ABSTRACT. The custard apple (Annona squamosa L.), also known as the sugar apple, is a fruit species native to Brazil that has been poorly studied, especially in relation to the effect of humic substances on its fruit quality and yield. An experiment was conducted from December 2010 to November 2011 to evaluate the fruit quality and yield of the custard apple as a function of nitrogen fertilising and the use of humic substances. The experimental design consisted of randomised blocks, with treatments distributed in a factorial arrangement (4 x 2), using four nitrogen doses (0, 100, 175 and 250 g of N plant -1 ) and two humic substance applications (with and without humic substances), with four replications. The fruit yield and fruit characteristics, such as fruit mass, titratable acidity (TA), soluble solids (SS), pulp pH and SS/TA ratio, were recorded. The humic substances and the nitrogen levels significantly affected the soluble solids, titratable acidity and SS/TA ratio, while the pH pulp was only influenced by the humic substances. The humic substances promoted a quantitative increase in the fruit yield of 0.63 ton ha -1 . The fruit quality and yield of the custard apple depend on the nitrogen fertiliser and the interaction of the humic substances. Nitrogen fertilising of 100 g per plant, associated with humic substances, could be recommended for use in the production of custard apples.

RESUMOO maracujazeiro-amarelo é uma frutífera de grande importância econômica para o Brasil, sendo especialmente consumido na forma de sucos e sorvetes, tornando a qualidade de frutos ainda mais relevante. Neste sentido, objetivou-se avaliar os atributos físico-químicos de frutos de maracujá-amarelo em solo fertilizado com calagem, biofertilizantes e adubação mineral com NK em cobertura no de Bom Jesus, PI. Utilizou-se o delineamento em blocos casualizados com fatorial 2 x 3 x 2 referentes, respectivamente, à acalagem (solo sem e com calcário), aos biofertilizantes (sem biofertilizante, biofertilizante simples e biofertilizante enriquecido e adubação mineral (50 e 100% da recomendação de adubação NK em cobertura), com quatro repetições e duas plantas por parcela, ou seja, as variáveis avaliadas. Foram tomadas as seguintes variáveis: diâmetro longitudinal (DL), transversal (DT), espessura de casca, número de sementes, massa do fruto, porcentagem de polpa, sólidos solúveis (SS), acidez titulável (AT) e pH. A qualidade de frutos de maracujá-amarelo quanto ao DL, DT, espessura de casca, número de sementes, massa do fruto, pH, SS e AT, é incrementada pelo uso do biofertilizante bovino. A aplicação conjunta de biofertilizante simples com 50% da dose de NK em cobertura pode substituir a adubação completa de NK em cobertura. Palavras-chave: adubação orgânica, Passiflora edulis Sims, qualidade de frutos Biofertilizer, liming and NK fertilizing of physical and chemical characteristics of yellow passion fruits ABSTRACTYellow passion fruit is a fruit species economically important for Brazil, specially consumed as juice, ice cream and compotes that makes fruit quality more relevant. Thus, the present study was developed aiming to evaluate the physical and chemical characteristics of yellow passion fruit as a function of biofertilizer, liming and NK fertilizing in Bom Jesus County, Piaui State, Brazil. Theexperimental design wasrandomized blocks withfactorial 2 x 2 x 3 referring to liming(soilwith and withoutliming), biofertilizers (without bioferilizer, simple biofertilizer and enriched biofertilizer) and mineral fertilizer(50 and100% forNK recommendation) with four repetitions and two plants per parcel. The following variables were recorded: fruit width (FW), fruit length (FL), skin diameter, seed number, fruit mass, pulp percentage, soluble solids (SS), titratable acidity (TA) and pH. Fruit quality related to FW, FL, skin diameter, seed number, fruit mass, pulp percentage, SS, TA and pH is increased by bovine biofertilizer. The use of bovine biofertilizer associated to 50% of NK recommendation may substitute the complete NK fertilizing.

Custard apple (Annona squamosa L.) is native to tropical America and it occurs spontaneously in the Brazilian northeast region, where it is exploited mainly at subsistence level owing to lack of adequate management and selected genetic material. In this study, we aimed to evaluate the physiological characteristics of custard apple as a function of nitrogen fertilization and application of humic substances in the municipality of Bom Jesus, Piaui state, Brazil. We adopted a randomized block experimental design with treatments arranged in a 4 × 2 factorial scheme, referring to four doses of nitrogen and the presence and absence of humic substances (Humitec ®). The following variables were evaluated: leaf area index (LAI), chlorophyll (A, B, and Total), and photosynthetic active radiation (PAR). The maximum agronomic efficiency for intercepted photosynthetically active radiation was registered under fertilization with 174.70 g/plant of N. RESUMO: A pinheira (Annona squamosa L.) é originária da América tropical, ocorrendo espontaneamente no Nordeste brasileiro, onde é explorada principalmente em nível de subsistência, pela falta de manejo adequado e material genético selecionado. O objetivo do presente trabalho foi avaliar características fisiológicas da pinheira em função de adubação nitrogenada e substâncias húmicas, em Bom Jesus-PI. Adotou-se o delineamento em blocos casualizados com tratamentos distribuídos em esquema fatorial 4 × 2, referentes às quatro doses de nitrogênio e a presença e ausência de substancias húmicas (Humitec ®). Foram avaliadas as seguintes variáveis: índice de área foliar (IAF), clorofila (A, B e Total) e radiação fotossinteticamente ativa (RFA). A máxima eficiência agronômica para radiação fotossinteticamente ativa interceptada é obtida com a dose de 174,70 g/planta de N. Physiological indexes of custard apple as a function of nitrogen fertilization and humic substances Índices fisiológicos da pinheira em função de adubação nitrogenada e substâncias húmicas