Morfologia, produtividade e composição química da palma orelha de elefante mexicana sob adubação e frequência de colheita

Abstract

The forage cactus pear is of great importance for the ruminants of the Agreste region of Pernambuco, being the main responsible for the maintenance of the milk basin of the state. This forage plant is well adapted to the edaphoclimatic conditions of the Brazilian semi-arid region, has high nutritional value, has the potential to present high forage production. The objective of this work was to evaluate the morphological, productive and chemical characteristics of the cactus pear 'Orelha de Elefante Mexicana' (Opuntia stricta Haw) under the effect of organic fertilization, nitrogen fertilization and harvest frequencies. The experimental design was randomized blocks, in sub-divided plots and four replications. The plants were submitted to four levels of organic matter (0, 10, 20 and 30 Mg ha-1 year-1) forming the main plot, four levels of nitrogen fertilization (0, 120, 240, 360 kg ha-1 year-1 of nitrogen), forming the sub-plot and the two harvest frequency (annual and biennial), forming the sub-subplot. Two annual harvests and one biennial were carried out. There was no effect of nitrogen fertilization on the morphological and productive characteristics. Significant isolated effects of organic fertilization and harvest frequency were observed for number of primary and total cladodes. Quadratic effect was observed for the length of primary cladodes, in response to organic fertilization, with a maximum value of 39.4 cm at the level of 28.1 Mg ha-1 year-1 and effect of the frequency of harvest on the length of primary cladodes , being 34.1 cm in the annual harvest and, 36.5 cm, biennial. Organic fertilization and harvesting frequency affected the width of primary cladodes in isolation. Maximum width of 19.1 cm was observed, with fertilization of 27.1 Mg ha-1 year-1, while values of 16.6 cm were obtained, at annual frequency and, 18.6 cm, at biennial. Average production values of 27.2 and 35.9 Mg ha-1 were obtained for annual and biennial harvests, respectively. The effect of organic fertilization was also observed, presenting quadratic behavior with maximum production of 49.2 Mg ha-1 2 year-1 with the fertilization of 30 Mg ha-1 year-1. The CP contents were affected by the harvest frequency, with values of 126.3 and 98.9g kg-1, respectively for the annual and biennial frequency. An interaction effect was observed at the level of 0.0 Mg ha-1 year-1 of organic matter and 360 kg ha-1 year-1 of nitrogen (161.8g kg-1). The effect of organic fertilization was observed for the levels of phosphorus (P) and sodium (Na), obtaining quadratic growth with the application of the fertilizer and interaction of organic fertilization x harvest frequency was observed for the potassium (K) content, as well as the effect of harvest frequency for sodium levels, with higher value (7.8 g kg-1) in the annual frequency. The greater growth of cladodes and plants promoted by the application of organic fertilizer, increases the productivity of the forage palm 'Orelha de Elefante Mexicana', with a higher level of 30 Mg ha-1 year-1. Biennial harvest promotes greater productivity of the 'Orelha de Elefante Mexicana' cactus pear. Increasing levels of nitrogen fertilization promote an increase in crude protein content and a reduction in potassium content.