EARLY GROWTH AND SEEDLING MORPHOLOGY OF SPECIES OF Sesbania Scop. (Leguminosae, robinieae)

DESENVOLVIMENTO INICIAL E CARACTERIZAÇÃO DAS PLÂNTULAS DE ESPÉCIES DE Sesbania SCOP. (LEGUMINOSAE, ROBINIEAE)

EARLY GROWTH AND SEEDLING MORPHOLOGY OF SPECIES OF Sesbania SCOP. (LEGUMINOSAE, ROBINIEAE)¹

Elisabeth Ann Veasey²; Marta Organo Negrão³; Paulo Sodero Martins^4,5; Gerhard Bandel^4*

²Instituto de Zootecnia, C.P. 60 - CEP: 13460-000 - Nova Odessa, SP.

³Pós-Graduanda do Depto. de Genética - ESALQ/USP. (In memorian)

⁴Depto. de Genética - ESALQ/USP, C.P. 83 - CEP: 13400-970 - Piracicaba, SP.

⁵In memorian

*e-mail: [e-mail]

ABSTRACT: The objective of this study was to characterize 17 accessions of Sesbania, representing S. exasperata, S. grandiflora, S. sesban, S. tetraptera and S. virgata at the seedling stage, and to evaluate the initial development during the first two months after planting. The trial was conducted in a greenhouse in a randomized block design, with 4 replications and 5 plants per plot. The traits recorded were: plant height (PH), from four observations at 15-day intervals, at 17, 32, 47 and 62 days after planting; length of hypocotyl (LH) and epicotyl (LEP); length (LE1) and width (WE1) of the first eophyll; and number of leaflet pairs of the second metaphyll (NLP), evaluated 17 days after planting. Univariate analyses of variance were performed, estimating the genetic parameters: coefficient of genotypic determination (b) and of genetic variation (CVg). Cluster analysis was also obtained, using the average Euclidean distance and Unweighted pair group method of arithmetic average (UPGMA) method. At 17 days after planting, S. exasperata presented the highest PH, followed by S. virgata. At 62 days after planting, S. sesban registered the highest PH. Length of hypocotyl displayed inter but not intraspecific variation. The characters LEP, LE1, WE1 and NLP showed both inter and intraspecific variation. Cluster analysis indicated the existence of 7 groups, separating the species and revealing intraspecific variation as well. The occurrence in low frequencies of two unifoliolate opposite eophylls for some species was observed, as well as bi- or trifoliolate first eophylls for one of the S. sesban accessions. These informations are basic for the selection of traits to be utilized for characterization and differentiation of Sesbania germplasm at the juvenile phase.

Key words: Sesbania, seedling morphology, genetic variation, early growth

DESENVOLVIMENTO INICIAL E CARACTERIZAÇÃO DAS PLÂNTULAS DE ESPÉCIES DE Sesbania SCOP. (LEGUMINOSAE, ROBINIEAE)

RESUMO: Este estudo teve como objetivo caracterizar 17 acessos de Sesbania, representando as espécies S. exasperata, S. grandiflora, S. sesban, S. tetraptera e S. virgata no estágio de plântula, avaliando também o desenvolvimento inicial nos primeiros dois meses após o plantio. O ensaio foi instalado em casa-de-vegetação, em blocos casualizados com 4 repetições e 5 plantas por parcela. Avaliaram-se os seguintes caracteres: altura da planta (AP) em 4 avaliações, espaçadas de 15 dias, aos 17, 32, 47 e 62 dias após o plantio; comprimento do hipocótilo (CH) e do epicótilo (CEP); comprimento (CE1) e largura (LE1) do eófilo 1; e número de pares de folíolos do metáfilo 2 (NPF). A primeira AP e os demais caracteres foram avaliados aos 17 dias do plantio. Foram realizadas análises de variância univariada, estimando-se os parâmetros genéticos: coeficiente de determinação genotípica (b) e de variação genética (CVg), e uma análise de agrupamento, usando distância Euclideana média e método UPGMA (Unweighted pair group method of arithmetic average). Aos 17 dias do plantio, S. exasperata apresentou maior AP, seguida de S. virgata. Aos 62 dias do plantio, S. sesban apresentou a maior AP. O caráter CH apresentou variação inter mas não intraespecífica. Já os caracteres CEP, CE1, LE1 e NPF mostraram variação tanto inter como intraespecífica. A análise de agrupamento indicou a existência de 7 grupos, separando as espécies e mostrando variação intraespecífica. Foi também observada a ocorrência, em baixas freqüências, de dois eófilos unifoliolados e opostos para algumas espécies, bem como a ocorrência de eófilos nº 1 bi- ou trifoliolados para um dos acessos de S. sesban. Estas informações são básicas para a escolha de caracteres a serem utilizados na fase juvenil para a diferenciação e caracterização de germoplasma de Sesbania.

