ABSTRACT
S-metolachlor is used to control/suppress yellow nutsedge, annual grasses
and several broadleaf weeds in sweetpotato.
However, a decline in storage root quality is suspected when excessive rainfall
occurs within 24-h after application. A greenhouse study was conducted to
determine the effect of S-metolachlor
application timing on sweetpotato growth and development. S-metolachlor treatments (0 and 1 kg·ha-1)
were applied over-the-top at 0, 5 and ten days after transplanting (DAT) and a simulated rainfall
treatment delivered 25 mm of rain, 51 mm·h-1 intensity, immediately
after herbicide application. Plants were harvested at 5, 10, 15, 20 and 80 DAT. During the first four
harvests, roots were scanned and analyzed with WinRHIZO-Pro image analysis
system to estimate root number, length, volume, and surface area along with aboveground growth parameters. At the final
harvest, plant growth and biomass components, and quality of storage roots were
recorded. Plants treated with S-metolachlor
on day 0 and 5 DAT were significantly less than those of 10 DAT and untreated control for
all measured parameters for the initial 20 days of plant growth. Even though
vine length, leaf number, stem biomass, and total storage roots were not
different among the treatments at 80 DAT, all other plant components and total
biomass production and leaf area development for plants treated at 0 and 5 DAT
were significantly (P < 0.05) less
than from those of 10 DAT and the untreated control. Marketable storage root
conversion efficiency declined by 18% and 16% for plants treated at 0 and 5 DAT, respectively, relative to the
untreated check. These
results indicate that delaying S-metolachlor
application to 10 DAT will be less
damaging to sweetpotato growth and
development, particularly marketable storage roots and yield.
Share and Cite:
Abukari, I. , Shankle, M. , Reddy, K. , Meyers, S. and Gao, W. (2019) Impacts of
S-Metolachlor Application Timing on Sweetpotato Growth and Development.
American Journal of Plant Sciences,
10, 780-795. doi:
10.4236/ajps.2019.105057.