Frações de fósforo e simbiose micorrízica em floresta secundária em resposta a disponibilidade de água e nutrientes na Amazônia oriental

A disponibilidade de nutrientes, especialmente fósforo, e de água no solo influenciam fortemente a simbiose micorrízica em ecossistemas florestais. O objetivo do estudo foi avaliar o impacto da remoção de serapilheira e do aumento da disponibilidade de água no solo sobre a densidade de esporos e a colonização micorrízica em raízes apogeotrópicas e não-apogeotrópicas em floresta secundária na Amazônia oriental. Foram analisadas a porcentagem de colonização micorrízica de raízes finas (diâmetro ≤ 2 mm) apogeotrópicas e não-apogeotrópicas (presentes na camada de 0-10 cm do solo), a densidade de esporos, o teor de glomalina e a disponibilidade de fósforo no solo. A remoção de serapilheira não reduziu a disponibilidade de fósforo no solo. A densidade de esporos também não foi afetada pela remoção de serapilheira. De forma geral, as variáveis estudadas variaram sazonalmente, com exceção da colonização micorrízica em raízes não-apogeotrópicas e do teor de glomalina, mas não foram afetadas pela alteração na disponibilidade de água no solo decorrente da irrigação. Danos mecânicos ao sistema radicular apogeotrópico, inerentes à remoção quinzenal da serapilheira, devem ter contribuído para reduzir a colonização micorrízica em raízes apogeotrópicas e não-apogeotrópicas e, consequentemente, o teor de glomalina no solo. Os resultados deste estudo sugerem que a redução da cobertura do solo pode impactar negativamente a simbiose fungo-planta.

Contaminação por metais pesados em peixes e água da bacia do rio Cassiporé, Estado do Amapá, Brasil

A participação dos metais pesados nas reações químicas do metabolismo dos peixes tornou esses elementos um dos principais focos nos estudos de contaminação. O objetivo deste estudo foi determinar as concentrações dos metais Cd, Cr, Cu, Pb, Zn e Hg no tecido muscular de peixes da bacia do rio Cassiporé (Estado do Amapá) e ambiente, visando avaliar os riscos de contaminação. As concentrações de Cd em Plagioscion squamosissimus (1,061 µg g-1) e Pb em Poptella compressa (4,280 µg g-1) apresentaram valores que ultrapassam os limites estabelecidos pela legislação brasileira. As concentrações de Cr em P. compressa (0,937 ± 0,5 µg g-1), Pimelodella cristata (0,463 ± 0,03 µg g-1) e Cyphocharax gouldingi (0,364 ± 0,12 µg g-1), bem como de Hg em P. squamosissimus (0,670 µg g-1), Pseudoplatystoma fasciatum (0,630 µg g-1), Hoplias malabaricus (0,570 µg g-1 e Serrasalmus rhombeus (0,548 µg g-1) foram acima do limite legal. A coluna d'água apresentou altas concentrações de metais pesados em todos os pontos analisados, mostrando uma contaminação dessa bacia. Portanto, essas elevadas concentrações de metais pesados no ambiente e tecido muscular dos peixes indicam um elevado grau de contaminação na bacia do rio Cassiporé e risco a saúde do homem.

Nota preliminar sôbre a absorção e a translocação do radiozinco no cafeeiro [Coffea arabica] cultivado em solução nutritiva

Two water-culture experiments were carried out to study the absorption and the translocation of radiozinc in young coffee plants as influenced by two factors, namely, concentration of heavy metals (iron, manganese, copper and molybdenum) and method of application. Inert zinc was furnished at a uniform rate of 0.05 p.p.m.; the levels of iron supply were 0, 1.0 and 10 p.p.m.; manganese was supplied in three doses 0, 0.5, and 5 p.p.m.; copper - 0, 0.02, and 0.2 p.p.m.; molybdenum - 0, 0.01 and 0.1 p.p.m. When applied to the nutrient solution the activity of the radiozinc was 0.15 microcuries per plant. In the study of the leaf absorption, the radiozinc was supplied at the level of 0.10 microcuries per plant; in this case the material was brushed either on the lower or in the upper surface or both of two pairs of mature leaves. In both experiments the absorption period was 8 weeks. The following conclusions can be drawn: 1. Among the heavy metals herein investigated the iron concentration did not affecc the uptake of the radiozinc; by raising the level of Mn, Cu and Mo ten times, the absorption dropped to 50 per cent and even more whe compared with the control plant; however, when these micronutrients were omitted from the nutrient solution an increase in the uptake of zinc was registered only in the minus - Cu treatment. The effects of high leveds of Mn, Cu and Mo probably indicate an interionic competition for a same site on a common binding substance in the cell surface. 2. The absorption of the radiozinc directly applied to the leaf surface reached levels as high as 8 times that registered when the root uptake took place. Among the three methods of application which have been tried, brushing the lower surface of the leaves proved to be the most effective; this result is easily understood since the stomatal openings of the coffee leaves are preferentially located in the lower surface. In this treatment, about 40 per cent of the activity was absorbed and around 12 per cent were translocated either to the old or to the newer organs. 3. Data herein presented suggest that leaf sprays should be preferred - rather than soil applications - to control zinc deficiency in coffee plants when growing in field conditions.

