Soil Seed Bank Phytosociology in No-Tillage Systems in the Southwestern Amazon Region

Lidiane A Vargas,Francis A Brugnera,Veronice A Marcílio,Rogério S C Costa,Alexandre M A Passos,Vivianni P D Leite

doi:10.4236/ajps.2017.813228

Abstract

Understanding the ecological dynamics of weed populations in no-tillage systems is important to establish strategies for integrated weed control capable of increasing agroecosystem sustainability. This study sought to evaluate the effect of succession systems on the seed bank in a no-tillage system. The effects of fifteen succession systems, composed of seven grasses, seven Leguminosae, and a fallow condition, were evaluated on the seed bank at two soil depths (0 to 10 and 10 to 20 cm). The species found in the seed bank were quantified and identified by species and family. The precision of sampling, density, dominance, the indices of diversity of Simpson and Shannon-Weiner; index of sustainability; analysis of groupings of dissimilarities; and the value of importance of each species were calculated. High weed diversity was observed; 29 species were counted, including members of 12 different families. The highest expression of weeds was observed at soil depths of 0 to 10 cm. The Simpson and Shannon-Weiner coefficients indicated high diversity in both systems of succession. The index of sustainability did not indicate significant alterations in the different systems of succession. The coefficients of confenetic correlation were 0.74% and 0.82% for the 0 - 10 and the 10 - 20 cm soil depths respectively. It is concluded that there is a high diversity of weeds in the agroecosystems of Amazonia, and different cover crops promote modifications in the community and expression of the weeds’ seed bank.

Highlights

Agricultural areas are a large pool of weed seeds, which are usually a significant problem for farmers, because seeds promote weed infestation in the long term, even without introduction of new propagules in the area
This study sought to evaluate the effect of succession systems on the seed bank in a no-tillage system
It is concluded that there is a high diversity of weeds in the agroecosystems of Amazonia, and different cover crops promote modifications in the community and expression of the weeds’ seed bank

Summary

Introduction

Agricultural areas are a large pool of weed seeds, which are usually a significant problem for farmers, because seeds promote weed infestation in the long term, even without introduction of new propagules in the area This is due to the characteristic survival strategies of weeds, which produce many seeds and make use of mechanisms of dormancy in the environment [1]. The chemical method is the most common, through the application of herbicides [4]. This isolated operation is no sufficient to control all weed interference with crops and may generate a higher latent risk of environmental contamination. The goal is to use integrated weed-control practices that are more sustainable, among which is the use of phytosociological tools such as seed banks studies [5]

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Conclusion