Júlio César Ramos

Development and Structure of the Grass Inflorescence

This work presents the basics for interpreting the adult inflorescence structure in grasses. It provides an analysis of the variations in the grass inflorescence structure and their correlation with some of the developmental processes that give origin to it.

Morphological characteristics of soybean root apexes as indicators of soil compaction

Plant soil compaction poses a serious problem to agriculture because it produces different types of changes in plant characteristics. No method has been implemented to date to use root morphological changes as indicators of soil compaction levels. Therefore, the aim of the present study was to evaluate whether or not the morphological changes in root apexes of soybean (Glycine max (L.) Merrill) can be used as indicators of soil compaction levels. To this end, a silt-loamy soil material (from a Typic Argiudoll, Esperanza series), sieved through a 2 mm mesh was used and the following soil bulk density levels were determined: 1.1, 1.3 and 1.5 g cm3 for which the corresponding mechanical resistances were < 0.1, 0.5 and 3.5 MPa, respectively. The distance from the apex to the first tertiary root and the root diameter at 1.5 cm from the apex were measured on the secondary root apexes. A form factor equal to the quotient between these two variables was subsequently calculated. An inverse relationship between soil mechanical impedance and secondary root length and form factor as well as a direct relationship with the secondary root diameter were observed. Changes in rhizodermis cells were also recorded. The following morphological characteristics were found to evidence the highest sensitivity to soil compaction: i) the form factor, ii) rhizodermis papillose cells, iii) apical malformations in root hairs, and iv) root diameter in expansion areas. Taken together, the morphological characteristics of root apexes could be considered to be indicative of soil compaction.

Digestión de láminas foliares de Bromus auleticus Trin. ex Nees sometidas a diferentes tiempos de incubación ruminal

A B S T R A C T The decrease in the digestibility of forage is linked with an increase in cell walls and lignification of tissues as they mature. All forages are composed of a heterogeneous group of cell types with particular characteristics that determine the availability of polysaccharides to the rumen’s microorganisms. In the present paper the degradation of Bromus auleticus Trin. ex Nees leaf tissues was studied at different incubation times in the rumen. Samples were taken in two phenological phases: vegetative and pre-flowering, which were submitted to different digestion times in situ on two dry Holando Argentine cows. Simultaneously, leaf blade sections were stained with phloroglucinol acid stain to detect the presence of lignin. Leaf anatomy influenced the degree of tissue digestion, whether due to lignified cell walls or accessibility. After 24 h incubation in the rumen, only the xylem, sclerenchyma and mestome sheath were undigested. The phloem and clorenchyma were digested after 18 h in the pre-flowering phase and 24 h in the vegetative phase. The epidermis was partially digested, and the abaxial epidermis was better digested. The accessibility of carbohydrates in cell walls to the microflora of the rumen is limited by the chemistry of cell walls, and thus, highly organized tissues with secondary lignified walls, such as sclerenchyma and xylem, have a double barrier (physical and chemical) which prevent their digestion.

ESTUDIO ANATOMICO DE VASTAGOS REPRODUCTIVOS EN BROMUS AULETICUS Trin. ex Ness (POACEAE)

El objetivo de este trabajo es caracterizar las variaciones anatomicas que se presentan en organos foliares y caulinares de vastagos reproductivos de Bromus auleticus Trin. ex Ness. Las muestras fueron fijadas en F.A.A., incluidas en parafina-cera, cortadas con micro-tomo rotativo, coloreadas con safranina-fast green en carboxilol y montadas en balsamo de Canada. Ademas, muestras de material fresco fueron cortadas con microtomo de congelacion y luego de la deshidratacion se las coloreo del modo antes descripto, agregandole un pasaje en xilol con eugenol, para montarlas finalmente en balsamo de Canada. Se caracterizan las estructuras foliares y caulinares desde el rizoma hasta el ambito de la inflorescencia. Se describen las variaciones anatomicas observadas en: 1) los organos foliares del rizoma, su transicion hasta hoja plenamente expandida, la hoja distal y las bracteas que conforman las espiguillas; y 2) el rizoma, los entrenudos del vastago aereo, el pedunculo, el eje principal de la inflorescencia, los paracladios primarios y la raquilla. Las variaciones en los componentes foliares estan relacionadas con: a) el desarrollo de estructuras fotosinteticas, b) el desarrollo de espacios lisigenos y c) la distribucion del escleren-quima; y en los componentes caulinares se relacionan con: a) el parenquima cortical y medular, b) el desarrollo y posicion de los haces vasculares y c) el desarrollo del anillo de esclerenquima con ellos asociado

