CHECK - LISTS, SOURCES AND RECORDS

See Manual 3 for sheets with letter C.
For problems with older nursery plants, see sheet C 60 in Manual 3.
For problems with rooting cuttings and growing good trees, see A 61 in Manual 1.

1. if it stays too wet:
   1. add more coarse sand to the mix;
   2. water with finer drops, and less often;
   3. make more drainage holes in seed trays, and stand them on gravel;

   4. improve drainage of seed beds.

2. if it quickly dries out:
   1. increase the shading;
   2. add more organic matter to the medium;
   3. try covering moist medium with mulch;

   4. use a deeper seed tray or a seed bed next time.

3. if its temperature fluctuates too much:
   1. provide more shelter for the seed propagation area;
   2. add more overhead or side shading;
   3. start seed germination within a building, close to a window;
   4. bring seed trays inside at night;
   5. check the water temperature being used;

   6. consider placing mulch over moist medium.

4. if the seedlings fall over:
   1. protect from wind and animals;
   2. add some loam to the medium;
   3. firm down the medium after sowing seeds;
   4. cover seeds a little deeper;
   5. check for damping-off disease.

1. Use a different shading material;
2. Hang mats for shade from early or late sun;
3. Cut back overhanging bushes or hedge;
4. Reduce the shading gradually;
5. Start germination off by a window inside a building.

1. Make the germination medium more freely drained;
2. Use fine gravel or coarse sand to cover seeds;
3. Decrease shading a little;
4. Water more sparingly at first;
5. Remove any dying seedlings at once;
6. If necessary use a fungicide.

1. Water early in the day;
2. Water more evenly and with finer drops;
3. Use a cleaner source;
4. Check water is not too warm or cool;
5. Train staff and workers.

1. Add a little rich organic matter to the germination medium;
2. Put in some sieved soil from a thriving stand of the same species, which may contain important micro-organisms;
3. Consider the possibility of too much of one nutrient restricting uptake of another;
4. Mix in a small quantity of a balanced fertiliser or micronutrients.

Juvenility and maturity in trees

Leakey, R.R.B., Ferguson, N.R. and Longman, K.A. (1981). Precocious flowering and reproductive biology of Triplochiton scleroxylon K. Schum. Commonwealth Forestry Review, 60, 117–126.

Longman K.A. (1987). The significance of juvenility for seed orchard management. Forest Ecology and Management, 19, 9–16.

Weigel, D. and Nilsson, O. (1995). A developmental switch sufficient for flower initiation in diverse plants. Nature (London), 377, 495–500.

Periodicity in flowering:

Longman, K.A. (1985). Tropical forest trees. Pp 23–29 in CRC Handbook of Flowering, ed. Halevy, A.H., CRC Press, Boca Raton, Florida, USA.

Mora, U. (1983). El pejibaye (Bactris gasipaes HBK.): origen, floral y manejo agronomico. Pp 118–160 in Proceedings of workshop on underutilized palms of tropical America, CATIE, San Jose, Costa Rica/FAO, Rome, Italy. (ref 20 in M3/A)

Flower formation and flower opening

Longman, K.A., Manurung, R.N. and Leakey, R.R.B. (1990). Use of small clonal, plants for experiments on factors affecting flowering in tropical trees. Pp 395–405 in Reproductive Ecology of Tropical Forest Plants, eds Bawa, K.S. and Hadley, M., UNESCO, Paris, France/Parthenon, Carnforth, England.

Sedgley, M. and Griffin, A.R. (1989). Sexual Reproduction of Tree Crops, Academic Press, London.

Soman, T.A. et al. (1995). Wintering pattern and floral biology of Hevea clones. Indian J. Natural Rubber Research, 8, 94–99.

Webber, J.E., Owens, J.N. and Stoehr, M.U. (1995). Biology and control of reproductive processes in forest trees. Tree Physiology, 15 (7/80), 419–557.

Pollination and fruit set:

Fruit and seed characteristics:

Dourojeanni, R.M. (1963). El barreno de los brotes (Hypsipyla grandella) en cedro y caoba. Agronomia, 30, 35–43.

Garwood, N.C. (1983). Seed germination in a seasonal tropical forest in Panama: a community study. Ecological Monographs, 53, 159–181.