Palavras-chave: Sesbania, morfologia de plântulas, variação genética, desenvolvimento inicial

INTRODUCTION

The genus Sesbania Scopoli is a member of the Leguminosae family, subfamily Papilionoideae and Robinieae tribe (Monteiro, 1984). This genus is represented by 60 species distributed in tropical and subtropical frost-free regions to the fringes of temperate zones bordering the subtropics. The altitudinal range of the genus varies from sea level to 2000m, in regions with rainfall distribution between 500 and 2000mm. Sesbania species are more commonly found in regions with alternating wet and dry periods than in those with evenly distributed rainfall (Evans, 1990).

Sesbania species are generally annual or biennial, some are perennial shrubs of short duration and few species are truly perennial. The high nitrogen fixation of these species results in rapid growth, even in soils deficient in nitrogen, and permits its utilization as green manure, intercropping and ground cover, and in agroforestry and wood production systems (Ndoye et al., 1990).

The seedling stage is considered a critical phase in the life cycle of an individual. Seeds and seedlings may reveal much information about the ecological and evolutionary history of any group of higher plants (Duke & Polhill, 1981). Seedlings are generally accepted as an important material for the classification of the Leguminosae family (Sousa & Sousa, 1981). Observations of Sesbania seedlings, associated with their taxonomy, have been carried out by various authors (Gillett, 1963, Sousa & Sousa, 1981, Leitão et al., 1982, Monteiro, 1984). The principal characteristics observed in the seedlings of the Sesbania genus were described by Monteiro (1984) as being: (1) epigeal germination with a long hypocotyl and short epicotyl; (2) foliaceous cotyledons, very short petiolate and escaping from the testa; (3) first eophyll simple, resembling the cotyledons; (4) second eophyll paripinnate with fewer leaflets than the metaphylls; (5) epicotyl longer than the internode between the first metaphylls.

Veasey et al. (1997) studied the early growth and nodulation of Sesbania species, as well as other leguminous shrub species belonging to the genera Cajanus, Codariocalyx, Cratylia, Desmanthus, Desmodium and Leucaena, with Sesbania sesban and S. exasperata presenting the highest plant heights and top growth dry weights (P<0.05) at 56 days after sowing, showing the rapid initial growth of these species.

The objective of this study was to evaluate the early growth, through the measurement of seedling height during the first two months after planting, as well as to characterize and differentiate 17 accessions of Sesbania at the seedling stage, estimating genetic parameters associated with morphological characteristics.

MATERIALS AND METHODS

Seventeen accessions, representing the species Sesbania sesban, S. virgata and S. grandiflora (perennials), plus S. exasperata and S. tetraptera (annuals), were evaluated. Identification and origins are presented in TABLE 1. These species belong to different subgenera that, originally, occur in distinct geographical areas: subgen. Sesbania (S. exasperata, S. sesban), originating from both the Old and New World; subgen. Daubentonia (S. virgata), from the Americas; subgen. Agati (S. grandiflora), from Australia and Asia; and subgen. Pterosesbania (S. tetraptera), originating from Africa (Monteiro 1984).

The experiment was carried out at the Genetic Department of Escola Superior de Agricultura "Luiz de Queiroz"/University of São Paulo, in Piracicaba, SP, from October to December 1994. The maximum and minimum temperatures during the experimental period were 31.5 and 19.0ºC (mean of three months). The maximum daily insolation were 12.6, 13.2, and 13.5 hours for October, November and December, respectively.

The experiment was carried out in the greenhouse, in 18x20cm plastic bags filled with soil whose analysis presented the following composition: 0.50, 15.0 and 3.12 meq/100cm3 of potassium, calcium and magnesium, respectively, 108.7 mg/cm³ phosphorus, 4.47% organic matter and pH 5.4. A randomized block design was utilized with four replications and five plants per plot. Data were obtained from individual seedlings. The characteristics evaluated were: plant height (PH) in four evaluations at 15-day intervals, length of hypocotyl (LH) and length of epicotyl (LEP), length (LE1) and width (WE1) of eophyll 1, and number of leaflet pairs of metaphyll 2 (NLP). Plant height, length and width measurements were made with a ruler. The length of eophyll 1 refers to the longitudinal distance between the apex and the base, while the width measurement was taken at the point of the greatest amplitude. The first PH and the other characters were evaluated 17 days after planting. The rate of occurrence of two opposite and unifoliolated eophylls, and of bi- or trifoliolated eophylls 1 was also recorded.

