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Variability in seed dormancy and germination potential in Desmodium desv. (Leguminosae)^*

Elizabeth Ann Veasey^I; Paulo Sodero Martins^II

^ISeção de Agronomia de Plantas Forrageiras, Divisão de Nutrição Animal e Pastagens, Instituto de Zootecnia, Caixa Postal 60, 13460, Nova Odessa, SP, Brasil
^IIInstituto de Genética, Escola Superior de Agricultura "Luiz de Queiróz", Caixa Postal 83, 13400, Piracicaba, SP, Brasil. Send correspondence to P.S.M.

ABSTRACT

A study was conducted in order to compare the germination potential and the level of dormancy of four native Brazilian Desmodium species, D. barbatum, D. discolor, D. incanum and D. tortuosum (two populations). In the first trial, scarified and nonscarified seeds of each species were exposed to constant and alternating temperatures, over a range of 15 to 45°C, and of 15-30, 20-35, 25-35, and 25-40°C, respectively. D. discolor and D. incanum showed the lowest dormancy and D. barbatum the highest at all temperatures. Nonscarified seeds had a higher dormancy breaking rate when subjected to the highest temperatures, up to a maximum at 40°C. Scarified seeds of all species germinated at high percentages, 20 to 40°C. Germination at 15°C was low, especially for D. barbatum and D. incanum. In the second trial, families within these species were exposed to 40°C for the germination tests. The coefficients of intraspecific genetic variation and genotypic determination were estimated. The results showed significant differences among families of D. discolor, D. incanum, and D. tortuosum (population 2) for seed dormancy. These three species also had a higher coefficient of genotypic determination (> 84%), indicating the possibility of selection for seed dormancy. D. tortuosum (population 2) had the highest coefficient of intraspecific genetic variation, which implies that a higher proportion of the observed variation was genetic rather than environmental. These results indicate the possibility of selection for either a higher or a lower level of dormancy within Desmodium species.

Keywords: Seed dormancy; Germination; Desmodium; Leguminosae

REFERENCES

Ararat, R.J.E. and Malaver, H.L.V. (1975). Respuestas de Ias semillas de cinco especies de leguminosas forrageras a tratamientos para germinacion. Acra Agron. 25: 1-12.

Azevedo, A.M.G. (1981). 0 gênero Desmodium Desv. no Brasil - Considerações taxonômicas. Masters Thesis, UNICAMP, Campinas.

Barriga, J.P. (1979). Autoecologia de Stylosanthes humilis HBK - avaliação da variabilidade morfológica e estudos da biologia da semente. Masters Thesis, ESALQ/USP, Piracicaba.

Baskin, J.M. and Baskin, C.C. (1973). Plant population differences in dormancy and germination characteristics of seeds; heredity or environment? Am. Midi. Nat. 90: 493-498.

Baskin, J.M. and Baskin, C.C. (1985). The annual dormancy cycle in buried weed seeds: a continuum. BioScience 35: 492-498.

Battistin, A. (1981). Estudo biossistemático de diferentes taxons do gênero Stylosanthes Sw. (Leguminosae - Papilionoideae). Masters Thesis, ESALQ/USP, Piracicaba.

Bewley, J.D. and Black, M. (1985). Seeds: physiology of development and germination. Plenum Press, New York.

Bryan, W.W. (1969). Desntodium intortum and Desntodium uncinatum. Herb. Abstr. 39: 183-191. CIAT (1984). Annual Report 1984. Tropical Pastures Program. CIAT, Cali.

Derieux, M. (1971). Comportement de quelques légumineuses fourragères em Guadeloupe. Fourrages 45: 93-132.

Dias Filho, M.B. and Serrão, E.A.S. (1984). Avaliação da adaptação de leguminosas forrageiras tropicais na Amazônia Oriental brasileira. In: Simpósio do Trópico Úmido, 1, Belém, 1984. Resumos. (Documentos, EMBRAPA/CPATU, 31).

Frost, R.A. and Cavers, P.B. (1975). The ecology of pigweeds (Amaranthus) in Ontario. I. Interspecific and intraspecific variation in seed germination among local collections of A. powellii and A. retroflexus. Can. J. Bot. 53: 1276-1284.

Hoehne, F.C. (1921). Leguminosas forrageiras do Brasil. I. Meibomia, Moehr. (Desmodium, Desv.).Anex. Mems. Inst. Butantan Secc. Bot. 1: 1-54.

Hooper, J.R. (1978). Studies on the germination and emergence of Florida beggarweed (Desmodium tortuosum (Sw.)) and its competition with soybeans (Glycine max (L.) Merr.) and peanuts (Arachis hypogaea L.). Diss. Abstr. Int. - B 39: 1575.

