Some of the Methods We Use
December 10, 2010
Nurseries are grown in organic fields in Ames, Iowa and East Troy, Wisconsin. Promising lines are exchanged between the MFAI and USDA breeding programs. Screening in the nurseries includes testing seedling vigor and seed vitality under cold stress and accelerated aging, insect and disease resistance though natural or artificial inoculation/infestation, standing ability, rating for overall plant leafiness and vigor, rating for competitiveness with weeds, grain moisture content, yield. Grain quality is also tested (% total protein, % of total S amino acids, methionine, lysine, and cysteine; % oil; and % starch in the whole grain). We also evaluate N efficiency/fixation in specific trials using several different methods which are in process of development.
In its generalized form, our breeding plan entails making numerous crosses between parents with desired traits, hybridizing those crosses with multiple testers, examining the hybrid test crosses in yield trials and thereby identifying the best crosses to work with, then selfing the best of those families to the S3 stage while systematically testing resulting lines in test crosses. Selection pressure on breeding lines is approximately 10%. The best S3 lines are be further tested, selected, and developed as inbreds for making hybrids or recombined to make synthetics which receive additional testing to identify those that best fit the organic ideotype. Because speed is essential we plan to do early and repeated testing for combining ability in top cross hybrids allowing resources to be devoted to those populations that demonstrate the greatest potential early on. Winter nurseries will be used to make new crosses, to self F2 plants, to make necessary topcrosses, and to self the summer’s topcrosses to test their grain quality. In the winter inbreds will be screened for their grain quality and this information will be used to decide which lines to keep and topcrosses to grow. As we learn more about old and new parents and improve our breeding lines, we will make appropriate new crosses and feed them into the selection process.
Testcrosses are mainly made in the Midwest and evaluated on cooperating organic farms in Iowa and Wisconsin. Hybrids are evaluated for agronomic traits (population density, lodging, weed score, grain moisture content, and yield and screened for seed quality. Each year, the grain from a set of the best hybrids will be characterized for its quality after the hybrid plants are sib-mated (to preclude outcrossing effects on seed quality).
Test cross data lets us know what yields well. This determines what goes into the nursery. In the nursery we apply different methods depending on what we want to achieve. A guideline is that selfing or intermating early, robust plants for successive generations, under the stress conditions associated with organic farming, coupled with high selection pressure results in lines or pools with better adaptation to organic conditions. We induce stress through inbreeding, low N soils, late plantings, inoculation with endophytes, induction of weed competition; and at times we also inoculate with diseases and insects. Stress induction includes planting sunflowers with maize.
Seed from the resulting inbreds are selected for nutritional value (protein quality and carotenoids). Eventually the most robust phenotypes from a given cross or desirable breeding family are intermated. The resulting pools seem even better adapted and have enhanced quality and they serve as the sources for further crosses and inbreeding.
We also intensely use biodynamic preparations and other biodynamic measures with the idea that they induce a better integrated, balanced, and adapted plant which may become more responsive to avoiding the variable stresses associated with organic conditions (‘smarter’ plants). Trials done at the institute in previous years suggest that the use of these preparations can strongly enhance root growth and root health and result in enhanced yields in stress years.
Novel techniques we use include: near infra red spectroscopic (NIRS) analysis of amino acid quality of grain. Screening of seed for opaque seed types. Screening for vigorous inbreds under stress conditions. We have done taste tests in the past and that was useful too.