Univariate analysis of variance was carried out estimating the genetic parameters: coefficient of genotypic determination (b) and genetic variation coefficient (CVg) (Vencovsky & Barriga, 1992). Cluster analysis was also performed using Euclidean distance as a measure of dissimilarity and Unweighted pair group method of arithmetic average method (UPGMA) (Cruz & Regazzi, 1994), utilizing the average of the characters LH, LEP, LE1, WE1, NLP, and PH 62 days after planting.

RESULTS AND DISCUSSION

The Sesbania seedlings evaluated presented a phaneroepigeal type development with foliar cotyledons and alternate eophylls with the first eophyll unifoliolate (Figure 1A), in accordance with the classification of Duke & Polhill (1981), and the observations of Sousa & Sousa (1981), Leitão Filho et al. (1982) and Monteiro (1984). However, the occurrence of seedlings with two opposite and unifoliolate eophylls was observed for the species S. grandiflora (Figure 1B), S. exasperata and S. sesban (NO 1030) at frequencies of 2.1, 1.6 and 1.6%, respectively. These findings corroborate the observations of DeCandolle cited by Monteiro (1984), mentioning the species S. aculeata and Sesbania sp. as possessing opposite eophylls.

Figura 1 - A) Seedling of S. exasperata with unifoliolate eophyll 1; B) seedling of S. grandiflora with two unifoliolate and opposite eophylls; C) seedling of S. sesban (NO 934) wtih trifoliolate eophyll 1.

Another interesting observation in this study was the occurrence, in relatively high frequencies, of seedlings presenting the first eophyll bifoliolate (20%) or trifoliolate (12%) for one of the accessions of S. sesban (NO 934) (Figure 1C). The other accessions of S. sesban did not present this characteristic. The occurrence of a trifoliolate eophyll 1 was described by DeCandolle, cited by Monteiro (1984) for S. punicea. In the present study, however, S. virgata, belonging to the same subgenus of S. punicea, subgenus Daubentonia, invariably displayed unifoliolate first eophylls. Preliminary studies, including the observation of seedlings of different accessions of S. punicea also confirmed the occurrence of unifoliolate first eophylls for this species.

A differential behavior was observed in relation to plant height (PH) from the seedling phase up to two months (62 days after planting) (Figure 2). Seventeen days after planting, S. exasperata presented the greatest PH, followed by S. virgata. At 62 days, however, S. sesban accessions, except for nº 5 (NO 934), presented the highest PH. S. grandiflora registered the smallest PH in all evaluations.

Figure 2
- Plant height averages recorded at 17 (PH1), 32 (PH2), 47 (PH3) and 62 (PH4) days after planting, for 17 accessions of Sesbania: S. exasperata (1-3); S. grandiflora (4); S. sesban (5-10); S. tetraptera (11); S. virgata (12-17). Plant heights with the same letters do not differ from each other at 5% level (Tukey test).

The average highest PH, for the accessions of S. sesban at 62 days after planting, may be reflecting greatest growth vigor, important for the initial establishment of the plants. This species possesses great potential as a forage plant (Gutteridge, 1994), presenting rapid initial growth, when compared to other species of tropical shrub legumes (Maasdorp & Gutteridge, 1986, Bisht & Toky, 1989). S. exasperata, described as perennial by Leitão Filho et al. (1982) and as annual by other authors (Evans, 1990), exhibited the greatest PH at 17 days, in addition to the second highest PH in all the other evaluations, revealing good initial development. Veasey et al. (1997) observed higher plant height and top growth dry weight at 56 days after sowing, for S. sesban and S. exasperata, when compared with other species of Sesbania, Cajanus, Codariocalyx, Cratylia, Desmanthus, Desmodium and Leucaena.

The smallest PH for all the evaluations for S. grandiflora, can be associated with the greatest perenniality of this species, which may last 20 years or more, while S. sesban may last up to 5 to 10 years (Evans, 1990). In a field trial, S. grandiflora presented a rather slow early growth, when compared to other species of Sesbania (Veasey, 1998).

