Influence of silicon, nitrogen and molybdenum doses on the production of bean pods

The bean-pod culture has its importance because it is widely appreciated and consumed by the Brazilian, being among the vegetables more commercialized in the central of supply. From the same botanical species of the common bean, the commercial seeds of the bean-pod are divided in relation to the habit of growth in indeterminate and determined. The majority of the farmers planted bean pods with an indeterminate growth habit (climber) in crop rotation with plants that need to be tutored, such as tomatoes and cucumbers, so the fertilization recommendations found in the literature are for this habit of growth. With the availability of cultivars of determined growth habit, it is necessary the study in the area of nutrition, as they present the shorter cycle, flowering and pod production in the concentrated period, smaller spacing and higher planting densities, with influence on the production per hectare. Different from the traditional cultivars of indeterminate habit, we seek the knowledge for the bean-pod of determined habit, in such a way, that the farmer can conduct his crops with rational and economic fertilization. They canthus achieve better environmental preservation and better utilization of nutrients and thus greater productivity.

The induction of resistance, through the possible activation of defense mechanisms existing in plants in response to biotic or abiotic agents, becomes an important strategy in the pursuit of sustainability. Thus, the silicon can act as an illicitor of the resistance process induced in plants according to [1]. Possibly some illiciting agents induce defense responses in plants, such as changes in cellular, physiological and morphological structure. An interesting source of silicon is eucalyptus ash, which has an average of 16.9% of SiO2, among other nutrients, being important in the vegetative development of plants, acting as a promoter of potato growth [2]; [3]. However, it is important to note that the [4] recommends for the indeterminate growth habit bean the use of 700 kg / ha of NPK formulation 4-14-8 or 350 kg / ha of the formulated 8-28-16, twenty days after emergence of the seedlings, it should be fertilized with 200 kg / ha of ammonium sulphate or 100 kg / ha of urea undercover and at the same time spray the plants with 100 g / ha of sodium molybdate to stimulate the fixation of atmospheric N. Although N is incorporated into numerous plant essential compounds, it is largely present in proteins. N has two general functions: establishments and maintenance of photosynthetic capacity; development and growth of reproductive drains [5]. It is also an important structural component of macromolecules and a constituent of enzymes, besides acting as precursor of plant hormones, chlorophyll and cytochrome [6].

The main functions of molybdenum in plants are related to nitrogen metabolism. These functions are linked to the action or enzymatic activation, more precisely, with respect to the enzymes nitrogenase and nitrate reductase [7]. In the bean-pod was observed by [8] the positive response in the production in the use of nitrogen in coverage. However it is in common bean culture that more studies on nitrogen and molybdenum are presented, [9] reported that the relative index of chlorophyll in the leaves of the bean was increased by the application of N in cover and the Mo via foliar. The application of N in cover provided an increase ingrain yield of the bean only when combined with the supply of Mo via foliar. The supply of 80 g ha-1 of Mo via leaf increased the efficiency of N utilization by bean, according to [10], both in the presence and absence of nitrogen in sowing or cover, the increase of the molybdenum dose up to 80 g ha-1 increases the number of pods per plant and grain yield of the bean.

In relation to molybdenum sources [11] observed that sodium molybdate or ammonium molybdate can be used indifferently for leaf application in common bean. With regard to the installment and application time [12] concluded that the foliar application of Mo, starting at 15 and 20 days after emergence in a single or split dose, increases grain yield in summer-fall cultivation. In winter-spring cultivation, productivity increases with Mo applied between 15 and 30 days after emergence, in a single or split dose. Thus, the objective of this work was to evaluate the influence of silicon application and different nitrogen and molybdenum doses on the economic production of the bean-pod of determined growth.