Bryophytes can be grown successfully if keptmoist, supplied

with nutrients, and out of direct sunlight. They remain greener

on peat than on sand. However, difficulties were encountered when

attempting to grow mosses and liverworts in an unshaded

glasshouse, in spring and summer. Even spraying hourly with water

did not prevent scorching and desiccation.

Growth can be measured using a variety of techniques; height

measurement and shoot elongation from thread markers proved the

most reliabl

Ashenden, T. W.

Bell, S. A.

Rafarel, C. R.

English

NERC Open Research Archive

ISSN 0260-6925 Bangor Occasional Paper No. 20 CULTIVATION AND USE OF BRYOPHYTES AS EXPERIMENTAL MATERIAL S Bell, T W Ashenden and C R Rafarel Institute of Terrestrial Ecology Institute of Terrestrial Ecology Bangor Research Unit University College of North Wales Deiniol Road Gwynedd LL57 2UP North Wales Great Britain February 1991 Cultivation and use of bryophytes as experimental material. S-Bell, T.W.Ashenden and C.R.Rafare1. SUMMARY Bryophytes can be grown successfully if keptmoist, supplied with nutrients, and out of direct sunlight. They remain greener on peat than on sand. However, difficulties were encountered when attempting to grow mosses and liverworts in an unshaded glasshouse, in spring and summer. Even spraying hourly with water did not prevent scorching and desiccation. Growth can be measured using a variety of techniques; height measurement and shoot elongation from thread markers proved the most reliable. INTRODUCTION Bryophytes are acknowledged to be difficult subjects for experimental work, primarily due to problems in both cultivating and maintaining them, (B.G.Bel1, pers.comm.). This paper outlines methods which were found to be successful during the preparation of bryophytes for an experiment, in which they were to be grown for several months in a glasshouse. Preliminary studies were carried out to assess suitable growth media, methods of cultivation and means for marking and measuring to evaluate growth. Using the information gained from these trials, experimental material was placed in an unshaded glasshouse for the main experiment. The practical use, in a glasshouse, of the various marking and measuring methods was assessed. The responses of the species used, to this hostile environment were investigated. MATERIALS AND METHODS Bryophyte material (10 mosses and 4 liverworts) was collected from 5 sites within 15 miles of Bangor (Table 1). 1 Preliminary trials. Most bryophytes are found in sheltered, moist habitats. Those workers who have successfully cultivated mosses and liverworts have maintained them in a humid atmosphere, and supplied nutrients. Therefore, material was kept moist and cool, and "potted on" within 2 to 3 days of collection, to prevent desiccation. Plants were grown in 3" pots, covered with polythene sheeting, and kept in a shady, unheated room. Stocks of all species were grown on 50:50 mix of acid washed sand and Irish moss peat. Distilled water was applied daily as a mist spray, and l/lOth concentration Long Ashton solution added once per week. (a) Growth media. Material of 9 species (5 mosses and 4 liverworts, Table 2) was grown on either acid washed sand or Irish moss peat. For branched species (e.g. Pleurozium schreberi) single stems were inserted into the medium, leaving a constant length of shoot exposed. The tufted species (e.g. Dicranum scouarium) were treated similarly, except that small groups of stems were used. Approximately even-sized pieces of liverworts and epiphytic mosses (e.g. Hyunum cuuressiforme), still attached to the substrate, were firmly pushed onto the sand or peat. Visual assessments of plant health were made throughout the trial. Three species were considered suitable for growth measurements, Pleurozium schreberi, Dicranum scouarium, and Racomitrium lanuqinosum. Stems