Growth and mycorrhizal colonization of maize plants treated with aqueous extracts from nonmycorrhizal weeds

Karla Andréia De Melo,Rosilaine Carrenho

doi:10.1590/s0100-204x2017001100010

Abstract

Abstract: The objective of this work was to evaluate the influence of aqueous extracts of nonmycorrhizal weedy species on dry matter accumulation and assimilate partitioning of maize plants, with or without Cetraspora pellucida inoculation. The experiment was carried out in pots, in a completely randomized design, in a 5x2 factorial arrangement consisting of four plant extracts (purple nutsedge, guinea-hen weed, slender amaranth, and knotweed), a control irrigated with water, and two conditions (mycorrhizal and nonmycorrhizal maize plants), with four replicates of each treatment. Plants were irrigated with aqueous extracts diluted at 15%. Root colonization (RC), shoot dry matter (SDM), root dry matter (RDM), and RDM/SDM were evaluated. Root colonization was not influenced by the extracts, and ranged from 41.5 to 65.2%. Shoot dry matter of mycorrhizal (AM) and nonmycorrhizal (NM) plants was not influenced by the extracts; however RDM showed varying responses. Mycorrhization favored the production of RDM, and increased plant sensitiveness to the extracts. Guinea-hen weed extract increased RDM of AM plants, while the other extracts inhibited it. In NM plants, the production of RDM was benefited by slender amaranth extract, to the detriment of SDM. Mycorrhizal and nonmycorrhizal maize plants respond differently to aqueous extracts of nonmycorrhizal weeds.

Highlights

In agricultural areas, the presence of weedy plants is a problem that compromises production, as they compete for space and nutritional resources with cultivated plants, including maize (Cerrudo et al, 2012)
Among species with weedy potential, purple nutsedge (Cyperus rotundus L.) is the most harmful, as it is found in most environments, while slender amaranth (Amaranthus viridis L.) is common in soils rich in organic matter (Lorenzi, 2008)
Assimilation partitioning between the radical and shoot systems (RDM/shoot dry matter (SDM)) was influenced by the two factors investigated in the present study

Summary

Introduction

The presence of weedy plants is a problem that compromises production, as they compete for space and nutritional resources with cultivated plants, including maize (Cerrudo et al, 2012). In order to suppress competing species, weedy plants produce allelopathic substances, which are released into the soil and impair seed germination, radicle. Among species with weedy potential, purple nutsedge (Cyperus rotundus L.) is the most harmful, as it is found in most environments, while slender amaranth (Amaranthus viridis L.) is common in soils rich in organic matter (Lorenzi, 2008). If the allelopathic compounds produced by these plants negatively affect both symbionts (plant and mycorrhizal fungus), the presence of weeds could interfere with many other processes, which would destabilize the agroecosystem

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