Silvério de Paiva Freitas

Recurrent selection in inbred popcorn families

Although much appreciated in Brazil, commercial popcorn is currently cropped on a fairly small scale. A number of problems need to be solved to increase production, notably the obtaintion of seeds with good agronomic traits and good culinary characteristics. With the objective of developing superior genotypes in popcorn, a second cycle of intrapopulation recurrent selection based on inbred S1 families was carried out. From the first cycle of selection over the UNB-2U population, 222 S1 families were obtained, which were then divided into six sets and evaluated in a randomized complete block design with two replications within the sets. Experiments were carried out in two Brazilian localities. The analysis of variance revealed environmental effects for all evaluated traits, except popping and stand, showing that, for most traits, these environments affected genotype behavior in different ways. In addition, the set as source of variation was significant for most of the evaluated traits, indicating that dividing the families into sets was an efficient strategy. Genotype-by-environment interaction was detected for most traits, except popping expansion and stand. Differences among genotypes were also detected (1% F-test), making viable the proposition of using the genetic variability in the popcorn population as a basis for future recurrent selection cycles. Superior families were selected using the Smith and Hazel classic index, with predicted genetic gains of 17.8% for popping expansion and 26.95% for yield.

Caracterização morfológica de acessos de batata-doce

To characterize morphologically accesses of sweet potato from the germplasm collection of the Universidade Estadual do Norte Fluminense (UENF) Brazil, as a way to optimize the utilization of important genomes for plant breeding, two experiments were carried out in field conditions, both in a randomized blocks design with three replications. The experiments were done in November at UENF and December in Campos. For such experiment, fourteen sweet potato accesses were evaluated for different traits related to aerial parts, and root descriptors, in a total of twenty characteristics. Genetic variability between accesses was observed, mainly due to characteristics of pubescence of the stem apex, pigmentation of the inferior veins of leaves and shape of roots. The accesses, Amarelinha, Roxinha, WON-B and Campina 3 presented interesting characteristics for the market of north-fluminense region.

Interferência de plantas daninhas no acúmulo de nutrientes e no crescimento de plantas de abacaxi

O objetivo deste trabalho foi verificar os efeitos da interferencia de Bidens pilosa, Cyperus rotundus e Digitaria horizontalis, em cinco densidades (0, 10, 20, 30 e 40 plantas por vaso), nos teores de nitrogenio, fosforo, potassio, calcio e magnesio presentes na folha D e no comprimento desta, aos 30, 60 e 90 dias apos o plantio do abacaxizeiro. Em geral, os teores dos nutrientes na folha D da cultura reduziram em razao do aumento da densidade das especies de plantas daninhas, e os elementos mais extraidos aos 30 dias foram fosforo e potassio; alem disso, C. rotundus e D. horizontalis foram as especies que mais interferiram no teor nutricional do abacaxizeiro. Com relacao ao comprimento da folha D, verificou-se comportamento analogo, ou seja, a medida que se aumentou a densidade de plantas daninhas, o valor dessa variavel foi reduzido.

Controle de plantas daninhas pelo indaziflam em solos com diferentes características físico-químicas

Herbicides in soil are subject to degradation and sorption processes that govern their fate and availability. The objective of this study was to evaluate the influence of three soils with contrasting physicochemical characteristics on a dose of indaziflam and the control efficiency of five weed species. The experiment was carried out in a greenhouse, in a randomized block design with four replications and a factorial 6 x 3 x 5. The treatments consisted of six doses of indaziflam (0; 30; 60; 90; 120 and 150 g a.i. ha-1), three soils (textural classes sand, clay, and sandy clay loam), and five weed species (Rottboellia cochinchinensis, Panicum maximum, Digitaria horizontalis, Euphorbia heterophyla, and Ipomoea grandifolia). The soil was sieved and placed on perforated trays, while the species were seeded at a depth of 0.015 m. The herbicide was applied to moist soils and trays placed under daily irrigation of approx. 5 mm. The emergence of weeds was assessed seven days after the emergence, and the control of weeds, 40 days after the treatment. The indaziflam was more effective in controlling the species D. horizontalis, P. maximum, and R. cochinchinensis. The first two were very sensitive to the herbicide, with full control of these species at all doses of the tested soils. In the clay soil, R. conchincinensis was effectively controlled from a dose of just 50 g a.i. ha-1. The control of E. heterophylla and I. grandifolia by indaziflam was more efficient in sandy clay loam soil.