were measured, (using a calliper gauge), when initially planted on the 2 growth media, and again after 10 weeks, (Table 2). (b) Methods of markinq and measurina bryophvte qrowth. Various methods of marking and assessing bryophyte growth, both experimentally and in the field, are described in the literature. These range from simply measuring shoot length from the substrate to the use of markers, either on the substrate (Pitkin,1975) or tied to shoots at known distance from the apex ( Longton & Greene, 1979 ) . Preliminary trials of all three methods were conducted, and then adapted for use on the plant material in the main experiment. 2 Glasshouse experiment. In most cases, experimental material had been potted on during August and September 1988, and kept moist until transfer to the glasshouse in late October 1988. The bryophytes were grown on Irish moss peat in 3" pots. The glasshouse was ventilated with charcoal filtered air; the flow rate set to change the atmosphere completely 1.5 times per minute. There was no shading, supplementary heating or lighting. Plants were sprayed with de- ionised water at least 3 times per day. During the exceptionally hot summer period this was increased to once per hour, during daylight hours. Nutrients were supplied weekly, initially as l/lOth concentration Long Ashton solution; from lat February 1989 this was lowered to 1/100th concentration. The liverworts and, the very delicate moss, Hookeria lucens were covered with polythene sheeting overnight,(1700-0900), to help maintain high humidity around the plants. Growth measurements were made, before transfer to the glasshouse, and at intervals throughout the study; the method used varied according to growth form. All liverworts, Hookeria lucens, Plaqiomnium undulatum and Poaonatum urniaerum were measured for maximum height and width. Prostrate, branched mosses, (Hypnum cu~ressifome, Is~theciummyosuroides and Thuidium tamariscinum), were measured from plastic markers in the pot to the shoot tip. Maximum height was recorded for upright growing species, (Dicranum scoparium. Pleurozium schreberi. Polytrichum formosum and Racomitrium lanuqinosum). For Polytrichum formosum, the numbers of shoots per pot were also counted and categorised as (a) old, (b) old with new growth, (c) small new shoots ( <  1 cm.) and (d) larger new shoots ( >  1 cm.). In December 1988, 15 extra pots fully filled with Pleurozium schreberi and 15 of Dicranum scoparium, were added. Thread markers were tied to randomly selected shoots. Growth from marker to shoot tip was measured, immediately after transfer to the glasshouse and at intervals throughout the experiment. From January this technique was extended to all the other mosses, except Hookeria lucens, (considered so fragile that attaching markers would damage plants). RESULTS 1 Preliminary trials of arowth media. After 10 weeks, all plants of all 9 species had survived on both 100% acid washed sand and 1008 peat. Plants on peat were slightly greener than those on sand. Growth measurements showed that Pleurozium schreberi, Dicranum scoparium and Racomitrium lanuqinosum had all increased in size, on both media, (Table 2). Peat was chosen for the glasshouse experiment as (a) plants remained greener on peat, (b) the pH (4.5 ) suited all the species to be used and (c) it would retain more moisture. 2 Glasshouse ex~eriment; visual assessments. All species, except Polvtrichum formosum, showed signs of desiccation soon after transfer to the glasshouse. Vigilant spraying with de-ionised water enabled all species to survive the winter period, with at least 50% of the material green. However, as temperatures rose in spring and summer, all except Polvtrichum formosum became increasingly damaged by scorching and desiccation, despite hourly moistening. The pots full of Pleurozium schreberi and Dicranum sco~arium were much less affected than pots with smaller amounts of plant material; these, and Poaonatum urniuerum remained 60% green until March-April. However, by !