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A STUDY OF THE RELATIVE LENGTH
OF THE FORCING PERIOD REQUIRED
BY THE NEW LILY LILIUM
LONGIFLORUM VARIETY DOWNINGI,
A8 COMPARED TO THE STANDARD
FASTFR LILY VARIETIES L.
LONGIFLORUM VARIETIES GIGANTEUM
AND ERABL‘

Thesis for the Degree of M. S.
MICHIGAN STATE COLLEGE

Evan Paul Roberts
I 941

 

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1. mm or m RELATIVE mm or m mom PERIOD
mum» at m: um mm m marrow vmm pgwmmz,
A8 courmn to m swmnn mm LIL! VARIETIES
g. mymm “moms M AND M

 

By
“A! Pm ROBERTS
‘ W

 

a '. .
Lie-1M ' . '
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A THESIS

azhnitted to the Graduate School of Elohim
State College of talculturo and Applied
Science in putlal fulfilmnt at the
requirements for the degree of

MOISOIW

Department of Horticulture
19M

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1' H 655

TABLE OF CONTLTITS

Introduction . . . . . . .
Statement of Roblem . . . .
Review of Literature . . . .
Materials and Methods . . .
Temperatures . . . . .
Potting . . . . . . .
Methods of Labeling Plants
Temperature Variation . .
Presentation of Data . . . .
Temperature Results . . .
Stem Production . . . .
Flower Production . . .
Supplementary Data . . .
Discussion . . . . . . .
Summary and. Conclusions . . .
Acknowledgement . . . . . .

Literature Cited. 0 o o o a

140,114

\ONO‘U‘IMN

10
ll
11
12
1h
20

23

Introduction

This investigation is the result of the interest displayed by the
florists of Michigan in the new, patented Easter lily, m lgngflgrum,
Ivariety flowing (I. P. Roberts).

The new lily ‘variety is a hardy form of the common comercial Easter
lily new extensively used by florists for forcing in the greenhouse for
Easter. It is the result of a selection from a group of seedlings pro-
duced by Mr. O. 3. Downing, Sunfield, Michigan, lily grower.

In his application for a plant patent for this new lily. Mr. Downing
describes its origination as follows:

“first, the pollen of L. reggle was placed

on a receptive stigma of mm W .variety

gfltm. Next, the pollen of Lilian 2259.: was
again placed on a receptive stignaof the issue of

the first developed above described cross. w new
.veriety of lily is an individual selection resulting
from the above two crosses after careful and extensive
testing under Open field and under glass conditions.

he above described crosses were sought. and per-
fected to obtain and combine the hardy characteristics
of the 24.1.3512 m and the forcing characteristics
of the Eli!!! n £10 ."

@he desirable characters of 34.1.1492 Wren”: M
seem to be included in the new 111:. In addition several other hide]:
desirable qualities are cleaned for it:

(1) It is winter hardy in Elohim.

(2) The lower leaves are held much longer than by

- 2 ..
either of the most popular commercial forcing
.varieties of M loggiflorum .variety agap-
tm and ‘variety m.

(3) There is a tendency to produce more stalks and
hence more flowers per plant than other pepular
commercial forcing varieties.

(It) The flowers tend to remain salable for a longer
period.

(5) Bulbs split readily to form several crowns, thus
permitting rapid propagation under comercial
culture.

None of the amorous attempts of the last 30 years to produce Anaer-
ican-g‘own Easter lily bulbs for the comnercial greenhouse forcing busi-
ness have been permanently successful with the possible exception of
those for the Creole lily which is now being grown in Louisiana and
other Southern states. If the new lily could be forced as successfully
as .variety agateum or ‘variety £291.: it would apparently be a satis-
factory knerican-grown lily bulb-stock. It has survived the Michigan
winter weather at Sanfield since its origination. Special winter pro-
tection is not necessary.

