TITLE:
Allelopathic Effects of Cereal Rye on Weed Suppression and Forage Yield in Alfalfa
AUTHORS:
Laxman Adhikari, Mohsen Mohseni-Moghadam, Ali Missaoui
KEYWORDS:
Allelopathy, Alfalfa, Cereal Rye, Biological Weed Control, Biomass
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.9 No.4,
March
14,
2018
ABSTRACT: Cereal rye (Secale cereale L.) is widely used
as cover crop because of its allelopathic effects and effectiveness in weed
suppression. In the Southeastern US, rye is traditionally grown for winter
grazing in dormant bermudagrass pastures, where alfalfa (Medicago sativa L.) is increasingly planted as a companion crop.
The effect of cereal rye on alfalfa as a succeeding crop is not known.
Therefore, the objective of this study was to evaluate the effect of cereal rye
on alfalfa seedling emergence, growth, forage yield, and weed suppression in
field conditions. Rye was planted in the fall (mid-October) and the biomass was
harvested in spring (March) followed by disking and incorporation of the
remaining stubble in the soil. Alfalfa seed was planted four weeks later. The
experiment design was a split-plot design with the main plots being no-rye and
after-rye and the sub-plots being alfalfa cultivars. Ten alfalfa cultivars were
planted in three replications after-rye and three replications with no-rye as a
previous crop. In the establishment year, weed density was significantly (p
0.01)
among the cultivars planted in the after-rye block compared to the no-rye, with
a seedling count reduction between 35% and 64%. Reduction in total dry biomass yield varied from 15% to 43% among the cultivars
planted in the after-rye block. The results of this study also suggest that the
allelopathic effect of rye on alfalfa may not persist beyond the establishment
season, but the enormous yield reduction in the first production season may
constitute a costly economic penalty in terms of forage production. There was
variation in the response of different alfalfa cultivars to the effect of rye
residue as indicated by the variation in the magnitude of reduction in stand
count and forage yield. This warrants more research in multi-location trials
with and without rye in order to establish whether there is genetic variation
in alfalfa germplasm in their tolerance to cereal rye allelopathy.