Temperature Impacts Cactus and Succulent research summarized here was to determine temperature effects (10 to Development Rate 28 °C) on cacti and succulent de- velopment rate to determine appro- priate greenhouse temperatures and/ John Erwin1,4, Ken Altman2, and Fran Esqueda3 or optimal geographic locations to produce these crops. ADDITIONAL INDEX WORDS. leaf unfolding, tubercle unfolding, Echeveria, Aloe, Materials and methods Crassula Three hundred sixty plants of 17 SUMMARY. One cactus and 17 succulent species/cultivars were grown at 10, 16, 22, ° two-year-old vegetatively propagated or 28 C (plant temperature) for 10 or 15 weeks. The change in leaf/tubercle succulent plant types and one sexually number at each temperature (after 10 or 15 weeks) was determined, and leaf/ tubercle-unfolding rate was calculated. ‘Jade Necklace’ kebab bush (Crassula propagated cactus species grown in rupestris ssp. marnieriana), ‘Lola’ echeveria (Echeveria), ‘Green Ice’ gasteraloe three 1/2-inch-diameter plastic pots (Gasteraloe), and lithops (Lithops species) leaf-unfolding rate per day was unaffected in a soilless media were received from by temperature. Leaf-unfolding rate per day increased as temperature increased Altman Plants, Inc., Vista, CA [20 from 10 to 16 °C on ‘Firebird’ aloe (Aloe), ‘Key Lime Pie’ adromischus (Adromi- plants of each species/cultivar (Table schus cristatus), prostate rainbow bush (Portulacaria afra variegata), burro’s tail 1)]. Plants were unpacked and accli- (Sedum burrito), and ‘Sir William Lawrence’ houseleek (Sempervivum calcareum). matized in a greenhouse for at least Leaf-unfolding rate per day increased as temperature increased from 10 to 22 °Con 2 weeks [22 ± 1 °C day/18 ± 1 °C mescal agave (Agave parryi truncata), ‘Firebird’ aloe, Sunrise anacampseros night temperature; natural photope- (Anacampseros telephiastrum variegata), ponytail palm (Beaucarnea recurvata), riod (10 h); daily light integral (DLI) = subsessilis echeveria (Echeveria subsessilis), zebra plant (Haworthia fasciata), pros- Á –2Á –1 trate rainbow bush, burro’s tail and ‘Sir William Lawrence’ houseleek. Increasing 4.4 mol m d ]. Two hundred temperature from 22 to 28 °C decreased ‘Kiwi’ tree houseleek (Aeonium percar- eighty-eight plants were selected for neum) leaf-unfolding rate per day, increased ‘Firebird’ aloe and tiger tooth aloe uniformity based on leaf number, (Aloe juvenna) leaf-unfolding rate, and resulted in shoot tip death on burro’s tail, plant height, and/or branch number and plant death of ‘Sir William Lawrence’ houseleek and ‘Silver Dollar’ jade (16 of each species/cultivar), and (Crassula arborescens). The cactus, ‘Arizona Snowcap’ mammillaria (Mammillaria were then further divided into four gracilis fragilis), tubercle-unfolding rate per day increased as temperature increased groups of 18 plants each (one of each from 16 to 28 °C. Taken together, temperature (10 to 28 °C) effects on species per group). Each group was development rate were species specific and related to the indigenous environment of moved into one of four environmen- a species. tal growth chambers (over time) where air temperatures were managed nterest in cacti and succulents as assessing the impact of temperature in each to achieve a 10, 16, 22, or ornamental-potted and landscape on leaf unfolding over time. In gen- 28 °C plant temperature (mean of Iplants has increased recently. eral, leaf-unfolding rate per day (de- three different infrared thermometer Cacti and succulents can have orna- velopment rate) increases as average brands across species). The upper- mental foliage, or spines, unique daily temperature increases within most ‘‘unfolded’’ (‡45° from the forms and occasionally showy flowers. a limited temperature range (Roberts main stem axis) leaf (succulents) or Cacti and succulents originate from and Summerfield, 1987; Vaid and tubercle (cactus) on each plant was a variety of climates (temperate, trop- Runkle, 2013). There is little or no marked using an indelible ink marker ical, desert) but are similar in that information on how temperature af- when plants were placed in chambers each environment has periodic or fects development rate of many com- based on the angle of that leaf/tuber- prolonged drought (Anderson, 2001; mercially grown cacti and succulents. cle to the main stem. Chamber irra- Bailey, 1976). Succulents and cacti differ in indige- diance and photoperiod were 300 Temperature effects on develop- nous habitat, which differ in temper- mmolÁm–2Ás–1 [75% wattage from fluo- ment rate are often quantified by ature, and how temperature impacts rescent lamps and 25% from incan- development rate of each species descent lamps (DLI = 12.96 molÁ may differ. Understanding how tem- m–2Ád–1)] and 12 h, respectively, and We thank Rene