, under normal farm conditions, an experiment with tagged superphosphate was carried out with the following methods of distribution of this material: (1) topdressed in a circular area around the trees; (2) placed in the bottom of a 15 cm deep furrow made around the plant; (3) placed in a semicircular furrow, as in the previous treatment; (4) sprayed directly to the leaves. It was verified that in the first case, circa 10 per cent of the phosphorus in the leaves came from the superphosphate; for the other treatments, the results ware, respectively: 2.4, 1.7, and 38.0 per cent. It is interesting to mention that the first and the last methods of distribution were those less used by the farmers; now they are being introduced in many coffee plantations. In a previous trial it was demonstrated that urea sprays were an adequate way to correct nitrogen deficiency under field conditions. An experiment was then set up in which urea-C14 was used to study the metabolism of this fertilizer in coffee leaves. In was verified that in a 9 hours period circa 95 per cent of the urea supplied to the leaves had been absorbed. The distribution of the nitrogen of the urea was followed by standard chemical procedures. On the other hand the fate of the carbonic moiety was studied with the aid of the radiochromatographic technique. Thus, the incorporation of C14 in aminoacids, sugars and organic acids was ascertained. Data obtained in this work gave a definite support to the idea that in coffee leaves, as in a few other higher plants, a mechanism similar to the urea cycle of animals does exist.

Estudos sôbre a alimentação mineral do cafeeiro. II: absorção do superfosfato radioativo pelo cafeeiro (Coffea arabica L., var. Bourbon Amarelo) em condições de campo

In order to find out the best way to supply phosphorus to coffee plants when growing in "terra roxa misturada", a red soil with a high fixing capacity, tagged superphosphate was applied by the following procedures: (1) topdressed in a circular strip around the trees; (2) placed in the bottom of a circular furrow 15 cm deep; (3) placed in a semicircular furrow also 15 cm deep; (4) sprayed directly to the leaves. In each case 150 gms. of ordinary superphosphate tagged with H3 P32 O4 to give 5 X 10(9) c.p.m. were given to the two and half year old coffee plants. It was found that for the several treatments of the total phosphorus in the leaves the following values, on a per cent basis, came from the applied superphosphates: (1) topdressed 10.2 per cent, (2) circular furrow 2.4 per cent, (3) semicircular furrow 1.7 per cent, (4) sprayed 38.0 per cent; one can see, then, that methods (2) and (3) commonly used by the coffee planters are a very inefficient way to supply phosphorus in this type of soil. The remarkable foliar absorption was checked twice: a water culture experiment was carried out, the radiophosphorus being supplied by brushing it in the upper and lower surfaces of a given leaf; radioactivity was detected all over the plant as a result both of absorption and translocation; on the other hand, leaves collected from the sprayed trees were radioautographed; the radioautographs showed the pattern of distribution of the P32 which indicates true absorption rather than a surface contamination. In another locality, an experiment was caried out with 8 year old plants growing in "arenito de Bauru" which is a sandy soil with much less phosphorus fixing capacity. In this experiment the aim was to compare absorption of tagged superphosphate by trees growin under mulch against plants not receiving this treatment, The uptake of phosphorus was the same for both sets of plants. In both field experiments soil samples down to 15 cm in the profile were collected and its 0.2NHC1 soluble phosphorus was counted; rather significant values were observed mainly in the upper 5 cm layers.

A absorção de nitrogênio, fósforo, potássio, cálcio, magnésio, enxôfre e silício pela cana de açúcar, Co 419, e o seu crescimento em função da idade

