Tropical Grasslands (2006) Volume 40, 157–164 157

Variation in chromosome number and its relationship with agronomic characteristics in a germplasm collection of eriantha sensu lato

MARISA TONIOLO POZZOBON1, have a tufted (almost 60%), and the tetraploid or ALBRECHT GLATZLE3, IONARA FATIMA near tetraploid ones a stoloniferous (about 70%) CONTERATO2, MARIA TERESA growth habit. As preliminary on-farm observa- SCHIFINO-WITTMANN2 AND VANESSA tions suggest, accessions which seem to approach GRUDSINSKE SMIDERLE2 best the persistence of common Pangola grass 1 Centro Nacional de Recursos Genéticos e under a wide range of environmental conditions Biotecnologia, Empresa Brasileira de Pesquisa belong to the groups with 2n = 36, 2n = 34 and Agropecuária, Brasília, Brazil 2n = 18 chromosomes. 2 Departamento de Plantas Forrageiras e Agrometeorologia, Faculdade de Agronomia, Universidade Federal do Rio Grande do Sul, Introduction Porto Alegre, Brazil 3 Iniciativa para la Investigación y Transferencia The genus Digitaria Haller (, Pan- de Tecnología Agraria Sostenible, Loma Plata iceae, Gramineae), commonly known as digitgrass, — Chaco, Paraguay comprises around 220 species, mostly occurring in warm regions. The are meso- or xerophytic, generally growing in open habitats and in a wide Abstract range of environments, including sandy beaches. Some species are very weedy, e.g. the well known In order to determine chromosome numbers and crabgrasses D. ciliaris and D. sanguinalis, but a possible correlation with some agronomic char- other taxa may also be invasive, such as D. abys- acteristics, accessions of the INTTAS (Iniciativa sinica, D. adscendens, D. fuscescens, D. horizon- para la Investigación y Transferencia de Tec- talis, D. ischaemum, D. longiflora, D. radicosa, nología Agraria Sostenible, Chaco, Paraguay) D. scalarum, D. setigera, D. ternata and D. violas- seed-producing perennial D. eriantha germplasm cens. Some are cultivated as forages, e.g. Pangola collection were examined. The tetraploid level grass, classically known as D. decumbens, recently (2n = 36) was verified in 27 plants, 11 plants renamed D. eriantha ssp. pentzii (Zuloaga et al. were diploid (2n = 18), 2 had 2n = 34 chromo- 1994), D. milanjiana, D. smutsii and D. eriantha. somes, one 2n = 20 and in 3 plants possible acces- Others, such as D. aridicola, D. didactyla, D. ga- sory (B) chromosomes were detected. Meiotic zensis, D. longiflora, D. milanjiana, D. nodosa, behaviour was generally regular and percentage D. pearsonii, D. velutina are components of native of viable pollen grains almost always exceeded pastures, or are cultivated for lawn, e.g. D. didac- 90% in all plants examined. No consistent corre- tyla, D. longiflora, D. swazilandensis and D. timo- lations between phenotype or agronomic charac- rensis (Watson and Dallwitz 1992). Some of the ters and chromosome numbers could be detected. invasive species such as D. sanguinalis may be However, 95% of the accessions originally col- used as grain crops in times of shortage and there lected from loamy were tetraploid or near are records of the utilisation of this species in tetraploid. Furthermore, diploid (2n = 18) or historical times. Other taxa such as D. cruciata, near diploid genotypes were much more likely to D. ciliaris, D. longiflora and D. exilis (fonio) are still explored as minor crops in some localities of Correspondence: Dr M.T. Schifino-Wittmann, Departa- Asia and (De Wet 1995). mento de Plantas Forrageiras e Agrometeorologia, Facul- Basic chromosome numbers in the genus are dade de Agronomia, Universidade Federal do Rio Grande do Sul, Caixa Postal 15100 91501-970 Porto Alegre, RS Brazil. x = 9, 15 and 17, the most frequent chromo- E-mail: [email protected] some numbers being 2n = 18, 36, 54 and 72, but 158 M.T. Pozzobon, A. Glatzle, I.F. Conterato, M.T. Schifino-Wittmann and V.G. Smiderle variants with 24, 27, 30, 34, 35, 40, 45, 60, 68, (Occumpaugh and Sollenberger 1995; Kretschmer 70 and 76 have also been reported, as well as and Pitman 2001). intra-specific variability in chromosome number Due to the high variability of D. eriantha (Fedorov 1969; Goldblatt 1981a, 1981b, 1984, sensu lato, there is great potential to broaden the 1985, 1988; Goldblatt and Johnson 1990, 1991, genetic base and develop cultivars