Resposta de mudas de coqueiro anão-verde do Brasil à calagem.

Abstract

Coconut farming plays an important role in Brazilian agriculture, with emphasis on the state of Pará, however, there are still major gaps in the development of the crop in the state, with high soil acidity being one of the main problems. In the production of seedlings, substrates with high acidity are considered a limiting factor in the production of quality seedlings, with liming being the most used practice for soil acidity correction, as well as raising the pH, neutralizing the toxic aluminum, root system of plants and improves the efficiency of nutrient use. Saplings with adequate nutritional content presuppose a good development and a good formation of the root system, with better capacity to adapt to the new place after planting, presenting advantages as increased resistance to diversities. In this context, the objective of this study was to study the effects of liming on soil chemical characteristics and vegetative development, evaluating the morphological, physiological and nutritional processes in Brazilian dwarf coconut saplings cultivated in Yellow Latosol, medium texture, of Santa Izabel do Pará, PA. For this, a greenhouse experiment was carried out from march to november, 2018. The treatments were five doses of dolomitic limestone (0.45, 0.83, 1.20, 1.58 and 1.95 t (V%) of 30, 40, 50, 60 and 70%, respectively, and one control, without limestone (V% equal to 18), with five randomized block replicates. The results showed that liming improved soil fertility by increasing pH, neutralizing toxic aluminum and increasing calcium, magnesium, phosphorus and base saturation; improved the growth of the seedlings, mainly at the dose of 1.58 t ha-1 of limestone, with a higher leaf area, higher root dry mass, higher dry mass of the shoot and consequently higher total dry mass; promoted higher absorption of calcium, magnesium, iron and zinc and a lower concentration of aluminum in the roots of the seedlings, especially in the dose of 1.95 t ha-1 of limestone; promoted higher concentrations of calcium, magnesium and phosphorus, and reduced nitrogen, boron, copper, iron, manganese and aluminum concentrations, and promoted improved gas exchange due to higher photosynthetic activity, higher transpiration rate, greater stomatal conductance, and higher intercellular concentration of carbon dioxide, mainly at the dosage of 1.58 t ha-1. Thus, it is concluded that liming is efficient in improving soil fertility, promoting better nutritional status with direct reflexes on the growth and development of Brazilian dwarf coconut seedlings.