Levey, D.J. and Byrne, M.M. (1993). Complex ant-plant interactions: rain forest ants as secondary dispersers and post-dispersal seed predators. Ecology, 74, 1802–1812.

Vázquez-Yanes, C. and Orozco-Segovia, A. (1984). Ecophysiology of seed germination in the tropical humid forests of the world: a review. Pp 37–50 in Physiological ecology of plants in the wet tropics, eds Medina, E., Mooney, H.A. and Vázquez-Yanes, C. Proc. internat. Symposium at Oxatepec and Los Tuxtlas, Mexico, 1983.

Okafor (1980) fr ht (B 14)

Voysey (199) ditto

Genetical variation and conservation:

Bajaj, Y.P.S. (1995). Biotechnology in Agriculture and Forestry, (See Vol 31, Springer, Berlin)

Bawa, K.S. and Ashton, P.S. (1991). Conservation of rare trees in tropical rain forests: a genetic perspective. Pp 62–74 in Genetics and conservation of rare plants, eds Holsinger, D. and Falk, A., UNESCO, Paris, France.

Haines, R.J. and Martin, B.E. (1997). Biotechnology and the sustainable production of tropical timber. Forest Genetics Information, 25, 52–58.

(1991). Balanites aegyptica: a monograph. Publ. 8, School of Agric. and Forest Sciences, University of Wales, Bangor,

(1993). Acacia seyal: a monograph. Publ. 8, School of Agric. and Forest Sciences, University of Wales, Bangor,

Hall, J.B. et al. (1996). Vittelaria paradoxa: a monograph. Publ. 8, School of Agric. and Forest Sciences, University of Wales, Bangor, 105 pp.

Hall, J.B. et al. (1996). Parkia biglobosa: a monograph. Publ. 9, School of Agric. and Forest Sciences, University of Wales, Bangor, 107 pp.

Khasa, P.D. and Dancik, B.P. (1997). Sustaining tropical forest diversity. J. Sustainable Forestry, 5, 217–235.

Leakey, R.R.B and Newton, A.C. (eds) (1994). Tropical trees: the potential for domestication and the rebuilding of forest resources, Institute of Terrestrial Ecology, Symposium 29, Penicuik, Edinburgh, Scotland.

Marin, A., Romero, J.L. and Wright, J.A. (1997). Gene conservation with Podocarpaceae in Colombia. Forest Genetics Information, 25, 10–13, FAO, Rome, Italy.

Newton, A.C., Baker, P., Ramnarine, S., Mésen, F. and Leakey, R.R.B. (1993). Mahogany shoot borer: prospects for control. Forest Ecology and Management,

Newton, A.C, Leakey, R.R.B. and Mésen, F. (1993). (1993). Genetic variation in mahoganies: its importance, capture and utilization. Biodiversity and Conservation, 2, 114–126.

Palmberg-Lerche, C. (1997). Towards a coherent framework for the conservation and sustainable utilization of forest genetic resources. Forest Genetics Information, 25, 15–18.

Patiño Valera, F. (1997). Genetic variation of Swietenia macrophylla and Cedrela odorata in the Neotropics. Forest Genetics Information, 25, 20–32.

Weigel and Nillson (1995) inserting genes for early fl. (D 20, p. 2) from above?

Wright, J.A., Marin, A.M. and Dvorak, W.S. (1996). Conservation and use of the Pinus chuapensis genetic resources in Colombia. Forest Ecology and Management, 88, 283–289.

General sources of info:

(B) refer to 25 Technical Notes on individual species concerning the Management of Forest Seeds, produced by PROSEFOR, CATIE, 7170 Turrialba, Costa Rica, a project supported by DANIDA, Humlebaek, Denmark. These deal with geographical variation, flowering, fruiting, collection, handling, storage and germination. The following were available in September 1998: 1. Guazuma ulmifolia; 2. Virola koschnyi; 3. Gliricidia sepium; 4. Vochysia ferruginea; 3. Albizia guachapele; Vochysia guatamalensis; 7. Cordia alliodora; 8. Tabebuia rosea; 9. Pithecellobium saman; 10. Terminalia amazonia; 11. Pinus caribaea; 12. P. tucunumanii; 13. P. pseudostrobus; 14. P. maximinoi; 15. Erythrina poeppigiana; 16. Hieronyma alchorneoides; 17. Bombacopsis quinata; 18. Alnus acuminata; 19. Leucaena leucocephala; 20. Cupressus lusitanica; 21. Swietenia macrophylla; 22. Pinus oocarpa; 23. Tabebuia chrysantha; 24. Cedrela odorata; 25. Enterolobium cyclocarpum.
(B)

Seed collection and handling:

Stubsgaard, F. (1997). Tree Climbing for seed collection. Technical Note 44, Danida Forest Seed Centre, Denmark.

