Cut foliage: potentiality of native Argentine ferns as new ornamental crops

The cut foliage constitutes an important part of the floricultural production since it represents a fundamental element in flower arrangements, and ferns are the complementary elements most used by florists. In Argentina, there is native material that has not been yet domesticated and could have suitable characteristics for foliage use. The objective of the work was to determine the potential use of 15 native ferns as cut foliage through quality parameters and vase life, generating a scoring system that allows a classification list. Morphological descriptors such as petiole length, length and width of the blade, planes in which the fronds are arranged, brightness, consistency, abundance of spores and presence of pests were taken into account. Also, the production of fronds of six selected species with good scores was recorded. The results showed that it is feasible to consider the commercial production of Pityrogramma calomelanos , Niphidium crassifolium , Campyloneurum nitidum , Blechnum austrobrasilianum and Pteris denticulata by the quantity of fronds obtained and their quality, represented by their size. Campyloneurum nitidum excelled for its vase life of more than 26 days and frond production of 273.61 fronds m -2 at second year cultivation. Pteris denticulata produces 179.44 fronds m -2 but vase life was only 7 days.


Introduction
The cut foliage constitutes an important part of the floricultural production since it represents a fundamental element in flower arrangements.Despite of this, very few species are available and in low quantities in the Argentinian flower market.
Within the cut foliages, ferns are the complementary elements most used by florists worldwide (Stamps, 2007).The most commercially important fern species and genera are: Rumohra adiantiformis, Adiantum, Cyrtomium, Nephrolepis, Platycerium, Polystichum and Pteris.Lesser important are Davallia and Polypodium.The most popular species globally is R. adiantifolia, because it has a vase life of 3 to 4 weeks (Benavente-Garcia et al., 1998).It is also the most commercialized fern in Argentina and is extracted from the wild.
The popularity of ferns for using as cut foliage is due to the availability, consumer acceptance, low cost, and longevity of fronds.The cut flower has been the protagonist within the arrangements, but its importance has been diminishing in favour of the accompanying elements (Gutiérrez et al., 2007).Even in floral design, arrangements also are made using foliage, without any type of flowers, a trend that favours the importance of foliage production.In addition, ferns can be grown as one of the horticultural crop of ornamental value on unutilized geographical regions to bring the unused soil under cultivation (Singh and Johari, 2018).Ferns also have been in use for food, as ornamental plants, valuable unexplored chemicals and for the phytoremediation of contaminated soils providing ecological services (Kumar and Fernandez, 2019;Anderson, 2021).
The Floriculture Institute has started a project for the domestication and use of native ferns for ornamental purposes in order to collaborate in the diversification of production and also, to reduce extractive use (Facciuto et al., 2014).This situation is aggravated when very little information is available about the sustainability of the extractive activities.
In Argentina, ferns comprise 28 families, 91 genera and 366 species distributed in four regions: the Yungas cloudforest, the Andean-Patagonian rainforest and the Pampas Hills (Ponce et al., 2002).This floristic richness creates an opportunity for diversification the production and to provide new textures and shapes for floral art.
There is no single methodology to determine the ornamental potential of a new species, but, before it is launched on the market, it is necessary to identify it taxonomically, to find out the propagation and cultivation methods and objectively determine its ornamental value.Stumpf et al. (2007) tested the ornamental potential of 11 species native to Rio Grande do Sul, Brazil, as a sum of scores given to ten traits chose by their importance for the floral art and for the market.Also, Beckmann-Cavalcante et al. ( 2017) evaluated ornamental potential of native species through a score system considering features of interest for floral art and consumer market.Sankar et al. (2019) evaluated 11 ferns native to India considering quantitative and qualitative characters to classify them and stablished their suitability for landscapes and commercial uses.Safeena et al. (2019) also in India, reflect the aptness of different cut foliages to function for various purposes in floristry through the evaluation of morphological characteristics and vase life of 18 species including ferns and Asparagus species.
In Argentina, there is native material that has not yet been domesticated and could have characteristics suitable for foliage use.Some basic parameters to optimize its production, harvest and handling are the propagation, its storage and postharvest life of the fronds (Stamps, 2007).
The objective of this work was to determine the potential use of native Argentine ferns as cut foliage through quality parameters and vase life.From these results, it is intended to value genetic resources to be considered as new crops for ornamental horticulture.

Materials and Methods
Fifteen species of ferns native to Argentina were studied.They were grown in a greenhouse with a minimum temperature control of 15 ºC in Floriculture Institute, INTA (Table 1).The plants used were propagated by spores.The evaluations were carried out when the plants reached their reproductive stage in 3 L containers, except for Microgramma squamulosa and Blechnum lanceola, which was grown in 400 cm 3 pots.

