South Africa has a large number of indigenous geophytes and many of these have been developed as cut flower crops. Sandersonia aurantiaca Hook. is one of the geophytes to be developed in the latter half of the 20th century. Most of the development work leading "domestication" of sandersonia occurred in New Zealand, led by pioneer growers working closely with researchers. Test marketing of the cut stems in Japan quickly demonstrated the commercial potential of the crop that derived its popularity from its distinctively shaped, golden orange lantern-shaped flowers.Today we have a good understanding of the physiology of the plant and protocols have been developed for production of high quality tubers and flowers, and for all year round production. Sandersonia has been used as a model crop for studying senescence of anethylene-insensitive flower, and postharvest handling protocols have been developed for the cut stems. Sandersonia is a monotypic species with limited genetic variation and further expansion of the crop and related species will occur with the introduction of new characteristics. New characters are being introduced through hybridisation with related genera. (C) 2008 Elsevier B.V. All rights reserved.

Pre-chilled potted plants of Paeonia ‘Coral Sunset’, ‘Monsieur Jules Elie’, ‘Sarah Bernhardt’, and ‘Karl Rosenfeld’ were placed in a range of controlled temperature regimes to ascertain the effect of temperature on the timing of shoot emergence and floral development. For all cultivars, warmer temperatures up to 25°C lead to more rapid shoot emergence and flower development. Linear temperature responses adequately described the rate of development from shoot emergence to flower bud appearance, and from bud appearance to flower opening, but a curvilinear response was required to describe the time taken for shoots to emerge. There were significant differences between cultivars in the number of heat units required for shoot emergence, with the shoots of the slowest-developing cultivar, ‘Monsieur Jules Elie’, taking 50% longer to emerge than those of the most rapid, ‘Coral Sunset’. No significant differences were found among cultivars in the time taken from shoot emergence to flower opening, although the ‘split’ stage (when the bud opens sufficiently for petal colour to be observed) was slightly earlier in ‘Karl Rosenfeld’.

Vegetative and floral development at the apical meristem of Zantedeschia Spreng. ‘Black Magic’ aff. Z. pentlandii (Wats.) Wittm. [syn. Richardia pentlandii Wats.] was traced through multiple seasons of growth. The growth habit was sympodial. For vegetative shoots, seven new structures were laid down on the primary axis for each season to form the over-wintering bud, from which all of the subsequent season’s visible growth arose. When a previously vegetative shoot flowered, the flower (spathe and spadix) arose directly from the apical meristem of the over-wintering bud which, at the time of planting (September; spring), was vegetative. At planting this over-wintering bud comprised six cataphylls, two leaf initials, and the as yet undifferentiated apex. For floral shoots, the terminal inflorescence consumed the original vegetative axis and a continuation shoot arose in the axil of the first leaf, the oldest leaf on the primary axis. While only the first three or four leaves of this continuation shoot actually emerged during the current season, a total of 14 structures were formed on the axis by mid-March (autumn). In the continuation bud of flowering plants a 4 month period of endo-dormancy occurred from mid-January through to mid-May (summer to late autumn). There was an apparent overlap between the onset of endo-dormancy of the continuation bud (January/February), the period when new foliage had stopped appearing (February), and attainment of the maximum number of structures in the continuation bud (March). Growers are recommended to wait until dormancy is complete (June; winter) before replanting tubers for the purposes of early forcing.

The influences of temperature and irradiance on flowering of two species of Leucocoryne [L. coquimbensis F. Phil and L. ixioides (Hook.) Lindl.] were examined in controlled environment growth rooms. Growing environments had day/night temperatures of 10/5, 15/10, or 20/15 °C, providing mean temperatures of 7.5, 12.5, or 17.5 °C, and photosynthetic photon fluxes (PPF) of 497 or 710 μmol·m-2·s-1. Inflorescence emergence data were recorded up to three times a week, measurements of floral development were made twice weekly and destructive harvests were carried out every 2 weeks. Both species of Leucocoryne flowered most quickly when grown at a mean temperature of 17.5 °C. Leucocoryne coquimbensis flowered first in all temperature regimes (means of 7.5, 12.5, or 17.5 °C), taking an average of 7.1, 5.1, or 4.5 months to flower, whereas plants of L. ixioides took 7.6, 5.4, or 4.7 months to flower. Although taking longer to flower, L. ixioides produced better quality flowers (taller scapes and more florets per inflorescence). Plants of L. coquimbensis grown in the two highest temperature regimes produced up to four inflorescences per bulb. As mean temperature decreased, the number of inflorescences produced by each bulb together with the number of florets in each inflorescence and the number of leaves produced before emergence of the inflorescence decreased. Decreases in these attributes were much greater with a 5 °C mean temperature drop from 12.5 °C, than a drop from 17.5 to 12.5 °C. At least half the florets in an inflorescence opened before the first floret began to senesce. The onset of senescence was delayed as mean temperature decreased. The highest irradiance level promoted development of further inflorescences of L. ixioides at all mean temperatures, and at a mean temperature of 17.5 °C for L. coquimbensis. Flower stem heights of L. coquimbensis increased as mean temperature increased and irradiance level decreased. An increase in irradiance level also promoted scape heights of L. ixioides, although maximum scape heights were attained at a mean temperature of 12.5 °C. Regardless of mean temperature or irradiance level, all cut stems were able to stand without support. These findings suggest days to flowering, inflorescence number and floral quality may be improved by growing these two species of Leucocoryne at mean temperatures greater than 17.5 °C, whereas mean temperatures below 12.5 °C will be detrimental to these floral attributes.