Willan, R.L. (Ed) (1985). A guide to forest seed handling, with special reference to the tropics. FAO, Rome, Italy and DANIDA Forest Seed Centre, Humlebaek, Denmark.

Seed types and storage ability:

del Zoppo, M., Galleschi, L. and Saviozzi, F. (1998). Long-term storage of Araucaria bidwillii Hook, seeds. Seed Science and Technology, 26, 267–270.

Farnsworth, E.J. and Farrant, J.M. (1998). Reductions in abscisic acid are linked with viviparous reproduction in mangroves. American Journal of Botany, 85, 760–769.

Longman et al. (Triplo seed store - B 33 p. 1)

Ouédraogo, A.S., Poulsen, K. and Stubsgaard, F. (Eds) (1996). Proc. Workshop Improved methods for handling and storage of intermediate/recalcitrant tropical forest tree seeds, June 1995, Humlebaek, Denmark.

Vázquez-Yanes (moist store - B 33, p.3)

Seed dormancy and germination:

Agboola, D.A. (1996). Studies of the effect of seed size on germination and seedling growth of three tropical tree species. J. Tropical Forest Science, 9, 44–52.

Chacon, P., Bustamente, R. and Henriquez, C. (1998). The effect of seed size on germination and seedling growth of Cryptocarya alba (Lauraceae) in Chile. Revista Chilena de Historia Natural, 71, 189–197.

Diallo, I. et al. (1996). Effects of different pretreatments on the germination of Faidherbia albida (Del.) A. Chev. seeds. Internat. Tree Crops J., 9, 31–37.

Flores, J. and Jurado, E. (1998). Germination and early growth traits of 14 plant species native to northern Mexico. Southwestern Naturalist, 43, 40–46.

Otsamo, R. et al. (1996). Effect of nursery practices on seed germination of selected dipterocarp species. J. Tropical Forest Science, 9, 23–24.

Purohit, M. Jamaluddin and Misra, G.P. (1998). Studies

Teketay, D., Granstom, A. and Demel-Teketay (1997). Germination ecology of forest species from the highlands of Ethiopia. Journal of Tropical Ecology, 13, 805–831.

Tietema, T., Merkesdal, E. and Schroten, J. (1992). Seed germination of indigenous trees in Botswana. African Centre for Technology Studies, P.O. Box 45917, Nairobi, Kenya.

Woods, P.V., Pesseta, O. and Webb, M.J. (1998). Effectiveness of organic potting media for raising mahogany (Swietenia macrophylla) seedlings in Western Samoa. J. Tropical Forest Science, 10, 552–560.

Tetrazolium tests

Seed supplies:

Kindt, R. et al. (1977). Tree Seed Suppliers Directory, International Council for Research in Agroforestry (ICRAF), P.O. Box 30677, Nairobi, Kenya. (Lists sources of seeds, and of inoculum for closely associated micro-organisms - see sheets C 30–32 and C 61 in Manual 3).

Supplies of nursery materials:

Brothers, C.T. and Lapierre, R.M. (1998). Coming to a root system near you. American Nurseryman, 188 (9), 89–93. (“Root Right” pots have copper salt in the container wall to control root growth)

Stuewe and Sons, Inc., 2290 S.E. Kiger Island Drive, Corvallis, OR 97333-9461, USA. Tel: (800) 553–5331; Fax: (541) 754–6617. (Free catologue of seedling containers.)

(See also sheet A 63 in Manual 1.)

General nursery information:

Anonymous (1996). Using pesticides: a complete guide to safe, effective spraying. British Crop Protection Council, Bracknell, England.

Anonymous (1997). People's Forestry, Andhra Pradesh Forestry Project, Aranya Bhaven, Hyderabad-500 004, India.

