Tolerant plants to fall and spring waterlogging within various cultivars were observed and two cycles of selection were completed at the  conclusion of a recent study conducted at Agriculture and Agri-Food Canada (AAFC), Nappan Research Farm.   The main objective of this study is to evaluate the newly developed alfalfa varieties and selection gain for persistence when grown under prolonged periods of fall and spring waterlogging conditions.  This project is associated with objective 1 of the Cellulosic Biofuel Network; Evaluate cellulosic biomass potential (yield, agronomic implications and energy balance), new compaction technologies, transport strategies and cost to the factory.  Subproject 1: Select annual and perennial biomass with enhanced yield and adaptability to marginal or crop land.

Sixteen new alfalfa synthetics (8 cycle 1 and 8 cycle 2, respectively, selected for tolerance to fall and spring waterloging conditions) and their respective parents were planted (July 1, 2009) in 2.5-cm H 14-cm root retainers containing Turface and Promix (50:50). Seedlings were clipped as needed and moved from the greenhouse to the field location (August 31, 2009). The experimental design consisted of 12 plants per experimental unit arranged in a split plot-randomized complete block design with 4 replications.  The main plot will be the flooding treatment (2); control (not flooded) and fall and spring flooding.  Plants were clipped once prior to moving to the field location to allow the plants to acclimatize to field environmental conditions.  The root retainers containing plants were placed in plywood boxes to accommodate designated flooding treatments which were initiated on October 15, 2009. At the end of the flooding treatment (6 weeks), the boxes were drained and the top growth trimmed back to 4 cm above the crown region.  Visible stress symptoms were observed following the fall flooding treatment. The boxes were covered with sheets of 5-cm Styrofoam bead board to simulate snow cover, for over wintering in the field location.  The boxes were also lined with 5-cm Styrofoam around the sides to prevent freezing from the sides.

The spring flooding treatment will be initiated on April 6, 2010 for a 6-week period.  At the end of the waterlogging treatment, boxes will be drained and the plants will be moved to the greenhouse.  The plants will be kept under natural day length in the greenhouse and top growth will be harvested twice, at 6-week intervals (5% blooms). Data collected prior to each harvest will include stage of development, persistence and dry matter (DM) yield.  After the last harvest the top 20% of the plants from each experimental synthetic will be kept for seed production of the third cycle of recurrent selection.  Prior to the first harvest tissue samples parental plants, cycle 2 plants, and non-selected control plants with and without flooding will be obtained, placed on dry ice and shiped to Saskatoon on dry ice for omics analysis.