The influences of temperature and irradiance on the time of flower initiation, sprouting, growth and flowering of Sandersonia aurantiaca were examined in a series of controlled environment studies. Plants were grown at constant temperatures of 15, 18, 21, 24 or 27degreesC; or at a mean temperature of 21degreesC with day/night differentials of -6, 0, +6, +12 or +18degreesC. Photosynthetic photon flux densities (PPF) were either 210, 460 or 700 mumol m(-2) s(-1) for 12 hours with photoperiod extension of 8 mumol m(-2) s(-1) for 2 hours. Flower initiation commenced after 62 days of sprouting at 12degreesC, 30 days at 18degreesC, and 22 days at 24degreesC. At all temperatures, flower initiation had commenced before shoot emergence from the soil. Flower numbers per stem increased with sprouting temperature, growing temperature and irradiance. Under differential temperatures, the greatest number of flowers were produced at differentials of 0, +6 and +12degreesC. However, the most desirable shaped flowers were grown at lower constant temperatures or smaller deviations in daily temperature. Stem length increased as constant growing temperatures increased to 24degreesC and as the day/night differentials increased from -6 to +12degreesC. In all cases, stem length decreased as irradiance increased. However, stem strength was in general inversely related to stem length, so that the strongest self-supporting stems were produced under combinations of lower temperature and higher irradiance. The number of days to flowering decreased as temperature increased. Under the day/night differential growing regimes, plants flowered quickest in the control temperature of a constant 21degreesC (0degreesC differential).

Sandersonia aurantiaca was grown in a controlled-environment (CE) experiment to determine the responses of flower stem quality attributes to day/night temperature differential (DIF) and irradiance. Other objectives were to determine if DIF could be used to manipulate flower stem quality and if irradiance modified plant responses to DIF. Five day/night temperature combinations 18/24, 21/21, 24/18, 27/15 or 30/12°C with respective DIFs of −6, 0, +6, +12 or +18 at a common 21°C mean daily temperature, and three photosynthetic photon fluxes (PPFs) of 700, 460 or 210μmolm−2s−1 with respective daily photon receipts (DPRs) of 30.2, 19.4 or 9.1molm−2 per day, were used. At flower harvest 16 vegetative and floral characteristics were measured. Stem length increased by 55% as DIF increased from −6 to +12, but a further increase in DIF to +18 resulted in markedly shorter stems. Stem shortening at +18 DIF (30/12°C day/night) was attributed to the adverse effects of the 30°C day temperature on stem growth. Stem strength was inversely related to stem length. Under high PPF, stem strength was highest in DIF treatments with the shortest stems (−6 and +18) and lower in DIF treatments with longer stems (0, +6 and +12). Under the low and intermediate PPFs, stem strength was low irrespective of DIF. Flower numbers on the main stem, and the number of days from shoot emergence to flower harvest, exhibited only small responses to DIF. Significant flower abortion was recorded only at negative to low positive DIF combined with low PPF. Interactions between DIF and PPF were significant for only 4 of the 16 parameters measured, with stem strength and flower abortion being the most important parameters affected. It was concluded that DIF (−6 to +18) could be used to manipulate flower stem quality in Sandersonia through its effects on stem length, provided the irradiance was high enough (>460μmolm−2s−1 PPF) to avoid stem strength problems. Stem length would be maximized at +12 DIF. Either negative DIF or high positive DIF (above +12) could be used to shorten stems, although small reductions in flower numbers on the stem would also occur.

