Barbara Olinda Nardis

Lettuce is the most important vegetable in the world and the most consumed in Brazil. Seedling production with a good quality substrate is very important in the lettuce crop production process. The objective of this study was to evaluate the performance of organic compost substrates in the production of lettuce seedlings. The experiment was carried out in a greenhouse, using polyethylene trays containing 128 trapezoidal cells in a completely randomized design with a 5 × 2 factorial scheme consisting of 5 substrates (commercial substrate; compost I; compost II; compost III; compost IV) and P2O5 supplementation (absent and 0.525 kg m−3 P2O5) and 4 replications. Substrates were produced by composting agro-industrial waste: sawdust, wood shavings and residues from a restaurant, pig litter, cattle manure, residues from the shoot and tubers of sweet potato, soybean residue, and drained bovine ruminal residue. The emergence, plant height, number of leaves, fresh root and shoot biomass, and clod stability of the substrate were evaluated. The substrate formulated from pig litter, cattle manure, and sweet potato (compost II) and pig litter and drained bovine ruminal residue (compost IV) formed seedlings with a greater clod stability of the substrate, plant height, number of leaves, and fresh root and shoot biomass. Substrates based on composting pig litter, cattle manure, and sweet potato (composts II) and pig litter and drained bovine ruminal residue (compost IV) were most suitable for producing lettuce seedlings.

Phytoremediation is a technique with high viability due to its low cost and minimal environmental impact. However, there are a few results regarding the use of tropical grasses in the phytoremediation of manganese (Mn), and there is no clear definition of which extractor is more suitable for assessing Mn availability in soils. The objective of this study was to evaluate the growth potential and phytoremediation of five tropical grasses in Mn‐contaminated soil, as well as to assess the efficiency of four extractors in Mn extraction. The grass cultivars evaluated included Aruana and Tanzânia of Megathyrsus maximus, Xaraés and Marandu of Urochloa brizantha, and Basilisk of Urochloa decumbens grown in Typic Hapludox (Oxisol) amended with 0, 50, 150, and 450 mg of Mn per kg⁻¹ of soil. The experiment was conducted in a greenhouse, using a completely randomized experimental design in a 5 × 4 factorial scheme, with five replications. The experimental period lasted for 90 days. The dry matter of the shoot and root of the grasses was evaluated. Mn concentration in dry matter and its availability in soil were extracted by Mehlich‐1 and DTPA pH 7.3, while the semitotal concentration was determined by USEPA 3051 and total Mn by USEPA 3052 method. Tropical grasses showed reduced growth with increasing Mn rates in the soil, with the following sequence in the reduction in growth: Aruana > Basilisk > Marandu > Xaraés and lastly the Tanzânia. The Aruana cultivar showed greater potential for phytoextraction due to its higher ability to accumulate Mn in its biomass, followed by the Basilisk cultivar. The four different evaluated extractors were efficient in measuring Mn concentrations in the soil, with higher toxicity critical levels for the USEPA 3051 method due to the semitotal extraction nature and USEPA 3052 due to total Mn extraction. The growth of tropical grasses is reduced with increasing Mn rates applied to the soil. The Aruana of M. maximus grass has greater potential for phytoextraction of Mn‐contaminated soils, followed by Basilisk of Urochloa decumbens, Xaraés and Marandu of U. brizantha, and Tanzânia of M. maximus. The Mehlich‐1, DTPA pH 7.3, USEPA 3051, and 3052 extractors were efficient in extracting and evaluating Mn availability in soil for tropical grasses. The USEPA 3051 and 3052 methods presented higher toxicity critical levels.

Determinar o tipo de distribuição espacial de uma praga agrícola é uma das principais ferramentas para estabelecer uma metodologia de amostragem, portanto o objetivo desse trabalho foi estudar a distribuição espacial de Aphis craccivora em feijão-caupi. Os estudos foram desenvolvidos no período de cultivo de feijão-caupi “da seca” na fazenda experimental da Universidade Estadual de Mato Grosso do Sul (UEMS), em Aquidauana-MS. A área experimental 300 m2, foi formada por 40 parcelas de quatro linhas com 5 metros de comprimento, espaçadas a 0,50 metros entre si, considerando-se como área útil as duas linhas centrais. As amostragens foram realizadas semanalmente a partir do aparecimento do primeiro pulgão. Foi determinada a variância media e os índices de agregassão. A distribuição de Poisson, distribuição binomial negativa e distribuição binomial positiva foram utilizadas para descrever a distribuição teórica de frequência para as amostras da população: As variâncias das amostragens foram sempre superior à média, o que indica ajuste à distribuição binomial negativa, com a disposição do inseto tendendo à agregação, o que normalmente ocorre no campo para os índices de Razão Variância-Média (I), Índice de Morisita (Iδ) e Expoente k da Distribuição Binomial Negativa (k), foi obtido para a distribuição da comunidade de pulgões pretos no feijão caupi, a distribuição no formato agregado. Para os testes de distribuição de freqüência o que mais se enquadra para as amostragens foi o da distribuição Binomial Negativa, indicando população de pulgão preto se comporta de forma agregada na cultura do feijão caupi.

The growth of coffee plants can be severely affected by competition with other plants, being necessary to the management of these, which can be performed by controls manual, mechanical, biological and chemical methods. This study aimed to evaluate the growth of coffee robusta due to no control of Urochloa ruziziensis (cv. Common) and control by manual weeding and herbicides in post emergence, seeking the most appropriate method. The experimental design was completely randomized, with four replicates of four treatments: control (no control of the U. ruziziensis); manual weeding; oxyfluorfen (1.44 kg a.i. ha-1); paraquat + diuron (0.40 + 0.20 kg a.i. ha-1) and glyphosate (1.92 kg a.i. ha-1), with the spray volume equivalent to 200 L ha-1. The herbicides were applied directly on the U. ruziziens plants 60 days after planting. 30 days after treatment, the following were evaluated: a, b and total chlorophyll content, stem diameter, plant height, number of leaves, leaf area, orthotropic and plagiotropic branches, dry shoot biomass, dry root biomass and root growth. U. ruziziens, when not controlled, caused a 42% reduction in the leaf area of robusta coffee in relation to those that were controlled through manual weeding. The herbicide oxyfluorfen and weeding were the most suitable for the control of U. ruziziens in the cultivation of coffee, since they did not affect seedling growth. Failure to control U. ruziziens or weeds leads to reduced growth of robusta coffee plants, except in the height due to the etiolation caused by competition with U. ruziziens. Key words: Coffea canephora Pierre ex Froehner; Coffee seedlings; Brachiaria; Chemical control.