NC State Floriculture


1998 Easter Lily Evaluations

Douglas A. Bailey and Ingram McCall
Department of Horticultural Science

Summary

Two named cultivars ('Nellie White and 'Eden') and five numbered selections (93-19, 93-24, 94-24, 94-31, 94-36) of Easter lily (Lilium longiflorum) were evaluated during the 1997 - 1998 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 23, February 6, and February 20; dates of shoot emergence; and dates of first open flower. Final height was recorded when the first flower was open on each plant. For all bulb sizes forced, 'Eden' was significantly shorter than 'Nellie White', the commercial control. 'Eden' averaged more than six buds per plant, regardless of bulb size grown. Among selections produced from 7 1/2 to 8 1/2 inch bulbs, 'Eden' and 93-24 averaged over eight buds, almost twice the number found on the other selections, including 'Nellie White'. 'Eden' plants from 7 1/2 to 8 1/2 inch bulbs forced significantly faster than 'Nellie White' plants from the same size bulbs. The greater number of buds plus less height and slightly shorter forcing gives 'Eden' a definite edge over the commercial control. 'Eden' looks very promising as a new cultivar for forcing as a flowering pot plant.


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 1997 - 1998 forcing period.


Experimental Design

Bulbs were received from the Easter Lily Research Foundation on 28 October 1997. They were case-cooled at 40 °F for six weeks beginning 6 November 1997. Bulbs were removed from the cooler on 18 December 1997 and potted into 6" standard pots containing Fafard 4P (Fafard Inc., Anderson, SC). Pots were placed in the greenhouse set to a 65 °F night temperature / 72 °F day temperature. The newly planted bulbs were drenched with metalaxyl (Subdue 2E; Novartis Crop Protection, Inc., Greensboro, NC) on 29 December 1997 as a root rot preventative. 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 23, February 6, and February 20, 1998. 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 seven Easter lily selections or cultivars in 1998. 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 n**
1/23 2/6 2/20 Final*
Eden 6 1/2 to 7 1/2 3.8 7.0 11.2 22.9 19.1 89.5 6.7 10
7 1/2 to 8 1/2 4.1 7.8 12.4 24.8 18.9 87.9 8.2 10
8 1/2 to 9 1/2 4.7 8.3 13.7 27.5 19.4 88.2 9.2 5
Nellie White 7 1/2 to 8 1/2 2.8 6.4 9.8 28.5 22.3 101.6 4.4 10
8 1/2 to 9 1/2 3.9 7.4 11.7 28.5 20.2 96.4 5.4 10
93-19 9 1/2 to 10 1/2 6.9 11.2 16.8 31.9 14.0 94.0 11.6 5
93-24 7 1/2 to 8 1/2 6.8 12.0 19.7 34.1 13.6 87.2 8.2 5
94-24 7 1/2 to 8 1/2 5.1 8.1 11.6 25.3 16.2 98.9 5.2 10
9 1/2 to 10 1/2 7.0 10.3 13.0 24.7 10.6 95.8 10.0 5
94-31 7 - 8 5.1 9.1 19.8 31.9 17.3 96.3 6.5 7
8 1/2 to 9 1/2 7.5 13.3 15.2 36.7 16.7 97.3 11.3 3
94-36 6 1/2 to 7 1/2 5.0 9.3 13.9 26.4 15.4 92.3 2.7 7
7 1/2 to 8 1/2 5.9 9.8 14.2 26.0 13.4 91.6 4.2 5
*Final height includes the pot; other heights do not.
**n = number of bulbs forced. Bulbs potted 18 December 1997 and forced at 65 °F NT.


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 n*
6 1/2 to 7 1/2
Eden 22.9 b** 89.5 a 6.7 a 10
94-36 26.4 a 92.3 a 2.7 b 7
7 1/2 to 8 1/2
Eden 24.8 c 87.9 d 8.2 a 10
Nellie White 28.5 b 101.6 a 4.4 b 10
93-24 34.1 a 87.2 d 8.2 a 5
94-24 25.3 c 98.9 b 5.2 b 10
94-36 26.0 c 91.6 c 4.2 b 5
8 1/2 to 9 1/2
Eden 27.5 b 88.2 a 9.2 b 5
Nellie White 28.5 b 96.4 a 5.4 c 10
94-31 36.7 a 97.3 a 11.3 a 3
9 1/2 to 10 1/2
93-19 31.9 a 94.0 a 11.6 a 5
94-24 24.7 b 95.8 a 10.0 b 5
*n = number of bulbs forced.
**Mean separations within columns conducted for each bulb size. Means followed by different letters are significantly different at alpha = 0.05. Bulbs potted 18 December 1997 and forced at 65 °F NT.

There were definite height differences among the selections, and bulb size did affect final height for some of the selections (Figure 1, Figure 2, Figure 3, and Figure 4). 'Eden' tended to be shorter than the other selections for all three bulb sizes evaluated. The 6 1/2 to 7 1/2 and 7 1/2 to 8 1/2 'Eden' were significantly shorter at first flower than 'Nellie White', the commercial control. Both bulb sizes of 94-24 and 94-36 produced plants shorter than 'Nellie White' while the 93-19, 93-24, and 94-31 plants were taller than the commercial control. Plant height increased with bulb circumference for 'Eden' and 94-31; bulb size did not affect height of 'Nellie White', 94-24, or 94-36. 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. All of the selections in our trial exceeded this height indicating that they all would need some type of height control.

The only significant differences in forcing time observed was among the plants arising from the 7 1/2 and 7 1/2 to 8 1/2 inch bulbs (Table 2). 'Nellie White' was slower than the other selections followed by 94-24, 94-36, 'Eden', and 93-24. Due to greenhouse space constraints, we had to force our lilies at warmer-than-desired temperatures, so our ability to target the commercial standard Easter marketing date of the week prior to Palm Sunday was nil. Although our timing was off, the study does give a good comparison among the selections with respect to relative timing during forcing for case-cooled bulbs.

All bulb size / selection combinations averaged more than four flower buds per plant, with the exception of 94-36. 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. 'Eden' averaged more than six buds per plant, regardless of bulb size tested. Among the plants produced from 7 1/2 and 7 1/2 to 8 1/2 inch bulbs, 'Eden' and 93-24 averaged over eight buds, almost twice the number found on the other selections, including 'Nellie White'. The 94-31 and the 9 1/2 to 10 1/2 94-24 plants averaged over 11 buds per plant; a very impressive bud count.

There were other differences among the selections that we were unable to quantify -- leaf width, leaf color, and canopy architecture (Figure 5). For example, 'Eden' has relatively broad leaves and the foliage tends to curl downward slightly at the leaf tip. This is definitely different than 'Nellie White', but it is difficult to define which canopy architecture is more desirable. Consumer preference analysis is needed to quantify this factor. We did not observe any differences among selections or bulb sizes with respect to lower leaf loss or leaf yellowing nor were there any clear difference in flower morphology (though 'Eden' tended to have a more open appearance than other selections).

The results from the 1998 Easter lily trial are very encouraging. The greater number of buds plus less height and slightly shorter forcing gives 'Eden' a definite edge over the commercial control. Hopefully future studies and other trials around the country will confirm these observations, and we can look forward to a new cultivar for future Easters.

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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