adapted to dif- 1994, 1996, 1998, 2000). ferent environmental conditions (Kretschmer and The most famous forage digitgrass is the Pan- Pitman 2001). Other species could also be used gola cultivar, a perennial stoloniferous , in programmed crosses to produce a type with native to Africa, that was introduced to the good performance as forage and also with good United States in 1935 and released as cv. Pangola seed production, which would solve the problem in 1945 (Duke 1983). It has wide environmental of propagation. adaptation, high forage production, quality, palat- Through INTTAS (Iniciativa para la Inves- ability and grazing tolerance, but produces very tigación y Transferencia de Tecnología Agraria little, if any, seed (Occumpaugh and Sollenberger Sostenible), a project is underway to evaluate, 1995). This lack of seed production, probably under the edaphic and climatic conditions of El due to a degeneration of the megaspore-mother- Gran Chaco, Paraguay, a broad range of seed- cell (Sotomayor-Ríos and Schank 2001) is the producing perennial D. eriantha germplasm, in major drawback to Pangola cultivation, as propa- order to select populations adapted to these con- gation is almost entirely vegetative, which raises ditions and persistent under on-farm grazing the costs to establish a pasture. As most of the conditions. Through agronomic evaluations and plants presently cultivated came from few orig- recurrent seed collection of lines with superior inal tillers, Pangola grass has a narrow genetic performance under well defined environmental base and lacks tolerance to some pests and dis- conditions, such as sandy or waterlogged soils, it eases such as the pangola stunt virus (PSV) is intended to form, through wide or controlled (Occumpaugh and Sollenberger 1995), leaf crosses, mixtures of genetic lines adequate for Puccinica oahuensis (Lenné and Trutmann 1994) different El Chaco regions. The material under and spittle bug (Glatzle 1999). In an attempt to study is highly variable with accessions provided by various institutions and collected in the field at overcome this susceptibility, the triploid (2n = 27) several locations in Africa. Earlier selection work Transvala (Schank et al. 1990a) and hexaploid done in the Chaco with a limited number of prese- (2n = 54) hybrid (Digitaria x umfolzi) Survenola lected (Hall and Walker 1994; Lowe et al. 1991) (Schank et al. 1990b), were released as vegeta- accessions of seed-producing digitgrass has pro- tively propagated cultivars. Efforts have been vided promising results (Glatzle 1999), although made to develop a stoloniferous digitgrass that all accessions tested were less competitive than would also produce seed. Using D. milanjiana, an common Pangola. erect, rhizomatous or pseudorhizomatous species, One point that must be considered when crosses cv. Mardi, was released in but failed to are involved is the chromosome number of the produce a high quantity of seed. The Australian potential parents, as differences in chromosome Jarra and Strickland cultivars, which have some number normally lead to decreased hybrid fertility of Pangola’s qualities but are less competitive, (or even sterility), owing to problems during mei- may produce good quantities of seed (Sotomayor- osis and therefore a low percentage of viable gam- Ríos and Schank 2001). etes. Therefore, the objective of this paper was to: D. decumbens Stent was the former taxo- determine the chromosome numbers of the acces- nomic denomination for Pangola grass. However, sions in the INTTAS Digitaria collection; estimate it is presently accepted that all forage digitgrasses their pollen fertility; and try to correlate chromo- should be named D. eriantha Steud. Therefore, some numbers and agronomic characteristics. the important stoloniferous subtropical species formerly known as D. decumbens, as the cvv. Pangola, Transvala and Slendertsen, D. pentzii Material and methods cv. Taiwan, the hybrid D. x umfolzi Survenola cultivar and the cespitous seed-producing D. The tested germplasm used was provided to smutsii cvv. Premier and Advance should be tax- INTTAS by the Australian Tropical Forages onomically aggregated as D. eriantha sensu lato Genetic Resource Centre (ATFGRC), Brisbane, Chromosome number of Digitaria eriantha sensu lato 159

