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- Author or Editor: John L. Lindquist x
Ecophysiological simulation models provide a quantitative method to predict the effects of management practices, plant characteristics, and environmental factors on crop and weed growth and competition. The INTERCOM interplant competition model was parameterized, calibrated by monoculture data for three cowpea (Vigna unguiculata) genotypes that differed in growth habit, common sunflower (Helianthus annuus), and common purslane (Portulaca oleracea), and used to simulate competition of cowpea cover crops with sunflower or purslane. The simulation results were compared with observations from field competition experiments in 2003 and 2004. INTERCOM did not simulate biomass production and leaf area index (LAI) of cowpea and purslane well, probably due to a lack of published data on purslane physiology. INTERCOM simulated the competition of cowpea genotypes and sunflower accurately. The simulation model of cowpea and sunflower at two densities was used to study the effects of cowpea growth habits on final biomass production of cowpea and sunflower. The model suggested that the erect growth habit was more competitive than the semi-erect and prostrate growth habits when cowpea genotypes were grown with sunflower. Cowpea leaf area distribution was important to higher cowpea biomass production, while cowpea height growth was important to reduce sunflower biomass.
Biobased sprayable mulch (BSM) films are a potential alternative to herbicides, polyethylene plastic mulch film, and hand weeding for specialty crops. We developed a series of BSM films using locally available biomaterials [including corn (Zea mays) starch, glycerol, keratin hydrolysate, corn gluten meal, corn zein, eggshells, and isolated soy (Glycine max) protein] and tested their effects on weeds and crop yield during a total of seven greenhouse or field trials between 2017 and 2019 in Nebraska, USA. Application rates of BSM films applied in pots (greenhouse), planting holes in plastic film (field), or bed tops (field) ranged from 0.9 to 18.2 L⋅m−2; they were applied before and after the emergence of weeds. Weed control efficacy was variable, and results of greenhouse pots were rarely replicated under field conditions. Increasing the viscosity of the final suspension tested [BSM7; a mix of corn starch (72.8 g⋅L−1), glycerol (184.7 mL⋅L−1), keratin hydrolysate (733.3 mL⋅L−1), corn zein (19.8 g⋅L−1), and isolated soy protein (19.8 g⋅L−1)] reduced weed biomass by more than 96% in field-grown kale (Brassica oleracea var. sabellica) when applied to bare soil bed tops before or after weed emergence, but kale yield in treated plots was not different from the weedy control. The results demonstrated the potential for postemergence applications of BSM films, which increase application timing flexibility for growers. Further research is needed to explore the effects of BSM films on soil properties and crop physiology and yield.