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Rhizomes of black cohosh (Actaea racemosa L.) grown in the deep woodland shade of eastern North America have been used historically as medicinals, but wild populations have declined because of collection pressure. The purpose of this study is to determine the potential for black cohosh production in perlite. Currently, cultivated plants represent just 3% of the total harvest. Perlite production should also result in clean, uniform plant material. Rhizomes were grown at 18 °C in controlled environment chambers in the North Carolina State University (NCSU) Phytotron in perlite for 42 days with fertigation 3, 6, or 12 times daily and 18.5, 21.5, or 24.5 °C root zone temperatures adjusted using heating cables. Leaf areas of the 21.5 and 24.5 °C root temperature treatments were greater than the 18.5 °C treatment. Stem number and new root number was highest in the 21.5 °C treatment. No effects of the fertigation treatments were significant. The second experiment was conducted 7 June–31 Oct. 2004 in a naturally lit temperature-controlled (22/18 °C) glass greenhouse in the NCSU Phytotron at nutrient solution EC levels of 0.7, 1.1, or 1.5 dS·m^-1 and shading levels of 0%, 50%, and 75%. Highest leaf area and increase in fresh weight of the rhizomes over the experimental period was in the 50% shading treatment, but no significant effects of EC treatments were observed. Rhizome fresh weight increased 310% in the 50% shade, compared to 193% and 196% in the 0% and 75% shading treatments, respectively. In conclusion, black cohosh appears to prefer some shading during summer and 21.5 °C root temperatures. Low EC (0.7 dS·m^-1) and infrequent watering (3 times daily) did not appear to limit growth in this system, but these results should be confirmed in larger studies in commercial greenhouses.

This experiment was performed to test the hypothesis that tuber formation in potato is inhibited by short-term increases in root-zone temperature. Micro-propagated potato cv. Norland plantlets were grown in recirculating nutrient film culture under daylight fluorescent lamps at 350 μmol·m^–2·s^–1 PPF with at 20/16°C thermocycle at 1200 μmol·mol^–1 CO₂ under inductive (12-hr light/12-hr dark) or non-inductive (12-hr light/12-hr dark with a 15-min light break 6 hr into the cycle) photoperiods for 42 days. Root-zone treatments consisted of continuous 18°C, continuous 24°C, 18°C with a 24°C cycle between 14 and 21 DAP (prior to tuber initiation), and 18°C with a 24°C cycle between 21 and 28 DAP (during the period of tuber initiation). The root-zone temperature was maintained with a recirculating, temperature-controlled, heat-exchange coil submerged in each nutrient solution. Warm root-zone temperatures did not inhibit tuber formation under an inductive photoperiod. The non-inductive photoperiod resulted in a 65% reduction in tuber biomass compared to the inductive photoperiod. Continuous 24°C and exposure to 24°C prior to tuber initiation reduced tuber formation an additional 40% under the non-inductive photoperiod. Both continuous and transient 24°C root-zone temperatures increased biomass partitioning to root/stolons compared to the 18°C treatment under both photoperiods. Total plant biomass was highest in plants exposed to continuous 24°C under both photoperiods. Results suggest that transient episodes of warm (24°C) root-zone temperature do not inhibit tuber formation in potato under inductive photoperiods. However, transient episodes of warm (24°C) root-zone temperatures did interact with stage of development under the non-inductive photoperiod.

Cuttings of Dendranthema ×grandiflorum `Paragon' were used as a model system to assess the effects of root heating on disease severity. Roots were exposed to single episodes of heat stress, after which they were inoculated with zoospores of Phytophthora cryptogea Pethyb. & Laff. Root damage resulting from heat stress, or heat stress plus Phytophthora, was quantified 5 to 7 days after treatment. Roots of hydroponically grown plants, immersed for 30 min in aerated, temperature-controlled nutrient solutions, were severely damaged at 45C or above. Relatively little phytophthora root rot developed on inoculated plants exposed to 25 or 35C, but infection was severe in roots heated to 40C. Plants grown in potting mix were exposed to heat stress by plastic-wrapping the containers in which they were growing and placing them in heated water baths until roots achieved desired temperatures for 30 min. This system heated roots more slowly than in the hydroponic experiments, and 45 and 50C were less damaging. The amount of Phytophthora-induced root damage was insignificant in containerized plants heated to 25 or 35C, but was highly significant in those heated to 40C or higher. In field experiments, plants were positioned so their containers were either fulIy exposed to the late afternoon sun or heavily shaded to prevent sun exposure. The root zones of sun-exposed pots heated to 45 to 47C, while those of shaded pots never exceeded 34 to 36C. There was a large, highly significant increase in phytophthora root rot severity in the sun-exposed pots compared to shaded plants. These experiments showed that temperatures of 40C or higher, which commonly occur in container-grown plants exposed to solar radiation, can predispose chrysanthemum roots to severe Phytophthora infection.

