Tillage effect on reproductive output by foxtail cohorts in corn and soybean

Abstract

Reliable estimates of weed fecundity require determination under ranges of management practices such as differing crops and tillage systems. We measured components of reproductive output per plant (numbers of primary tillers, panicles, and seeds; and sizes of panicles) in three emergence cohorts of green foxtail and yellow foxtail growing among corn and soybean in moldboard plow (MP), chisel plow (CP), ridge till (RT), spring disk (SD), and no till (NT). Differences in emergence between crops and foxtail Cohorts 1, 2, and 3 were 5, 0, and −7 d, respectively. In MP, Cohort 1 of green foxtail produced 2.3 primary tillers and 5.6 panicles per plant, and Cohort 1 of yellow foxtail produced 4.6 primary tillers and 9.0 panicles per plant. Panicle size was variable for both species across tillage systems, crops, and cohorts both years. Green foxtail plants produced the most seeds per plant (3,811) in NT corn, and cohorts did not vary greatly, whereas fecundity was highly variable across tillage systems and cohorts in soybean, where it averaged 3,240 (± 388) seeds per plant. Green foxtail seed number per plant were closely related to panicle numbers per plant for each year in corn (r 2 = 0.90) and soybean (r 2 = 0.78), and the relationship did not vary among tillage systems. Yellow foxtail seed number per plant was closely related to panicle number per plant, and it was specific for each tillage system in corn (r 2 = 0.60 to 0.85) and soybean (r 2 = 0.65 to 0.92). Estimates for vegetative and reproductive growth were more reliable for green foxtail than for yellow foxtail across tillage systems, crops, cohorts, and years.

Sensitivity of weed emergence and dynamics to life-traits of annual spring-emerging weeds in contrasting cropping systems, using weed beet (Beta vulgarisssp.vulgaris) as an example

“…The lower impact of life-traits on total emergence and surviving plants argues that in the cropping systems tested in the present study, with annual spring crops and frequent tillage, there is not a large range of possible strategies for successful emergence. Similar conclusions have been reported from maize/soybean rotations (Kegode & Forcella 2006). The life-trait effect however increases when looking at bolters and seed bank.…”

Can reducing tillage and increasing crop diversity benefit grain and forage production?

“…However, green foxtail seed densities were negatively correlated to corn grain yields in the ST-4y treatments. Similarly, greater weed seed production of green foxtail in corn crops occurred under no-till than moldboard plow and was correlated with greater weed biomass (Kegode and Forcella, 2006). This positive correlation to biomass might explain the significantly lower corn grain yields observed in 2003 in the ST-4y system.…”

“…Weed seed bank analysis has been applied to address impacts of crop rotation and tillage management (Cardina et al, 2002) and informing agricultural management of weeds (Rahman et al, 2001). Weed seed production is correlated with weed biomass and can represent successful competitive pressure (Wilson et al, 1995; Kegode and Forcella, 2006). From 2002 to 2005, we isolated in-season production of the weed seed bank by sampling the soil surface at the end of the growing season.…”