Sweet potato crops take up large amounts of nutrients, especially nitrogen. In low-fertility soils, the addition of nitrogen (N) increases the sweet potato yield. Green manure may be an alternative method for improving soil quality and supplying nutrients to this crop. This study aimed to evaluate the plant's nutritional status and the amount of nutrients taken up and removed by sweet potato plants subjected to green manure and mineral N fertilization. The experiment was carried out in the field for two growing seasons using a randomized block design in a split-plot scheme with four replications. The plots consisted of a control treatment (spontaneous weeds) and the previous cultivation of Crotalaria spectabilis and Mucuna aterrima. The subplots consisted of four N rates (0, 50, 100, and 200 kg ha -1 ) that were applied to the sweet potato. The species M. aterrima is more suitable for use as green manure in the sweet potato than C. spectabilis. Nitrogen application rates promoted a greater increase in the biomass of the storage root, nutrient uptake, and removal in the sweet potatoes unfertilized with green manure. In the sweet potato fertilized with M. aterrima, mineral N supply in excess (above 50 kg ha -1 ) increases the nutrient uptake and removal without a significant increase in the biomass of the storage root. In the sweet potatoes unfertilized with green manure, high rates of N (greater than 120 kg ha -1 ) must be applied to obtain the utmost biomass of the storage root, nutrient uptake and removal.
O objetivo deste trabalho foi avaliar o efeito da influência dos fatores ambientais, cor e altura de instalação de armadilhas com toletes de bambu na captura do Dinoderus minutus, considerado a principal praga pós-colheita do bambu. A literatura aponta a cor e altura das armadilhas como elementos capazes de influenciar na captura deste inseto. Para avaliar essas hipóteses, foram fabricadas 30 armadilhas de garrafas PET nas cores amarela, preta, branca, azul e transparente. Toletes de bambu Bambusa vulgaris foram cortados e secos em uma estufa a 50±3°C durante 48 h. Em cada armadilha foi inserido um tolete de bambu na posição vertical. As armadilhas foram instaladas a 1,5 m e 2,5 m de altura em relação ao solo, em uma touceira de B. vulgaris. No período do experimento foram capturados 3301 carunchos. Houve uma correlação positiva entre a captura de carunchos e a pluviosidade, porém não houve correção entre a captura de carunchos e a temperatura. A altura influenciou na captura de D. minutus de modo que um maior número de insetos foi encontrado nas armadilhas instaladas a 2,5 m do solo. Não foi detectada influência da cor das armadilhas na captura de carunchos, tampouco da interação entre cor e altura de instalação das mesmas.
Bamboo wood is a widely used raw material for the manufacture of special furniture and handicraft products, and can also be used in construction and architecture. In Brazil, the usage of this material has gained great space in the last decades. However, it can suffer from the attack of the bamboo borer [Dinoderus minutus Fabricius (Coleoptera: Bostrichidae)], causing damages and making the use of this wood unviable. Hence, the purpose of this work was to verify the behavior of D. minutus in culms of three bamboo species (Bambusa vulgaris, B. vulgaris var. vittata e B. multiplex) in two seasons of the year, one dry and one rainy season, in addition to testing alternative methods of insect control. In relation to the behavior, we verified the damages caused by the larvae from the oviposition of D. minutus in nodes and internodes of the bamboo species. While the alternative control methods were based on the spraying of the bacterium Proteus mirabilis, as an entomopathogenic agent, on B. vulgaris nodes, and the immersion treatment of nodes of same bamboo species in aqueous extract of Dracaena arborea leaves, and in vinasse. In relation to the insect behavior, there was a higher activity (consumption and reproduction) during the rainy season and a higher attack preference for the species B. vulgaris. Regarding the alternative control methods, it was verified a better performance of the treatments with P. mirabilis and D. arborea, since they provided a mortality index superior to 90% of the insects.
In field conditions, the more usual application of cytokinins is based mainly on seed treatment and foliar spraying. Nowadays, seed priming with plant growth regulators is a successful agricultural practice due to its easy application in annual crops, resulting in a higher vigor and production. In order to evaluate the effect of the treatment of common bean seeds with N6-benzyladenine (6-BA), in the morphophysiology and crop yield, an experiment was carried out in a greenhouse, in a completely randomized design with four replicates and five doses of 6-BA (0, 0.0375, 0.075, 0.1125 and 0.15 g kg-1 of seed). The growth regulator was applied to the seeds in order to cover their entire surface. At 30 days after emergence, the physiological parameters were increased as a function of the doses of 6-BA. On the other hand, at 30 and 45 days after emergence of the crop, there was a drastic reduction in nodulation with increased 6-BA doses, which resulted in the lower accumulation of leaf nitrogen, pod number, and common bean yield. The ranging doses till 0.15 g kg-1 of seed of the cytokinin 6-BA are not recommended in seed priming of common beans. However, the effective recommendation of cytokinin as a seed priming is still not determined, and studies about products and doses must be improved before recommendation.
Silicon (Si) and biostimulant management have been proposed techniques to reduce the impacts of abiotic stresses and to increase the productivity of several crops, however, there are still few concise results of the management of this crop. The objective of this work was to evaluate the effects of biostimulant and silicon treatments on isolated or mixed applications on mineral nutrition, yield and fiber quality of two cotton varieties. For this, an experiment was carried out in a randomized block design in the municipality of Luís Eduardo Magalhães-BA, in a 4 × 2 factorial arrangement, with four replications, in which four biostimulant treatments (control, without application; Si; biostimulant; and Si + biostimulant) were evaluated in two cotton varieties (FM 954GLT and FM 983GLT). The nutrient content of leaves, relative water content, electrolyte leakage, fiber yield, and quality were evaluated, the data collected were submitted to the F test and means were compared by Tukey at 5% probability. At the end of the experiment, it was verified that the management of Si and biostimulants increase the integrity of the cell wall, the association of Si + biostimulant increases the levels of N, Fe and Si foliar and reduces the levels of B and Mn, and do not influence on yield and fiber quality.
Potassium (K) fertilisation at planting time may not be sufficient to achieve high cassava yields. Experiments were conducted over two growing periods using sweet cassava (SC) variety IAC 576-70 and bitter cassava (BC) variety IAC 13 aiming to evaluate the effects of K fertilisation rate (0–150 kg K/ha) and timing of application (one, two, or three) on leaf K concentration, yield components, and storage-root and starch yields. The SC and BC varieties were grown in a randomized block design in a 3 × 4 + 1 factorial scheme with four replications during growing periods of 10 and 20 months respectively. For SC, split application of K at planting plus 3 months after planting (MP) or at planting plus 1.5 and 3 MP was more effective at increasing the marketable root yield, with greater rainfall at the beginning of the growing period. Split application of K at planting plus 3 MP also reduced the cooking time and cooked root firmness. For BC, split application of K at planting plus 12 MP more effectively increased the storage-root and starch yields; however, root yield response to K fertilisation in the second growing period, with greater rain intensity during the initial crop stages, was greater than in the first growing period. In K-deficient soils, the optimal K application rate for SC marketable root yield varied from 79 to 111 kg/ha when K was applied after 1.5 MP, and linear responses to K application rate occurred when K was applied earlier. For BC, the optimal K application rate varied from 75 to 92 kg K/ha. Our data suggest that K application times should be different for cassava varieties with short and long growing periods.
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