Ornamental Potentiality
The quality parameters were evaluated considering the leather fern (R. adiantiformis) as a reference (Verdugo et al., 2006) and other characteristics of the cut foliage.The length of the frond petiole and length and width of the frond blade were measured.Brightness and consistency of the fronds, abundance of spores, presence of pests and diseases were analysed visually.Also, frond development in one or more than one plane was record.Thirty fronds were used for the morphological characterization.These values were transferred to categories as presented in Table 2.The sum of the scores reached a maximum value of 21 for the best condition.For the vase life another 20 points were considered, since it is an essential characteristic for cutting foliage aptitude.For the determination of the vase life, homogeneous fronds were selected; the basal 2 cm were cut and placed in 250, 500 and 100 mL containers depending on the size of the plant materials to be evaluated, with distilled water immediately after being harvested.The upper part of the containers was covered with film to avoid the loss of water by evaporation.The film was perforated to place the fronds.Three vases were used per species with three fronds each, and the test was carried out in triplicate, in a postharvest room (18 ºC, 64% RH, 700 lux).
The variation in the external appearance of the fronds was recorded daily, in order to determine the end of the vase life.It was determined by the occurrence of some symptom that indicated a loss of quality and that made it impossible to fulfil its ornamental function, such as wilting and / or yellowing and / or curving of the fronds.
The ornamental potential was defined by the sum of the scores.

Productivity of selected species
The production of fronds of six selected species with good scores was recorded.Despite M. squamulosa and A. auritum showed very good vase life, they were discarded in this experiment due to the small sizes of the fronds.The arborescent habit of L. schomburgkii was considered not suitable for cut foliage production and it was also discarded.
Once the plants had a size according to a 3 L pot, 12 plants per species were planted in 2 batches of 6 plants, in 90 cm wide ridges and staggered at a distance of 45 cm, in a greenhouse with 10 °C minimum temperature control (Figure 1A).A 50% shading mesh was placed that covered the roof and the sides of the trial.The substrate was a recycled with the addition of 40% bark to generate aeration.Irrigation was manual and biweekly fertilizations were carried out with a 15:15:15 NPK fertilizer.
Mature fronds were collected, the number of fronds per plant was counted in the second year of cultivation and the fronds production per square meter was calculated.Petiole length and blade length and width of 30 fronds were measured.The data were statistically analysed with an analysis of variance and Fisher's test with the statistical program Infostat 2009 (Di Rienzo et al., 2011).

Ornamental Potentiality
The evaluation of ornamental potentiality through morphological descriptors and vase life is presented in ascending order in Table 3. Phlebodium areolatum, N. crassifolium and C. nitidum stood out with values of 37, 36 and 35, respectively.Phlebodium areolatum retained its appearance in vase for 26 days (Figure 2), and its large fronds with a developed petiole gave it interesting properties.The petiole is curved, so it is suggested for pendulous arrangements.Campyloneurum nitidum presented a very high vase longevity, more than 30 days (Figure 2), and also presented high values in other important characteristics such as frond length, leathery consistency, absence of pests and diseases and spores that do not make dirty the fronds.The morphology of the frond in one plane is interesting because it is suitable for the transport in boxes (Figure1B).Preparation of cut flowers and foliages is a tedious job and require specific packaging for each species (Ahmad et al., 2021).
Niphidium crassifolium excelled for its vase life of days long fronds and, as C. nitidum, in one plane.
Microgramma squamulosa reached a score of 35 value that positions it, together with the previous species, as a potential new crop as cut foliage, although the size of its fronds is small depending on the quality standards of ferns.Despite of this, it could be used for small bouquets or other non-traditional arrangements.
These four species are epiphytes, so they could have low nutritional and water requirements.Epiphytic ferns grow naturally in soilless condition, without using the typical water and nutrient storage of soil and typically have adaptations to endure periods of desiccation (Anderson, 2021) Microgramma has stout suberified stems storing water and amylaceus reserves (Dubuisson et al., 2009).It is interesting to mention here that in phylogenetic studies, Labiak and Moran (2018) confirm that Campyloneurum forms a clade with Microgramma and Niphidium.
The species that presented a short vase life, P. deflexa, A. radiata, D. nobilis and B. lanceola, were discarded as possible candidates for cut foliage crops.A long vase life is the main attribute that a species must have to be used as cut foliage, and like cut flowers, it should remain vigorous and attractive for at least 10 days (Weiss, 2002).In these cases, fronds longevity was less than 5 days (Figure 2).
Blechnum brasiliense, B. austrobrasilianum, P. denticulata, A. tomentosa, L. schomburgkii and P. calomelanos presented medium vase life that was later reflected in intermediate scores.These ferns can be subjected to trials to improve longevity using different vase solutions, in order to maximize the quality and facilitate commercialization.The use of floral preservatives has been found to influence to a great extent, it can offer at least double longevity of cut flowers and foliages duo (Malakar et al., 2017).Furthermore, dehydration methods, like glycerinization, were developed for cut foliage (Jhanji et al., 2018).
The indicators of end of vase life differed among species (Table 3).Wilting, curving, yellowing and/or loss of brightness of fronds were the symptoms of senescence observed.In some species used as cut foliage, the rate of water absorption is less than the rate of transpiration; this leads to leaf wilting, destroys or disrupts its physical structures, and causes activity imbalances in macromolecules and organelles (Teerarak and Laosinwattana, 2019).  . lanceola, A. radiata, D. nobilis, B. brasiliense and T. deflexa; mass material in A. tomentosa, B. austrobrasilianum, N. crassifolium, A. auritum, P. denticulata, L. schomburgkii and P. calomelanos; filler material in M. squamulosa and P. areolatum; and a distintictive shape in C. nitidum.