CATIE (1996). Manejo de semillas forestales. Guia technica para el extensionista forestal. Manual Téchnico no. 27, CATIE, 7170 Turrialba, Costa Rica.

Debergh, P.C. and Zimmerman, R.H. (Eds) (1991). Micropropagation. Technology and Application, Kluwer Academic Publishers, Dordrecht, Netherlands.

Gera, M., Gera N, Sharma, S. and Bhandari, A.S. (1998). Improved seedling quality of polybag pots - use of mounted angle iron beds. Indian Forester, 124, 116–121.

Kubota, C., Fujiwara, K., Kitaya, Y. and Kozai, T. (1997). Recent advances in environmental control in micropropagation. Pp 153–169 in Plant Production in Closed Ecosystems, eds Goto, E., Kurata, K., Hayashi, M. and Sasa, S., Kluwer Academic Publishers, Dodrecht, Netherlands.

Gouin, F.R. (1998). Commercial composting systems. HortScience, 33, 932–933.

Kulkarni, N. and Joshi, K.C. (1998). Insect pests of forest tree seeds: their economic importance and control measures. J. Tropical Forest Science, 10, 438–455.

Lindquist, R.K. (1998). Attacking aphids. Greenhouse Grower, 16, 144, 146, 148.

Lu, X, Malajczuk, N. and Dell, B. (1998). Mycorrhiza formation and growth of Eucalyptus globulus seedlings inoculated with spores of various ectomycorrhizal fungi. Mycorrhiza, 8, 81–86.

Munyanziza, E., Kuyper, T.W. and Oldeman, R.A.A. (1998). Iron deficiency in Pterocarpus angolensis nursery seedlings: symptoms and cure. J. Tropical Forest Science, 10, 292–296.

Richards, E.M. (1991). The forest ejidos of south-east Mexico: a case study of community based sustained yield management. Commonwealth Forestry Review, 70, 290–311.

Shrivastava, R., Nanhorya, R. and Upadhyaya, J.K. (1998). Selection of proper potting mixture for root trainer of Eucalyptus hybrid. Indian Forester, 124, 502–510.

Thomas, M.B., Spurway, M.I. and Smith, B.E. (1998). A review of factors influencing container-media temperatures. International Plant Propagators' Society, Combined Proceedings 1997, 47, 125–131.

For more information:

(A) see sheets C 61 in Manual 3 and D 71 in Manual 4;

(B) refer to 25 Technical Notes on individual species concerning the Management of Forest Seeds, produced by PROSEFOR, CATIE, 7170 Turrialba, Costa Rica, a project supported by DANIDA, Humlebaek, Denmark. These deal with geographical variation, flowering, fruiting, collection, handling, storage and germination. The following were available in September 1998: 1. Guazuma ulmifolia; 2. Virola koschnyi; 3. Gliricidia sepium; 4. Vochysia ferruginea; 3. Albizia guachapele; Vochysia guatamalensis; 7. Cordia alliodora; 8. Tabebuia rosea; 9. Pithecellobium saman; 10. Terminalia amazonia; 11. Pinus caribaea; 12. P. tucunumanii; 13. P. pseudostrobus; 14. P. maximinoi; 15. Erythrina poeppigiana; 16. Hieronyma alchorneoides; 17. Bombacopsis quinata; 18. Alnus acuminata; 19. Leucaena leucocephala; 20. Cupressus lusitanica; 21. Swietenia macrophylla; 22. Pinus oocarpa; 23. Tabebuia chrysantha; 24. Cedrela odorata; 25. Enterolobium cyclocarpum. (maybe shorten if in B 51)

(C) Technical Notes and other publications (many available free) of the Danish Forest Seed Centre (DANIDA), Krogerupvej 21, DK-3050 Humlebaek, Denmark (Fax: +45 49 16 02 58).

When would one need to assess germination accurately?

In several different circumstances, including:

1. checking the date when germination started in a particular seed-lot;
2. comparing the rates and percentages of germination of different seed-lots;
3. doing a standard germination test (B 48); or
4. recording the progress of germination in the various treatments in a seed experiment.

Wouldn't those involve differing procedures?

Yes, they would. For instance:

1. could just involve the noting of the date on a record sheet (C 65 in Manual 3);
2. might be done by a series of estimates of the numbers germinating on successive dates;
3. would require actual counts and a calculation of the percent germinated; and
4. might need an appropriate method to be chosen for the particular situation.