liichigan-gown bulbs would be welcomed by the florists because the
Japan-gown bulbs, now the largest supply for forcing, are rapidly be-

coming more generally infected with ,virus diseases.
Statement of Problen

The object of this investigation was to determine the relative

length of the forcing period required by the new lily, Lilium

- 3 ..
iongiflormnyariety Downigé, (Plant patent #36) as compared to the stand-

ard Easter lily‘varieties, L; longiflorum varieties giganteum and Eabu.
Review of Literature

Lilies are the subject of a large literature, but most of this is in
the form of ”notes" written by amateur admirers of lilies as garden plants.
Lilies, by Woodcock and Ooutts (18) is probably the best of the more tech-
nical of these writings on general lily culture. Slate (ll) confines his
work to the lilies suitable for American gardens. Wilson's _L_i_l_i_gs_ 9;
Eastern is}; includes much of interest on lily culture, but the book is a
monograph, primarily largely taranomic, on the Eastern Asiatic species.

Florists have contributed many notes on their observations on green-
house culture, especially for Easter forcing. Most florists use some modi-
fication of the methods smarized by Laurie and Poesch (9) and l‘rits Bahr
(2). These are the most recent revisions of Iilmsden‘s (10) recomendations.

Little accurate investigation has been reported on the physiology of
forcing in lilies.

Most of the accurate investigations in lilies has been concerned with
the effectiveness of supplementary illumination as an aid to forcing.

Lenlrie and Poesch (8) concluded that bulbous plants show, in general,
little or no response to increased illumination. m longiflorum, how-
ever, appeared to be an exception in that additional ligit produced the
same advancanent in date of flowering in this species as was promised by
increasing the temperature of the greenhouse.

Withrow (17) concluded that the use of additional illumination does
not produce predictable results. With h1g1 intensities favorable results

were obtained by using lights for a few weeks to hasten flowering, but

.. n -
the results obtained where low intensities were used.were extremely.vari-
able.

.Wdthrow (17) also concluded.that temperatures must be kept favorable,
even when the plants were irradiated.

Green et a1 (6) found.that,variety giganteum flowered earlier when
irradiated for the first 20 days after they appear above the soil with a
500 watt lamp for five hours each night.

Later, Kalin (7), working with lgligg;longiflorum.varieties Downingi,
giganteum and Eggpg, concluded that supplementary illumination has no
practical aid in forcing these three,varieties under Michigan greenhouse
conditions. Only a two day increase in earliness was secured in,variety
Eggyg. This and other results he obtained from irradiation were not in
agreement with those of other investigators who claimed the use of sup-
plementary illumination produced an increase in earliness of from one to
fifteen days. In his trials with the .variety agatemn, the average flow-
ering date of the check (unlighted) plants was earlier than that of the
illuminated.plants. Variety Downingi appeared to benefit from the addi-
tional illumination. A.six day increase in earliness was obtained when
the lights were used for four weeks in the second.month before flowering,
providing that the temperature was maintained at YOEF. from the date of
the first lighting until the plants flowered.

The most comprehensive investigation on Easter lily forcing was done
by White (14). Unfortunately, his publication was not available until
after the completion of these experiments.

A.second comprehensive investigation on lily forcing (M) was also

pubiiShed after completion of this investigation. However, in a personal

. - 5 -
communication (3) Brierley kindly made the general outline of his results
available. Rom his work: Brierley concluded that lily bulbs stored at low
temperatures flower earlier than non-treated bulbs, and the idea is pro-
posed that the difference in length of time to flower, as reported by .var-
ious commercial growers, may be accounted for by the variations in the tem-
peratures and the length of the storage period.

Because of the conflicting conclusions of the literature, it was de-
cided to work only'with temperatures as the controlling factor for rate of

forcing in this present study.

Materials and Methods

Japan-gown bulbs of Lilium Mvarieties gganteum and m
were purchased in the open market in December, 1938. The Japan-grown bulbs

were shipped in the usual type of lily case, a heavy wooden box in which
the bulbs are packed in dry soil.
the bulbs of .variety habu were grown in the Yokohama district, and

 

were shipped from Yokohama, Japan, on August lIvth, 1938. They were placed
in cold storage in Chicago on August 29th. Three months later they were
removed from storage and shipped to East Lansing.

