Understanding the 2015 Roundup Ready Soybean Variety Evaluation Tables

It’s that time of the year when the MPSG publishes the Soybean Variety Evaluation.  This article will look at how to use the variety evaluation tables effectively when considering yield and maturity. Additional variety characteristics are also listed in these tables. The 2015 Soybean Variety Evaluation can be found at http://www.manitobapulse.ca/variety-data.  Hard copies will be available as part of Seed MB 2016 and as an insert in the December 2015 issue of the Pulse Beat.

Roundup Ready Soybeans – Variety Descriptions Table

The first table to look at is the Roundup Ready Soybeans – Variety Descriptions table. The varieties are divided into Short Season, Mid Season and Long Season Manitoba Variety Zones based on relative days to maturity, with the shortest maturing varieties at the top of the table and the longest maturing varieties at the bottom.  The Relative Days to Maturity +/- of Check, are averaged over the 3 growing seasons but some varieties may only have 1-2 years of testing. Use these parts of the table to select varieties that have similar maturity to where you farm. Your goal in using this table is to assemble a short list of varieties you might consider growing.

The Yield % Check and Site Years Tested should be used together when comparing the varieties. The Site Years Tested represents the total number of locations a particular variety has been tested at. The greater the number of sites years, the more confident you can be that the Yield % Check reported is representative of the variety.  For example, 24-10RY (check variety), has 41 sites years.  Given that there are six to seven soybean variety trial sites per season, 24-10RY has been tested for at least six growing seasons.

Using Relative Days to Maturity +/- of Check and Yield % Check, your goal is to identify varieties, with maturities suitable to your farm that give you the highest yields relative to the check.  Keep an eye open for varieties that provide satisfactory yields but are earlier maturing.  These may represent good opportunities to avoid late season frost.

Yield By Location – Roundup Ready Soybeans Table

Here the sites are listed individually and are grouped into Core Sites, Early Sites, and Late Sites.  All varieties are tested at core sites. At early sites only early to mid season varieties are tested and at the late sites only mid to long season varieties are tested.

To assess real yield differences between any two varieties within a location using this table start by looking at the LSD% at the bottom of the table. The LSD (Least Significant Difference) is the minimum difference required between any two varieties compared at the same site. For example, the LSD% for the Carman Site is 12% and yield for 24-10RY has been set at 100%.  Only varieties that yielded 112% or greater would be higher yielding than the check.  Only varieties that yielded 88% or less would be lower yielding than the check. Any other varieties are considered as yielding the same as the check. We are not restricted to only comparisons with the check variety.  Yield comparisons can be made between any two varieties at the same site using the LSD% for that site.  Caution should used when making variety decisions based on one year’s data.  Using the long term data listed in the Variety Descriptions table will give you a better feel for how a variety performs over multiple site years.

Submitted by Dennis Lange, FPE Altona and Terry Buss, FPE Beausejour

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