Inêz Pereira da Silva

Chemical properties and rates of external color of strawberry fruits grown using nitrogen and potassium fertigation

El cultivo de la fresa entra en el mercado mundial como una importante alternativa para la diversificacion agricola, siendo la nutricion mineral estrechamente relacionada con la calidad de la produccion; sin embargo, todavia hay muchas preguntas acerca de la relacion entre la nutricion de plantas y la calidad de la fresa. Por lo tanto, los estudios relacionados con la nutricion mineral de fresa van a contribuir a una mejor comprension de ese cultivo. En este sentido, el presente estudio tuvo como objetivo evaluar el efecto del nitrogeno y potasio en fertirrigacion en la fresa, bajo condiciones de campo, con respecto a las propiedades quimicas y los indices de color externo de la fruta. El experimento se llevo a cabo en la Universidad Federal de Lavras, Lavras, MG, Brasil. Se utilizo un diseno de bloques completos al azar con tres bloques y 16 tratamientos en un factorial 4x4, cuatro niveles de nitrogeno (100, 200, 300 y 400 kg ha-1) y cuatro niveles de potasio (150, 300, 450 y 600 kg ha-1 de K2O), utilizando como fuentes de estos nutrientes, urea y cloruro de potasio, respectivamente. Utilizamos las plantulas del cultivar de fresa Aromas. Las propiedades quimicas y los indices de coloracion externa de frutas de fresa se ven influidas por la fertirrigacion de nitrogeno y potasio, que varian segun la propiedad estudiada.

Adubação fosfatada em mudas de bananeira 'Prata anã'(AAB), cultivadas em dois Latossolos

Phosphorus fertilization in banana ‘Prata ana’ (AAB) cultivated in two latosols Data on the effect of phosphorus on the development of banana are scarce. The objectives of this work were to evaluate the effect of the application of phosphorus on the development of banana “Prata Ana” growing in a Red Latosol (RL) and a Red-Yellow Latosol (RYL), as well as to determine the phosphorus critical level. The treatments were arranged in a randomized design , using a 8 x 2 in factorial arrangement, with three replications . The factors corresponded to eight phosphorus doses (0; 50; 100; 150; 300; 450; 600; 750 mg.dm -3 ) and the two soil types. The dry mass production of banana seedlings increased with phosphorus application to both soils. Phosphorus soil critical levels in RL and RYL were 18.9 and 40.2 mg dm -3 , respectively. The phosphorus critical levels in the leaves of banana seedlings growing in RL and RYL were 0.20 and 0.31 dag kg -1 , respectively. Phosphorus was used more efficiently by banana seedlings

Production and nutrition of irrigated Tanzania guinea grass in response to nitrogen fertilization

The objective of this study was to evaluate the effects of nitrogen (N) fertilization in the four seasons of the year on forage production, nitrate (NO3) in the sap, total N in the forage and relative chlorophyll index (SPAD reading) in the leaves of irrigated Panicum maximum cv. Tanzania grass, establishing their critical ranges. In addition, we evaluated the ability to predict forage production based on NO3 in the sap, total N in the forage and relative chlorophyll index. The soil in the experimental area was classified as an Oxisol (Red-Yellow Latosol) with a clayey texture. Annual rates of N (0, 200, 400 and 800 kg ha-1) in the form of urea were the treatments tested. Irrigation was performed through a conventional spray system. The NO3 content in the sap and the relative chlorophyll index were measured in leaves using a portable meter with NO3 selective electrode and the SPAD-502 portable chlorophyll meter device, respectively. Tanzania guinea grass was very responsive to N fertilization, except in the winter. The critical ranges of the SPAD reading proved to be more adequate for monitoring the nutritional state of N of Tanzania guinea grass in the different seasons of the year than the NO3content in the sap and the total N content in the dry matter. Use of the chlorophyll meter is more advantageous than the use of the portable meter with an nitrate selective electrode for predicting the nutritional status of Tanzania guinea grass.