-lay these plants were yellowing, and most of the others were 80% brown. Polvtrichum formosum plants had remained green with slight browning of leaf tips, and produced much new growth. 3 Growth measurements. (a) Maximum heiaht and/or width. In preliminary trials, this method was used successfully on both mosses and liverworts. It proved less useful in the glasshouse, where die-back and regrowth of plants caused measurements to fluctuate, (Tables 3 & 4 ) .  However, it could still be a useful technique for those species not suitable for attachment of thread markers. Ib) Plastic markers. This method was also successfully used, on mosses and liverworts, in the preliminarytrials; measurable growth occurred beyond the markers. Unfortunately, it too proved impractical when employed in the glasshouse. Many markers were dislodged or lost, due to rain drips from the roof, and by movement of pots, during measuring and when covering with polythene sheeting, (Tables 3 & 4). Ic) Thread markers. Accurate growth measurements were consistently obtained using this method. It also allowed the use of full pots of moss, helping to alleviate desiccation, (Tables 3 & 4 ) .  Most species of mosses and all the liverworts grew very poorly in the glasshouse, (Tables 3 & 4,. Polytrichum formosum increased in height over the first 13 weeks of the glasshouse experiment, and produced new growth in spring (Table 5). DISCUSSION Preliminary trials showed that bryophytes can be successfully grown, for several months, on sand or peat; if kept out of direct sunlight, moist and supplied with nutrients. Under these conditions, health and growth can be assessed (a) visually, (b) using height and width measurements and (c) measuring increase in width, or shoot extension, from markers. Thus, if only simple cultivation and/or growth assessments are required, bryophytes can be kept on peat, under polythene, in a shady room and regularly moistened and supplied with nutrients. As these requirements are easily met, bryophtyes can be suitable experimental subjects. As expected, the glasshouse environment proved too hostile to maintain bryophytes, in spite of regular mist spraying. All species except Polytrichum formosum suffered scorching and desiccation. The leaves of Polvtrichum formosum often became adpressed, but recovered soon after spraying. This species has a rhizome and a water conductance system, and was thus less prone to desiccation than the other species.The spring and summer of 1989 were exceptionally hot and temperatures in the glasshouse were often over 30°C for prolonged periods. During a cooler summer or in autumn and winter, it would probably be feasible to grow mosses (but not liverworts) successfully in a shaded glasshouse. Simple height measurements, for upright growing species, and the use of thread markers to assess shoot elongation, proved the most reliable methods of assessing growth. ACKNOWLEDGMENTS The work was part of a project funded by the Nature Conservancy Council. Mr.T.Blackstock and Dr.M.O.Hil1 advised on selection of species. Dr.S.Woodin and Professor J.Lee provided helpful discussion throughout. REFERENCES Longton,R.E. and Greene, S.W., (1979). Experimental studies of arowth and re~roduction in the moss ~leurozium schreberi  r rid. ) Mitt. - J-Brvol. 10, 321-338. Pitkin,P.H., (1975). Variability and seasonality of the growth of some corticolous pleurocarpous mosses. J.Brvo1. 