Intraspecific variation was observed for PH (Figure 2). Accession nº 5 of S. sesban presented the lowest PH (P<0.05) at all evaluations, compared with the other accessions of this species. On the other hand, accession nº 13 of S. virgata presented the highest PH at all evaluations among the S. virgata accessions.

The length of hypocotyl (LH) displayed interspecific variation, but not intraspecific, clearly differentiating the species, in contrast with the length of epicotyl (LEP), which presented inter and intraspecific variation (Figure 3). The estimated values for the coefficient of genotypic determination (b) were 0.6786 and 0.7693 for LH and LEP, respectively (TABLE 2), indicating that these characters might suffer modifications when submitted to natural selection pressures. The annual species S. tetraptera produced the highest LH (4.84 cm), and one of the smallest LEP (1.49 cm), similar to S. grandiflora (1.26 cm). S. grandiflora registered the smallest LH (1.94 cm).

Figure 3
- Length of hypocotyl (LH) and epicotyl (LEP) of 17 accessions of Sesbania: S. exasperata (1-3); S. grandiflora (4); S. sesban (5-10); S. tetraptera (11); S. virgata (12-17). Averages with the same letters do not differ from each other at 5% level (Tukey test).

The general description of seedlings of the genus Sesbania as having a long hypocotyl and a short epicotyl (Monteiro, 1984) is suitable for the species S. tetraptera and S. grandiflora. However, this description was not confirmed in this study for S. exasperata, S. sesban and S. virgata, where epicotyls were observed to be longer than hypocotyls, or of the same magnitude (Figure 3).

Characters LE1, WE1 and NLP also presented inter and intraspecific variation, with values of 0.4678, 0.9457 and 0.6367 for b and 10.58, 43.56 and 6.71% for CVg, respectively (TABLE 2). Character WE1 showed the greatest interspecific variation, reflected in the high b (0.9457) and CVg (43.56%) values, indicating the existence of sufficient genetic variability upon which, natural selection could operate, giving rise to plants with higher or lower WE1 values. S. virgata presented the highest WE1, followed by S. grandiflora (Figure 4).

Figure 4
- Length (LE1) and width (WE1) of eophyll 1, and number of leaflet pairs of metaphyll 2 (NLP) of 17 accessions of Sesbania: S. exasperata (1-3), S. grandiflora (4), S. sesban (5-10), S. tetraptera (11), S. virgata (12-17). Averages with the same letters do not differ from each other at 5% level (Tukey test).

Intraspecific variation can be observed in Figures 3 and 4, with accession nº 13 (NO 1289) of S. virgata presenting the highest values for LE1 and WE1 (P<0.05), as well as for LEP in relation to the other accessions of this species. On the other hand, accession nº 5 (NO 934) of S. sesban showed the smallest LE1 (P<0.05), as well as the highest number of leaflet pairs (NLP) of metaphyll 2 (7.09 vs 5.69, on average), when compared to the other S. sesban accessions. The highest NLP of metaphyll 2 was presented by S. tetraptera (9.59) followed by S. grandiflora (7.66).

The cluster analysis classified the accessions in seven groups, showing inter and intraspecific variation, separating the species (Figure 5). The groups formed were: I - S. tetraptera (11), II - S. virgata (13), III - S. grandiflora (4), IV - S. sesban (6-10), V - S. sesban (5), VI - S. virgata (12, 14-17), and VII - S. exasperata (1-3). Accession nº 5 (NO 934) of S. sesban was classified in a separate group, as it presented low PH and LE1, and high NLP. The same was observed for accession nº 13 (NO 1289) of S. virgata, classified in a distinct group for presenting the highest PH in all evaluations and greatest LEP, LE1 and WE1 as previously discussed.

Figure 5
- Dendrogram obtained by the cluster analysis, using the average Euclidean distance as a measure of dissimilarity and the UPGMA method. Groups: I - S. tetraptera (11); II - S. virgata (13); III - S. grandiflora (4); IV - S. sesban (6-10); V - S. sesban (5); VI - S. virgata (12, 14-17); and VII - S. exasperata (1-3).

CONCLUSIONS

A differential behavior was observed in relation to plant height (PH) from the seedling phase until two months after planting. S. exasperata presented the highest PH at 17 days, followed by S. virgata, and S. sesban showing the highest PH at 62 days after planting. Inter and intraspecific variation was observed for characters: plant height, length of epicotyl, length and width of the first eophyll, and number of leaflet pairs of the second metaphyll. The length of hypocotyl character showed only interspecific variation.

