Developing a Standard test for Lodging Resistance in Alfalfa for North America Debra Sharpee, Gary Hoard, Mark Smith, Dave Miller Pioneer Hi-Bred International Inc.

Introduction Lodging resistance (LR) or standability is an important trait in many crops. Improved LR often results in increased harvestable yield and crop quality.

Introduction Alfalfa has been improved for LR primarily in germplasm adapted to France. French varieties must meet minimum standards for LR to be eligible for inscription. Testing for LR in France is based on observations prior to cutting, and on stubble after cutting.

Introduction Varieties with improved LR are beginning to be marketed in North America. There is a need to describe LR in North American adapted varieties for purposes of variety description.

Objectives Examine the relationship between LR in solid-seeded plots vs. spaced planted alfalfa. Develop criteria for evaluating individual plants for lodging resistance. Take the first step in developing a standard test for LR in North America.

Experimental Procedure Establish solid seeded yield plots (~1m x 4m) with LR varieties and commercial varieties in spring Transplant 100 plants (4 reps, 25 plants/rep) of same varieties in spring Allow both trials to grow until commercial varieties are obviously lodged and score in Johnston, IA and Arlington, WI in spring 2002.

Experimental Procedure Score plots on a 1-9 scale where 9 = no lodging and 1 = completely lodged. Score each plant in transplanted test and determine a Percent Resistant Plants (PRP) to lodging.

Experimental Procedure Spaced plant scoring criteria: –9=Erect, plants instantly spring back to vertical. –7=Mostly erect, but leans some. –5=Plant leans ~45 degrees. –3=Plant leans more than 45 degrees. –1=Plant flat on ground.

Spaced Plant rated a “9”.

Johnston, IA LR LS Lodging Resistant vs Lodging Susceptible plots

Results Variety Plots-IAPlots-WIPRP-JHPRP-WI Europe Exp A Exp B H V Geneva LSD(.05) Plots= whole plot scores; PRP based on classes 7-9

Discussion There is a clear relationship for LR between solid-seeded and spaced planted tests. The spaced plant scoring criteria was useful for describing solid-seeded performance.

Discussion Progress on developing a standard test: –Good “first-step” in developing scoring criteria. –Europe (French variety) is a candidate for an HR check. –Several candidates for lodging susceptible check (eg. 54V54, Geneva).

Discussion Additional data has shown that LR in seeded plots is very consistent across cuts, locations, and years.

Future work Generate additional spaced plant data to determine appropriate level of LR for resistant check (likely Europe). Run cooperative trials to determine consistency across organizations for checks and scoring criteria.