Em ensaios em vasos foram estudados os efeitos do boro na cana-de-açúcar var. CB 41-14 (cana-planta e cana-soca), através da administração de doses crescentes do elemento à cana-planta cultivada em solo da série Ibitiruna, do Município de Piracicaba, com teor muito baixo de boro solúvel em água quente. Ao solo dos vasos (80 litros de capacidade) foram administradas as doses de 0, 0,5, 1, 2, 3, 4 e 8 ppm B, sob a forma de ácido bórico. Foram obtidos dados de produção de cana (planta e soca) e do teor de boro em folhas de três posições na planta (+3, +1 e -1), em amostragens feitas aos cinco e oito meses de idade da cana-planta, e calcularam-se dados de açúcar-provável (cana-planta e soca). O boro aplicado ao solo não proporcionou aumentos nas produções de cana e de açúcar-provável, tanto em cana-planta como em cana-soca, induzindo, entretanto, efeito depressivo em ambos os casos, pela dose mais elevada (8 ppm B) na cana-planta. Os teores de B nas folhas ( + 3, +1 e -1) de cana-planta, aos cinco meses de idade, cresceram com as doses administradas ao solo, alcançando níveis muito elevados (289 ppm) no tratamento 8 ppm B, com a média geral atingindo 124,4 ppm B. Aos oito meses, os valores foram bem mais baixos (média geral 61,4 ppm B) e não seletivos em relação à dose do boro aplicada. A melhor época de amostragem estaria em torno de cinco meses. As três posições de folha estudadas mostraram-se eficientes em relação às doses de boro aplicadas ao solo, sendo que +3 e +1 deram valores mais altos do que -1.

The effects of boron on the behaviour of sugarcane (plant-crop and first ratton crop) var. CB 41-14 were studied in a trial pot with increasing doses of this micronutrient to Ibitiruna soil from Piracicaba, SP, considered poor in boron content. The boron applied did not increase cane growth nor sugar content, but 8 ppm B reduced both cane and sugar production. Chemical analysis with leaves 5 months old revealed increasing boron contents according to the amounts given to the soil. With leaves 8 months old, the B levels were lower and non selective with respect to the boron amounts applied. The best time to sample leaves for B analysis seems to be 5 months, in the conditions of the study.

Seis solos do município de Piracicaba foram submetidos a provas de respostas à administração de boro e avaliação desse elemento assimilável, pelo método biológico do girassol. Esses solos (Ibitiruna, Sertãozinho, Bairrinho, Pau d'Alho, Luiz de Queiroz e Guamium), mapeados ao nível de séries, se mostraram ligeiramente deficientes ou não deficientes em boro. Destacou-se o solo da série Pau d'Alho, por não ter dado reação à adição do micronutriente em apreço.

Six soils of Piracicaba county. SP, Brazil, were tested and evaluated for assimilable boron by the sunflower biological method. The soils (Ibitiruna, Sertãozinho, Bairrinho, Pau d'Alho, Luiz de Queiroz and Guamium series) were found to be slightly deficient or non deficient in boron according to the Colwell criteria. The Pau d'Alho series showed to be superior to the other soils because the sunflower did not show response to boron. Sugar cane field plot and pot experiments in the same soils showed no responses to B addition.

Em condições de campo foram estudados os efeitos do boro na cana-de-açúcar var. CB 41-14, através da administração de doses crescentes do elemento a seis solos do município de Piracicaba, SP, mapeados ao nível de séries, a saber: Sertãozinho, Ibitiruna, Pau d'Alho, Bairrinho, Luiz de Queiroz e Guamium, Administrou-se bórax ao solo, nas quantidades de 0, 10, 20, 30 e 40 kg/ha. Nos ensaios foram incluídos tratamentos que consistiram na aplicação de duas doses de zinco (10 e 20 kg/ha de sulfato de zinco), uma combinação de boro e zinco (20 kg/ha de cada produto), e um tratamento com B, Cu, Fe, Zn, Mn e Mo, além da testemunha geral, sem adubação. Foram coletados dados de produção de cana, calculado o açúcar-provável do caldo e determinado o teor de boro em folhas de três posições na planta (+3, +1 e -1), em amostragens feitas aos cinco meses de idade. Constatou-se que o boro e outros micronutrientes estudados não influenciaram a produção de cana e o teor de açúcar-provável. A análise foliar do boro revelou teores muito elevados, que indicam um suprimento em boro, nesses solos, acima do normal. Não houve respostas nos teores foliares, à aplicação de doses crescentes do elemento aos solos.

