Growth, Gas Exchanges and Maize Productivity Under Potassic Fertilizer Management and Residual Response on Bean

Potassium (K) is the second nutrient of greater absorption by plants, and it is of fundamental importance for the development of the cultures and acts in the activation of enzymes that participate in the photosynthetic processes. However, there are still doubts about its residual effect on crop succession. Therefore, the objective of the research was to evaluate the effect of K doses on growth, gas exchange and maize yield and its residual effect on bean culture. The experiment was a randomized complete block design, in a 5x2 factorial scheme, totaling 10 treatments, with five K doses (0, 50, 100, 150 and 200 kg ha-1) and two fertilization periods (seeding and V5 stadium) in maize plants. Growth parameters, gas exchange and yield were evaluated in maize plants, and growth was evaluated in Bean plants in an experimental area belonging to the Department of Plant Science and Environmental, Federal University of Paraíba in Northeast Brazil. For the analysis of the data, we performed the analysis of variance, according to the design adopted. Subsequently, the data were submitted to regression analysis, with curve fitting, according to the parameters evaluated. Results revealed that, K fertilization influenced the growth of maize plants in the two fertilization periods (seeding and V5 stadium) at 45 and 75 days after planting, as well as in gas exchange and productivity. Fertilization at the V5 stadium in maize presented higher values compared to fertilization at seeding, in which the dose of 150 kg ha-1 presented the best results at both planting times. In relation to the residual effect of K on bean growth, it was verified that, there was influence of the doses on the growth of plants, in which the dose of 200 kg ha-1 recorded the highest values. The results showed that there is the residual response of K on bean cultivation in succession with maize. For the greater development of maize, it is recommended to use the dose of 150 kg ha-1 at the V5 stage of plants.