Imrie, B.C., Jones, R.M. and Kerridge, P.C. (1983). Desmodium. In: The Role of Centrosema, Desmodium, and Stulosanthes in Improving Tropical Pastures (Burt, R.L., Rotar, P.P., Walker, J.L. and Silvey, M.W., eds.). Westview Press, Boulder, Colorado.

Jain, S.K. (1982). Variation and adaptive role of seed dormancy in some annual grassland species. Bot. Gaz. 143: 101-106.

Jana, S., Acharya, S.N. and Naylor, J.M. (1979). Dormancy studies in seed of Avena fatua. 10. On the inheritance of germination behaviour. Can. J. Bot. 57: 1663-1667.

Jana, S. and Naylor, J.M. (1980). Dormancy studies in seed of Avena fatua. 11. Heritability for seed dormancy. Can. J. Bot. 58: 91-93.

Labouriau, L.G. (1970). On the physiology of seed germination in Vicia graminea Sm. - I. Anais Acad. Bras. Ciênc. 42: 235-262.

Lenné, J.M. and Stanton, J.M. (1990). Diseases of Desmodium species - a Review. Trop. Grassi. 24:.1-14.

McKeon, G.M. and Mott, J.J. (1982). The effect of temperature on the field softening of hard seed of Stylosanthes humilis and S. hamata in a dry monsoonal climate. Austr. J. Agric. Res. 33: 75-85.

Mott, J.J., McKeon, G.M., Gardener, C.J. and Mannetje, E.L. (1981). Geographic variation in the reduction of hard seed content of Stylosanthes seeds in the tropics and subtropics of Northern Australia. Aust. J. Agric. Res. 32: 861-869.

Naylor, J.M. (1983). Studies on the genetic control of some physiological processes in seeds. Can. J. Bot. 61: 3561-3567.

Naylor, J.M. and Jana, S. (1976). Genetic adaptation for seed dormancy in Avena fatua. Can. J. Bot. 54: 306-312.

Oliveira, E.M.P. (1979). Avaliação da variabilidade de caracteres morfológicos e agronômicos em populações de Desmodium uncinatum (Jacq.) DC. e Desmodium intortum (Mill.) Urb. Doctoral Thesis, ESALQ/USP, Piracicaba.

Pontes, O.F.S. and Martins, P.S. (1982). Determinação de parâmetros genéticos relacionados à dormência de sementes em soja perene (Glycine wightii). O Solo 74: 13-17.

Popinigs, F. (1977). Fisiologia da semente. Ministério da Agricultura/AGIPLAN, Brasília.

Probert, R.J., Smith, R.D. and Birch, P. (1985). Germination responses to light and alternating temperatures in European populations of Dactylis glomerata L. - I. Variability in relation to origin. New Phytol. 99: 305-316.

Quinlivan, B.J. (1961). The effect of constant and fluctuating temperatures on the permeability of the hard seeds of some legume species. Aust. J. Agric. Res. 12: 1009-1022.

Ouinlivan. B.J. (1971). Seed coat im^permeabilit^y in le^gumes. J. Aust. Inst. Aeric. Sci. 37: 283-295.

Reis, M.S. (1984). Autoecologia de diferentes espécies de Stylosanthes Sw.: análise da alocação de energia e estudos da biologia da semente. Doctoral Thesis, ESALQ/USP, Piracicaba.

Rolston, M.P. (1978). Water impermeable seed dormancy. Bot. Rev. 44: 365-3%.

Skerman, P.J. (1977). Tropical forage legumes. FAO Plant Production and Protection Series, 2, Rome.

Sokal, RR. and Rohlf, F.J. (1969). Biometry. The principles and practice of statistics in biological research. W.H. Freeman and Company, San Francisco.

Steel, R.G.D. and Torrie, J.H. (1980). Principles and procedures of statistics. (2nd. ed.) McGraw-Hill, New York.

Vieira, I.C.G. (1987). Distribuição fracionária de energia e biologia da semente de Stylosanthes angustifolia Vog. (Leguminosae - Papilionoideae). Masters Thesis, ESALQ/USP, Piracicaba.

Younge, O.R., Plucknett, D.L. and Rotar, P.P. (1964). Culture and yield performance of Desmodium intortum and D. canum in Hawaii. Tech. Bull. Hawaii Agric. Exp. Stn. 59.

* Part of a thesis submitted by E.A.V. to the Instituto de Genética, ESALQ-USP, in partial fulfillment of the requirements for the Masters degree.