Anatomical adaptations to different soil moisture contents in palisade grass and smooth pigweed

Daniel Valadão Silva,Evander Alves Ferreira,Jeferson Luiz Dallabona Dombroski,José Barbosa Dos Santos,Felipe Paolinelli De Carvalho,Cassia Michelle Cabral

doi:10.1590/0034-737x201865040002

Abstract

ABSTRACT Weed adaptations to different environments contribute to their success in establishing in different agroecosystems. A greenhouse and laboratory study was carried out to evaluate the effects of different levels of soil moisture on the anatomical characteristics of two weed species. The treatments were arranged in a 2 x 5 factorial design, with the first factor representing the weed species (Amaranthus hybridus and Brachiaria brizantha) and the second factor being the soil moisture levels in which they were grown (100%, 80%, 74%, 67%, and 60% of field capacity). At 55 days after weed emergence, the material for anatomical evaluations was collected. The water stress affected the two weed species differently, causing changes both in the thickness of the tissues evaluated and in their proportions. These changes seem to be related to how each species tolerates water stress. A. hybridus showed thickening of all leaf tissue and change in the proportion of these tissues, whereas B. brizantha showed a decrease in thickness of the leaf tissue and an increase in the proportion of adaxial epidermal and parenchymal tissues.

Highlights

The success of a weed species in the colonization of agroecosystems will depend on its adaptive capacity to different environmental conditions
Each weed species varies in its ability to respond to changes in water availability
Water stress induces anatomical, physiological, and biochemical changes in plant tissues, with intensity depending on the species and the intensity and duration of the water deficit

Summary

Introduction

The success of a weed species in the colonization of agroecosystems will depend on its adaptive capacity to different environmental conditions. Among the environmental factors required for plant growth, water is one of the most limiting factors in agricultural systems and is often the target of competition between crop species and weeds. The first plant adaptation strategy to water stress conditions is that the shoot is reduced in favor of the roots, limiting its capacity to compete for light because of the decrease in leaf area and a consequent reduction in productivity (Taiz & Zeiger, 2009). Studies on the effects of water deficit on plants have been mainly concentrated on changes in the stomatal opening that act to minimize water losses by transpiration and limit CO absorption for the photosynthesis (Reddy et al 2004; Shao et al, 2008). Anatomical effects are usually neglected in studies of water stress response (Kulkarni et al, 2008)

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