Improving Alfalfa Germination and Vigor Under Early Spring
Conditions
Kathy L. E. Klos and E. Charles Brummer
Iowa State University, Ames, IA 50011
No-till seeding of alfalfa into existing pasture is often complicated by
competition with weeds and grasses. The need for herbicide application may
delay planting past the optimum date, and increase problems due to disease.
Alfalfa seedlings exhibiting early germination and rapid growth in cold
(above freezing) soils may be able to establish more successfully in the
early spring, reducing problems with disease and weed competition. Previous
studies have identified variation in germination and growth response curves
to different temperatures among forage legumes (Brar et al., 1990, 1991); and
differences in rate of germination and initial radicle growth rate among and
within alfalfa cultivars (Esvelt and Brummer, 1996; Klos and Brummer, 1997).
The purpose of this study was to evaluate four methods of recurrent mass
selection for the improvement of alfalfa seedling establishment and growth
under early spring conditions. Two to three cycles of mass selection were
conducted within six commercial alfalfa cultivars. Individuals were selected
based on days to germination in germination boxes at 5 oC, seedling growth in
a 10 oC growth chamber, and for extremes of germination rate and seedling
growth rate under these conditions combined. Resulting lines and commercial
cultivar source populations were planted in the early spring at two locations
in Iowa, and evaluated for emergence eight days after planting, seedling
height one month after planting, dry matter yield, and other plant
characteristics. Lines were also evaluated for germination and seedling
growth under selection conditions. This paper will present results of the
evaluation of selected lines for field emergence and seedling growth, and
correlations between field emergence, seedling height in the field, and
traits measured under laboratory conditions. Methods of selection for
seedling establishment will be compared within and among commercial cultivar
source populations.
References
Brar, G.S., J.F. Gomez, B.L. McMichael, A.G. Matches, and H.M. Taylor. 1990.
Root development of 12 forage legumes as affected by temperature. Agron. J.
82:1024-1026
Brar, G.S., J.F. Gomez, B.L. McMichael, A.G. Matches, and H.M. Taylor. 1991.
Germination of twenty forage legumes as influenced by temperature. Agron. J.
83:173-175
Esvelt, K.L., and E.C. Brummer. 1996. Variation among alfalfa cultivars for
germination at cold temperatures. Agronomy Abstracts,p. 91.
Klos, K.L.E., and E.C. Brummer. 1997. Variation among seed lots of alfalfa
cultivars for germination at suboptimal temperatures. Agronomy Abstracts, p.
87.
Previous Page