Do Weeds From Seeds or Regrowth in Coexistence Periods Alter Biochemical and Yield Characteristics of Soybeans?

Ana Paula Rockenbach,Mauro Antônio Rizzardi,Theodoro Schneider,Andréa Michel Sobottka,Adriana Favaretto

doi:10.5539/jas.v11n10p264

Ana Paula Rockenbach, Mauro Antônio Rizzardi + Show 3 more

Open Access

https://doi.org/10.5539/jas.v11n10p264

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Abstract

The objective of this study was to evaluate changes in soybean secondary metabolism and soybean yield components when subjected to coexistence periods with volunteer corn and established horseweed (Conyza spp.) regrowth. Two field experiments were conducted in the agricultural years 2015/2016 and 2016/2017 at Passo Fundo University, Passo Fundo, Rio Grande do Sul, Brazil. Experiment I was conducted in the agricultural year 2015/2016 in order to establish periods of coexistence between soybean and corn. The treatments consisted of two soybean densities in the main plots (175,000 and 350,000 plants ha-1) and different periods of coexistence between soybean and corn in the subplots. Experiment II was conducted in the agricultural year of 2016/2017 in order to investigate the interference of regrowth horseweed during coexistence periods with soybean. The total phenols, flavonoids, saponins, soybean yield components and seed yields were evaluated. Volunteer corn that initiates growth after the V4 soybean stage and horseweed regrowth during cultivation do not adversely affect secondary metabolism, seed yield or soybean yield components.

Highlights

The competition between weeds and crops is a type of negative interference where the organisms involved compete for the environment resources, light, nutrients and water
The objective of this study was to evaluate the changes in soybean secondary metabolism and yield components when subjected to periods of coexistence with volunteer corn and with regrowth of horseweed plants (Conyza spp.)
When the flavonoids were evaluated in the R2 stage, an interaction between soybean density and coexistence periods was observed, where the higher flavonoid content, occurred in the competition started in V2 with both densities, it did not differ from the other treatments (Table 1)

Summary

Introduction

The competition between weeds and crops is a type of negative interference where the organisms involved compete for the environment resources, light, nutrients and water. The competition period is a determinant of the degree of interference, since weeds that emerge prior to or together with a crop have greater competitive potential than weeds that emerge later in the crop cycle This is primarily due to the priority access to environmental resources (Piasecki, 2015; Tironi et al, 2014). The late weed emergence in relation to the crop development is less competitive in terms of yield, the weeds may be still problematic in terms of crop and seed quality (Swanton et al, 2015) Morphological variables parameters, such as height, dry matter, and yield components, are normally used to determine the effects of plant competition (Piasecki, 2015; Tironi et al, 2014; Trezzi et al, 2015). The secondary metabolism is directly related to plant’s defense in response to environmental factors (Taiz & Zeiger, 2013), which would include weed competition (Agostinetto et al, 2016; Broz et al, 2010; Gal et al, 2015; Silva et al, 2014)

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