O’Connell (Altman Plants, Inc.) for her help in selection of plant material. We also perature affects cacti and succulent chamber humidity was set to 40%. acknowledge the University of Minnesota Agriculture development rate would facilitate Plants were watered as needed (media Experiment Station, the USDA-ARS Floriculture and Nursery Research Initiative, the Society of Allied greenhouse environment manage- at the bottom of the pot never dried) Florists, and the Floriculture Research Alliance for ment and help identify geographic and were fertilized once weekly with their financial support of this project. locations to successfully produce and a solution containing 250 ppm 1Department of Horticultural Science, 1970 Folwell schedule each crop. The objective of nitrogen from a 15N–2.2P–12.5K Avenue, University of Minnesota, St. Paul, MN 55108 2President, Altman Plants, Inc., 3742 Blue Bird Canyon Road, Vista, CA 92084 Units 3Cactus and Succulent Production Manager, Altman To convert U.S. to SI, To convert SI to U.S., Plants, Inc., 3742 Blue Bird Canyon Road, Vista, CA multiply by U.S. unit SI unit multiply by 92084 2.54 inch(es) cm 0.3937 4 Corresponding author. E-mail: [email protected]. 1 ppm mLÁm–3 1 doi: 10.21273/HORTTECH03515-16 (°F – 32) O 1.8 °F °C(°C · 1.8) + 32 • February 2017 27(1) 65 RESEARCH REPORTS Table 1. Succulent and cactus plant material evaluated for variation in temperature increased from 22 to temperature effects [10 to 25 °C (50.0 to 77.0 °F)] on leaf/tubercle-unfolding 28 °C (Table 2). The apical meristem rate per day and the indigenous habitat that each plant is from. of burro’s tail died, and the entire Plant Indigenous habitatz plant of ‘Sir William Lawrence’ house- leek and ‘Silver Dollar’ jade died when ‘Kiwi’ tree houseleek Canary Islands temperature increased from 22 to Mescal agave Southwest United States and Mexico 28 °C(Table2). ‘Firebird’ aloe Southern Africa Tiger tooth aloe Southern Africa Discussion Sunrise anacampseros South Africa Intermediate temperature (simi- ‘Key Lime Pie’ adromischus South Africa (mountains) lar to here) effects on development Ponytail palm Texas and Mexico rate of some succulents and tropical ‘Silver Dollar’ jade Madagascar cacti have been studied. Kalanchoe ‘Jade Necklace’ kebab bush South Africa/Madagascar [Kalanchoe blossfeldiana (indigenous ‘Lola’ echeveria Texas to Argentina to Madagascar; Bailey, 1976)] time to Subsessilis echeveria Texas to Argentina flower decreased 19 d when temper- ‘Green Ice’ gasteraloe South Africa ature increased from 18 to 24 °C, but Zebra plant South Africa decreased only 2 d more when tem- Lithops Western South Africa/Namibia perature was increased further from ‘Arizona Snowcap’ mammillaria Central Mexico 24 to 26 °C (Carvalho et al., 2006). Prostrate rainbow bush South Africa Thanksgiving cactus [Schlumbergera Burro’s tail Eastern Mexico (mountains) truncata (indigenous to Brazil; Bailey ‘Sir William Lawrence’ houseleek Europe, Morocco/west Asia 1976)] days from flower induction z Bailey (1976), Anderson (2001). to anthesis decreased from 100 to 52 d when average daily temperature increased from 12 to 20 °C and was fertilizer (Excel 15-5-15 Cal-Mag; at P £ 0.05 was employed for mean unchanged when average daily tem- Everris, Marysville, OH). Plants were separation. perature was further increased from not leached to insure media fertil- 20 to 24 °C (Erwin et al., 1990). ity was similar between temperature Results Maximum (64 to 71 °C) or minimum treatments. How temperature affected devel- temperature(–22to–5°C) tolerance Nine succulent species/culti- opment rate differed among species of desert cacti has been studied; how- vars with more rapid leaf unfolding and cultivars (Table 2). Temperature ever, there is little work on intermediate were removed from chambers after (10 to 28 °C) did not affect develop- temperature effects on desert cacti de- 10 weeks (greater than three leaves ment rate of ‘Jade Necklace’ kebab velopment rate [as ‘Arizona Snowcap’ unfoldedafter10weeks).Asecond bush, ‘Lola’ echeveria, ‘Green Ice’ mammillaria here (Nobel and Bobich, group of nine species/cultivars with gasteraloe, and lithops (Table 2). In 2002; Nobel and De la Barrera, 2003)]. a slower leaf/tubercle-unfolding contrast, leaf-unfolding rate per day There was considerable diversity in rate (less than three leaves/tubercles increased as temperature increased temperature effects on development rate unfolded after 10 weeks) was re- from 10 to 16 °C on ‘Firebird’ aloe, of the cactus and succulents species/ moved after 15 weeks. ‘‘Unfolded’’ ‘Key Lime Pie’ adromischus, pros- cultivars studied here (Table 2). In some leaf/tubercle number above the mark trate rainbow bush, burro’s tail, and cases, we could identify temperatures when plants were moved