Critical levels for Brachiaria brizantha and Panicum maximum using different sources of phosphorus

El nivel critico de fosforo se ve influenciado por los atributos fisicos y quimicos del suelo y las caracteristicas de cada especie vegetal. El objetivo de este estudio fue determinar los niveles criticos de fosforo en el suelo y las plantas de Bracharia brizantha cv. Marandu y Panicum maximum cv. Tanzânia, utilizando diferentes dosis y fuentes de P. El trabajo se llevo a cabo bajo condiciones de invernadero utilizando muestras de suelo con diferentes contenidos de arcilla. En el experimento con la hierba Marandu, 20 tratamientos se aplicaron en un diseno factorial (5 x 4), correspondiente a cinco niveles de fosforo (0, 100, 200, 400 y 800 mg dm�3) y cuatro fuentes de fosforo (fosfato monoamonico, superfosfato triple, simple superfosfato y fosfato natural de Gafsa). En el experimento con la hierba Tanzânia, se aplico tambien termofosfato magnesiano. Los tratamientos se dispusieron en un diseno de bloques al azar con cuatro repeticiones. No se observaron diferencias entre los efectos de fosfato monoamonico, superfosfato triple, simple superfosfato, fosfato natural de Gafsa y termofosfato magnesiano en la produccion de materia seca de gramineas Marandu y Tanzânia. El super triple proporciona valores mas bajos de nivel critico de P en el suelo, al paso que el fosfato natural de Gafsa proporciono mas bajos niveles criticos de P en los brotes de hierbas.

Produção da bananeira 'Prata anã'(AAB) em função de diferentes doses e fontes de potássio

Production of banana tree cv. Prata ana (AAB) as a function of different doses and sources of potassium Among the nutrients required by the banana tree, the potassium (K) is what most influences the production of the crop. This study aimed to compare the effects of two K sources, potassium chloride (KCl) and potassium sulfate (K 2 SO 4 ) on production, and estimate the dose of K for maximum physical efficiency (MPE) and maximum economic efficiency (MEE), besides determine the critical levels of leaf K for the banana tree, cultivar Prata ana (AAB) irrigated, cultivated in the semi-arid region of northern Minas Gerais State, Brazil. The experiment was conducted in an oxisol, medium texture. The treatments were derived from the factorial (4 x 2), being four rates of K (0, 400, 800 and 1200 kg ha1 yr-1 of K 2 O) and two K sources (KCl and K 2 SO 4 ), resulting in eight treatments. These were distributed in randomized blocks with four replications. There were no differences among the effects of KCl and K 2 SO 4 on the production of banana. The KCl showed greater economic viability to be used as a source of K. The estimated doses for MPE of banana in the 2nd and 3rd production cycles using the KCl were 827 and 835 kg ha -1 yr -1 of K 2 O, respectively, while for MEE, doses were 157 and 670 kg ha -1 yr -1 of K 2 O, respectively. The critical levels of leaf K obtained in the 2nd and 3rd production cycles were 2.85 dag kg -1 for the MPE and for MEE, the values were 2.41 and 2.80 dag kg -1 , respectively.

QUALITY OF ‘TAHITI’ ACID LIME FERTILIZED WITH NITROGEN AND POTASSIUM IN THE SEMIARID REGION OF MINAS GERAIS

this study aimed to evaluate external characteristics and juice obtained from ‘tahiti’ acid lime produced under nitrogen and potassium fertilization. this study had a completely randomized design with three replicates of four fruits of the two central plants, 4 x 5 factorial and four N doses (0, 25, 50 and 100 Kg ha-1 year1) and five K2O doses (0, 25, 50, 100 and 200 Kg ha -1 year1), totaling 20 treatments. In the postharvest period, external characteristics (size, color and skin thickness, firmness and fresh mass) and juice (content, percentage, soluble solids, technological index, pH, titratable acidity, ratio and ascorbic acid) of fruits were evaluated. Size, skin color, soluble solids content and pH of ‘tahiti’ acid lime juice were not affected by N and K2O fertilization. Skin thickness, juice percentage and technological index increased with the N and K2O doses applied to the soil. Juice content and fruit firmness decreased with application of K2O doses. titratable acidity and ascorbic acid content increased with K2O doses. the different nitrogen and potassium doses influenced more the juice quality than the external characteristics of ‘Tahiti’ acid lime in the postharvest period.