NC State Floriculture

1999 Easter Lily Evaluations

Douglas A. Bailey and Ingram McCall
Department of Horticultural Science

Summary

One named cultivar ('Nellie White') and five numbered selections (90-11, 93-19, 93-24, 94-16, and 94-24) of Easter lily (Lilium longiflorum) were evaluated during the 1998 - 1999 production season. The study included various bulb sizes of each selection, ranging from 6 1/2 to 10 1/2 inches in circumference. Data recorded during forcing included plant heights on January 19, February 8, and February 25; dates of shoot emergence; and dates of first open flower. Final height was recorded when the first flower was open on each plant. For 6 1/2 to 7 1/2 inch bulbs, 94-16 plants were taller, forced in less time and produced more flower buds than the other selections (90-11, 93-19, 93-24, and 94-24). Plants of 90-11 were shorter than the other selections grown from 6 1/2 to 7 1/2 inch bulbs. Among selections produced from 7 1/2 to 8 1/2 inch bulbs, plants of 94-16 produced more flowers and forced in less time than the other selections ('Nellie White', 90-11, 93-19, 93-24, and 94-24). Plants of 93-24 were the tallest and plants of 90-11 were the shortest of the selections grown from 7 1/2 to 8 1/2 inch bulbs. As with smaller bulb sizes, plants of 94-16 grown from 8 1/2 to 9 1/2 inch bulbs forced sooner and developed more flowers than the other selections ('Nellie White', 90-11, 93-19, 93-24, and 94-24). For plants grown from 8 1/2 to 9 1/2 inch bulbs, 90-11 were the shortest and 93-24 the tallest selections. Within the selections grown from 9 1/2 to 10 1/2 inch bulbs, 'Nellie White was the tallest, while there was no height difference among the other three cultivars (93-19, 93-24, and 94-24). Plants of 93-24 forced quicker than the other three selections grown from 9 1/2 to 10 1/2 inch bulbs, and there was no significant difference among cultivars for number of flower buds produced. Given that every selection was not grown within each bulb size, it is difficult to summarize performance of each selection across bulb size. However, it does appear that some conclusions can be drawn. For example, 94-16 plants always forced faster than the other selections of the same bulb size. Plants of 94-16 also always produced more flower buds than all other selections within a given bulb size. Interestingly, 'Nellie White' was never shorter, quicker to force, or more floriferous than other selections of the same bulb size.


Introduction

Each year the Easter Lily Research Foundation (located in Harbor, Oregon) distributes bulbs of experimental selections to research institutions for evaluation. Currently, over 80% of all Easter lilies forced as a flowering potted plant are the cultivar 'Nellie White' (Miller, 1992). Thus, 'Nellie White' is used in selection evaluations as the commercial control. The objectives of the breeding program at the Foundation include: shorter plants, earlier flowering plants, and plants with increased flower counts. This report is a summary of the selections received for evaluation during the 1998 - 1999 forcing period.


Experimental Design

Bulbs were received from the Easter Lily Research Foundation on 20 October 1998. Bulbs were potted into 6" standard pots containing Fafard 4P (Fafard Inc., Anderson, SC). The newly planted bulbs were drenched with metalaxyl (Subdue 2E; Novartis Crop Protection, Inc., Greensboro, NC) as a root rot preventative. Pots were placed in the greenhouse set to a 63 °F night temperature / 72 °F day temperature. They were placed into a 40 °F for six weeks beginning 10 November 1998. Pots were removed from the cooler on 21 December 1998 and placed in the greenhouse set to a 65 °F night temperature / 72 °F day temperature. Plants were grown in a glass house with no light reduction. They were fertilized at each irrigation with 250 ppm nitrogen and 207 ppm K supplied from 15N-0P-12.5K (15-0-15 Peatlite Special; The Scotts Co, Marysville, OH). Imidacloprid (Marathon 1% Granular; Olympic Horticultural Products Co., Mainland, Pennsylvania) was applied during mid-January to control aphids. No growth regulator was used and no effort was made to control plant height with negative DIF or with cool temperatures during the first two hours of light each morning. Plants were not moved (to different temperature zones) to control timing. Plant heights were measured from the top of the pot to the top of the plant and recorded on January 19, February 8, and February 25, 1999. Final height was recorded when the first flower was open on each plant. Final heights reported include the pot height as well as the plant. Dates of shoot emergence and first open flower were recorded. Flowers and buds were also counted.