The bulbs of variety M were gown in the Nagasaki district
and were shipped from Yokohama on September 2nd, arriving in Chicago for
cold storage on September 28th. After two months storage they were shipped
to East Lansing.

Mr. Olarence I. Downing, the originator of variety Downing, donated
a supply of bulbs of this lily. The bulbs were grown on muck soil at Sun-
field, Michigan. They were dug in late November and stored in an unheated

shed at near freezing temperatures for two weeks before they were shipped

- e, -
to East Lansing on November 3rd. The roots onvariety Downing had not
been clipped. The usual practice of the Japanese lily growers is to clip
all the roots from the bulb before shipping them, and all of the Japan-
grown bulbs were so treated.

All bulbs were examined for evidence of disease or mechanical injury,
and all were graded for size on the basis of their circumference. Eight
groups of 15 large bulbs each and eight groups of 15 small bulbs each were

selected for each of the three lily varieties.

Tab ie I

Schedule of Bulb Sizes Used

 

 

Lilium longiflorun (circufl‘gegemilnbfnches)
Var. Downingl 8
Var. " 7
Var. sigante‘m 8
Var. " 7
Var. B‘abu 7
Var. " b

 

 

 

 

Note: Of the 720 bulbs planted all but 17 eventually
produced flowers.

Temperature 3

Eight temperature ranges were used in the experiment. These tempera-
tures were chosen because they are practical combinations for use by a
small florist who wishes to grow his own Easter lilies. They are combina-

tions of four basic greenhouse temperatures - 55, 60, 70 and 80°F.

- 7 -
Table 11

Schedule of Temperature Treatments

 

 

 

 

 

 

 

 

 

mint 3:12:11 ‘ High High 4/5-14/9
1 55 55 55 55
2 60 60 60 be
3 b0 70 7O 70
It 70 70 7O 70
5 70 55 55 55
b 70 60 60 60
7 60 55 55 55
L 8 60 7O 80 55
Note: All bulbs were rooted at 55". for two weeks after
being potted.

The pm was to maintun these tenpsratures at nifit, with the day
temperatures to be held as near these desired tenperatures as possible.
hiring the first two weeks when the newly pot ted bulbs were kept under
the geenhouse benches, all were subJected to a 55". temperature.

Tauperature and relative humidity of each house were recorded on
hiets hyyothermog'aphs, with one of these instruments being used in
each of the four houses. These instruments make weekly charts scored
for two hour intervals. me accuracy of the Iriets hygrothermographs
was checked weekly or more frequently against a sling psychrometer and
a precision laboratory themnometer.

Potting

All bulbs were planted on Decanber 13, 1938 in new 6 inch standard

cm pots. The pots were not soaked or otherwise specially prepared before

being used.

I'lorists usually subscribe to the belief that new pots should be
soaked in water before they are used to prevent the pot from absorbing
the water from the soil in the pot. This idea appears to lack scientific
substantiation. Wilde (15) found that soaking the new pots in water be-
fore using them produced no appreciable beneficial response in the plants
subsequently grown in them, especially 1: the soil nitrogen-was suffi-
cient. Since it was planned to add nitrogen at freqmnt intervals during
the course of this study, the pots were not pre-soaked.

The soil mixture used was made by thoroughly mixing four parts of a
one year old compost with one part of sand and one part of leaf mold.

The mixture was screened through a one-fourth inch screen, but it was not
sterilized.

Bulbs were covered with three inches of soil. All .varieties of
Lil-.122! longiflorum are sten rooting, that is, roots can be formed along
the stem for some distance above the bulb. Occasionally, bulbs which are
planted less than 3 inches deep produce a few roots above the soil line,
but these appear to act only as brace roots. The 3 inch planting depth
was used to rednce the likelihood of their procbiction. finall pieces of
crockery were added to each pot to aid in drainage, although the soil mix-
ture itself appeared to have a good physical structure.

