Activity of aerial and root esterases in wheat DHR lines of chromosome 6AS was tested. Different patterns were found after applying phytohormone treatments that mimic stress conditions. Ethylene treated plants showed the lowest aerial and root weights; also, the smallest foliar area, in conjunction with absence of esterase activity in more than half of the lines, was observed. Additional studies will contribute to clarify the key role of ET in the expression of defense related genes.

Se probo la actividad de estearasas en parte aerea y raices de lineas de trigo DHR para el cromosoma 6AS. Se encontraron diferentes patrones luego de la aplicacion de tratamientos fitohormonales que simularon condiciones de estres. Las plantas tratadas con etileno mostraron los pesos mas bajos de parte aerea y de raices, asi como tambien la menor area foliar, junto con ausencia de actividad estearasa en mas de la mitad de las lineas de trigo. Estudios adicionales contribuiran a clarificar el rol clave del ET en la expresion de genes relacionados con la defensa.

The systemic movement of glyphosate is determined by the transport of photoassimilates. In turn, the capacity of a destination to consume assimilates is conditioned by their metabolic activity. Despite its importance, the relationship between the glyphosate and the sugar synthesis from source leaves has been little studied. The aim of this work was to determine the effect of glyphosate on the growth and free sugar accumulation of two Lolium perenne biotypes of low and high glyphosate sensitivity. It was worked with clones of both types, in tillering, sprayed with 1,440 g a.e. ha-1 of glyphosate as treatments and without herbicide as controls. The glyphosate effects on the regrowth of leaves was studied until 50 hours post-application and on total free sugar, reducing free sugar and nonreducing free sugar from leaves to 1, 2, 3 and 5 days post-application were periodically evaluated. From 25 hours after glyphosate application, it caused on the susceptible biotype a growth decrease of 58% and an accumulation of free sugar above 90% compared to controls. In susceptible biotypes, growth inhibition does not depend on a reduced photoassimilate translocation from the overground part. Therefore, the free sugar accumulation in leaves could be explained by the fall in the rate of growth. These effects are limited in the low sensitivity biotype, where growth inhibition has not been detected.

El movimiento sistémico del glifosato está determinado por el transporte de fotoasimilados. A su vez, la capacidad de un destino de consumir los asimilados está condicionada por su actividad metabólica. Pese a su importancia, la relación entre el glifosato y la síntesis de azúcares en hojas fuente ha sido poco abordada. El objetivo del presente trabajo fue evaluar los efectos del glifosato sobre el crecimiento y la acumulación de azúcares libres en dos biotipos de Lolium perenne de baja y alta sensibilidad al herbicida. Se trabajó con clones de ambos tipos de plantas, en macollaje, tratados con 1.440 g e.a. ha-1 de glifosato y sin tratamiento herbicida como controles. Se evaluó periódicamente el efecto del glifosato sobre el rebrote de hojas hasta las 50 horas post-aplicación y sobre los niveles de azúcares libres totales, reductores y no reductores en hojas a 1, 2, 3 y 5 días post-aplicación. A partir de las 25 horas post-aplicación, el glifosato provocó una disminución del crecimiento del 58% en el biotipo susceptible, con una acumulación de azúcares libres superior al 90% con relación al control, desde el primer día post-aplicación en adelante. La inhibición del crecimiento, inducida por el glifosato en plantas susceptibles, no depende de la limitación del traslado de fotoasimilados desde la parte aérea. Por tanto, la acumulación de azúcares libres en hojas podría explicarse por la caída en la tasa de crecimiento. En el biotipo de baja sensibilidad, en el que no se detectó inhibición del crecimiento, estos efectos fueron limitados.

Objetivando estudar a influência do condicionamento de ramos, através do anelamento e estiolamento parcial, sobre o enraizamento de estacas de laranjeira cv. Valência, conduziu-se o experimento no período de fevereiro a dezembro de 1993. Para o anelamento foi utilizado arame fino de cobre com o qual provocou-se um estrangulamento na base do ramo. No estiolamento, utilizou-se fita preta de polietileno, que foi enrolada na base das brotações. De cada ramo condicionado, obteve-se apenas uma estaca com 15 cm de comprimento, diâmetro médio de 0,5 cm e um par de folhas apicais, cortadas pela metade. O plantio das estacas foi realizado em 12.04.93, em substrato de areia lavada e peneirada. Adotou-se o delineamento inteiramente casualizado, em esquema fatorial 3x3, resultante das combinações entre os períodos de zero, 30 e 60 dias dos fatores anelamento e estiolamento. Verificou-se que não ocorreu enraizamento nas estacas que permaneceram três meses no substrato e variou de 0 até 26,04% para aquelas que permaneceram oito meses. O período de estiolamento influenciou significativamente o percentual de estacas enraizadas.

With the aim of studying the effect of branch conditioning through girdling and banding on Valência orange cuttings a rooting trial was carried out from February to December of 1993. The girdling was performed with a thin cooper wire tightly tied at the branch base reaching the log, and the banding with black poliethylene tape, covering the branch at the base of the sprouts. Each conditioned branch gave one cutting of 15 cm length, 0.5 cm diameter and a pair of half cut apical leaves. Cuttings were planted on Dec.04, 93, in washed and sieved sand substrate. The experimental design was completely randomized, with a factorial 3 x 3 from 0, 30 and 60 day periods, girdling and banding. There was no rooting in cuttings that remained three months in the substrate and there was up to 26.04% rooting for those ones that lasted for eight months in the substrate. The banding period significantly affected the cuttings rooting percentage.