Sandersonia flowers can vary from being lantern- to tubular-shaped. Lantern-shaped flowers are considered to be most commercially desirable when the ratio of the widest to the narrowest diameters of a flower, termed the ratio of hips to waist, is 1.5 or greater. Pedicel length can also affect the overall appearance of a flower stem. Short pedicels are considered more desirable. The influences of temperature and irradiance on Sandersonia aurantiaca flower shape and pedicel length were examined in controlled environment (CE) growth rooms. The growing environments were at constant temperatures of 15, 18, 21, 24 or 27°C; or day/night temperature differentials of −6, 0, +6, +12, or +18°C, with a mean of 21°C. Photosynthetic photon flux densities (PPFD) were 700, 460 or 210μmolm−2s−1. At harvest, measurements were made of the widest and narrowest diameters of the oldest flower on each stem and the ratio of these parts was calculated. The pedicel length of the oldest flower was also measured. Environments with constant temperatures below 23°C and the least day/night temperature differentials (−6, 0 and +6°C) produced flowers of the most desirable shape, defined as having a hips to waist ratio of 1.5 or greater. At these temperatures, irradiance had a variable effect on flower shape. Pedicel length was also highly dependent on temperature and PPFD. As mean temperatures increased or as the temperature differential changed towards a differential of 12°C, and as PPFD decreased, pedicel length increased significantly. Hip diameter was more sensitive to environmental changes than waist diameter and thus had a greater effect on flower shape. This work indicates to growers that they can enhance Sandersonia flower quality by producing more desirably shaped flowers with short pedicels through maintaining relatively low (less than 23°C) mean temperatures, minimising temperature differentials, and maintaining irradiance levels as high as possible.

Dormant second year potted plants of Paconia 'Coral Sunset', 'Monsieur Jules Elie', and 'Sarah Bernhardt' were placed into three chilling regimes constant 1, 4, or 7 degreesC) for different durations (3, 6, 9, or 12 weeks) to ascertain their chilling requirements for shoot and flower production. Chilling was followed by forcing for up to 5 weeks at 18 degreesC, then plants were maintained in a controlled greenhouse until flowering had finished. Mean number of shoots and flowers per plant were recorded and the time taken for shoots to sprout was calculated.Control plants (forced immediately without chilling) produced no shoots or flowers. For all cultivars, the proportion of plants that sprouted, and the mean number of shoots and flowers increased as plants were subjected to colder chilling temperatures, or longer chilling durations. However, there were no significant within-cultivar differences between different treatments of 9 weeks or more. The time taken for sprouting to occur after the completion of each chilling treatment consistently decreased as the duration of the chilling treatment increased. In most cases, lower chilling temperatures lead to more rapid sprouting once plants were placed in the 18 degreesC forcing conditions.When a simple model was fitted where the chilling temperature and duration of each treatment was described by a cumulative normal curve rising from zero to some maximum value (or potential) once adequate chilling had been received, we found that temperatures of 4 and 7 degreesC provided only 83 and 59%, respectively, of the chilling accumulated per unit time at VC. 'Coral Sunset', an interspecific hybrid early flowering type, required the greatest amount of chilling to sprout consistently, while 'Sarah Bernhardt', a very late flowering type, required the least. Of the three cultivars, 'Sarah Bernhardt' also required the least amount of chilling to achieve its potential shoot and flower numbers, while 'Monsieur Jules Elie', a mid-season flowering type, required the most chilling to achieve the same end for these two variables. This suggests that the response to spring temperatures as well as chilling influences the time of flowering. (C) 2001 Elsevier Science B.V. All rights reserved.

Tubers of Sandersonia aurantiaca Hook. were soaked in 1000 mg·L -1 GA 3 , 20 mg·L -1 uniconazole, 200 mg·L -1 benzyladenine, or water for 2 hours and then sprouted at 12, 18, or 24 °C. The effects of these treatments on flower stem quality were then determined at forcing temperatures of 18, 24, or 30 °C. Stem length increased with sprouting temperature only at a forcing temperature of 18 °C. Floret numbers increased with sprouting temperature at all forcing temperatures, but the effect was greatest at the 18 °C forcing temperature. The 12 °C sprouting treatment reduced floret numbers at all forcing temperatures. Soaking tubers in GA 3 increased stem length but drastically reduced floret numbers, while soaking in uniconazole reduced stem length but had no significant effect on floret numbers. Soaking in BA strongly promoted branching, which resulted in large increases (>30%) in floret numbers per stem with little change in stem length. Of the three growth regulators, only BA was effective in improving cut flower stem quality. Chemical names used: gibberellic acid (GA 3 ); (E)-(+)-(S)-(4-chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl)-pent-1-ene-3 -ol (uniconazole); N 6 -benzylamino purine (benzyladenine; BA).

