RESPOSTAS FISIOLÓGICAS DA CULTURA DO MILHO À DIFERENTES MANEJOS DE ADUBAÇÃO

Abstract

Maize is one of the world's and Brazil most important crop, the Northeast is the second region that least participates in the production of this grain, ranked as the region that has the lowest productivity, one of the main factors responsible for the low maize yield is attributed to soil fertility. Based on that, the objective of this study was to evaluate the development of maize cultivated under different nutritional managements, aiming to determine an alternative for mineral fertilization. The present fertilization experiment was carried out in the experimental area Chã-de-Jardim belonging to the Centro de Ciências Agrárias da Universidade Federal da Paraíba (CCA/UFPB), in the city of Areia-Paraíba, a randomized complete block design (DBC) was used, with six treatments and four replications, T1 being the treatment corresponding to the planting without fertilization; T2 corresponds to chemical fertilization; T3 organic fertilization; T4 Organic fertilization + P and K; T5 organic fertilization + N in the coverage; T6 Organic fertilization with correction + P, K and + N in the coverage. The parameters of plant height, stem diameter, number of leaves, chlorophyll A, B, total chlorophyll, photosynthetic rate, transpiration, stomatal conductance and Internal CO2 concentration in the leaf were evaluated. Data were submitted to analysis of variance and the means were compared by the Tukey test at 5% of probability. For plant height, at 30 days after emergence (DAE), the chemical fertilization along with organic fertilization + P and K and organic fertilization + P, K and + N in coverage presented higher values and at 60 DAE, it was observed that there was a significant difference where the highest value was the chemical fertilization and the lower value was the treatment without fertilization. At 30 and 60 DAE there was a significant difference for stem diameter and leaf number, where the treatment without fertilization presenting the lowest value. The treatment with the highest rate photosynthesis rate was the organic fertilization with + P and K and + N in the coverage, differing significantly from the treatment of organic fertilization. The transpiration values presented significant difference, where the treatment with organic fertilization + P and K and + N in the coverage presented the highest mean. There was no significant difference for the stomatal conductance parameter. The internal carbon had a significant difference, where the treatment with organic fertilization + P and K and + N in the coverage presented the highest mean. For the Falker chlorophyll chlorophyll B index, the maize plants had the highest values in the chemical fertilization, but there was no statistical difference for the treatment with organic fertilization with mineral coverage. The Falker chlorophyll A index, behaved correlatively to the total chlorophyll, in the chemical fertilization presenting higher means and the organic fertilization + P and K the lower means. The organic fertilization with + P and K and + N in the coverage are a viable alternative to chemical fertilization.