This paper describes the data obtained for the growth of sugar cane, Variety Co 419, and the amount and rate of absorption of nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, and silicon, according to the age of the plant, in the soil and climate conditions of the state of S. Paulo, Brazil. An experiment was installed in the Estação Experimental de Cana de Açúcar "Dr. José Vizioli", at Piracicaba, state of S. Paulo, Brazil, and the soil "tèrra-roxa misturada" presented the following composition: Sand (more than 0,2 mm)........................................................................ 8.40 % Fine sand (from 0,2 to less than 0,02 mm)................................................. 24.90 % Silt (from 0,02 to less than 0,002 mm)...................................................... 16.40 % Clay (form 0,002 mm and less)................................................................ 50.20 % pH 10 g of soil and 25 ml of distilled water)..................................................... 5.20 %C (g of carbon per 100 g of soil)................................................................. 1.00 %N (g of nitrogen per 100 g of soil)............................................................... 0.15 P0(4)-³ (me. per 100 g of soil, soluble in 0,05 normal H2SO4) ............................... 0.06 K+ (exchangeable, me. per 100 g of soil)....... 0.18 Ca+² (exchangeable, me. per 100 g of soil)...... 2.00 Mg+² (exchangeable, me. per 100 g of soil)...... 0.66 The monthly rainfall and mean temperature from January 1956 to August 1957 are presented in Table 1, in Portuguese. The experiment consisted of 3 replications of the treatments: without fertilizer and with fertilizer (40 Kg of N, from ammonium sulfate; 100 Kg of P(2)0(5) from superphosphate and 40 Kg K2 O, from potassium chloride). Four complete stools (stalks and leaves) were harvested from each treatment, and the plants separated in stalks and leaves, weighed, dried and analysed every month from 6 up to 15 months of age. The data obtained for fresh and dry matter production are presented in table 2, and in figure land 2, in Portuguese. The curves for fresh and dry matter production showed that fertilized and no fertilized sugar cane with 6 months of age presents only 5% of its total weight at 15 months of age. The most intense period of growth in this experiment is located, between 8 and 12 months of age, that is between December 1956 and April 1957. The dry matter production of sugar cane with 8 and 12 months of age was, respectively, 12,5% and 87,5% of the total weight at 15 months of age. The growth of sugar cane in relation to its age follows a sigmoid curve, according to the figures 1, 2 and 3. The increase of dry matter production promoted by using fertilizer was 62,5% when sugar cane was 15 months of age. The concentration of the elements (tables 4 and 5 in Portuguese) present a general trend of decreasing as the cane grows older. In the stalks this is true for all elements studied in this experiment. But in the leaves, somme elements, like sulfur and silicon, appears to increase with the increasing of age. Others, like calcium and magnesium do not show large variations, and finally a third group, formed by nitrogen, phosphorus and potassium seems to decrease at the beginning and later presents a light increasing. The concentration of the elements was higher in the leaves than in the stalks from 6 up to 15 months of age. There were some exceptions. Potassium, magnesium and sulfur were higher in the stalks than in the leaves from 6 up to 8 or 9 months of age. After 9 months, the leaves presented more potassium, magnesium and sulfur than the stalks. The percentage of nitrogen in the leaves was lower in the plants that received fertilizer than in the plants without fertilizer with 6, 7, 8, 10, 11 and 13 months of age. This can be explained by "dilution effect". The uptake of elements by 4 stools (stalks and leaves) of sugar cane according to the plant age is showed in table 6, in Portuguese. The absorption of all studied elements, nitrogen, phosphorus, potassium, calcium, magnesium, sulfur and silicon, was higher in plants that received fertilizer. The trend of uptake of nitrogen and potassium is similar to the trend of production of dry matter, that is, the maximum absorption of those two nutrients occurs between 9 and 13 months of age. Finaly, the maxima amounts of elements absorbed by 4 stools (stalks and leaves) of sugar cane plants that received fertilizer are condensed in the following table: Element Maximum absorption in grams Age of the plants in months Nitrogen (N) 81.0 14 Phosphorus (P) 6.8 15 Potassium (K) 81.5 15 Calcium (Ca) 19.2 15 Magnesium (Mg) 13.9 13 Sulfur (S) 9.3 15 Silicon (Si) 61.8 15 It is very interesting to note the low absorption of phosphorus even with 100 kg of P2O5 per hectare, aplied as superphosphate. The uptake of phosphorus was lower than calcium, magnesium and sulfur. Also, it is noteworthy the large amount of silicon absorbed by sugar cane.

Avaliação da capacidade de fixação de fósforo pelo solo

Phosphate "fixation" is the convertion of soluble into insoluble phosphate in the soil. There are many factors conditioning phosphate fixation by soil such as reactions originating less soluble compounds (phosphates of iron, aluminum, calcium, magnesium, etc.), PO4-3 adsorption by the colloidal fraction of soils, PO4-3 absorption by the soil microflora, etc. Certain soils of the state of São Paulo (Brazil) are relatively rich in both iron and aluminum oxides. PO4-3 fixation, using P31 and P32 has been verified by researchers, specially with "Terra Roxa". The known methods for fixation evaluation are conventional as this depends on phosphate solution concentration, pH, time of contact between soil and solution, relation of sample weight to solution volume, shaking time, etc. In this experiment, the following conventional method was used: 4 g of soil were shaken for 15 minutes at 30-40 rpm, in 300 ml Erlenmeyer flask in a Wagner shaking machine, together with 100 ml of 0,03 normal phosphate solution (being 0,01 normal as PO4-3 contributed by H8PO4 and 0,02 normal as PO4-3 from KH2PO4). After shaking it was set aside for 24 hours and then filtered. Phosphate was determined in a suitable aliquot of both the original solution (blank) and the soil extract, by the vanadomolibidic-phosphoric acid method. From phosphate concentration in the blank minus phosphate concentration in the soil stract the rate of fixation by 100 g of soil was calculated. The data obtained show that "Terra Roxa" and "Terra Roxa Misturada" have a fairly high PO4-3 fixation capacity, varying from 10 to 24 milliequivalents of PO4-3 per 100 g of soil.

A disponibilidade do potássio da "leucita de Poços de Caldas", estudada por meio do arroz

In order to know potassium availability in "leucita de Poços de Caldas" from Poços de Caldas, Minas Gerais, a Mitscherlich pot experiment was set up. The pots were filled with 6 kilograms of sieved (4 mm) "Terra Roxa Misturada" soil. Rice (Oryza sativa, L.), Dourado Agulha variety was the testing plant. Doses of potassium referred to are 1,5 g (as K(2)0) from both KCl and "leucita de Poços de Caldas". There were 6 treatments, with 3 repetitions, as follows: 1) Control; 2) NP + 1 dose K (KCl); 3) NP + 2 doses K (KCl)); 4) NP + 3 doses K (KCl); 5) NP + 1 dose K (leucita); 6) NP + 2 doses K (leucita) and 7) NP + 3 doses K (leucita). Each pot received 50 seeds. Five days after germination the seedlings were thinned to 35. Harvesting took place 4 months after germination. Potassium (as KCl) promoted an increase in yield of both stalk and grain as compared with control. Potassium content in the leaves was also higher in all treatment in which KCl was supplied. Potassium, as "leucita de Poços de Caldas» did not show any favorable effect on both stalk and grain yield and on its content in the leaves.