Results and Discussion

We did not receive the same bulb sizes for every selection, so we could not compare all selections to our commercial control, 'Nellie White' (Table 1). Direct comparisons were made among selections within each bulb size we received (Table 2).

Table 1. Growth and flowering of six Easter lily selections or cultivars in 1999. Trials conducted at NC State University, Raleigh.*

Selection

Bulb size (inches circumference)

Plant height (inches)

Days to shoot emergence

Days to 1st open flower

No. of flower buds

1/19

2/8

2/25

Final*

Nellie White

7 1/2 to 8 1/2

1.3

5.5

8.3

26.0

22.0

104.8

4.8

8 1/2 to 9 1/2

2.3

7.8

12.3

29.0

16.6

97.4

7.2

9 1/2 to 10 1/2
1.8
8.0
13.5
32.8
19.8
101.4
8.8

90-11

6 1/2 to 7 1/2
2.5
4.5
9.0
24.5
13.3
98.4
7.2
7 1/2 to 8 1/2
1.8
6.0
10.8
22.5
17.0
91.4
8.0
8 1/2 to 9 1/2
1.5
5.5
10.0
22.8
5.0
93.2
8.6

93-19

6 1/2 to 7 1/2

2.3

6.0

10.5

25.0

10.2

95.2

7.4

7 1/2 to 8 1/2
2.5
5.8
10.8
23.8
5.8
92.6
8.0
8 1/2 to 9 1/2
2.3
7.3
12.8
28.8
14.8
98.2
9.6
9 1/2 to 10 1/2
1.3
5.3
9.5
27.0
17.6
103.0
8.2

93-24

6 1/2 to 7 1/2

2.8

6.3

11.8

24.5

-10.6***

90.6

6.2

7 1/2 to 8 1/2
2.0
7.3
13.0
28.0
15.4
93.6
8.2
8 1/2 to 9 1/2
2.3
8.0
14.8
30.0
16.4
93.0
9.0
9 1/2 to 10 1/2
2.0
7.3
13.3
28.5
16.3
93.8
9.3

94-16

6 1/2 to 7 1/2

2.5

8.0

16.5

27.3

13.3

79.5

12.8

7 1/2 to 8 1/2
1.8
6.5
13.8
26.0
19.2
86.8
12.2

8 1/2 to 9 1/2

1.5

7.8

15.8

27.0

19.8

86.2

14.2

94-24

6 1/2 to 7 1/2

2.5

7.0

10.3

24.0

13.8

98.2

5.2

7 1/2 to 8 1/2

2.8

8.3

11.8

26.5

14.4

97.6

6.8

8 1/2 to 9 1/2

2.5

7.8

11.0

27.3

18.6

100.6

8.6

9 1/2 to 10 1/2

2.3

7.8

11.5

29.0

19.8

102.0

10.3

*Means based on five plants (n = 5). Number of days counted from placement into the greenhouse on 21 December 1998.

**Final height includes the pot; other heights do not.

***Negative days to emergence indicate the shoots emerged while still in the cooler.




Table 2. Final height (including the pot), days to 1st open flower, and number of flower buds per plant comparisons within bulb sizes.