Since mlson's (16) comments that "since lilies inhabit waste places
of the Northern Hanisphere it is obvious that they are unaccustomed to
rich food; for this reason even stable manure should not be used in their
culture and artificial fertilizers are absolutely inimical“, the amateur

and commercial lily growers have contributed many "notes" to the effect

- 9 -
that lilies actually need a relatively fertile soil. Woodcock and Goutts
(18), Slate (11), and Taylor (13) agree that both well-rotted stable man-
ure and inorganic fertilizers are beneficial to lilies.

To reduce somewhat the soil fertility factor as an influence on rate
of forcing it was decided to start the bulbs in a fairly rich composted
soil and to make fertiliser additions as needed during the enqaeriment to
maintain the original fertility level.

At each addition of fertilizer during the course of the experiment
(Table III) the soil in each pot was thoroughly watered with a solution
of the fertilizer material. Each plant was subsequently winged with

tap water to renove any solution which had fallen on the leaves.

 

 

Table III
Schedule of fertiliser Additions
Date Mat erial 9.3:)322 Efu'itga ’
2/15 (mm 80;; 1
2/23 " 2
3/1 “ 2
5/15 {2801; 2
5/16 (unwzsou 2

 

 

 

 

 

Note: lnougi 35PM was added to the solution to lower its pH
to ll».O (p3 5.0 on solution of 3/16).

Methods of labeling plants

Each pot was labeled with a six inch wooden pot label, and each plant
was numbered. mick identification of varieties and bulb sizes was made

possible by the use of a code consisting of narrow bands of ‘various colors

(Table IV) on the pot label.

- 10 -
able 1'
Key to Plant Labeling

 

 

 

 

 

 

 

 

Position of Lib color Size
Color Band Variety of 3nd of nilb
50? Downing» White
' gigsnteum B‘een
" Irabu Bed
Lower Downing. white 8
w s 39d 7
" agentm mite 8
e :- Bed 7
" habu mite 7
' " Red 6
imperature

Careful observation of the hypothermogreph charts covering the
four month period shows that there was an average teaperature .variation
of only approximately 10". The occasional large .variations recorded
were only for short intervals, usually of one two-hour period or less.

an. relative hunidity was taken during this investigation because
the particular instruments were so equipped that they recorded it on the
same chart as the tenperature. It had originally been planned to regu-
late relative humidities, but the idea was discarded when the plantings
were made. No attunpts were made to regulate the humidity of the houses
becmse the usual watering practices used by the camercial powers pre-
clude any possibility of a control which might be scientifically sig-

nificant in such a stuw of growth rates as this one includes.

Presentation of Data

Eenperature Results

fable Y

Average Eemperatures from Date of Planting Until taster Bandy

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Desired __4Lctual Imperature Relatige Humidity;
Temperature Day may: Day Ni an
559. 60.570 58.209. 70.3075 69.9%
60 63.83 61.88 65.93 67.60
70 71.11 70.50 71.114 69.09
80 75.15 77.82 67.147 65.58
fable VI
Average llonthly Temperatures
£332. 12/13/38 wouwgfifim I1/5/35 11/9/39
“1’" 1/10/39 2/3/39 3/7/39 11/5/39 L1/3739 wan/39
n n D N r r r u D n D x
55'1- 55 55 55 57 56 57 57 52 55 '49 61 58
60 66 66 63 62 68 63 65 61 66 61+,
70 71 72 71 72 71 69 75 73 75 72
80 75 78

 

 

 

 

 

 

 

 

 

 

 

 

 

 

-12-

Table VII

Temperature Entrance

 

Lowest ' Difference

 

 

House ' Hi asst
55"- 97".
60 9O

70 90

80 98

 

 

39’!-
1&8

515
511

 

58".
ua
36
101

 

Stan Production

in accurate count was made weekly of the number of stems produced 15'

each of the 3+8 fifteen-bulb youps.
tion to April 7, 1939.

