Efeitos do herbicida lactofen sobre três cultivares de soja I. Alterações morfológicas externas e internas de folhas

O lactofen, herbicida do grupo dos difenil éteres, é indicado para uso na cultura da soja, em pós-emergência, devido sua eficácia no controle de plantas daninhas latifoliadas. No presente trabalho, conduzido em casa-de-vegetação, foram utilizadas as cultivares de soja Foscarin-31, IAC-8 e IAC-9, tratadas com lactofen nas doses 0,018 e 0,36 kg de lactofen i.a./ha, aplicadas quando as plantas apresentavam a Segunda folha composta totalmente expandida. Aos quatro e doze dias após as aplicações, foram analisadas e descritos os sinais macroscópicos e microscópicos de intoxicação nos folíolos das folhas. Os resultados indicaram que o lactofen ocasionou expressivas alterações morfológicas externas e internas das folhas, nos locais onde foi depositado, e que a dose maior acentua os efeitos do produto sobre as plantas, sendo que as cultivares de soja apresentaram diferentes graus de sensibilidade ao produto.<br>Lactofen, a diphenil ether herbicide, is indicated for use in soybean crop, at post-emmergence, due to its efficacy on broad-leaf weed control. In the present assay, under greenhouse conditions, soybean cultivars as Foscarin-31, IAC-8 and IAC 9 were used. The herbicide was applyed at the 2nd whole expanded composed leaf stage at 0, 0.18 and 0,36 kg of lactofen a.i./ha. At four and twelve days after applications, external and internal morphological aspects on the attainned leaves were evaluate. Results showed that the lactofen generally raised injurious effects in the loci where it was deposited. Sensitivity of the three tested soybean cultivars to the herbicide was different

Deficiências e excessos minerais no feijoeiro (Phaseolus vulgaris L., cv. carioca)

This work had the purpose of studying some aspects of the mineral nutrition of the bean plant (Phaseolus vulgaris L., var. Carioca) checking the effects of the ommission of macronutrients and also B and Fe and the excesses of Al and Mn. Some changes in heigth of the plants and the number of leaves, yield of dry matter and mineral composition of leaves and roots were observed. To check the effects of ommission of N, P, K, Ca, Mg, S, Fe and B, and excesses of Mn and Al, bean plants were grown in controlled conditions. The harvest was done when the induced symptoms were well established. From the obtained data, it is concluded that: 1. Ca was the element that, when missing, had the major depressive effect on heigth of the plants, number of leaves, and dry matter weight. 2. It is possible to induce symptoms of mineral deficiencies, and excesses in the bean plant if it is grown in the nutrient solution in the absence or excess of some elements. 3. Dry matter production was affected by treatments in the following increasing order: complete, - S, - K, + Al, -B, + Mn. - Mg, - Fe, - P, - N and - Ca. 4. The main interactions among the leaf elements, detected through this trial were: K x Ca x Mg, Fe x Mn. 5. The absence of an elements causes a decrease of its content in the leaves, when compared to the complete treatment.O feijoeiro foi cultivado em solução nutritiva com deficiências de macronutrientes, de B e Fe e excessos de Al e Mn. Foram obtidos sintomas típicos de falta e de toxidez e as plantas foram analisadas