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The efficacy and cost efficiency of using various plastic soil mulches in the production of pepper (Capsicum annuum L.), corn (Zea mays L.) and muskmelon (Cucumis melo L.) were examined over four growing seasons in Saskatchewan, Canada. Clear mulch with or without preemergent herbicides was compared with black or wavelength selective mulches. In all three crops, mulches enhanced yields relative to bare ground in most site-year combinations. Clear mulch usually produced the highest yields. Herbicides applied under the clear plastic provided effective weed control with no observable changes in product efficacy or toxicity to the crop. The weed control provided by the herbicides had no effect on yields in the clear mulch treatments. Consequently, clear mulch without added herbicide usually represented the most cost-effective production option for all three crops.
Abstract
Inoculum of the vesicular–arbuscular mycorrhizal fungus (VAMF) Glomus aggegratum Schenck and Smith emend. Koske was propagated on the roots of sweetcorn (Zea mays L.) grown in sand “nurse” cultures fertilized with either modified Johnson's nutrient solutions (JNS) or Osmocote 19N–2.6P–9.9K. Shoot and root dry weights after 12 weeks increased 87% and 132%, respectively, with increasing rates of Osmocote between 0.82 g·kg–1 and 1.32 g·kg–1. However, VAMF spore production and leaf tissue P concentrations did not increase significantly over this range of Osmocote rates. Average spore production of Osmocote cultures was 3.25 million spores per 10 kg of nurse culture, 261% greater than in JNS cultures. Higher spore yields in the Osmocote compared to the JNS cultures were associated with lower P concentrations at 6 and 12 weeks after planting (WAP) and higher intensities of root colonization by the VAMF at 6 WAP.
Seeds of celery, spinach, onion, cress, water cress, iceberg lettuce, Great Lakes lettuce, cabbage, tomato, sweet corn and celery were pre-treated with 0.1 μM/g seed of both ABA and analogs of ABA. The chemicals were dissolved in a mixture of methanol:hexane (9:1/v:v) and applied to the seeds for approximately 3 minutes. The solvent was removed from the seeds within 5 minutes by rotary evaporation under reduced pressure. Effects on petri plate germination and soil emergence were monitored daily at 5, 10 and 15°C. The methanol/hexane solvent alone improved spinach seed emergence at 10°C from 10% to 100% and from 50% to 90% at 15°C in celery. Certain ABA analogs reduced time to 50% emergence in celery by at least 7 days at 15°C. Two ABA analogs synchronized emergence in celery and effect was temperature-dependent. One analog improved seed germination in tomato from 15% to 90% at 10°C. In most cases treatment effects on radicle germination on petri plates was not a good indicator of treatment effects on emergence from a soil based system.