WL 306
1. Five populations of diverse breeding were subjected to three cycles of screening for pea and spotted alfalfa aphid resistance between 1963 and 1966 as follows: (1) PX seed of 4 Falcata x Vernal crosses, (2) WL 303 and 304,(3) WL 202, 210, and 211, (4) Atlantic clones and Atlantic x Flemish crosses, and (5) Misc. PX progenies with spotted alfalfa aphid resistance. From a total of more than 200,000 seedlings exposed to aphid pressure (pea and spotted independently) in the greenhouse over the 3-year period, the best 941 survivors were planted under screen cages at Bakersfield, California, in 1966 to produce experimental 303 AWR. A minimum of 78 and maximum of 246 plants were selected from each group at the conclusion of each screening cycle to produce the next generation. Following the second cycle of screening, the survivors of populations 2, 4 and 5 were inoculated with bacterial wilt organism at planting time. Only resistant and moderately resistant plants produced the seed used in the third and final screening for aphids. Each population was increased in a separate cage. Breeder seed was composited from populations 2 and 4 to comprise 50% of the total. Equal quantities of populations 1, 3 and 5 comprise the other 50%. The 21+ pounds of seed thus produced became the breeder seed as well as initial seed for testing.
2. Adapted for hay or greenchop in the Central Region of Alfalfa Adaptation. Has been tested in Kansas, Missouri, Illinois, Iowa, Nebraska, Minnesota, Ohio, and Pennsylvania.
3. Approximately 70% purple, 20% blue or bluish-green variegated, and 10% yellow, yellow variegated and white flower color. Less uniform than Buffalo or Cody but as uniform as Vernal. Slightly less fall dormant than Buffalo or Saranac. Predominantly upright but moderately decumbent under short days. Moderately variegated for an intermediate type alfalfa. Pod shape varies from tightly to loosely coiled with some sickle-shaped.
4. The initial isolated increases of 941 surviving plants from the third cycle of screening for pea and spotted alfalfa aphids comprise the breeder seed for WL 306. Foundation seed is the first-generation seed from fields planted with breeder seed between the 37 and 44 parallels. Certified seed is the production from fields planted with either foundation or breeder seed. No other seed class or generation is to be certified.
5. 1970.