A.C.P. Rodrigues-Costa

Determinação dos períodos de interferência de plantas daninhas na cultura do girassol

The aim of this study was to determine the period prior to interference and the total period of prevention against interference of weeds in sunflower (hybrid M 734). The experiment was arranged in a complete randomized block design, with four replications. The treatments consisted of plots constituted by periods of control and presence of weeds. For the control periods, the sunflower plants were kept wedd free during increasing periods of 7, 14, 21, 28, 35, 42, 49 and 125 days after emergence (DAE). During cohabitation, the sunflower culture was maintained in the presence of the weed community during the same periods. Total density and dry weight of the weeds and plant height, chapter diameter, seed yield and oil of the sunflower plants were evaluated. For seed yield, the period before interference was 15 DAE of the culture, and the total period of prevention against weed interference was 39 DAE. The critical period of weed interference covered 24 days of the sunflower cycle. As for oil yield, the period before interference was 32 DAE, while the total period of prevention against weed interference was 28 DAE.

Levantamento de plantas aquáticas no reservatório de Salto Grande, Americana-SP

The objectives of this work were to determine the relative frequency and infestation level of each species present in the Salto Grande Reservoir in Americana-SP. The survey and identification of the aquatic plants were carried out in the Salto Grande reservoir on a boat. Twenty evaluation sites were established along the reservoir, photographed and geo-referenced. Values from 0 to 100% were assigned for both the species present and for the aquatic plants that could possibly occur within the sampled sites. Based on the number of individuals and points evaluated, the relative frequency of each species was determined. Thirteen species were identified along the reservoir, 12 vascular species and one green alga (Chlorella spp.). Among the vascular species , nine were floating plants, anchored or not on the bed of the reservoir, namely, Alternanthera philoxeroides, Brachiaria subquadripara, Cyperus difformis, Echinochloa polystachia var. spectabilis, Eichhornia crassipes, Panicum rivulare, Pistia stratiotes, Salvinia auriculata and Typha angustifolia. Other three species were found only on firm ground, namely, Aeschynomene sensory, Hedychium coronarium and Mimosa pigra.

Uniformidade de deposição de gotas de pulverização em plantas de amendoim e Brachiaria plantaginea

The objective of this study was to evaluate the uniformity of spray deposition on peanut and on the weed Brachiaria plantaginea in crop rows and inter-rows. The study was conducted in the field with the peanut cultivar IAC Tatu-ST, and the applications were carried out at the vegetative (V1) and reproductive (R2) stages of the culture. Brilliant Blue (FDC only the spray nozzle XR 11002 VS (200 L ha-1) showed no deposition failures at both stages of development of B. plantaginea located on the crop line. As for the plants located between the rows, the spray nozzles were most efficient at the 3-5 tiller stage.

Seletividade de herbicidas aplicados em pré-emergência em gramíneas forrageiras

This study aimed to evaluate the selectivity of pre-emergence herbicides on yield and seed quality of Brachiaria brizantha cv. Brizantha and Brachiaria decumbens cv. Basilisk. The herbicides evaluated were: diuron (800 and 1.600 g ha-1), ametryn (625 and 1.250 g ha-1), imazaquin (75 and 150 g ha-1), imazethapyr (50 and 100 g ha-1) and flumetsulam (70 and 140 g ha-1), plus a control without herbicide application. The species were evaluated separately in the field. The experiments were arranged in a randomized block design with four replications. The herbicides ametryn (625 g ha-1), imazaquin (75 and 150 g ha-1), imazethapyr (50 and 100 g ha-1), and flumetsulam (70 and 140 g ha-1) provided the highest selectivity to B. brizantha plants, while for B. decumbens, diuron (800 and 1.600 g ha-1), ametryn (625 and 1.250 g ha-1), and imazethapyr (50 and 100 g ha-1) were more selective, especially diuron, at the lowest dose. However, the tested herbicides do not affect the yield and quality of the seeds of the forage grasses studied.

Avaliação de pontas de jato plano na deposição da calda de pulverização com diferentes combinações de plantas de feijão, Brachiaria plantaginea e Bidens pilosa

The objective of this study was to evaluate flat fan nozzle spray deposition on different combinations of the common bean plants, Brachiaria plantaginea and Bidens pilosa, in two volumes of application, with and without the addition of surfactant. Brilliant blue FDC -1 was used as tracer solution at the concentration of 500 ppm to evaluate the deposition. The treatments consisted of 7 combinations of plants: (common bean); (B. plantaginea); (B. pilosa); (common bean + B. plantaginea); (common bean + B. pilosa); (B. plantaginea + B. pilosa) and (common bean + B. plantaginea + B. pilosa). The experiment was arranged in a randomized block design. The flat fan nozzles XR 110015 VS and XR 11002 VS were evaluated, with volumes of application of 150 and 200 L ha-1 , respectively, with and without the surfactant Silwet at 0.05% v v-1. After application, the plants were immediately collected and washed in 100 mL of distilled water for posterior tracer quantification in the spectrophotometer. The flat fan nozzles presented distinct behavior in droplet deposition on the species studied; the addition of a surfactant to the spray solution increased deposition uniformity, and contributed to the reduction of the volume application.