Table 711!

Stan Promiction - I4/7/39

Table '11! records the stem produc-

 

Lilium longiflorum

average number of "er!
per fifteen-bulb you}:

 

vue mun-n4
Var. giganteum
Var. Irabu

 

 

327
307
239

 

The claim that .variety w produces a larger number of stems per

plant is substantiated.

During the course of the investigation each lily was measured weekly

to determine its heigat. Table I! gives the average heifits on April 7,

1939.

 

 

.. 13 .-
Table 11
Stem Length - l1/7/39

 

 

1.1 lium longif lorum Avrerasgtfii ght
Yfl'. Downing. 38cm.
Var. gauntemn 35
'6'. lrabu 53

 

 

 

 

Since the plants of .variety M had not completed their full
growth in heigt, the weekly gowth measurements were continued later
than taster. The final measurements (Table I) were made on June 16,

1939, when the plants had obviously completed their growth for the season.
Table 1
Stan Length - 6/16/39

 

 

m Average Height
Lilium longiflorum P er Stem
Var e M11381 . 516m.
Var. giganteum 1&5
Var. Irabu 60

 

 

 

 

Inspection of Table 1 reveals that .variety M is a taller lily
than ,variety W1: but not as tall as.variety Drabu. It is not sur-
prising that ,variety habu should be the tallest because it is noted as
an exceptionally tallyariety of 2241-2 loggiflorum.

The ,variety Downing increased five inches in height in the two

 

month period after Easter while .variety Bram had evidently been within
three inches of its full height on April 7th. This may indicate that

.variety awning is a slow maturing lily which is, however, able to flower

.. 1h ..
long before it has attained its full .vegetative gowth for the season.

Flower Pro duction

In 1939 Easter occurred on April 9th. Obviously, any lilies which
were grown for sale at Easter in 1939 must have flowered In the 9th to
produce a profitable crop. Of the 98 groups grown in this investigation
22 groups had an average flowering date of April 9th or en'lier.

Table 1:

Dates of Flowering at Various Temperatures
55".

 

 

 

 

 

 

 

 

 

 

L11: mu Average umber Average date Percent flower-
Variety 31.. rig/131186;;- 0101;132:115 1113': a; mere
Downingi 8" 166 1 5/26 80

' 7 165 5/25 87
giganteune 8 1514 5/11; 73
" 7 156 5/16 37
”3b“ 7 152 5/12 117
t " 6 150 5/10 50
" One bulb failed to flower
55 - 609.
Downingi 8" 132 W22 55
" 7 135 14/25 30
818th 8 116 we (,7
" 7 122 4/12 1;;
new. 7 121 u/11 6M
" 6 119 11,9 6h

 

 

 

 

 

 

 

- 15 -

Table 11(continued)

 

 

 

 

 

 

 

 

 

 

55 - 70”.
Average number Ayerage date Percent flower-
Vaiiigy 23:: of days to of’flowering ing on or before
first flower of group average date
Downing. 8" 113 '4/3 67
' 7 111 ”/1 73
giganteum 8 109 JIfiO M7
' 8 107 3/28 67
Irabu 7 98 5119 '40
' 6 101 3/22 60
55 - 60 - 559‘.

Downingi 8" 161 5/21 no
u 7 157 5/17 “7
giganteumfl 8 1M7 5/7 67
' 7 151 - 5/11 67
Item 7 1115 5/5 5:
I 6 1175 5/5 1&0

 

 

 

 

 

 

 

 

-15..

