Influence of Nitrogen Source and Rate on Growth of
Epipremnum aureum Stock Plants and Quality of Cuttings

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University of Florida, IFAS,
Central Florida Research and Education Center-Apopka,
CFREC-Apopka Research Report RH-91-16

R.T. Poole and A.R. Chase*

Equal amounts of nitrogen from ammonium (NH₄) and nitrate (NO₃) sources were previously recommended for production of good quality acclimatized foliage plants (4) based on research with other ornamental crops. Research with foliage plants has now shown that response to nitrogen (N) source does vary, but most genera produced acceptable quality plants regardless of N source (1, 2, 6). These results led researchers to conclude that N source could most often be determined, for the majority of foliage plant genera, based primarily on economic considerations (5), since NH₄ and urea are less expensive than NO₃. The two experiments described here were conducted to determine influence of N source on growth of Epipremnum aureum (golden pothos) stock plants and cutting production.

Methods

Experiment 1, a 3 x 3 factorial test with 10 replications, tested influence of 3 N sources at 3 application rates on growth of golden pothos stock plants and cuttings. Research was initiated 13 April 1990 when rooted cuttings were planted in 6 inch pots containing Vergro container mix A (Verlite Co., Tampa, FL 33680) amended with 1 lb/yd² Micromax (Grace-Sierra Co., Milpitas, CA 95035). The plants were maintained in a greenhouse where light intensity did not exceed 2500 ft-c and minimum and maximum temperatures were 70°F and 90°F, respectively. Overhead irrigation was used to water plants twice a week. Plants were fertilized once per week, using liquid stock solutions, applied 50 ml/ pot, with one of the two irrigations per week. The nine fertilizer treatments are listed in Table 1.

Electrical conductivity (µmhos/cm) of leachate was measured initially on 27 April and again on 20 June 1990, 6 days before cuttings were harvested. Stock plants were graded on 19 June 1990 based on a scale of 1 = poor growth, few cuttings produced, 3 = fair growth, average number of cuttings produced, and 5 = vigorous growth, many cuttings produced.

Cuttings were taken on 26 June 1990 and rooted, 10 per 6 inch pot, 5 pots per treatment, using Vergro Container Mix A (Verlite Co., Tampa, FL 33680). The cuttings were placed on a mist bench in a greenhouse receiving 1400 ft-c maximum and top-dressed with 6 g 19-6-12 Osmocote (Grace-Sierra Co., Milpitas, CA 95035) per pot. On 19 July the cuttings were graded based on a scale of 1 = dead, 3 = moderate growth and 5 = excellent growth. Experiment 1 was terminated on 19 July 1990.

Experiment 2 differed from experiment 1 in the time and place plants were grown and propagated, and the type of data recorded. Research was initiated 8 August 1990 and terminated 29 January 1991. Golden pothos stock plants were maintained in a greenhouse under a maximum of 1500 ft-c because of the lower light levels occurring during fall and winter months compared to spring and summer in central Florida. The number of nodes per vine, the number of vines and the number of cuttings produced by the stock plants were recorded on 26 September and again on 6 November 1990. Plants were also assigned a plant grade, based on the scale described above, on 5 November and 28 December 1990.

Electrical conductivity was measured on 30 August, 27 September and 2 November 1990. Cuttings obtained from the stock plants on 5 November 1990 were graded 31 December 1990 and those obtained on 18 December 1990 were graded on 29 January 1991. The cuttings were graded based on the same scale used in experiment 1.

Results

Nitrogen source did not influence golden pothos stock plant or cutting grade when plants were grown in the summer months (Table 2); however, stock plants and cuttings were affected by N rate, with the best plants and cuttings receiving the highest N rate. The lowest application rate (12.5 mg N/6 inch pot/week) produced poor quality stock plants, which yielded so few cuttings that cutting grade for the cuttings harvested from these stock plants was not determined (Table 2). Electrical conductivity (µmhos/cm) of the leachate was related to N source, with plants receiving N solely from NH₄ having higher electrical conductivity levels. Electrical conductivity also rose as N rate increased.

Growth of golden pothos stock plants in experiment 2, during the fall and winter months, was clearly affected by N rate, as in experiment 1. Plants receiving the highest rate, 112.5 g N/6 inch pot, had more vines and number of nodes per vine compared to plants treated with the two lower application rates (Table 3). Cutting grade increased greatly when N rate was increased from 12.5 to 62.5 mg N/6 inch pot, but did not respond to a further increase, from 62.5 to 112.5 mg N/6 inch pot. Electrical conductivity (µmhos/cm) of the leachate rose as N rate increased.

Plants grown during cool weather were slightly influenced by N Source (Table 3). Number of vines produced per plant was not significantly affected, but the number of nodes per vine decreased when plants received only NO₃. Cutting grades of plants receiving NO₃ were slightly higher than cuttings from stock plants receiving NH₄ or NH₄NO₃. As in experiment 1, electrical conductivity of the leachate was higher from plants receiving only NH₄ (Table 4).