Sorbímetro (Um aparêlho para a determinação das relações solo/água)

Os autores descrevem um aparelho destinado à medida contínua da água absorvida pela TFSA em condições de laboratório. O sorbímetro, cujo funcionamento obedece ao princípio dos vasos comunicantes, consta de um tubo em U cujos ramos verticais se ligam respectivamente à uma coluna de terra e à uma bureta de 100 ml. A bureta restabelece no tubo, a água absorvida pela terra. As leituras de bureta substituem as pesagens do método gravimétrico. O aparelho é recomendado para medidas a intervalos de tempo para os quais, o método usual é ineficiente.

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.

Estudos sôbre alimentação mineral do cafeeiro: VIII. Estudo da absorção e da translocação do radiozinco no cafeeiro (Coffea arabica L.)

WATER-CULTURE EXPERIMENTS. Two water-culture experiments were carried out to study the absorption and the translocation of radiozinc in young coffee plants as influenced by two factors, namely, concentration of heavy metals (iron, man ganese, copper and molybdenum) and method of application. Inert zinc was supplied at an uniform rate of 0. 05 p. p. m.; the levels of iron supply were 0, 1.0, and 10.0 p. p.m.; manganese was supplied in three doses 0, 0.5, and 5.0 p. p.m.; copper- 0, 0. 02, and 0. 2 p. p. m.; molybdenum- 0, 0. 01, and 0. 1 p. p. m. When applied to the nutrient solution the activity os the radiozinc (as zinc chloride) was 0. 15 microcuries per plant. In the study of the leaf absorption, Zn65 was supplied at the level of 0. 10 microcuries per plant; in this case the radioative material was brushed either on the lower or on the upper surface or both two pairs of mature leaves. The absorption period was 8 weeks. The radioactivity assay showed the following results: 1 - Among the heavy metals herein investigated the iron concentration did not affect the uptake of the radiozinc; by raising the level of Mn, Cu and Mo ten times, the absorption dropped to 50 per cent and even more when compared with the control plants; when, however, these micronutrients were omitted from the nutrient solution, an increase in the uptake of zinc was registered in the minus Cu treatment only. The effects of high levels of Mn, Cu and Mo probably indicate an interionic competition for a same site on a common binding substance in the cell surface. 2 - The absorption of the radiozinc directly applied to the leaf surface reached levels as high as 8 times that registered when the root uptake took place. Among the three methods of application which have been tried, brushing the lower surface of the leaves proved to be the most effective; this result is easily understood since the stomatal openings of the coffee leaves an preferentially located in the lower surface - in this treatment, about 40 per cent of the activity was absorved and around 12 per cent were translocated either to the old or to the newer organs. Chemical analyses for heavy metals, were carried out only in the plants received Zn65Cl2 in the nutrient solution; the results were as follows; 1 - Control plants had, per 1,000 gm, of dry weight the following amounts in mg.: Zn- 48 in the roots and 29 in the tops; Fe- 165 in the roots and 9 in the tops; Mn- 58 in the roots and 15 in the tops, Cu- 15 in the roots and 1. 2 in the tops; Mo- 2. 8 in the roots and 0. 45 in the tops. 2 - The effect of different levels of micronutrients in the composition of the plants can be summarized as follows: Fe and Zn- when omitted from the nutrient solution, the iron and zinc contents in the roots decreased, no variation being noted in the tops; the higher dosis caused an accumulation in the roots but no apparent effect in the tops; Mn- by omitting this micronutrient a decrease in its content in the roots was noted, where as the concentration in the tops was the same; Mo- no variation in roots and tops contents when molybdenum was omitted; higher dosis of manganese and molybdenum increased the amounts formed both in the roots and in the tops. 3 - The influence of the different concentrations of micronutrients heavy metals on the zinc content of the coffee plants can be described by saying that: Fe and Mo- no marked variation; Mn- no effect when omitted, reduced amount when the high dosis was supplied; Mn- when the plants did not receive manganese the zinc content in roots and tops was the same as in the control plants; a decrease in the zinc content of the total plant occurred when the high dosis was employed; Cu -the situation is similar to that described for manganese. Hence, results showed by the chemical analyses roughly correspond to those of the radioactivity assay; the use of the tracer technique, however, gave best informations along this line. SOIL-POTS EXPERIMENTS. The two types of soils which when selected support the most extensive coffee plantations in the State of São Paulo, Brazil: "arenito de Bauru", a light sandy soil and "terra roxa legitima", a red soil derived from basalt. Besides NPK containing salts, the coffee plants were given two doses of inert zinc (65 and 130 mg ZnCl2 per pot) and radiozinc at a total activity of 10(6) counts/minute. The results of the countings can be summarized as follows: 1 - When plants were grown in "arenito de Bauru" the activity absorbed as per cent of the total activity supplied was not affected by the dosis of inert zinc. The highest value found was around 0. 1 per cent. 2 - For the "terra roxa" plants, the situation is almost the same; there was, however, a slight increase in the absorption of the radiozinc when 130 mgm of ZnClg2 was given: a little above 0. 2 per cent of the activity supplied was absorbed. The results clearly show that the young coffee plants practically did not absorb none of the zinc supplied; two reasons at least could be pointed out to explain such a fact: 1 - Zinc fixation by an exchange with magnesium or by filling holes in the octahedral layer of aluminosilicates, probably kaolinite; 2 - No need for fertilizer zinc in the particular stage of life cycle under which the experiment was set up. The data from chemical analysis are roughly parallel to the above mentioned. When one attempts to compare - by taking data herein reported zinc uptake from nutrient solution, leaf brushing or from fertilizers in the soil, a practical conclusion can be drawn: the control of zinc deficiency in coffee plants should not be done by adding the zinc salts to the soil; in other words: the soil applications used so extensively in other countries seem not to be suitable for our conditions; hence zinc sprays should be used wherever necessary.