Floriculture is growing at a frenetic pace in India. From a few units in 1990, nearly hundred units are either fully operational or at various stages of implementation. Almost seventy of these produce rose for the cut flower export market. The average unit size is two hectare under poly-cover. Anthurium, carnation, chrysanthemum, orchids and gerbera comprise the other cut flower producing units. Technology has come mostly from Holland, with Israel now giving severe competition to the Dutch. Germany, France, United Kingdom, and New Zealand are the other countries involved in technology transfer. Many units have the fan and pad system for temperature control along with drip irrigation and computer mediated operations. Most units use natural soil as the medium of growth whereas some have a combination of sand and natural soil and a few have adopted complete sand bed culture as practiced by Israeli growers. These hybrid as well as the state-of-the-art floriculture technologies are competing for the Indian market and the next few years will determine the system that is most suitable for adoption under local conditions. The Agricultural and Processed Food Products Export Development Authority (APEDA), a wing of the Commerce Ministry of the Government of India, and the National Horticulture Board have indeed provided substantial support for the growth of Indian floriculture Industry. Meanwhile, more and more entrepreneurs are, on their own, setting up cold storages and operating cold trucks near major airports to maintain appropriate temperatures from harvest to destination. It is widely expected that more than 50% of the existing floriculture units will make good whereas the remaining may not survive either due to sourcing of unsuitable technologies or lack of expertise in floriculture production and management as well as international marketing prowess. There is also consensus that no single foreign technology giver is capable of meeting adequately the total needs in the Indian context and often it is a matter of the collaborators learning together. What seems certain is that India will, by the year 2000, be a major player in international floriculture because of the diverse agroclimatically suitable locations, lower labor cost, and talented human resource.

Flowering responses of Heliconia psittacorum L.f. × H. spathocircinata Aristeguieta `Golden Torch' to temperature and photosynthetic photon flux (PPF) were determined in controlled-environment conditions using a 2 × 2 factorial combination of temperature (32C day/20C night and 24C day/20C night) and PPF (475 and 710 μmol·m<sup>–2</sup>·s<sup>–1</sup>). Temperature had no significant effect on new shoot production, with an average of 9.3 shoots per plant being produced over the 248 days of treatment. More shoots, however, were produced at the higher PPF level (10.1 compared with 8.3 shoots). The proportion of shoots that initiated flowers (85%) was similar in all treatments. The duration from shoot until inflorescence emergence was significantly less at 32C day/20C night than at 24C day/20C night (140 and 146 days, respectively) and was unaffected by PPF. This duration also was significantly affected by the interacting effects of order of shoot appearance and the number of leaves subtending the inflorescence. The second shoots to emerge had the shortest duration from shoot emergence to inflorescence emergence. The number of leaves subtending the inflorescence increased at the higher temperature and decreased as shoot order increased but was unaffected by PPF. Temperature and PPF levels influenced total leaf area at flowering, with highest areas being achieved in the high temperature–low PPF combination. Acceptable flower quality with at least two, opened, well-formed, well-colored bracts was obtained in all treatments, although flower stems were taller and thicker at 32C day/20C night and these dimensions increased further with increasing order of shoot appearance. Stem diameters tended to be thinner at the lower PPF level. Overall, temperature was more dominant than light in influencing production and quality of flowers, but developmental factors associated with the order of shoot appearance also played a significant role. Flower production of `Golden Torch' should be feasible in temperature-controlled glasshouses in temperate regions where mean air temperatures can be maintained at ≈20C.