8, 337-356. Smith,A.J.E., (1978). The Moss Flora of Britain and Ireland. Cambridge University Press, Cambridge. Watson,E.V., (1981). British Mosses and Liverworts (3rd edition). Cambridge University Press, Cambridge. Table 1. Species used in the glasshouse study, and details of collection sites. SPECIES COLLECTION SITE GRID REFERENCE Mosses : - Dicranum Stabilised slate waste tip scoparium Hedw. near Bethesda, slate waste. Hookeria Banks of river Ogwen, near lucens (Hedw.)Sm. Bethesda, shady, humid area under mature trees. Hypnum Stabilised slate waste tip cupressiforme agg. near Bethesda, tree bark. Isothecium Stabilised slate waste tip mvosuroides Brid. near Bethesda, tree bark. Plaaiomnium Wooded road verge, near undulatum(Hedw.)Kop.Lla~Adona~ Soil. Pleurozium schreberi Stabilised slate waste tip (Brid.) Mitt. near Bethesda, slate waste. Poaonatum urniaerum Exposed boulders in stone (Hedw.) P.Beauv. wall in road verge, Llanddona. Polytrichum Experimental pots at formosum Hedw. I.T.E. Bangor. Racomitrium Stabilised slate waste tip lanuainosum near Bethesda, slate waste. (Hedw.) Brid. Thuidium Wooded road verge, near tamariscinum Llanddona. Soil. (Hedw.) Br.Eur. Plaaiochila Banks of river Ogwen, near SH 608687 porelloides (Torrey Bethesda. Shady, humid ex Nees) Lindenb. area, under mature trees. Plaqiochila s~inulosa(Dicks.)Dum. Scapania qracilis Lindb. Scapania nemorea (L.) Grolle Plant names according to Smith, 1978 (mosses) and Watson, 1981 (liverworts). Table 2. Bryophytes grown on Irish moss peat or sand, for 10 weeks. SPECIES INITIAL SHOOT LENGTH LENGTH AFTER (in centimetres) 10 WEEKS ON PEAT AND SAND PEAT SAND Dicranum scoparium 4.0 4.5 5.5 Pleurozium schreberi 7.0 10.0 10.0 Racomitrium lanuainosum 2.0 3.5 2.8 Species used for peat:sand comparison, not measured:- Hypnum cupressiforme Isothecium myosuroides Plaaiochila porelloides Plaaiochila spinulosa Scapania aracilis Scapania nemoreum Table 3. Growth of mosses in the glasshouse. SPECIES TIME MEASUREMENT (cm. ) Dicranum scoparium 10/88-1/89 Height increase -0.19 (11 weeks) 12/88-1/89 Shoot -0.03 (4 weeks) elongation 1/89-4/89 Shoot -0.03 (12 weeks) elongation Hookeria lucens 10/88-1/89 Height increase -1.30 (11 weeks) Diam-increase -2.96 1/89-4/89 Height increase +0.18 (12 weeks) Hwnum cu~ressiforme 10/88-1/89 +0 -17 ( 11 weeks) Shoot +0.01 1/89-4/89 elongation +0.18 (12 weeks) Isothecium mvusu~oides 10/88-1/89 +O. 06 ( 11 weeks) Shoot +0.03 1/89-4/89 elongation +O. 22 ( 12 weeks) +0.38 Plaqiomnium undulatum 11/88-1/89 Height increase +0.60 (8 weeks) Diam.increase +2.54 1/89-4/89 Height increase -0.41 (12 weeks) Diam.increase -3.56 Shoot elongation +0.19 Pleurozium schreberi 10/88-1/89 Height increase -0.02 ( 11 weeks) 12/88-1/89 Shoot +O. 04 (4 weeks) elongation 1/89-4/89 Shoot +O. 15 (12 weeks) elongation Poaonatum urniqerum 11/88-1/89 Height increase +0.41 (8 weeks) Diam.increase +2.01 1/89-4/89 Height increase +0.37 (12 weeks) Diam-increase +l. 60 Shoot elongation +0.19 Polytrichum formosum 10/88-1/89 Height increase +0.26 (13 weeks) 1/89-3/89 Height increase +0.17 (8 weeks) Shoot elongation +0.01 Racomitrium lanuqinosum 10/88-1/89 Height increase -0.02 (11 weeks) 1/89-4/89 Height increase -0.19 (12 weeks) Shoot elongation +0.20 Thuidium tamariscinum 11/88-1/89 +O. 34 (8 weeks) Shoot 1/89-4/89 elongation +0.26 (12 weeks) Table 4. Growth of liverworts in the glasshouse. SPECIES TIME GROWTH MEASUREMENT MAX-HT. MAX.WIDTH (cm. (cm. ) Plaqiochila porelloides 11/88-1/89 + 0.07 + 1.25 (8 weeks) 1/89-4/89 - 0.08 + 0.86 ( 12 weeks) Plaqiochila svinulosa 10/88-1/89 - 0.44 + 0.10 (11 weeks) 1/89-4/89 + 0.19 + 0.09 ( 12 weeks) Sca~ania aracilis (11 weeks) 1/89-4/89 + 0.14 + 0.23 (12 weeks) Scapania nemoreum 10/88-1/89 + 0.04 + 0.3P (11 weeks) 1/89-4/89 + 0.05 + 0.10 (12 weeks) Table 5. Numbers of shoots of Polvtrichum formosum. TIME IN SHOOT TYPE GLASSHOUSE NUMBER OF SHOOTS 4/4/89 Old shoots 22.1 4/4/89 New shoots( > 1 cm.) 44.8 4/4/89 New shoots( < 1 cm.) 6.6 2/5/89 Old shoots with new growth 6.9 19/5/89 Old shoots with new growth 7.5 

Cultivation and use of bryophytes as experimental material

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