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M. 2009. Crop response to current and previous season applications of phosphorus as affected by crop sequence and tillage. Can. J. Plant Sci. 89: 49Á66. Field studies were conducted over a 4-yr period at two locations in western Manitoba, Canada, to evaluate the effect of phosphorus (P) fertilizer management on crop growth as affected by tillage system through a 2-yr cropping sequence. In the first phase of the cropping sequence, canola (Brassica napus L.), a non-mycorrhizal crop, and spring wheat (Triticum aestivum L.), a mycorrhizal crop, were grown under conventional (CT) and reduced (RT) systems, with 0, 11 and 22 kg P ha(1 applied as monoammonium phosphate (MAP). In the second phase of the sequence, flax (Linum usitatissimum L.) was seeded following the spring wheat or canola, with application of 0 or 11 kg P ha(1 as MAP. Phosphorus application increased the early-season biomass, P concentration, and P accumulation of canola and wheat and the seed yield of canola. Tillage system had no consistent effects on growth, P concentration or uptake, or seed yields of canola or wheat, nor were P by tillage system interactions observed. Early-season biomass production and seed yields of flax were relatively unaffected by P fertilization whether applied in the same season as flax or in the previous season, although early-season P concentration and P accumulation were increased when P fertilizer was applied to the flax. Of the factors evaluated in this study, preceding crop had the greatest influence on flax growth with flax establishment, early-season biomass, and P accumulation, and seed yield all being significantly greater when flax was seeded after wheat than after canola. Plant Sci. 89: 49Á66. Pendant quatre ans, les auteurs ont proce´de´a`des e´tudes sur le terrain, a`deux endroits de l'ouest du Manitoba, au Canada, afin d'e´valuer l'incidence des pratiques de gestion des engrais phosphate´s (P) sur la croissance de la culture, selon la me´thode de travail du sol dans le cadre d'un assolement de deux ans. Dans le premier volet de l'assolement, ils ont fait pousser du canola (Brassica napus L.), une culture sans mycorhizes, et du ble´de printemps (Triticum aestivum L.), une culture avec mycorhizes, apre`s travail classique (CT) ou travail re´duit (RT) du sol et application de 0, de 11 ou de 22 kg de P par hectare sous forme de phosphate d'ammonium diacide (MAP). Lors de la deuxie`me phase de la rotation, ils ont ensemence´du lin (Linum usitatissimum L.) apre`s le ble´ou le canola, avec application de 0 ou de 11 kg de P par hectare sous forme de MAP. L'application de phosphore accroıˆt la biomasse en de´but de saison, la concentration de P, l'accumulation de P par le canola et le ble´, et le rendement grainier du canola. La me´thode de travail du sol n'a aucun effet cohe´rent sur la croissance, la concentration de P, l'absorption de P ni le rendement grainier du canola ou du ble´; il n'existe non plus aucune interaction entre les applications d'engrais et le type de travail du sol. La production de biomasse au de...

Arbuscular mycorrhizae (AM) are symbiotic associations, formed between plants and soil fungi that play an essential role in plant growth, plant protection, and soil quality. The AM fungi expand their filaments in soil and plant roots. This filamentous network promote bi‐directional nutrient movement where soil nutrients and water move to the plant and plant photosynthates flow to the fungal network. AM fungi are ubiquitous in the soil and can form symbiosis with most terrestrial plants including major crops, cereals, vegetables, and horticultural plants. In agriculture, several factors, such as host crop dependency to mycorrhizal colonization, tillage system, fertilizer application, and mycorrhizal fungi inoculum's potential can affect plant response and plant benefits from mycorrhizae. Due to their obligate symbiotic status, AM fungi need to associate with plant for growth and proliferation. Consequently, the cultivation of AM fungal strains and the maintenance of reference collections require methodologies and infrastructures quite different from those used with other microbial collections and inoculum production. Interest in AM fungi propagation for agriculture is increasing due to their role in the promotion of plant health, in soil nutrition improvement, and soil aggregate stability. The comprehensive life cycle of AM fungi and methods currently used for the propagation of inoculum and the maintenance of in vivo and in vitro source collections are described. Methods and regulations of large‐scale production of commercial inoculum that provide users with products of high quality and efficiency are discussed.

Field studies were conducted over 4 years at two locations in Manitoba, Canada to evaluate effects of preceding crop, tillage and phosphorus (P) fertilization on Cd and Zn concentration in oilseed flax (linseed-Linum usitatissimum L.). Canola (Brassica napus L.) and spring wheat (Triticum aestivum L.) were grown under conventional and reduced tillage with three rates of monoammonium phosphate. Flax was seeded the year following the spring wheat or canola, with or without P fertilizer, and Cd and Zn concentration and accumulation were determined in the flax tissue at 5 weeks and in the mature seed. Flax following canola had lower Zn concentration and accumulation and higher Cd concentration and Cd:Zn ratio in the tissue and seed relative to flax following wheat. Phosphorus fertilization tended to increase Cd concentration and Cd:Zn ratio and decrease Zn concentration in the tissue and seed. Effects of tillage and interactions among tillage, preceding crop, and P fertilization were inconsistent. Changes in flax Cd and Zn concentration may be due to changes in mycorrhizal colonization or by the high concentration of Cd in the decomposing canola residue. Crop sequence and P management can be used to improve flaxseed food quality, by increasing Zn and decreasing Cd concentration.