A absorção do manganês pela cana de açúcar, Co 419, em função da idade

In this paper the authors have studied the manganese absorption by the sugar cane plant, variety Co 419, in samples cut monthly, from the 6th to 15th month of life in the climate prevailing at Piracicaba, State of Sao Paulo, Brazil. From October to February (6 th to 10 th month of the plant life), which coincided with the rainy season, the manganese content was higher in the stalk than in the leaves, for both treatments, fertilized and unfertilized. There was a sharp decrease in manganese content in the stalks, after February, in both reatments. In the leaves there was little variation in manganese content throughout the plant tissue. The stalks from the unfertilized plots had a larger variation in manganese content, specially from the 6 th to the 10 th month. In the leaves of the sugar cane from the unfertilized plots, the manganese content varied from 116 to 220 ppm, whereas in the fertilized treatments thire was a variation from 150 to 220 ppm. From these results, althoug not being a foliar analyses, and considering the easy availability of manganese in acid soils, there must be enough of it, if we consider 40 ppm (EVANS, 1955) as a minimum for healthy plants.

Absorção de zinco pela cana de açúcar, Co 419, em função da idade

The status of zinc in sugar cane, variety Co 419, troughout its life cyle, was studid in samples cut monthly, from the 6th to 15th month, from an experiment carried on under the conditions of soil and climate prevailing in Piracicaba, State of São Paulo, Brazil. The experiment consisted of 6plots, 3 fertilized and 3 unfertilized. The fertilized ones received 40 kg of N (ammonium sulfate), 100 kg P2O5 (superphosphate) and 40 kg K2O (potassium cloride) per hectare, just before planting. The zinc content was determined by the Zincon method, after separation of zinc from other ions by means of the ion Exchange Resin III, Merck. The results obtained show that there was a tendency to decrease the zinc level in the stalks, whereas it kept more or less constant in the leaves; there was an exception in January, when the zinc level in the stalks had a sharp raise: 38-90-20 and 28-60-23 ppm for the fertilized an unfertilized treatments. There was a parallelism in the absorption of zinc by the plants from 4 hills of both treatments, through the whole - plantcycle but, the total amount taken up was higher with the fertilized plot due to its greater mass production.