Table 11 (continued)

 

 

 

 

 

 

 

 

55 " 7O " 60°F.
Lily Bulb Average number Average date Percent flower-
73.1.” 81" of days to of flowering ing on or before
_ first flower of group average date
Downingi 8" ‘ 12 W22 117
“ " 7 155 4/25 38
‘glganteum 8 116 W16 I43
5 fl 8 122 17/12 1+3
Ira‘m. 7 121 IH1]. "-7
' 6 109 3/20 67
" One bulb failed to flower
" Two bulbs failed to flower
55 " 60 " YOQe
awning. 8" 117 14/7 117
" 7 116 14/6 55
‘gi’ganteum 8 107 3/28 67+
" 7 110 3/31 117
babe 7 1017 5/25 60
* || 6 107 3/28 1&0

 

 

 

 

 

 

" One bulb failed to flower

 

 

- 17 -

Table 11(c0ntinued)

 

 

 

 

 

 

 

 

 

 

 

55 - 70 - 55'!-
Lily ms Average number Average date Percent £16m-
variety Size 0f dflF‘ *0 0f flaidring ing on or befor
first flower of group average date
Downinsi 3' 155 5/15 73
" 7 15“ 5/111 60
giganteum. 8 196 5/6 M7
" 7 m 5m 1+7
“ram 7 135 17/25 50
ham 6 135 2/23 60
' One bulb failed.to flower
55-60-70- 80-55'1'.
Downing. 8" 109 3/30 80
' 7 107 3/28 60
giganteum 8 106 3/27 60
‘ " 7 107 3/28 614
“Drabu 7 100 3/21 62
" 6 10“ 3/25 55

 

 

 

 

 

 

‘ One bulb failed.to flower
‘* Two bulbs failed to flower

Groups Flowered.Defore April 9, 1939

Table III

 

 

 

Variety Bulb Bise Temperature Treatment 3635:7533;
Deanna 8" 55-60-70-80-55'1'. 3/30
" 7 55-60-70-80-55 372s
' 3 55-70 2/3
" 7 55-70 m
" 3 55-60-70 kn
" 7 55-60-70 2/6
5193““ 3 55-60-70-80-55'! 3,27
" 7 55-60-70-80-55 5,23
' 3 55-70 3/30
' 3 55-70 3/28
' 3 55-60570 3/28
” 7 55-60-70 3731
' 3 55-60 we
" 3 55-70-60 we
”‘1’“ 7 55-70 3/19
' b 55-70 3/22
. 7 55-60-70-80-55 3,21
' b 55-60-70-80-55 3/25
a 1 55-60-70 3/25
' 5 55-60-70 3/28
" ° 55-70-60 3/3o
" 3 55-60 17/9

 

 

 

 

 

- 19 -

The response of the .verieties giggteum and m to temperature
appears to correlate well with the results of forcing reported by lily
growers.

The groups of .variety m flowered on an average of three to
seven days before the corresponding youps of ,variety gigteum. Ellie
smaller intervals occurred in the groups flowering the earliest. This
increase in earliness of .variety £9.33 ever .variety aganteum is to be
expected because the former is normally an earlier flowering lily. It
is, however, usually grown for cut flowers for sale throughout the year,
especially during the period from christmas to Easter, with .variety
giggteum being the favorite for the Easter forcing trade.

The average flowering date of the groups of .variety M was
from one to three ms later than the average flowering date of the cor-
responding groups of ivariety giganteum which flowered from Easter. The
youps of .variety Mpg; which had not flowered by Taster were delayed
in their average date of flowering by approximately ten to fourteen days.

Further investigations should be conducted to determine if this ob-
served delay of from one to three days in the before-Easter flowering of
,variety mg is caused by some genetic factor or by environmental fac-
tors operating dnring the period of storage of the bulbs. he bulbs of
the .variety H.921. used in this study were held in cold storage for three
months, and the bulbs of the “variety giganteum were held at a similar tem-
perature for two months. The bulbs of .variety _D_owningi had only the two
week period of storage in the unheated shed in Sunfield, Michigan, before
they were planted.

Drierley (3, I4) reported that low temperature during storage hastened
subsequent flowering of the bulbs. He also noted that it reduced the

- 20 ..
number of flowers produced. It is possible that bulbs of .variety M
would have flowered as early as those of variety Minn, or possibly
even as early as those of .variety m, if they had received the same

storage treatment. nu. question deserves further consideration.