Conclusions

Wiedenfeld (7) reported that when Ficus benjamina were grown with various N sources, the lowest N concentrations were found in tissue of plants receiving NO₃-N, even though all N sources produced plants of similar dry weight. Tsujita et al. (4) found chrysanthemums receiving NO₃ under winter light intensity had improved keeping quality and higher levels of soluble carbohydrates. The slower growth of golden pothos grown in experiment 2, under the winter light intensity, and receiving only NO₃ could have accumulated less nitrogen in plant tissue compared to plants getting NH₄NO₃ or only NH₄, and therefore grew slower.

Gilliam and Wright (3) found N concentration in Ilex crenata tissue steadily increased until a concentration point was reached, then a new flush of growth began and N concentration in tissue gradually decreased until growth stopped. Rein et al. (7) found a decrease in percent rooting of Ilex crenata 'Rotundifolia' cuttings was due to increases in shoot growth activity and decreased tissue maturation. Cuttings from golden pothos stock plants grown in experiment 2 with NO₃ only received higher grades possibly because mature tissue has a higher carbohydrate:nitrogen ratio compared to immature tissue.

Overall, N source had very little effect of growth of golden pothos and on grade of cuttings taken from these plants. Although some NO₃ is advisable for stock plants during the cool months, N rate appears to be much more important than N source in golden pothos production. Best plants and cuttings were produced with 112.5 mg N/6 inch pot/week.

*professor of Plant Physiology and Professor of Plant Pathology respectively, Central Florida Research and Education Center - Apopka, 2807 Binion Road, Apopka, FL 32703-8504.

Literature Cited

1. 1. Conover, C.A. and R.T. Poole. 1986. Nitrogen source effects on growth and tissue content of selected foliage plants. HortScience 21(4):1008-1009.

   2. Conover, C.A. and R.T. Poole. 1986. Effects of nitrogen source and potting media on growth of Chamaedorea elegans, Dieffenbachia maculata 'Camille' and Peperomia obtusifolia. Proc. Fla. State Hort. Soc. 99:282-284.

   3. Gilliam, C.H. and R.D. Wright. 1978. Effects of three nitrogen levels on tissue fluctuation during a flush of growth on 'Helleri' Holly (Ilex crenata Thunb.). HortScience 13(3):301-302.

   4. Joiner, J.N., C.A. Conover and R.T. Poole. 1981. Nutrition and fertilization. p. 229-268. In: Foliage Plant Production, Prentice-Hall, Inc., Englewood Cliffs, NJ.

   5. Rein, W.H., R.D. Wright and D.D. Wolf. 1991. Stock plant nutrition influences the adventitious rooting of 'Rotundifolia' holly stem cuttings. J. Environ. Hort. 9(2):83 85.

   6. Tsujita, M.J., D.C. Kiplinger and H.K. Tayama. 1974. The effects of nitrogen nutrition, temperature and light intensity on the growth, flowering, quality and chemical composition of Indianapolis Yellow Chrysanthemum. HortScience 9:294 (Abstr.).

   7. Wiedenfeld, R.P. 1985. Nitrogen loss and plant responses of Ficus benjamina to different fertilizer sources applied preplant. HortScience 20(4):720-722.

1. Table 1. Fertilizer formulation and application rate for the nine treatments applied in experiments 1 and 2.

1. Table 2. Plant grade, cutting grade and electrical conductivity (µmhos) of medium leachate of Epipremnum aureum stock plants grown in Experiment 1, from 13 April until 20 June 1990.

1. ^ZStock plants were graded based on a scale of 1 = poor growth, few cuttings produced, 3 = fair growth, average number of cuttings produced and 5 = vigorous growth, many cuttings produced.
   ^YCuttings grades were based on a scale of 1 = no growth 3 = moderate growth and 5 = excellent growth.
   ^XFertilizer source and rate see Table 1.
   ^WMean separation in rows by Duncan's multiple range test, 5% level.
   ^VCuttings not available from this treatment due to insufficient growth of stock plants.
   ^Uns, **; Nonsignificant and significant at P = 0.05 respectively.

1. Table 3. Influence of nitrogen source and rate on growth and cutting response of Epipremnum aureum, experiment 2 (13 August until 31 December 1990).

1. ^ZCutting grade based on a scale of 1 = no growth, 3 = moderate growth 5 = excellent growth.
   ^YFertilizer source and rate see Table 1.
   ^XMean separation in rows by Duncan's multiple range test, 5% level.
   ^Wns, *, **; Nonsignificant, significant at P = 0.05 and P = 0.01 respectively.

1. Table 4. Influence of nitrogen source and rate on electrical conductivity (µmhos/cm) of leachate from pots containing Epipremnum aureum, experiment 2 (13 August until 31 December 1990).

1. ^ZNitrogen source and rate see Table 1.
   ^YMean separation in columns by Duncan's multiple range test, 5% level.
   ^Xns, *, **; Nonsignificant and significant at P = 0.05 or P = 0.01, respectively.