Agriculture Reference
In-Depth Information
14 days, seedlings are not suficiently developed for positive evaluation, the test may be extended
seven additional days by repeating steps 6, 7, and 8.
10. The percentage of seedling roots luorescing green or yellow may be determined using the follow-
ing formulas:
%greenfluorescentseedlings=
No.greenfluorescentseedlings
Totalno.of normalseedlings
%yellowfluorescentseedlings=
No.yellowfluorescentseedlings
Totalno.of normalseedlings
ﾠ
The percentage of seedling roots luorescing green or yellow is not necessarily equal to the percent-
age of red or hard fescue present in the sample. Therefore, only the luorescence percentages are
reported, accompanied by the following suggested statement:
Of the total number of normal seedlings, _____% luoresced green and _____% luoresced yellow.
Seedling evaluations should be performed according to AOSA rules. Record and report only the luo-
rescence of normal seedlings. Abnormal seedlings and ungerminated seeds should be ignored.
If you are unfamiliar with this test, it is advisable to irst practice on known samples of red and hard
fescue to learn to distinguish the yellow and green luorescence colors. The yellow and green colors disap-
pear on the paper when the ammonia solution dries.
Caution
: Ammonium hydroxide is corrosive and causes burns; the vapor is extremely irritating, and
may be fatal if swallowed. Follow proper safety procedures when handling this chemical.
ryegrass (
Lolium
spp.) fluorescence Test
This test was originally developed to distinguish between seeds of annual ryegrass (
Lolium multilorum
),
which was totally luorescent, and perennial ryegrass (
Lolium perenne
), with less than 5% luorescence.
Later research indicated that growth habit and luorescence were not genetically linked. Additionally, many
of the recently released cultivars have atypical luorescence pattern that reduce the utility of this test for
differentiating annual from perennial ryegrass. However, since luorescence is a dominant character, it can
be used as a cultivar characteristic.
The roots of luorescing seedlings exude a chemical substance called annuoline (Axelrod and Belzile,
1958) which produces bluish luorescent lines on white ilter paper when viewed under ultraviolet light
(Fig. 9.9).
Procedure
1. Plant four 100 seed replicates on two layers of white ilter paper in large plastic boxes with lids.
Moisten ilter paper with distilled or deionized water unless dormancy is a problem. For dormant
seed, use 0.2% KNO
3
solution and prechill at 5 or 10°C for 5 days.
2. Arrange seeds in such a manner that the roots of adjacent seedlings do not come in contact with
each other. With 6 x 9 inch boxes, the usual procedure is to place the seeds in four rows of 25
seeds each with 1.5 inches between the rows and the top row 0.5 inches from the edge of the box.
3. Germinate at alternating 15-25°C with light during the 8 hour 25°C period. Place replicates in the
germinator in an upright slant position at an angle of approximately 60-65°. Tests should not be
allowed to dry out.