The effects of temperature and irradiance on tuber growth and the development of secondary tubers in Sandersonia aurantiaca (Hook.) were investigated.Plants were grown to flowering during summer in a glasshouse. At flowering, plants were trimmed to leave nine leaves on the stem, and transferred to controlled environment rooms set at constant temperatures of 15, 18, 21, 24 and 27 degrees C. Within each room, three irradiance treatments were imposed using neutral density shade cloth: 210, 460 and 700 mu mol.m(-2).s(-1) photosynthetic photon flux density (PPFD). Plants were sampled at intervals during tuber growth and at maturity to assess tuber fresh weight, tuber dimensions and the development of secondary tubers. The date of leaf senescence was also recorded.Tuber growth rates were significantly affected by both temperature and irradiance, responding positively to increasing irradiance at all temperatures. Senescence date was similar amongst treatments. Across all treatments, mean tuber fresh weights at maturity ranged from 8.1 to 18.0g with maximum weights in the 21 degrees C/700 mu mol treatment. The incidence of secondary tuber formation was strongly influenced by both temperature and irradiance. Very few secondary tubers were formed at 15 or 18 degrees C, irrespective of irradiance. At temperatures greater than or equal to 21 degrees C, the incidence of secondary tubers increased with both increasing temperature and irradiance, reaching a maximum of 88% in the 27 degrees C/700 mu mol treatment. Treatment conditions which maximized tuber fresh weight and minimized secondary tuber incidence were those with cool temperatures and high irradiance i.e., 15 or 18 degrees C and 700 mu mol. Across all treatments, there was no correlation between the presence of a secondary tuber and the fresh weight of the primary tuber. Taken together with the relatively small effect of temperature on tuber growth rate prior to the onset of secondary tuber formation, this suggests that assimilate supply is not the primary factor involved in the onset of secondary tuber formation. It is proposed that the primary effect of temperature on secondary tuber development is mediated via the hormonal status of the growing point on the primary tuber.

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 –2 ·s –1 ). 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.

Plants of Gypsophila paniculata cvs Bristol Fairy and Bridal Veil were grown in controlled environments at 20 degrees C day and either 20 degrees C (WN) or 7 degrees C (CN) night temperatures with the daylength being either 18 h (LD) or 9 h (SD). This provided four daylength/night temperature combinations: LD/WN, LD/CN, SD/WN and SD/CN. One quarter of the plants were subjected to a vernalization pre-treatment (eight weeks at 11/ 5 degrees C, day/night; 9 h daylength), while unvernalized plants were sprayed with either gibberellic acid (GA(3)) or 6-benzyladenine (BA) at 300 mg 1(-1) at the start of the environmental regimes. The objective was to determine whether vernalization and growth regulators could modify the flowering responses of G. paniculata to daylength and night temperature. Both cultivars bolted and formed flower buds very rapidly in LD/WN irrespective of pretreatment, but both final stem height and yield were low. Vernalized plants flowered in the other regimes (LD/CN, SD/CN, SD/WN) and best yields and stem height were obtained under LD/CN conditions. CN prevented flowering in unvernalized 'Bristol Fairy', but not in unvernalized 'Bridal Veil'. SD prevented flowering in unvernalized plants of both cultivars. GA(3) or BA or 300 mg 1(-1) promoted flowering ana improved yield in all plants grown in LD/CN, but only 'Bridal Veil' responded weakly to these treatments in SD. Flower quality was diminished by WN, particularly under SD conditions, due to a loss of apical dominance and branch weakness. BA application also resulted in poor flower quality due to the matting of fine branchlets in the inflorescences.

In defining current science- and grower-based knowledge of cutflower crops, questions were raised of how the resulting information could be used to enhance production systems. A descriptive model of decision-making in the flower-growing industry was proposed as a means of answering some of these questions. Agricultural management and decision-making literature was reviewed. No models specific to entire cutflower production systems were found but some of the models cited were used as a basis for the model. Some data of a general and anecdotal nature were available, and to augment this, qualitative data were also gathered from growers. It is concluded that current management and decision-making models failed to make sufficient allowance for the complexity of growers' goals in a dynamic operating environment. It may be that the developers of science-based models also do not adequately understand the dynamic nature of agricultural-based production system decisions and therefore can not adequately meet growers' needs.