The authors studied the effects of boron on the behaviour of sugar cane var. CB 41/14 through field experiments with increasing doses (0, 1, 2, 3 and 4 kg/ha B) of this micronutrient to six soils of Piracicaba county, SP, Brazil, classified at serial levels (Sertãozinho, Ibitiruna, Pau d'Alho, Bairrinho, Luiz de Queiroz, and Guamium). Boron did not influence cane growth nor sugar content. Leaf analysis showed high levels independently of the amount of boron added to the soils, revealing their good supplying.

The present work was carried out in order to study: (1) The symptoms of deficiency of macronutrients (N, P, K, Ca, Mg, S) in guava (Psidium guajava L.). (2) The modifications induced by those treatments in the histological make up of the leaves. Young guava plants were grown in nutrient solution two treatments being used, namely: complete solution (HOAGLAND and ARNON, 1950), deficient solution, in which a given element was ommitted. The main conclusions can be summaryzed as follows. a) Symptoms Clear cut symptoms of malnutrition were observed in the treatments: -N, -P, -Ca, -K, -Mg, and -S. The signal - stared respectively for deficient level. b) Histological effects Usually the characteristics of the chloroplasts were affected: loss of the green and coalescence into irregular bodies.

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.

In several cotton crops areas of the State of S. Paulo it was observed, during the years of 1948, 1949, and 1951, the appearance of a purple color of the leaves; the color appears in the opening of the bolls and was correlated with a decrease of production. The opinions concerning the cause of such abnormality were very different and sometimes contradictory; certain investigators attributed the disease to insect attack, others to bad climatic conditions whereas others to a potassium deficiency now called "fome de potássio" (potash hunger); our ideas on the subject is another one. We think that the disease is caused by lack of a suitable supply of magnesium. This opinion is largely based on the syntomatology found in the literature. To study the problem, several experiments were carried out, namely: 1. pot experiments using soil collected in areas where the disorder had appeared; 2. pot experiments controlling the water supply; 3. sand culture experiments omitting either potassium or magnesium; 4. leaf analysis of plant matrial collected troughout the Piracicaba County; 5. plot experiments with the varieties Texas, Express, and I.A. 817 Campinas. The first four experiments were discussed elsewhere. To study the point 5 an experiment was carried out, with the following treatments : 1 - NPKCaMg (no K added) - Mg supplied as MgSO4 (a soluble form); 2 -NPKCa (no Mg added); 3 -NPKCaMg (complete) - Mg supplied as MgSO4; 4 - NPKCaMg (complete) - Mg supplied as dolomitic limestone (a slightly soluble form) as a rate 2.5 higher than in the treatment 1 and 3. Organic matter as cottonseed meal was applied in the proportion of 500 kg per hectare. The experimental design was randomized blocks with 4 replications and the results can be summarized as follows: 1 the I.A 817 variety was the most strongly affected by the physiological disorder, with severe decrease in yield; 2. the disease occurred more frequently in the minus magnesium treatment; 3. dolomitic limestone is so effective as magnesium sulfate in the control of the disease as well in the raising of the yield; 4. in the minus K treatment it was observed a marked occurrence of the typical symptoms of potassium deficiency (cotton rust); 5. magnesium was actually, in the experimental conditions the responsible for the purple color (vermelhão) of the cotton leaves.