Resumo O potássio é um nutriente que afeta o crescimento e a qualidade dos frutos do abacaxizeiro. O estudo objetivou avaliar a qualidade de frutos em abacaxizeiro ‘Vitória’ submetido à aplicação de doses de potássio. O experimento foi realizado de maio de 2017 a novembro de 2018, em São Francisco do Itabapoana (RJ), Brasil. O delineamento foi em blocos ao acaso, com quatro repetições. Os tratamentos foram cinco doses de K2O: 0; 6; 12; 18 e 24 g planta-1, aplicadas na forma de KCl, parceladas em duas aplicações, após a indução floral. As massas frescas do fruto e da coroa, os diâmetros do fruto e do cilindro central,os comprimentos do fruto e da coroa, a acidez titulável, os sólidos solúveis, a vitamina C, o pH do suco e a relação sólidos solúveis/acidez titulável foram avaliados. A adubação potássica promoveu maiores comprimento, diâmetro e massa de fruto. Os valores de acidez titulável, dos sólidos solúveis e da vitamina C aumentaram linearmente em função das doses de potássio. A adubação potássica promove a melhoria da qualidade dos frutos de abacaxizeiro ‘Vitória’ em condições de campo.

Abstract Potassium is a mineral nutrient that affects the growth and quality of pineapple fruits. This study aimed to evaluate the quality of ‘Vitória’ pineapple fruits submitted to application of potassium doses. The experiment was carried out from May 2017 to November 2018, in the municipality of São Francisco do Itabapoana (RJ), Brazil. The design was randomized blocks, with four replicates. Treatments were five K2O doses: 0; 6; 12; 18 and 24 g plant-1, applied as KCl, split into two applications after flower induction. Fruit and crown fresh masses, fruit and crown diameters, fruit and crown lengths, titratable acidity, soluble solids, vitamin C, juice pH and soluble solids/titratable acidity ratio were evaluated. Potassium fertilization promoted greater fruit length, diameter and mass. Titratable acidity, soluble solids and vitamin C values increased linearly as a function of potassium doses. Potassium fertilization improves the quality of ‘Vitória’ pineapple fruits under field conditions.

Resumo Objetivou-se avaliar a influência das deficiências de macronutrientes e de boro nas características físico-química dos frutos de abacaxizeiro da cultivar Vitória. O delineamento experimental foi em blocos ao acaso, com oito tratamentos (solução completa, -N, -P, -K, -Ca, -Mg, -S e -B) e seis repetições. A condução do experimento foi de outubro de 2016 a março de 2018, e as variáveis avaliadas foram: massas frescas do fruto e da coroa, diâmetro do fruto, comprimentos do fruto e da coroa, volume e massa do suco, acidez titulável (AT), sólidos solúveis (SS), vitamina C, pH do suco e relação SS/AT. Todos os tratamentos com deficiência de nutrientes reduziram a massa fresca do fruto. Nos tratamentos -N e -Ca houve redução de 41,9 e 35,3%, respectivamente, na massa fresca da coroa. O diâmetro dos frutos sob deficiência de N, K e Mg, foi menor, já o comprimento do fruto, os sólidos solúveis e o pH do suco foram menores no tratamento deficiente em N. Deficiências isoladas de cada um dos macronutrientes e de B reduziram a massa fresca do fruto inteiro e do fruto sem coroa. O nutriente que mais limitou o tamanho e qualidade do fruto de abacaxizeiro ‘Vitória’ foi o nitrogênio.

Abstract The objective of this study was to evaluate the influence of macronutrient and boron deficiencies on physico-chemical characteristics of pineapple fruits, ‘Vitoria’ cultivar. The experimental design was a randomized complete block with eight treatments (complete solution, -N, -P, -K, -Ca, -Mg, -S and -B) and six replicates. The experiment was conducted from October 2016 to March 2018, and the variables evaluated were: fresh fruit and crown mass, fruit diameter, fruit and crown length, juice volume and mass, titratable acidity (TA), soluble solids (SS), vitamin C, juice pH and SS/TA ratio. All treatments with nutrient deficiency reduced the fresh fruit mass. In treatments -N and -Ca there was a reduction of 41.9 and 35.3%, respectively, in the crown fresh mass. Fruits diameter under N, K and Mg deficiency was lower, fruit length, soluble solids and juice pH were lower in treatment with N deficiency. Isolated deficiencies of each of the macronutrients and B reduced the mass of the whole fruit and the crownless fruit. The nutrient that most limited the size and quality of ‘Vitoria’ pineapple fruit was nitrogen.

ABSTRACT Eight rumen-cannulated steers were assigned to two 4 × 4 balanced Latin squares to evaluate degradability and kinetics of fiber particles from diets based on corn silage and supplements with or without addition of lipids. Dietary treatments were: only corn silage (T1), corn silage plus concentrate with no added lipids (T2), corn silage plus concentrate with added soybean oil (T3), and corn silage plus concentrate containing ground soybean seeds (T4). Kinetics of gastrointestinal transit of fibrous particles was evaluated based on chromium-mordanted fiber. Events of rumen degradation dynamics of fibrous carbohydrates were quantified using the in situ incubation procedure. The mixed models methodology from SAS was used to fit models and the Tukey test was used to compare means. The ruminal digestibility of fiber was lower in treatments T3 and T4 and, consequently, lower proportions of potentially digestible fraction of standardized fiber and higher proportions of indigestible fraction of standardized fiber for treatments T3 and T4 compared with T1 and T2 were observed. However, there were no differences in mean retention time of the rumen, total mean retention time, mean digestion time, and rumen fill among diets. Animals from T2, T3, and T4 showed higher dry matter intake, organic matter intake, and crude protein intake rates than animals receiving T1 diet, but there was no effect of the addition of lipid. Treatments did not differ regarding neutral detergent fiber intake. Animals from T1 had lower crude fat intake than animals from T2, which showed lower crude fat intake than those from T3 and T4. The addition of lipid to concentrate has no effect on passage rate, digestion rate, and intake, when a good quality roughage is used.