Aspectos quantitativos da deposição de gotas de pulverização em plantas de amendoim e Brachiaria plantaginea

Objetivou-se avaliar a deposicao de gotas de pulverizacao em plantas de amendoim (Aracahis hypogaea) e Brachiaria plantaginea, presentes na linha e entrelinhas de semeadura da cultura, alem da deposicao no solo. O estudo foi realizado em campo no cultivar de amendoim IAC Tatu-ST, sendo as aplicacoes dos tratamentos realizadas nos estadios vegetativo (V1) e reprodutivo (R2). Foi utilizado como marcador o corante Azul Brilhante (FDC as maiores perdas de gotas para o solo nas aplicacoes no estadio vegetativo (V1) foram proporcionadas pelas pontas AI 110015 VS e AI 11002 VS, e no estadio reprodutivo (R2) a ponta XR 11002 VS foi a que promoveu maior perda; e as pontas XR 11002 VS, AI 110015 VS e TJ60 11002 VS (150 L ha-1) proporcionaram os maiores depositos nas plantas de B. plantaginea na linha em relacao as da entrelinha da cultura nas aplicacoes no estadio vegetativo (V1), enquanto no estadio reprodutivo (R2) as pontas apresentaram comportamento semelhante entre si na deposicao de gotas sobre a planta daninha.

Alocação de biomassa de Brachiaria subquadripara sob diferentes concentrações de N, P e K

This work was carried out to evaluate biomass allocation in Brachiaria subquadripara plants at different concentrations of N, P and K in nutritional solution. The experiment was arranged in a completely randomized design with six replications and treatments were 5 levels of N, P and K (0, 25, 50, 75 and 100% of the base solution concentration) for 5 times (intervals of 7 days). The base solution used refers to the dilution of 20% of the nutritional solution used for crops. The absence of N provided greater allocation of biomass in roots than on stems until the fourth week (28 DAT). The addition of 25 and 75% phosphorus in the solution provided biomass increments of 6.6 and 5.8%, respectively, in relation to the absence of phosphorus. Under potassium deficiency conditions, the plants tended to maintain a constant proportion of stems and roots, but leaf production decreased with plant age.

Alterações anatômicas do limbo foliar de plantas de Polygonum lapathifolium submetidas à aplicação de herbicidas

The aim of this research was to evaluate the efficacy of some herbicides (2,4-D, diquat, and glyphosate) and the leaf blade anatomic changes such herbicides caused in Polygonum lapathifolium. The plants were cultivated in reservoirs containing water under field conditions and were sprayed with herbicide when reaching full development (before flowering). The following anatomical characteristics were quantitatively evaluated from the central nervure regions and the leaf inter nervural blade: adaxial and abaxial epidermis percentage, bundle sheath percentage, vascular bundle percentage, sclerenchyma and colenchyma percentage, palisade and lacuna parenchyma percentage and leaf thickness (μm). The following treatments were carried out: diquat (400 g a.i. ha-1 - Reward), 2,4-D (1.340 g a.e. ha-1 DMA 806 BR) and glyphosate (4.320 g a.e. ha-1 - Rodeo) with the Silwet L-77 surfactant addition at 0.01% v v-1. The main quantitative anatomical region characteristics of the central nervure of the leaf limbus which changed after herbicide application were: adaxial epidermis percentage, vascular bundle percentage, colenchyma percentage, palisade and lacuna parenchyma percentage, and leaf thickness. For the inter-nervural region of the leaf blade, the major quantitative anatomical characters which changed after herbicide application were: adaxial epidermis percentage, bundle sheath percentage, and leaf thickness. The herbicides diquat and 2,4-D were inefficient for P. lapathifolium plants and glyphosate showed a good control over 90% at 100 days after application. However, all herbicides allowed plant re-growth.

Spray deposition on weeds of common bean crops

Los fracasos en el control de malezas en frijol (Phaseolus vulgaris L.) pueden estar relacionados con inadecuadas tecnicas de aplicacion de herbicidas. Se determino la cantidad de deposicion de las gotas de pulverizacion en las plantas de Bidens pilosa L. y Brachiaria plantaginea (Link) Hitch., presentes en la linea y entre la linea de frijol. Se evaluaron 6 boquillas de pulverizacion: de abanico plano XR 110.015 (150 L ha-1) y XR 11002 VS (200 L ha-1), de cono TX VK 6 (150 L ha-1) y TX VK 8 (200 L ha-1) y de doble abanico plano TJ60 11002 VS (150 L ha-1) y TJ60 11002 VS (200 L ha-1). Se utilizo un diseno de bloques al azar con 4 repeticiones. Los resultados mostraron que la perdida de caldo al suelo se produjo principalmente en las lineas de frijol y con mayor intensidad con el uso de volumen de aplicacion de 200 L ha-1. A los 30 dias post siembra del frijol, la boquilla TX (150 L ha-1) fue el unico tratamiento que promovio depositos menores a 210,0 μL g-1 de materia seca. Las boquillas de pulverizacion evaluadas mostraron un buen desempeno en la deposicion de gotas en la maleza B. pilosa y B. plantaginea presentes en la linea y en la entre linea. Sin embargo, existio una gran variacion en los depositos individuales de ambas especies segun su ubicacion en relacion al cultivo

Efficacy of herbicides applied to Digitaria horizontalis plants under different water conditions

This project aimed to relate the control efficiency of ACCase inhibiting herbicides applied post-emergence to Digitaria horizontalis plants under different soil water contents. The experiments were conducted in a greenhouse, with the application of three different herbicides (fluazifop-p-butyl, haloxyfop-methyl, and sethoxydim + mineral oil Assist). The experimental design used for each herbicide was completely randomized, with four replications, consisting of a 3 x 4 factorial, with the combination of water management strategies (-0.03, -0.07 and -1.5 MPa) and four doses of these products (100%, 50%, 25%, and 0% of the recommended dose). Herbicide application was made at two vegetative stages, 4-6 leaves and 2-3 tillers. The visual phytotoxicity evaluations were performed at 14 days after application and the plant dry weight at the end of the study was evaluated. The control efficiency was not affected by water management strategies when applied to the recommended dose of the herbicides in early stages of plant development (4-6 leaf stage). In late applications (2-3 tiller stage) the plants held under drought stress showed less phytotoxicity.