TITLE:
Phenotyping of Weedy Rice to Assess Root Characteristics Associated with Allelopathy
AUTHORS:
Brooklyn Schumaker, Shandrea Stallworth, Auriana Tucker, Ziming Yue, Te-Ming Tseng
KEYWORDS:
Weed Suppression, Sustainable Agriculture, Integrated Weed Management, Barnyardgrass, Root System Architecture
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.12 No.8,
August
9,
2021
ABSTRACT: Weedy rice is a species of Oryza, and is a
wild relative of cultivated rice. The weed possesses unique hardiness that allows them to thrive in
dynamic and stressful environments. These characteristics suggest that weedy
rice is a stored source of novel genes for competitive traits. One such trait
is allelopathy, where a species releases secondary metabolites that suppress
the growth and development of neighboring species. Weed competition is a
limiting factor in rice production systems; therefore, it is critical to
identify specific allelopathic weedy rice accessions to determine the genetic
pathways and mechanisms associated with allelopathy to be used in breeding
programs. Due to the complex nature of allelochemical production and the lack
of knowledge of allelopathy mechanisms in weedy rice, phenotypic traits,
particularly root traits, can be used to overcome this limitation and serve as
target characteristics for breeding weed suppressive rice varieties. Five weedy
rice accessions were chosen from preliminary screenings of larger sample sizes
with the ability to suppress barnyardgrass weed seedling growth. Another five
weedy rice with low barnyardgrass suppression was selected for the current root
phenotypic study. Five cultivated rice lines were used as a comparison. All
plants were propagated in a transparent germination pouch for four weeks. Roots
were scanned and analyzed for root length and area covered. No differences were
found in the seedling root area among weedy rice and rice accessions; however,
allelopathic weedy rice plants exhibited a 14% increase in root length than
non-allelopathic weedy rice plants. The allelopathic weedy rice accession B2
possessed the most extended root system (22.4 cm root length). The highly
allelopathic weedy rice accessions (including B2) screened and phenotyped in
this study are ideal candidates for identifying the genetic controls of early
root length, a possible trait contributing to underground allelopathic
production and competitive advantage.