Twenty fungal genera, including 14 Fusarium species, were examined for ice nucleation activity at-5.0°C, and this activity was found only in Fusarium acuminatum and Fusarium avenaceum. This characteristic is unique to these two species. Ice nucleation activity of F. avenaceum was compared with ice nucleation activity of a Pseudomonas sp. strain. Cumulative nucleus spectra are similar for both microorganisms, while the maximum temperatures of ice nucleation were-2.5°C for F. avenaceum and-1.0°C for the bacteria. Ice nucleation activity of F. avenaceum was stable at pH levels from 1 to 13 and tolerated temperature treatments * Corresponding author.
La société de protection des plantes du Québec, 1996 Ce document est protégé par la loi sur le droit d'auteur. L'utilisation des services d'Érudit (y compris la reproduction) est assujettie à sa politique d'utilisation que vous pouvez consulter en ligne.https://apropos.erudit.org/fr/usagers/politique-dutilisation/ Cet article est diffusé et préservé par Érudit.
Agronomic and economic performance of the corn (Zea mays L.)–soybean [Glycine max (L.) Merr.] rotation is well documented, but few studies have investigated the addition of spring wheat (Triticum aestivum L.) to this rotation, particularly at the northern limit of corn and soybean production in North America. A 6‐yr field study was initiated in 1999 on a clay soil in eastern Canada to identify the best crop rotation (continuous corn, continuous soybean, corn–soybean, corn–corn–soybean, corn–soybean–spring wheat, or corn–spring wheat–soybean) under moldboard plow (MP) and reduced tillage (RT) in terms of grain yield, soil aggregate distribution, and annual net returns. To isolate the effect of annual climatic conditions, all crop phases of each rotation were present each year for a total of 13 rotation sequences within each soil tillage practice. Corn grown in rotation had greater yield (+0.6 to +0.9 Mg ha−1) than continuous corn or second‐year corn regardless of soil tillage. Soybean grown once every 3 yr had consistently greater yields (+0.20 Mg ha−1) than continuous soybean. The addition of spring wheat in the rotation improved both corn and soybean yields compared with either continuously cropped. The RT management did not affect crop yield but increased the soil macro‐aggregation only when corn was present in the rotation. Economic analysis revealed that continuous soybean, the 3‐yr corn–soybean–spring wheat with wheat straw being sold, and the 2‐yr corn–soybean were the most profitable and most efficient rotations when averse risk is considered.
Core Ideas
Corn in rotation yielded 0.7 Mg ha−1 more than continuous corn, regardless of soil tillage.
Soybean grown once every 3 yr had consistently higher yields than continuous soybean.
Including spring wheat in the corn and soybean continuous cropping improved corn and soybean yields.
Reduced tillage did not affect crop yield but improved soil macro‐aggregation when corn grown continuously or in rotation.
Continuous soybean, corn–soybean, and 3‐yr rotation with corn, soybean, and spring wheat with wheat straw being sold were the most efficient economic rotations when considering the risk aversion.
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