More info for the term: fresh
Winterfat reproduces by seed and sprouts from buds near the plant's base
when browsed or damaged [111]. Under favorable conditions, winterfat
may produce seed in its first growing season, but it may require up to 5
years to produce seed in areas of low rainfall [85]. Seed production,
especially in desert regions, is dependent on precipitation [101]. Good
seed years occur when there is appreciable summer precipitation and
little browsing [85]. Winterfat produced approximately 350 seeds per
plant on a site in western North Dakota during a slightly drier than
normal year [44].
Seeds are dispersed a short distance by wind. In a study of seed
dispersal, 67 percent of seed was found within 12 inches (30 cm) of
the parent plant, and no seeds were farther than 35 inches (90 cm) away
[44]. All seedlings observed on southwestern Idaho sites were within 3
feet (1 m) of a mature plant [60].
The hairy bracts help anchor seed to soil which in turn helps the
radicle penetrate and begin growth. Entire fruits have better seedling
establishment and seedling vigor than threshed seed, which may be
damaged [13].
An undetermined percent of winterfat seeds are dormant when fresh. A
10-week afterripening period generally breaks dormancy [82]. In the
laboratory, a 14-day prechill period at 41 degrees Fahrenheit (5 deg C)
effectively breaks dormancy of fresh seed [3].
Germination generally occurs during warm, wet weather [1]. Germination
occurs near the soil surface [104]. Seedlings emerged substantially
better from a 0.06-inch (0.02-cm) depth than than from greater depths
[81]. Germination is reduced as moisture stress increases, regardless
of temperature [80]. However, seeds are sensitive to deficient aeration
and have poor germination rates when soils approach saturation.
Germination was best at field capacity soil moisture [81].
Germination of viable seeds generally exceeds 90 percent within a
constant temperature range of 50 to 80 degrees Fahrenheit (10-27 deg C).
Optimum temperatures for germination depend on seed source [105].
Germination is generally complete within 5 days at 59 degrees Fahrenheit
(15 deg C) or higher [83]. Dettori and others [23] achieved greater
than 95 percent germination when they used an alternating temperature
regime with a 32, 36, or 41 degree Fahrenheit (0, 2, or 5 deg C) cold
period and a 59 or 68 degree Fahrenheit (15 or 20 deg C) warm period.
For laboratory germination, a 59 degrees Fahrenheit (15 deg C) constant
temperature for 14 days without light is recommended [3]. Booth [11,12]
reports that post germination growth is affected by mother-plant
transpiration, imbibition temperature, windstress, and nutrition.
As the level of soil salinity increases, germination decreases [17,105].
Choride salts reduce germination more than sulfide salts. Germination
was severely restricted by soil sodium chloride levels of 2 percent [17]
and 3 percent [105].
Winterfat seeds stored in an open (temperature unregulated) warehouse in
Utah maintained high germination rates (greater than 74%) for 4 years,
but germination after 5 years was only 18 percent, and germination was 0
percent after 10 years of storage [86]. After 8 years of refrigerated
storage at 34 to 42 degrees Fahrenheit (1-6 deg C), viability ranged
from 51 to 80 percent [84].
Natural reproduction in central New Mexico had greatest survival on
disturbed soils with low-growing vegetation that afforded some shelter
but little shade. By July, when summer rains began, the only seedlings
surviving were either close to mature winterfat, in grass clumps, or in
litter. The seedling roots penetrated beneath those of the grasses.
Seedlings were successful on land protected from grazing or lightly
grazed range dominated by grasses, but did not survive heavy grazing
[104]. Seedling survival was poor in the Mojave Desert. Of the 44
seedlings that established on plots during a 5-year period, none lived
to a second growing season [1].
