Seedbank Persistence of Palmer Amaranth (Amaranthus palmeri) and Waterhemp (Amaranthus tuberculatus) across Diverse Geographical Regions in the United States

Nicholas E Korres,Greg R Kruger,Mark Loux,Shawn P Conley,Thomas C Mueller,Daniel B Reynolds,Reid J Smeda,William G Johnson,Karla L Gage,Bryan G Young,Jason K Norsworthy,Muthukumar V Bagavathiannan,Douglas J Spaunhorst

doi:10.1017/wsc.2018.27

Abstract

AbstractKnowledge of the effects of burial depth and burial duration on seed viability and, consequently, seedbank persistence of Palmer amaranth (Amaranthus palmeriS. Watson) and waterhemp [Amaranthus tuberculatus(Moq.) J. D. Sauer] ecotypes can be used for the development of efficient weed management programs. This is of particular interest, given the great fecundity of both species and, consequently, their high seedbank replenishment potential. Seeds of both species collected from five different locations across the United States were investigated in seven states (sites) with different soil and climatic conditions. Seeds were placed at two depths (0 and 15 cm) for 3 yr. Each year, seeds were retrieved, and seed damage (shrunken, malformed, or broken) plus losses (deteriorated and futile germination) and viability were evaluated. Greater seed damage plus loss averaged across seed origin, burial depth, and year was recorded for lots tested at Illinois (51.3% and 51.8%) followed by Tennessee (40.5% and 45.1%) and Missouri (39.2% and 42%) forA. palmeriandA. tuberculatus, respectively. The site differences for seed persistence were probably due to higher volumetric water content at these sites. Rates of seed demise were directly proportional to burial depth (α=0.001), whereas the percentage of viable seeds recovered after 36 mo on the soil surface ranged from 4.1% to 4.3% compared with 5% to 5.3% at the 15-cm depth forA. palmeriandA. tuberculatus, respectively. Seed viability loss was greater in the seeds placed on the soil surface compared with the buried seeds. The greatest influences on seed viability were burial conditions and time and site-specific soil conditions, more so than geographical location. Thus, management of these weed species should focus on reducing seed shattering, enhancing seed removal from the soil surface, or adjusting tillage systems.

Highlights

Knowledge of the effects of burial depth and burial duration on long-term seed viability and, subsequently, seedbank persistence of A. palmeri and A. tuberculatus populations originating from different locations and dispersed among diverse regions with different soil and climatic conditions can be used for the development of efficient weed management approaches
The plot area was 1-m wide by 3-m long, and the subplot was 1 m2, the experiment was limited to a polyvinyl chloride (PVC) cage, and the sub-subplot was limited within the PVC cage (i.e., 60-cm diameter) (Figure 2)
Higher seed damage averaged across ecotype, burial treatment, and retrieval year was recorded for the seed that originated from Illinois (51.3% and 51.8%) followed by Tennessee (40.5% and 45.1%), and Missouri (39.2% and 42%) for A. palmeri and A. tuberculatus, respectively

Summary

Introduction

Knowledge of the effects of burial depth and burial duration on long-term seed viability and, subsequently, seedbank persistence of A. palmeri and A. tuberculatus populations originating from different locations and dispersed among diverse regions with different soil and climatic conditions can be used for the development of efficient weed management approaches. (2) Was seed viability of A. palmeri and A. tuberculatus, seedbank persistence of these species, reduced as burial depth and burial duration increased?

Results

Conclusion