107006 Effects of Cropping System Diversification on Weed Community Composition: A Case Study in Iowa.
Poster Number 616
See more from this Division: C03 Crop Ecology, Management and Quality
See more from this Session: Crop Ecology, Management and Quality General Poster I
Monday, October 23, 2017
Tampa Convention Center, East Exhibit Hall
Abstract:
Repeated use of a single weed control technique can shift the treated weed community to one in which species that are least affected by the control tactic are dominant. Shifts in weed community composition toward glyphosate-tolerant species have become important concerns in cropping systems that rely heavily on glyphosate for weed control (Benbrook, 2012; Brookes and Barfoot, 2013; Duke and Powles, 2009; Heap, 2017; Mortensen et al., 2012).
We tested the effects of cropping system diversification and herbicide regimes on weed community dynamics in a field experiment conducted in Boone County, Iowa, USA, over a three-year period. We compared weed relative abundance and Shannon’s diversity and evenness indices for aboveground weed biomass and weed seed densities in soil in three cropping systems (a 2-year corn-soybean rotation, a 3-year corn-soybean-oat/red clover rotation, and a 4-year corn-soybean-oat/alfalfa-alfalfa rotation) managed with either conventional or low herbicide regimes (Hunt et al., 2017).
No interactive effects between the fixed factors were observed on the aboveground community’s Shannon’s diversity and evenness indices (p=0.5176 and 0.1490, respectively) and seedbank community Shannon’s diversity and evenness indices (p=0.7946 and 0.5370, respectively).
Herbicide regimes and rotation had significant effects on Shannon’s diversity index in the aboveground community (p=0.0004 and p=0.0093, respectively).
Herbicide regimes and rotation did not have significant effect on Shannon’s evenness index in the aboveground (p=0.1680 and 0.7648, respectively) and seedbank communities (p=0.0746 and 0.1129, respectively).
Herbicide regimes did not have significant effect on Shannon’s diversity index in the seedbank community (p=0.1214). Rotation had significant effect on Shannon’s diversity index in the seedbank community (p=0.0265).
We tested the effects of cropping system diversification and herbicide regimes on weed community dynamics in a field experiment conducted in Boone County, Iowa, USA, over a three-year period. We compared weed relative abundance and Shannon’s diversity and evenness indices for aboveground weed biomass and weed seed densities in soil in three cropping systems (a 2-year corn-soybean rotation, a 3-year corn-soybean-oat/red clover rotation, and a 4-year corn-soybean-oat/alfalfa-alfalfa rotation) managed with either conventional or low herbicide regimes (Hunt et al., 2017).
No interactive effects between the fixed factors were observed on the aboveground community’s Shannon’s diversity and evenness indices (p=0.5176 and 0.1490, respectively) and seedbank community Shannon’s diversity and evenness indices (p=0.7946 and 0.5370, respectively).
Herbicide regimes and rotation had significant effects on Shannon’s diversity index in the aboveground community (p=0.0004 and p=0.0093, respectively).
Herbicide regimes and rotation did not have significant effect on Shannon’s evenness index in the aboveground (p=0.1680 and 0.7648, respectively) and seedbank communities (p=0.0746 and 0.1129, respectively).
Herbicide regimes did not have significant effect on Shannon’s diversity index in the seedbank community (p=0.1214). Rotation had significant effect on Shannon’s diversity index in the seedbank community (p=0.0265).
Dissimilarity in community composition among rotations was readily apparent, compared to between herbicide regimes. Weed community species tended to be more even under longer rotations.
See more from this Division: C03 Crop Ecology, Management and Quality
See more from this Session: Crop Ecology, Management and Quality General Poster I