Water erosion in surface soil conditions: runoff velocity, concentration and D50 index of sediments in runoff

Water erosion and contamination of water resources are influenced by concentration and diameter of sediments in runoff. This study aimed to quantify runoff velocity and concentration and the D50 index of sediments in runoff under different soil surface managements, in the following treatments: i) cropped systems: no-tilled soil covered by ryegrass (Lolium multiflorum Lam.) residue, with high soil cover and minimal roughness (HCR); no tilled soil covered by vetch (Vicia sativa L.) residue, with high soil cover and minimal roughness (HCV); chiseled soil after ryegrass crop removing the above-ground residues and keeping only the root system, with high roughness (HRR); chiseled soil after vetch crop removing the above-ground residues and keeping only the root system, with high roughness (HRV); ii) bare and chiseled soil, with high roughness (BHR). The research was conducted on a Humic Dystrupept under simulated rainfall. The design was completely randomized and each treatment was replicated twice. Eight rainfall events of controlled intensity (65 mm h−1) were applied to each treatment for 90 minutes. The D50 index, runoff velocity and sediment concentration were influenced by crop and soil management. Runoff velocity was more intensely reduced by cover crop residues than by surface roughness. Regardless of surface condition, the D50 index and concentration of sediment in runoff were lower under ryegrass than vetch crop. Runoff velocity and the D50 index were exponentially and inversely correlated with soil cover by residues and with surface roughness, while the D50 index was positively and exponentially correlated with runoff velocity.

WATER EROSION UNDER THREE TILLAGE METHODS IN A CULTIVATION OF Eucalyptus benthamii

1 Received on 28.08.2017 accepted for publication on 14.11.2017. 2 Instituto Federal Catarinense, Blumenau, Santa Catarina – Brasil. E-mail: <junaflorestal@hotmail.com>. 3 Universidade do Estado de Santa Catarina, Departamento de Solos, Lages, SC – Brasil. E-mail: <ildegardis.bertol@udesc.br>. 4 Universidade Federal do Paraná, Mestrado em Engenharia Florestal, Curitiba, Paraná – Brasil. E-mail: <bruno.magro@yahoo.com.br>. 5 Universidade do Estado de Santa Catarina, Programa de Pós-Graduação em Ciência do Solo, Lage, SC – Brasil. E-mail: <barbarabagio@yahoo.com.br>. 6 Associação Sulina de Crédito e Assistência Rural, São José dos Ausentes, RS – Brasil. E-mail: <julianamarioti@gmail.com>. 7 Empresa de Pesquisa Agropecuária e Extensão Rural de Santa Catarina, Chapecó, SC – Brasil. E-mail: <julioramos@epagri.sc.gov.br>. *Corresponding author.

Índices de rugosidade do solo e sua relação com a erosão hídrica

The objective of this work was to express soil roughness through statistical, geostatistical, and fractal indexes, comparing and relating them to soil and water losses in different experimental conditions. The study was conducted from 2012 to 2015, in the municipality of Lages, in the state of Santa Catarina, Brazil, in a completely randomized design with two replicates. Three treatments were evaluated: T1, scarified soil at the end of the ryegrass (Lolium multiflorum) crop cycle after removal of the shoot residue; T2, scarified soil at the end of the vetch (Vicia sativa) crop cycle after removal of the shoot residue; and T3, scarified soil without cultivation and without cover. The heights of the microrelief were read with a surface roughness tester with rods. Soil roughness was analyzed through the statistical, geostatistical, and fractal indexes. The fractal dimension and intersection distance showed a clear difference between the treatments with cultivation. All indexes, except R1, are associated with soil losses in the treatments with cultivation. As for water losses, there is only an association with the fractal dimension index and only in the treatment without cultivation.

Anatomía del sistema caulinar subterráneo de Cyperus corymbosus var: subnodosus (Cyperaceae)

Se estudia la anatomia del sistema de ramificacion subterraneo en Cyperus corymbosus Rottb. var. subnodosus (Nees et Meyen) Kuk. Se describe la anatomia del rizoma y del tuberculo en este taxon. Se realiza un analisis comparativo de las variaciones observadas en diferentes estadios de desarrollo. Las caracteristicas anatomicas de rizoma y tuberculos estan asociadas al tipico sistema caulinar subterraneo, a la forma de crecimiento de la especie y a su modo de propagacion vegetativa.