A absorção de ferro pela cana de açúcar, Co 419, em função da idade

This paper describes the results obtained from the determination of iron in sugar cane according to the age of the plant, in the soil and climate conditions of the state of S. Paulo, Brazil. The iron was determined by 1-10- phenanthroline method, in samples cut monthly from 7th to 15th month from an experiment consisted de 3 plots fertilized with amonium sulfate, superphosphate and potassium cloride. The concentration of iron in the stalks and in the leaves varies according to the age of the plant. A ton of fresh stalks 15 months old contains 78,71 g of iron.

A absorção do cobre pela cana de açúcar Co 419 em função da idade

O presente trabalho teve por objetivo a determinação da concentração de cobre e o estudo das quantidades absorvidas do elemento citado, pela cana de açúcar Co 419, crescendo em condições de campo na região de Piracicaba, Estado de São Paulo. As amostras eram provenientes de 3 repetições, de um tratamento no qual as nlantas sofreram adu-bação com nitrogênio, fósforo e potássio, variando as plantas de 6 a 15 meses de idade. O método utilizado na determinação do cobre, foi o do dietilditiocarbamato de sódio. A concentração de cobre apresentou um relativo decréscimo, com o aumento de idade da planta, variando os teores de cobre no colmo de 7,4 a 62,8 ppm e na folha de 10,0 a 30,0 ppm. Quanto a absorção do cobre, a planta apresentou um aumento proporcional a idade. A mesma absorveu maior quantidade no 14.° mês, 412,2 miligramas de cobre, por 4 touceiras.

Absorção de molibdênio pela cana de açúcar variedade Co 419, em função da idade

In this paper the authors describe the results obtained from the determination of molybdenum in sugar cane plant, grown in soils and climate prevailing in Piracicaba, State of São Paulo, Brazil. The molybdenum was determined in samples cut monthly from the 8th to 14th month, from an experiment consisting of 6 plots, 3 fertilized and 3 unfertilized. The fertilized treatment received 40 kg N (ammonium sulfate) 100 kg P2O3, (superphosphate) and 40 kg K2O (potassium chloride) per hectare, just before planting. Molybdenum was determined by thiocyanate-stannous chloride method, using carbon tetrachloride-butyl alcohol misture, for extrating the colored complex. The results obtained show a parallelism in the absorption of molybdenum by the plants of both treatments. The concentration of molybdenum in the stalks have a tendency to decrease, where as it kept more or less constant in leaves, with a exception in the 14° month when it rised probable because of a migration of molybdenum of the stalks to the leaves. The total amount molybdenum taken up was higher with the fertilized plot due its greater mass prodution.

A absorção de nitrogênio, fósforo, potássio, cálcio, magnésio e enxofre pelo cafeeiro: coffea arabica variedade mundo novo |(B. Rodr.) Choussy | aos dez anos de idade

O presente trabalho relata os dados obtidos sôbre a concentração e a quantidade de macronutritntes, N, P, K, Ca, Mg e S no tronco, ramos, fôlhas e frutos do cafeeiro, Coffea arabica, L, variedade mundo novo [(B. Rodr.) Choussy], aos dez anos de idade e crescendo em solo latossólico da Escola Superior de Agricultura "Luiz de Queiroz", em Piracicaba. São apresentados também os dados obtidos nas mesmas condições, sôbre o pêso de diversas partes (tronco, ramos, fôlhas e frutos) do cafeeiro.

Estudos sôbre a alimentação mineral do cafeeiro: XVIII. nota sôbre a absorção foliar e radicular do fósforo por plantas jovens de Coffea arabica L., var. Mundo Novo

Young coffee plants were allowed to absorb radiophosphate via leaves during 30, 60, 90 and 120 minutes and via roots during 24 hours. It was verified that leaf absorption was almost twice more intense than root uptake despite the considerable difference in time of contact which would favour the latter. Translocation of leaf applied material was also more marked.

Observações preliminares sôbre o modo de aplicação do fósforo e a sua absorção pela videira, empregando-se superfosfato radioativo

O presente trabalho foi realizado em um vinhedo comercial na região de Jundiaí com a finalidade de se estudar o efeito do modo de aplicação do superfosfato-P32 na sua absorção pela videira. A variedade IAC 313 foi a escolhida. Os resultados dêste ensaio permitem concluir preliminarmente que, para as condições de solo e da variedade estudada, a absorção do fósforo do superfosfato aplicado em cobertura se efetua de maneira mais rápida do que quando em profundidade.