Bulb size / selection

Final height (inches)

Days to 1st open flower

No. of flower buds

6 1/2 to 7 1/2

90-11

22.0 b

98.4 a

7.2 b

93-19

25.0 ab
95.2 ab
7.4 b

93-24

24.5 ab
90.6 b
6.2 b

94-16

27.3 a
79.5 c
12.8 a

94-24

24.0 ab

98.2 a

5.2 b

7 1/2 to 8 1/2

Nellie White

26.0 b

104.8 a

4.8 c

90-11

22.5 c

91.4 c

8.8 b

93-19

23.8 c
92.6 c
8.0 bc

93-24

28.0 a

93.6 c

8.2 bc

94-16

26.0 b

86.8 d

12.2 a

94-24

26.5 b

97.6 b

6.8 bc

8 1/2 to 9 1/2

Nellie White

29.0 ab

97.4 a

7.2 b

90-11

22.8 b

93.2 b

8.6 b

93-19

28.8 ab
98.2 a
9.6 b

93-24

30.0 a
93.0 b
9.0 b

94-16

27.0 ab
86.2 c
14.2 a

94-24

27.3 ab
100.6 a
8.6 b

9 1/2 to 10 1/2

Nellie White

32.8 a
101.4 a
8.8 a

93-19

27.0 b
103.0 a
8.2 a

93-24

28.5 b
93.8 b
9.3 a

94-24

29.0 b
102.0 a
10.3 a

*Means based on five plants (n = 5). Number of days counted from placement into the greenhouse on 21 December 1998.

**Mean separations within columns conducted for each bulb size. Means followed by different letters are significantly different at alpha = 0.05.



There were definite height differences among the selections, and bulb size did affect final height for some of the selections including 'Nellie White, (Figure 1), 93-19 (Figure 2), 93-24, and 94-24 (Figure 3). Height of two of the selections, 90-11 (Figure 4) and 94-16 (Figure 5) was not correlated with bulb size. Plants of 'Nellie White' were never the shortest, and for the largest bulb size forced, they were taller than plants of the other selections grown. Plants of 90-11 tended to be shorter than the other selections for all three bulb sizes evaluated. Plant height increased with bulb circumference for 'Nellie White' and 94-24. There was no strong correlation with bulb size and final height for the other selections grown. Establishing a specific desired height for Easter lilies is difficult. Miller (1992) suggests that "The best height for your plants is the height your customer wants them." An informal poll of lily growers during Spring of 1998 indicated that a general target height (including the pot) is about 22 inches. Only 1 of the 21 size x selection groups averaged a final height at or below 22 inches, indicating that most would require some type of height control.

For every bulb sized forced, 94-16 was the fastest to flower (Table 2). 'Nellie White' and 94-24 tended to require the longest time to flower, regardless of bulb size. Due to greenhouse space constraints, we had to force our lilies at warmer-than-desired temperatures (from the standpoint of a late Easter), so our ability to target the commercial marketing date of the week prior to Palm Sunday (day 91-95 of forcing) was hindered. Only 8 of the 21 size x selection groups averaged a first flower date between day 91 and 95. Although our timing was off, the study does give a good comparison among the selections and bulb sizes with respect to relative timing during forcing of CTF bulbs.

All bulb size / selection combinations averaged more than four flower buds per plant. Four seems to be the minimum number of flower buds required for the mass market while many high-end retail shops require five to six buds. There was a positive correlation with flower bud number and bulb size for all selections forced. The 94-16 plants (Figure 5) averaged over 12 buds per plant for all bulb sizes; a very impressive bud count.

The results from the 1999 Easter lily trial are very encouraging. The significant increase in flower bud number, reduced height, and reduced forcing time in some of the selections as compared to the industry standard 'Nellie White' suggests that it is possible to select a cultivar superior to what we are currently producing.

The authors wish to acknowledge the Easter Lily Research Foundation for sending bulbs for the evaluation, to Fafard for contributing the 4P substrate, and to Scotts for donating the fertilizer.


Literature Cited

  • Miller, W.B. 1992. Easter and hybrid lily production. Timber Press. Portland, Oregon.

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