Efeitos de dejeto de suínos na incidência de plantas daninhas e na eficiência do herbicida metribuzin na cultura da batata-doce

O experimento foi realizado em condicoes de campo, na Fazenda Experimental da EPAMIG, em Ponte Nova-MG, no periodo de janeiro a julho de 1995, com o objetivo de avaliar o efeito de doses de dejeto de suinos na forma liquida, sobre a producao de batata-doce, cultivar Paulista, na incidencia de plantas daninhas e na eficiencia de controle de especies de plantas daninhas pelo metribuzin. Utilizou-se o delineamento em blocos ao acaso, no esquema fatorial, com quatro repeticoes. Foram avaliados os efeitos das doses 0, 20, 40 e 60 m3 ha-1 de dejeto de suinos combinadas com 0, 300, 600 e 900 g ha-1 de metribuzin. Houve incremento linear de biomassa fresca das plantas daninhas de folhas largas, plantas de folhas estreitas e total de plantas daninhas em funcao do aumento das doses dejeto de suinos. O metribuzin foi seletivo para a cultura de batata-doce, nao sendo observado nenhum sintoma visivel de fitotoxicidade a cultura e eficiente no controle das principais plantas daninhas presentes na area. A producao maxima de raizes comerciais (22,94 t ha-1) foi obtida com o metribuzin na dose 810,17 g ha-1. Isto representou cerca de 89% superior ao peso obtido pela testemunha sem tratos culturais. Esta produtividade foi semelhante aquela observada nos tratamentos que receberam tres cultivos. As plantas daninhas interferiram negativamente nas principais caracteristicas avaliadas de producao da batata-doce. A cultura da batata-doce respondeu positivamente a adubacao com dejeto liquido de suinos, com aumento linear da producao de raizes das classes extra A, comercial e total. Verificou-se tambem que houve correlacao negativa entre plantas daninhas e as principais caracteristicas de producao da cultura de batata-doce.

Eficiência de trifloxysulfuron-sodium no controle de Cyperus rotundus L. na cultura da cana-de-açúcar

Control of Cyperus rotundus L. with trifloxysulfuron-sodium in sugar-cane The aim of this study was to evaluate the efficiency of trifloxysulfuron-sodium used alone, mixed or in sequential application with other herbicides to control Cyperus rotundus L. in sugar cane. The study was conducted in an area of commercial production of variety RB 72-454 at “Paraiso Plant” and a greenhouse at the State University “Darcy Ribeiro”, Campos dos Goytacazes, RJ. The field plots were subjected to nine treatments: 2,4-D; trifloxysulfuronsodium + ametryn; trifloxysulturon-sodium, 2,4-D + 2,4-D (20 days after the first application - DAP) 2, 4-D + ametryn trifloxysulfuron-sodium (20 DAP), 2,4-D + trifloxysulfuron-sodium (20 DAP); halosulfuron (20 DAP), control with and without hand weeding. The greenhouse trial evaluated the viability of purple nutsedge bulbs as a function of the treatments used in the experiment carried out in the field. The results indicated that the trifloxysulfuron-sodium applied alone or mixed with ametryn in sequential application to 2,4-D was excellent in controlling C. rotundus. These herbicides, along with halosulfuron applied alone reduced the capacity for reinfestation of this specie by reducing propagation and growth.

Manejo de plantas daninhas em maracujazeiro amarelo cultivado com adubação química e orgânica

The objective of this work was to evaluate different types of weed management in passion fruit culture under chemical and organic fertilization. The experimental design was in randomized blocks with 15 treatments, arranged in a splip-splot design, with four repetitions containing 10 plants each. The treatments consisted of three types of fertilization (organic, chemical and chemical + organic) and five types of weed management in each subplot (hand-hoeing, without hand-hoeing, diuron (pre-planting) + glyphosate (postemergence), diuron (pre-planting) + MSMA (postemergence) and diuron (pre-planting) + (diuron + paraquat) (postemergence). Diuron applied in pre-planting induced phytotoxicity symptom in the leaves around 20 to 26 days after planting (DAP). However, it was more evident in plants undergoing chemical fertilization. The treatments with chemical + organic fertilization associated to hand-hoeing, diuron (pre-planting) + glyphosate (postemergence) and diuron (pre-planting) + (diuron + paraquat) (postemergence) provided the highest fruit productivity. For the cultivation using organic fertilization, hand-hoeing promoted the highest productivity. On the other hand, under, chemical fertilization, highest crop production and weed control were observed in the treatment diuron (pre) + glyphosate (post).