Productivity of selected species
The production of fronds per plant of the species selected by the highest scores is presented in Table 4.It is important to mention that the ferns that are grown for cut foliage begin to be productive in the second year after implantation, approximately.
The production of C. nitidum stood out, producing 82.08 fronds per plant, which translates into 273.61fronds m -2 , P. denticulata produced 179.44 fronds m -2 (Figure 1C) and N. crassifolium 136.66 fronds m -2 (Table 4).Considering that the leather fern (R. adiantiformis) produces 114 fronds per square meter in the second year in cultivation (Chahin and Azocar, 2012), the mentioned species exceeded this value, so they could be competitive crops.Pityrogramma calomelanos and B. austrobrasilianum produced 99.66 and 99.44 fronds m -2 respectively, values also near those mentioned for R. adiantiformis.
Phlebodium areolatum produced only 51.6 fronds m -2 , this low productivity, as well as the difficulty of its cultivation due to the little rigid petioles, do not make it suitable for bed production as cut foliage, despite the long postharvest life.Nevertheless, some methods for conducting the production could be analysed.
It is also important to mention that the reference value comes from outdoor crops with shading mesh, and in this case the experiment was carried out in a greenhouse, a probable reason for the higher productivity found.Besides, in this study the cultivation was initiated with already developed plants, in commercial crops many times it begins with pieces of rhizomes.
According to Strandberg (2003), frond production and development rates of R. adiantiformis varied greatly with the seasons and were strongly associated with weather variables, but significant rate fluctuation unrelated to weather were also detected.Therefore, it is probably that the production of the studied ferns could be considered for other production sites.
Compared with the values of the quality standards for internal use and export of fronds of R. adiantiformis according to Verdugo et al. (2006), being the minimum length 40 cm and the optimum 55 cm, the selected ferns presented values within or exceeding that range (Table 4).Phlebodium areolatum and P. denticulata had the longest fronds with petioles of 34.78 cm and 43.47 cm and blade length of 61.66 cm and 90.32 cm, respectively.
Despite N. crassifolium and C. nitidum do not have a developed petiole, they reached the reference value and provide a different morphology from that available in the markets.Blechnum austrobrasilianum had the shortest fronds but also within the accepted range in markets.
The present work showed that it is feasible to consider the commercial production of P. calomelanos, N. crassifolium, C. nitidum, B. austrobrasilianum and P. denticulata by the quantity of fronds obtained and their quality represented by their size.It would be important to continue the studies to determine the maximum production period.Campyloneurum nitidum and P. denticulata stood out as the most productive species in the period tested.Inclusion of new species in cultivation also promote ex situ conservation of biodiversity and sustainable use, preventing extractive practices.Many other ferns of Argentine are still to be prospected and the protocol proposed can be an alternative to evaluate them.

Conclusions
Ferns species were selected objectively for their aptitude to be used as cut foliage through morphological attributes, vase life and fronds production.Campyloneurum nitidum and P. denticulata stood out for their frond production.

Figure 2 .
Figure 2. Vase life (days) of 15 ferns native to Argentina values of three experiments.

Table 1 .
Institute of Floriculture INTA (IF) codes, species, procedencies and growth habit of 15 ferns native to Argentina.

Table 2 .
Attributes of frond quality of ferns native to Argentina.

Table 3 .
Scores of ornamental attributes of 15 ferns native to Argentina, sum of scores and indicators of end of vase life.It is interesting to consider the frond form variability obtained for flower arrangement according toStamps  classification of greens (1987)as linear like in Aspidistra, mass material in Pittosporum, filler in Asparagus, and distintictive like in palms.Here, it is represented as linear in B A. Petiole length, B. Blade length, C. Blade width, D. Plane, E. Brightness, F. Consistency, G. Spores abundance, H. presence of pest and diseases, I.

Table 4 .
Production of selected fern fronds after 24 months of cultivation in beds.