ACKNOWLEDGMENTS

The authors wish to thank Prof. Dr. Reinaldo Monteiro of Universidade Estadual Paulista, Campus of Rio Claro, SP, for identification of the Sesbania species and for reviewing the manuscript; Instituto de Zootecnia, Nova Odessa, SP, and Companhia do Vale do Rio Doce, Linhares, ES, for providing the seed; and the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) for financial support.

Recebido para publicação em 19.01.98

Aceito para publicação em 06.04.98

• BISHT, R.P.; TOKY, O.P. Production of biomass in Leucaena leucocephala (Lam.) de Wit and Sesbania sesban (L.) Merr. under a short rotation cycle. Nitrogen Fixing Tree Reseach Reports, v.7, p.1-2, 1989.
• CRUZ, C.D.; REGAZZI, A.J. Modelos biométricos aplicados ao melhoramento genético. Viçosa: Universidade Federal de Viçosa, 1994. cap.6, p.277-314: Divergęncia genética.
• DUKE, J.A.; POLHILL, R.M. Seedlings of Leguminosae. In: POLHILL, R.M.; RAVEN, P.H. (Ed.) Advances in legume systematics: part II. Kew: Royal Botanic Gardens, 1981. p.941-949.
• EVANS, D.O. What is Sesbania? Botany, taxonomy, plant geography, and natural history of the perennial members of the genus. In: MACKLIN, B.; EVANS, D.O. (Ed.) Perennial Sesbania Species in Agroforestry Systems Waimanalo: Nitrogen Fixing Tree Association, 1990. p.5-16.
• GILLETT, J.B. Sesbania in Africa (excluding Madagascar) and southern Arabia. Kew Bulletin, v.17, p.91-159, 1963.
• GUTTERIDGE, R.C. The perennial Sesbania species. In: GUTTERIDGE, R.C.; SHELTON, H.M. (Ed.) Forage tree legumes in tropical agriculture Wallingford: CAB INTERNATIONAL, 1994. cap. 2/3, p.49-64.
• LEITĂO FILHO, H.de F ; ARANHA, C.; BACCHI, O. Plantas invasoras de culturas. Săo Paulo: HUCITEC, 1982. v.2.
• MAASDORP, B.V.; GUTTERIDGE, R.C. Effect of fertilizer and weed control on the emergence and early growth of five leguminous fodder shrubs. Tropical Grasslands, v.20, p.127-134, 1986.
• MONTEIRO, R. Taxonomic studies on Brazilian legumes with forage potential: Sesbania, Lupinus. St. Andrews, 1984. 446p. Tese (Ph.D.)- St. Andrews University.
• NDOYE, I.; TOMEKPE, K.; DREYFUS, B.; DOMMERGUES, Y.R. Sesbania and Rhizobium symbiosis: nodulation and nitrogen fixation. In: MACKLIN, B.; EVANS, D.O. (Ed.) Perennial Sesbania Species in Agroforestry Systems Waimanalo: Nitrogen Fixing Tree Association, 1990. p.31-38.
• SOUSA, M.; SOUSA, M.P. New World Lonchocarpinae. In: POLHILL, R.M.; RAVEN, P.H. (Ed.) Advances in legume. Kew: Royal Botanic Gardens, 1981. v.1, p.261.
• VEASEY, E.A. Variabilidade genética em acessos de espécies de Sesbania Scop. (Leguminosae): caracterizaçăo morfológica, agronômica e isoenzimática. Piracicaba, 1998. 142p. Tese (Doutorado) - Escola Superior de Agricultura "Luiz de Queiroz", Universidade de Săo Paulo.
• VEASEY, E.A.; GUISI, O.M.A.A.; VALARINI, M.J.; OTSUK, I.P.; CARDELLI, M.A.; SANCHEZ, M.J.F.; BEISMAN, D.A. Early growth and native nodulation of leguminous shrub and tree species in Brazil. Tropical Grasslands, v.31, n.1, p.40-48, 1997.
• VENCOVSKY, R.; BARRIGA, P. Genética biométrica no fitomelhoramento Ribeirăo Preto: Revista Brasileira de Genética, 1992. 486p.

¹

Trabalho apresentado no 41º Congresso Nacional de Genética, Caxambú, 1995.

Publication Dates

• Publication in this collection
  08 July 1999
• Date of issue
  1999

History

• Accepted
  06 Apr 1998
• Received
  19 Jan 1998