But isn't it easy to see which seeds have germinated?

Yes and no. In practical terms, one can see whether there are many, few or no seedlings coming up after a reasonable period of time; but For research purposes, one usually has to decide on a standard that is:

1. reasonably easy to do in the time available;
2. unbiased and sufficiently accurate for the purposes; and often
3. possible without damaging the germinating seedlings.

How can I avoid bias?

1. By choosing a germination environment that is as uniform as possible;
2. Through mixing up the batch of seeds and sowing them as evenly as possible;
3. By randomising the different batches or treatments to be compared;
4. Through taking samples that can give a reliable estimate or count of germination (C 55 in Manual 3); and
5. By choosing a ‘fair’ criterion of germination.

What do you mean by that?

Suppose, for example, that you were comparing a thicker and a thinner seed covering (B 43). If you simply recorded the germinating seeds as they became visible, there would be an inbuilt bias towards those under a shallow covering.

A more complex decision might for instance be required when comparing germination in the light and the dark, since young shoots usually show much greater elongation in darkness.

Are there any ways of avoiding such problems?

1. Germinating the seeds in petri dishes or Copenhagen tanks, where they are not covered with soil, and so the splitting of the seed coat as the root emerges can be seen;
2. Digging sample seedlings out and washing them carefully; or
3. Delaying the assessment until most or all the germinating seedlings are clearly visible.

However, each of these solutions may involve other problems: of cost, waste of valuable seedlings or loss of valuable results in an experiment.

Which is the quickest way of estimating germination percent?

By scoring the amounts of germination visible on an appropriate date. This can give rapid, useful results if it is done properly (C 68 in Manual 3, A 65 in Manual 1), and may also indicate whether or not it is worthwhile doing a more detailed assessment.

What categories could I choose for scoring germination?

For how many seedlings are present, you might choose for example: 0 = none; 1 = very few; 2 = few; 3 = moderate number; 4 = moderately large number; 5 = large number; 6 = very large number; and 8 = more or less fully stocked.

For how fast the seedlings are developing, you would need to decide on a set of recognisable stages (C 68-D), label a ‘standard seedling’ at each stage, and complete the scoring within a few hours (since the seedlings may be growing fast).

If I am taking samples, how many and how large should they be?

This will vary according to the number of comparisons to be made and how many seeds were sown. As a first guide-line, consider how much the estimate of percent germinated would alter if one more seedling had succeeded. Thus, if 20 seeds were sampled, the germination percent would increase by 5%, but in a sample of 50 seeds, it would only alter by 2%.

So it depends on how accurate I need the result to be?

Yes, that's right. Remember also that the likelihood of statistically significant differences (C 69-G in Manual 3) declines rapidly with samples of less than ten.

How should I select samples?

1. Randomly across the entire seed bed or from all the seed trays (C 69-B);
2. Neither avoiding the bare patches nor favouring parts with the best germination; and
3. Avoiding unnecessary damage to the remaining seedlings.

How often is it worth while assessing germination?

Sometimes a single observation is enough, when most or all the seedlings have emerged. Often it is useful to do it 3 times; for example:

1. recording the date when the first signs of germination are visible;
2. scoring any differences between batches or treatments, on a day when they are clearly seen; and
3. estimating or counting the final number of seedlings produced;

Occasionally more detailed assessments may be needed, for instance:

1. if germination is spread over a long time;
2. when the rate of germination is being studied in a seed experiment.

What about seeds or seedlings that are damaged?

Try and distinguish between:

1. seedlings that were damaged after germinating, which could be counted as ‘germinated’; and
2. seeds that never germinated properly, which might be regarded as ‘not germinating’, or as a separate category.

Supposing I am doing a very accurate count?

In that case you might:

1. assess the whole batch or experiment, rather than using sampling;
2. record at least 5 times, in order to make graphs of the rates of germination;
3. dig up the remaining seeds at the end, if they are large enough to find, to check your numbers with the totals sown.

What about analysing the results?

You could do this:
Either by chi-square analysis of the numbers germinated and ungerminated, with Yates's Correction (C 68-E in Manual 3);
Or by analysis of variation (C 67, C 69-F), following a square-root or log transformation for scores, or an arcsin transformation of percentages (C 69-O).