Supplementary Data

The plan of the emerhent was to secure data on the dates of bloom-
ing at the ,various tunperature treatments. Additional data secured in-
clude records of the number of flowers per stem, weekly growth rates of
the plants, and the number of plants exhibiting signs of disease.

Correspondence with approximately~ 20 menbers of the Lily Committee
of the Royal Horticultural Society furnished information on some of the
ideas held by these various lily yowers in connection with the forcing
requiranents of the .variousvarieties of A1329; lgmflorum.

from general observation it appeared that .variety Mpg; did hold
its lower leaves much longer than either m or giganteum, and that there
were more flower stalks produced per bulb although actual flower counts
showed no sigiificant increase in the average total number of flowers per
plant. There also appeared to be only a slight difference in the lasting

quality of the uncut flowers of .variety M.
Discussion

These data show that the new laster lily L. lgngflorumyariety
Ewing, is a promising .variety for forcing in the greenhouse.

Tenperatures above the 60-70%. range are not necessary except in
an emergency to force a late planting. be marked response to the 80°l'.

temperature indicates that the new lily would flower at Lester even if

planted a week later than the usual planting date of .variety M.

- 21 ..

The 5531'. temperature for rooting was. used because it is the tempera-
ture normally employed by the florist on the newly potted lilies. The
more favorable response of the 55-70'I'. temperature groups as compared
with the 55-60-709. groups seems to indicate that a hiaer rooting ten-
perature would be desirable.

Subsequently, Ihite (1”) reported that both .varieties aggteum and
33931.1. flowered earlier and produced more flowers per plant when the root-
ing temperature was abqve 60°F.

Thus it would seem that .variety M would probably respond most
favorably to a 60 to 62°17. rooting temperature. If this were combined
with a 7031'. growing temperature until flowering, [variety M would
evidently produce a profitable commercial crop for Easter from the usual
date in Decenber for planting variety giganteum. '

Recommendation is made that the Michigan florists substitutevariety
awning only for a part of their standardvariety plantings until further
investigation is made to determine if the apparent delay in flowering of
‘variety mm is an inherited tendency or a result of enviromnental fac-
tors Operating during storage.

Prom the results obtained by Brierley in advancing the date of bloom
by subjecting the bulbs to cold storage it would seen that the apparent
tardiness of bloom in .variety mwning results from the fact that Japa—
grown bulbs are held in cold storage whereas the Michigan-gown bulbs are
dug and planted without being subjected to such storage. Suggestion is
made that digging time for the Michigan-grown bulbs be advanced snow to
allow time for a cold storage treatment.

American-grown lily bulbs are of increasing importance as the Japan-

gown bulbs are becoming more difficult to obtain. Variety M is

winter-harm? in Michigan, and high quality bulbs for forcing can be pro-

duced economically. These data indicate ease of forcing by the florist.

Variety awning thus promises to be of increasing importance.

(1)

(2)

(3)

(3)

(5)

Summary and Conclusions

gum longiflorum .variety Emingi, a new, patented hardy
lily recommended for greenhouse forcing for Easter flower-

ing by its originator, was compared with L. loggiflorum

.varieties giganteum and gabu, the two most cannon forcing

lilies used by the Michigan florists, to determine the

advisability of substituting it for the two standard

.varieties.

Eight different forcing temperature treatments were used

on each of the three .varieties of lilies.

There was no significant difference in the rate of flower-
ing of the three varieties, althougi there appeared to be

a tendency for .variety 2% to flower earliest andvariety
312.123. to flower latest.

Any forcing temperature which will produce an Easter crop

of .variety M932 appears equally as efficient for produc-
ing the Easter crop of .variety awning.

A rooting temperature of 60 to 65%., followed by a 70°].
growing temperature, scans desirable for .variety Mi.
Under such a tanperature schedule ,variety Ewing; will flower
for Easter without additional forcing if the regular planting

date for .variety aganteum is used.

.2}.

