2.2 Field trials
A paddy field was selected at the experimental station during the 2020
growing season. The paddy had previously been planted with rice for
several seasons. Several weeds occurred in the paddy, includingEchinochloa crusgalli (barnyardgrass), Leptochloa
chinensis , Cyperus difformis and Eclipta prostrata but
barnyardgrass was dominant. Other weedy species such asAlternanthera sessilis and Monochoria vaginalisoccasionally occurred in the field. The field was divided into a series
of 3×5 m plots arranged in a completely randomized design with four
replicates of each treatment or control. Each plot was separated by
trenches with at least 30 cm discard strips on each side. Each focal
cultivar ‘Huagan-3’ or ‘Lingyou-6173’ was paired with itself, or with a
closely or distantly related cultivar, and planted at a density of 50
m-2 by direct seeding at a 1:1 proportion. Plots not
planted with rice served as controls for weed growth. All plots received
fertilizer (nitrogen, phosphorus pentoxide, and potassium oxide at the
rates of 7.5 g m-2, 9.0 g m-2 and
8.5 g m-2 respectively) 1 day before the plots were
saturated with water. All other field management followed the rules of
the rural administration in Anhui Province, China except chemical or
hand weeding. After 50 days, weed species and numbers in each plot were
identified and their aboveground biomass dry weights measured.