Efeitos de dejeto de suínos na forma líquida e de composto orgânico na atividade do metribuzin

Este trabalho objetivou avaliar a atividade do metribuzin em funcao da adicao de doses de dejeto de suinos na forma liquida e de composto orgânico. Foram conduzidos dez experimentos utilizando delineamento experimental inteiramente casualizado, com quatro repeticoes, em condicoes de casa-de-vegetacao do Departamento de Fitotecnia da UFV. Foram avaliados cinco substratos: areia lavada, solo Podzolico Vermelho-Amarelo argilo arenoso, da regiao de Ponte Nova-MG misturado com doses correspondentes a 0, 20, 40 e 60 m3 ha-1 de dejeto liquido e 0, 30, 60 e 90 t ha-1 de composto orgânico associados a 10 doses de metribuzin. A aplicacao do metribuzin foi feita com pulverizador costal pressurizado a CO2, apos a semeadura de cinco sementes/vaso da planta indicadora (Cucumis sativus L.) hibrido caipira AG.221. A irrigacao dos vasos foi realizada, tres vezes ao dia, por meio de simulador de chuvas, mantendo-se a umidade dos substratos em aproximadamente 80% da capacidade de campo. Aos 14 dias apos a aplicacao dos tratamentos foi realizada a colheita dos experimentos, seguida pela determinacao da biomassa fresca da parte aerea da planta indicadora. As concentracoes dos herbicidas, que resultaram em 50% de inibicao do crescimento da planta teste (I50), foram calculadas a partir de equacoes ajustadas por meio de analise de regressao. A adsorcao do metribuzin aumentou linearmente com adicao de dejeto liquido ou composto orgânico ao solo, sendo que a maior adsorcao ocorreu com a adicao do composto orgânico. Para a maior dose de dejeto liquido (60 m3 ha-1), a relacao de adsorcao foi 4,79 e o aumento na adsorcao em relacao ao solo foi 28,01%. Entretanto, com a adicao da maior dose do composto orgânico (90 t ha-1), a relacao de adsorcao foi 6,63 e o aumento na adsorcao 32,51%.

Effect of Growth Regulators in Production and Rooting of Coffea arabica L. Minicuttings

The plants of C. arabica do not naturally produce a large number of orthotropic sprouts, hindering clonal multiplication by cutting, which would be the simplest technique with a lower cost of production compared to other methods of vegetative propagation. An alternative form, used successfully in the propagation of eucalyptus, is propagation by minicutting, which consists of pruning the shoot apex of the plant, forming the ministumps, which in variable time interval emits the shoots that will be used to make minicutting. In C. arabica plants the number of shoots can be increased with the application of growth regulators and fertilizers. So, the purpose of this work was to verify the effect of growth regulators and foliar fertilizers on the emission and development of orthotropic shoots of C. arabica. The experiment was installed in a randomized complete block design, with ten treatments composed by growth regulators and fertilizers: T1 (Control); T2 (Stimulate + Sturdy + Enervig); T3 (Stimulate + Vitakelp + Biozyme); T4 (Tiba + Sturdy + Enervig); T5 (Tiba + Vitakelp + Biozyme); T6 (Brs + Sturdy + Enervig) T7 (Brs + Vitakelp + Biozyme); T8 (Stimulate); T9 (TIBA); T10 (Brs-Brassinoesteroid), each plot consisting of two plants. Biometric and physiological parameters were evaluated for the ministumps, as well as the biometric parameters of the shoots and plant survival. The results showed that there was no influence of the treatments on the biometric parameters of the ministumps. A greater number of orthotopic sprouts were obtained in treatments with the TIBA growth regulator, as well as a greater plant survival of the minicuttings, after 25 days of transplanting in a greenhouse. It was concluded that TIBA treatments influenced the production and quality of clonal minicuttings of C. arabica.