Acknowledgement

The writer is geatly indebted to Professor C. D. Wilden, of the
Department of Horticulture, for suggesting the subject of this investiga-
tion and for his man helpful suggestions and criticisms. The writer
also takes pleasure .in extending his sincere appreciation to Mr. Clarence
D. Downing for his gift of the bulbs of .variety Downing; to Mr. Phillip
Brierley for furnishing his unpublished data on the effects of low tem-
perature during storage of the bulbs; to Mrs. George E. Weldon and Mrs.
liven Paul Roberts for aid in recording data on growth rates; to the .var-
ious members of the Lily Comittee of the Royal Horticultural Society for
their aid in locating information about methods of lily culture; and to
Mr. Leonard Vaughan for his assistance in locating Japan-grown bulbs of

known origin.

(1)

(2)

(3)

(7)

(3)

(9)

.. 211 ..
Literature Cited

Anonymous. Physiolog of forcing. Gard. Chron. (L0nd.) 102:2173.
October, 1937.

Babr, l‘rits. In W m. A practical manual for
the retail grower. Fourth (revised) edition. pp. 1187-
1490. A. T. DeLaMare Company, Inc., New fork, 1937.

hierley, Phillip. Letters to the mthor from U.S.D..i. Hort. Pield
Station, Deltsville, Maryland. 1938-39.

Cool storing of Easter lily bulbs to hasten flowering.
The Plorists' Review 88 (2267):2l-2ll. May, 1991.

Cochran, 1'. D. and Gill, D. L. Prediction of Easter lily bulbs in
Louisiana. La. Agr. Exp. Sta. Circ. 22. January, 1939.

Green, L., Withrow, B. 3., and BicMan, W. I. The response of green-
house crops to electric 1.1ng supplementing dayligt.
Ind. Agr. Exp. Sta. 3.11. 366: pp. 13. 1932.

Kalin, Elwood. Unpublished data on the effect of supplementary il-
lumination as an aid to forcing ELI-.122 19‘an lorum var-
ieties pgwningi, aggtm and m. On file at Michigan
State College. 1939.

Laurie, Alex and Poesch, G. H. Photoperiodism. The ,value of sup-
plenentary illumination and reduction of light on flower-
ing plants in the geenhouse. Ohio Ly. Exp. Sta. Dul.
512: 17-18. 1932.

In Comercial £1919; l'orcing. The fundanentals and their
practical application to the culture of greenhouse crops.
Second (revised) edition. pp. 7703-7408. P. Dlaklston's

Son and Company, Inc., Philadelphia. 1939.

(10)

(11)

(12)

(13)

(1”)

(15)

(1b)

(17)

(18)

- 25 _

Lumsden, David. In The Standard Cyclopedia 03; Horticulture II:
1865-1866. The MacMillan 00., New'York. 1937.

Slate, G. L. £13.33 £35 American Gardens. Charles Scribner's
Sons, New York. 1939.

Spurway, C. H. Soil Testing. A practical system of soil fertility
diagmsis. Mich. Agr. Exp. Sta. Tech. Dul. 132
(second.revision). 1932.

Taylor, J. 0. Why Starve Lilies? American LiLy Year Book. 1940.
The Amer. Hort. Soc. pp. 39-35. 1990.

White, H. H. The culture and forcing of Easter lilies. Mass. Ag.
Exp. Sta. Dul. 376. August, 1990.

Wilde, J. H. The influence of certain water source and.pot treat-
ments on the subsequent yowth of representative
greenhouse plants. Thesis. Michigan State College.
1936.

Wilson, H. H. E! Egg; pf Dastern £173. The Stratford 00., Des--
ton. 1925.

Withrow, H. 3. Plant forcing with electric 1i@ts. Ind. Ag. Exp.
Sta. Oirc. 206. pp. 9. 1939.

Woodcock, H. D. and Coutts, J. In Elias, 3331}; Culture £41m-
ment. pp. 55-60. Chas. Scribner's Sons, New York.

1935.

e
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