Frequent fertigation of soilless-grown bell pepper (Capsicum annuum L.) can increase fruit production, but development of fruit disorders may offset the increase in yield of first-quality (blemish-free) fruit in greenhouses with minimal environmental control. Fruit yield and quality were studied as affected by water volumes and nutrient concentration levels, delivered with irrigation events initiated after determined cumulative solar radiation levels, in ‘HA3378’ bell pepper from October to May in north–central Florida. Irrigation events occurred after solar radiation integral levels (SRI; ±SD) 1.7 ± 0.42, 3.7 ± 0.42, 5.7 ± 0.42, 7.7 ± 0.42, and 9.7 ± 0.42 kW·min⁻¹·m⁻², which led to mean number of daily irrigation events of 61 ± 31, 26 ± 12, 17 ± 8, 12 ± 5, and 10 ± 4 respectively. In peat mix, perlite, and pine bark media, volume per irrigation event and concentration levels of the nutrient solution were, in the first experiment, 74 mL standard (74-s), and in a second concurrent experiment, 74 mL half-standard (74-½s) or 3) 37 mL standard (37-s). In both studies, combined marketable fruit yields of first quality and second quality (minor cracking patterns and yellow spots) increased linearly with decreasing SRI (increased events per day). First-quality fruit weight with 74-s was unaffected by media and, in a quadratic response to SRI, reached 5.4 kg·m⁻² at 5.7 kW·min⁻¹·m⁻². First-quality weight with 74-½s and 37-s did not differ. Weight was unaffected by SRI in peat mix and perlite, and a quadratic response was recorded in pine bark, with yields of ≤3.6 kg·m⁻². Fruit cracking incidence decreased with increased SRI, and was generally greater in pine bark. Incidence of yellow spots doubled with 74-½s compared with 37-s, and decreased linearly with increased SRI; the disorder was minor with 74-s. Compared with 37-s, 74-½s decreased fruit with blossom-end rot by 14%, increased marketable fruit weight by 10% in media with the lowest water-holding capacity (perlite, pine bark), and increased nutrient use efficiency. With any media used, the SRI set point of 5.7 kW·min⁻¹·m⁻² (daily mean of 17 irrigation events) and 74 mL, at standard nutrient concentration levels, appeared to produce greater blemish-free fruit yield than delivering 37 mL/event or half-concentrated 74 mL/event within the range of SRI means of 1.7 to 9.7 kW·min⁻¹·m⁻² (61–10 irrigation events/day). Disorder-tolerant pepper cultivars, better temperature control, and August plantings are additional suggestions for irrigation management to increase first-quality fruit yield.

Controlled-release fertilizer (CRF) use is a best management practice that may reduce nitrogen (N) loss to the environment. Several factors affect CRF nutrient release; therefore, including CRF in a fertilization program may have challenges. Thus, the study objective was to evaluate the effects of CRF N rate, source, release duration, and placement on seepage-irrigated marketable tomato (Solanum lycopersicum L.) yield, leaf tissue N (LTN) concentration, post-season soil N content, and postharvest fruit firmness and color. There were two soluble fertilizer (SF) controls [University of Florida/Institute of Food and Agriculture Sciences (UF/IFAS) (224 kg·ha⁻¹) and grower standard (280 kg·ha⁻¹)] and six and seven CRF treatments (alone or in combination with SF) in Fall 2011 and 2012, respectively. Cumulative rainfall totaled 31.4 and 37.4 cm during the 2011 and 2012 seasons with average air temperatures of 22.4 and 22.1 °C, respectively. Soil temperatures ranged from 14.2 to 40.6 °C in 2011 and 11.1 to 36.6 °C in 2012 with a strong correlation (r = 0.95) to air temperature. Controlled-release urea resulted in 7.5% to 17.9% plant mortality in 2011 and reduced yields in 2012 compared with CRF N–phosphorus–potassium (NPK) at a similar N rate. LTN concentrations were above or within the sufficiency range for all treatments. In 2011, using CRF-urea at 190 kg·ha⁻¹ N produced similar marketable tomato yield in all fruit categories except season total large tomatoes, which produced significantly fewer marketable tomatoes with 13.5 Mg·ha⁻¹ compared with UF/IFAS and grower standard with 17.9 and 14.2 Mg·ha⁻¹, respectively. In 2012, CRF-NPK (168 kg·ha⁻¹ N) significantly reduced first and second harvest combined large and season total large and total marketable yields compared with the UF/IFAS rate and grower standard treatments. Marketable yield was not significantly affected by CRF (urea or NPK) release duration, but CRF-NPK 180-day release duration significantly increased residual soil N in 2012 compared with CRF-NPK 120-day release with 74.2 and 34.3 kg·ha⁻¹ N, respectively. Rototilling CRF-urea into the bed, which was only evaluated in 2011, significantly increased total season yields compared with CRF-urea broadcast in row before bedding (BIR) with 43.0 and 46.5 Mg·ha⁻¹, respectively. There were no significant yield differences when 50% or 75% of the total N was CRF placed in the hybrid fertilizer system, which is a system with CRF placed BIR with the remaining N as SF-N banded on the bed shoulders. No significant differences among treatments were found for total residual soil N in 2011; however, higher soil N remained in CRF (NPK and urea) treatments compared with SF treatments in 2012, except for Treatment 9. No significant differences were found among treatments for fruit firmness or color in 2011 or 2012. CRF-NPK at 190 to 224 kg·ha⁻¹ N with a 120-day release may be recommended as a result of similar or greater first harvest and total season marketable yields compared with IFAS-recommended rates and low residual soil N. Further research must be conducted to explore CRF placement and percentage urea composition, although use of the hybrid system or rototilling may be recommended.