Sistemas de cultivo e composição isotópica de carbono e nitrogênio em palma forrageira (Opuntia e Nopalea)

• Ano de defesa: 2018
• Autor(a) principal: MENOR, Talita Roberta Firemand de Lira
• Orientador(a): LIRA, Mario de Andrade
• Banca de defesa: TABOSA, José Nildo, CUNHA, Márcio Vieira da, SILVA, Maria da Conceição, SOUZA, Toni Carvalho de
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal Rural de Pernambuco
• Programa de Pós-Graduação: Programa de Pós-Graduação em Zootecnia
• Departamento: Departamento de Zootecnia
• País: Brasil
• Palavras-chave em Português: Palma forrageira; Composição isotópica; Carbono; Nitrogênio
• Área do conhecimento CNPq: CIENCIAS AGRARIAS::ZOOTECNIA
• Link de acesso: http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/8115

The cactus pear (Nopalea and Opuntia) presents the acid metabolism of crassulaceae (MAC), which gives these plants adaptations to the adverse conditions of the semiarid region. Morphological, productive and mineral and isotopic characteristics can be affected by planting density, harvest frequency and levels of residual fertilization applied to this crop. The objective of the first experiment was to evaluate the effect of harvest frequency and cut intensity associated with different planting densities on yield and mineral chemical composition of cactus pear cv. Miúda in Agreste Pernambucano. The second experiment aimed to evaluate the residual effect of organic and nitrogen fertilization of forage palm cv. Productivity and morphological characteristics and isotopic composition, at two harvest frequencies. In the third experiment the objective was to evaluate the isotopic composition of twenty palm clones (Opuntia and Nopalea). Both experiments were installed at the Experimental Station of the Instituto Agronômico de Pernambuco IPA, Caruaru - PE, from August 2013 to August 2015. The experiment 1 evaluated the combination of plant densities (10,417, 20,833, 41,666 and 83,333 plants ha-1), harvest frequencies (annual and biennial). The experimental design was the randomized blocks, with 4 replications and arrangement of subdivided plots, being the plot formed by the different planting densities and the subplots by the factorial arrangement between harvest frequencies and cut intensities. The variables evaluated were productivity, number of cladodes per plant, cladodes area index (IAC), height and width of plants (cm), crude protein, Na, K, Ca and Mg (mg kg -1). The increase in planting density favored productivity, which presented in the density 10,417 plants ha-1 the yield of 9.42 t of DM ha-1 2 years-1, and in the density 83,336 plants ha-1 the yield of 30.01 t of MS ha-1 2 years-1. the population density of 83,336 plants per hectare with biennial crop frequency is recommended. The contents of dry matter, nitrogen and calcium were: MS 71,2 and 85 g kg-1; N 25,7 and 16.9 g kg-1; Ca 12,4 and 9,4 g kg-1 at the densities of 10,417 and 83,336 plants ha-1, respectively. The sodium, magnesium and potassium contents were: Na 0,00257 g kg-1; Mg 0,01798 g Kg-1; K 26,84 g kg-1 in the biennial crop. Experiment 2 evaluated the effect of organic and mineral fertilization on two harvest frequencies, on the morphological characteristics and isotopic composition of the forage palm cv. Miúda. The experimental design was a randomized complete block design, with arrangement of sub - divided plots, with four replications. The main plots (14,4 x 8,0 m) were used to test the organic matter levels; the subplots (7,2 x 8,0 m) to evaluate the harvesting frequencies and the sub-plot (14,4 x 2,0 m) to evaluate the nitrogen levels. The variables measured were productivity (t ha-1), dry matter, number of cladodes per plant, cladode area index (IAC), plant height, plant width, crude protein, Na, K, Ca and Mg (g kg-1) and the isotopic composition of ⸹13C and ⸹15N. As the level of residual organic fertilizer increased, at biennial frequency, plant productivity, height and width, number of cladodes per plant and cladodes area index also increased. The δ13C isotopic composition was not influenced by any of the factors tested (residual organic fertilization, residual mineral fertilization and harvest frequency). The average of the isotopic values δ13C was -13,97 and indicate that under the conditions presented the forage palm cv. Miúda behaves like a mandatory CAM plant. The values of δ15N ranged from 13, 71 to 12,99 and indicate absence or minimum levels of biological fixation of atmospheric N2 by Miúda palm. In the third experiment the isotopic composition of twenty palm clones (Opuntia and Nopalea) was evaluated. A randomized block design with three replications was used, containing seven plants per plot, with 5 plants in the useful area and one row per plot, except in the small cultivar that presented three rows. The spacing used was 1,0 x 0,5 m, with a total area of 3,5 m² and a floor area of 2,5 m². The clones studied present values of ⸹13C between -14.43 and -13.22 ‰, which allows to observe that the values obtained are typical of the PEP-carboxylase fixation and indicate that, independently of the environmental conditions and the age of the plant, the photosynthesis occurs through the CAM process, possibly with CO2 fixation at night. For the isotopic composition of δ15N (‰), in forage palm clones, there was no significant difference between the evaluated periods, with a significant difference only between the clones.