Vol. 15—1961 - NorthEastern Weed Science Society

354.
A clos.e correlation was found between number of tillers' and number of
seed heads. To assess the seed producing potential of foxtail, seed counts
of 7 heads selected at random were made. An average of ISO seeds per head
were foun1~ On uncro'Wded plants, with an average of 47 heads per plant in this
eXl)eriment; over 0000 seeds nerplant were found •.
Discussion
Post-harvest 10rmancy in foxtail l'18.S quite na rked, In Connecticut,
foxtail seed shatters from the seed heads at least by mid-Sept6m"fler. Several
weeks of weather favorable for germination remains in the season. As a warm
season annual, obviously foxtail would be ecologically adapted at high
latitudes only if a post-harvest dormancy did exist.
A'gradual change in the condition of seed under warm-dry conditions
occurred. Seed collected in' different years varied in the time interval re-:
quirecl to induce germination. Even after passage of several months, hO","'ever,
germination of such seed averaged well below 25 percent.
Of the many treatments used, the "treatment having the most oreneunced
effect on germination was scarification. Soaking the seed in fuming H 2S04
was considerably more effective than rubbing with sandpaper.
The pitting of the lemma and palea following scarification increased
penetration of 'ltm.ter. This was readily demonstrated by the movement of a
Loeffler's methylene blue dye onto the embryo"of the caryopsis while little
or none can be detected in non-scarified seed. A close correlation was
found between the percenta~e of seeds absorbing dye in 'Oarticular seed lot
and the germination percentage in the same seed lot. A close correlation
betNeen weight. of water absorbed by seed and the observed ra.te of germination
was noted fo:- both 1955 and 1959 seed. The older seed having a germination of
about 50 percent, increased in weight 19 pereenb after being imbibed, "1959
seeding giving no germina:t ion imbibed only 2.6 percent, water by weight. It
is suggested, therefore, that lack of l'18.ter entry is an important factor in
the dormancy of net-fly shattered yellm· r foxtail seed.
Any condition in the field '\Amich"lould tend to erode the lemma.and
palea would be ax:pedcaito increase l'Tater uptake and thus germination. 1959
seed remaining in the soil over winter '\A!S.Sgerminating 33 percent by Hay 27.
In general, tem1')erature treatments of seed. held in dry condition had little
effect on germdnatd on, Seed fi:-st imbibed. and then dried or seed held in
moist,cold or moist fluctuating temperature conditions showed an increased
germina.tion.,
Of the several chemical. treatments used" only the nitrate compounds"
IO.T0 ~e:nnination
3
and NH4N03increased markedl~. S-:::arification prior to
treatment near'ly doubled the effect again sugResting that inc reased permeabilit.y
of the liquid into the cary-opsis was a factor.
Observation of thedeveloy:ment· of foxtail plants substantiates the
marked abilit:v of this ann1.ial s'Oecies to reproduce itself. Plants slow to
develop because of delayed gerrid.rtation associated lrith 10rmancy or tillage