Australia (lines S02, S05, S06, S19, S21, S22, inflorescences. The anthers were squashed in pro- S24, S41, S42, S66, S69, S70, S89, S91, T02– pionic carmine and well stained grains were con- T06, T24, T25, T28, T33, T34, T43), Kevin Lowe sidered potentially fertile, while empty or very (Queensland Department of Primary Industries weakly stained grains were considered as sterile. and Fisheries), Mutdapilly, (S72), Inter- national Livestock Research Institute (ILRI), Addis Ababa, Ethiopia (S74–S76), Tony Palmer Results and discussion (Agricultural Research Council), Grahamstown, (S77, S78, S80–S82), AGRICOL, Chromosome number was determined in 47 plants Brackenfell, South Africa (S93, S94) and Ernesto of D. eriantha sensu lato (Table 1). In earlier Nienstedt (Instituto de Forrajes y Manejo de Pas- determinations, 36 of them had been classified as turas), Córdoba, (S86), while some was D. eriantha, 1 as D. smutsii, 1 as D. natalensis and collected by Albrecht Glatzle in (S30, 9 as D. milanjiana (Henrard 1950; Chippindall S34, S46, S47, S49, S51, S79, S88, T8, T10, T20, 1955). For a better presentation and discussion of T36, T38, T39, T44). The lines S62 and S85 are the results, the number of chromosomes was rep- commercial cultivars, while the other lines are resented as 2n for all plants, even when obtained either spontaneous crosses (S87) or morpholog- from pollen-mother-cells. Pollen fertility was esti- ical variants within other (mixed genotype) acces- mated for 35 of these plants plus another 13 D. eri- sions (S95, T45, T52, T53). antha plants (Table 2), in which it was not possible The original field plots had been established by to determine the number of chromosomes. Chro- seed in Isla Poi, Central Chaco (22′5″ S, 59′7″ W) mosome numbers of 18 (Figures 1 and 2), 20 in October 2001. After successful establishment, (Figure 3), 34 (Figure 4), 36 (Figure 5) and 36 + 1 accessions were transplanted by tillers to about B-chromosomes (Figure 6) were observed. The 50 farms in the Paraguayan Chaco for field evalu- tetraploid level (2n = 36) was verified in 27 acces- ation under commercial grazing conditions, pres- sions, whereas 11 plants were diploid (2n = 18), ently underway. 2 had 2n = 34 chromosomes, 1 had 2n = 20 and in The cytogenetic analysis was developed at the 3 accessions possible accessory (B) chromosomes Cytogenetics and Electrophoresis Laboratory, were detected. In 3 plants (S87, S95, T28), the Departamento de Plantas Forrageiras e Agrome- exact number of chromosomes could not be ascer- teorologia, Universidade Federal do Rio Grande tained, due to a very dense cytoplasm and sticky do Sul, Porto Alegre, Brazil. For that purpose, chromosomes (this could have a genetic basis or tillers from the INTTAS Digitaria germplasm be caused by technical problems, e.g. a wrongly collection (Tables 1 and 2) were cultivated in pots prepared fixative). in a greenhouse, where the study material (root- These results show how variable cytogeneti- tips or inflorescences) was collected. cally D. eriantha is. Literature reports 2n = 18, Somatic chromosome number (2n) was deter- 36, 40 and 18 + 0–5 B chromosomes for the mined in root-tip cells pretreated with a satu- species (Fedorov 1969; Goldblatt and Johnson rated solution of paradichlorobenzene at 4°C for 1990, 1991, 1994). To our knowledge, this is the 18–20 h, fixed in 3:1 ethanol-acetic acid, stored first report of the 2n = 20 chromosome number in 70% ethanol in a freezer until required, and in a Digitaria species. For the 9 accessions for- stained with Feulgen. At least 10 cells per plant merly classified as D. milanjiana, we found dip- were examined. Gametic chromosome number (n) loid (2n = 18) and tetraploid (2n = 36) plants, was determined in pollen-mother-cells undergoing plus 2 with 1 B-chromosome. Literature reports meiosis, with inflorescences at various stages of 2n = 18, 34, 36, 45 and 54 for D. milanjiana development being fixed in 3:1 ethanol-acetic (Fedorov 1969; Goldblatt 1981, 1984; Goldblatt acid for 24 h, stored in 70% ethanol in a freezer and Johnson 1994). For the 2 plants formerly until required and stained with propionic carmine. classified as D. smutsii and D. natalensis, chromo- Meiotic behaviour was also analysed, especially some numbers were 2n = 36. chromosome associations at diakinesis and meta- B-chromosomes, also called accessory or phase I. As many cells as possible were analysed extra-numerary, are chromosomes not homolo- for gametic number and meiotic behaviour. gous to any of the normal complement, gener- Pollen viability was estimated by examining ally smaller than the normal ones, frequently, 1000 mature pollen grains per plant from stored but not always, heterochromatic and appear 160 M.T. Pozzobon, A. Glatzle, I.F. Conterato, M.T. Schifino-Wittmann and V.G. Smiderle

Table 1. Species and accession identification, flowering time and habit, chromosome numbers and pollen fertility.

Plant Species Accession Origin Flowering Habit2 2n Number of Pollen number1 cells viability (%)

S02 D. milanjiana 59814, Carapé Kenya late stoloniferous 36 6 96 S05 D. milanjiana ATF2943 South África late stoloniferous 36 42 96 S21 D. eriantha ATF2103 South Africa early stoloniferous 36 12 93 S34 D. eriantha GL52 early stoloniferous 36 11 n d3 S47 D. eriantha GL33 Botswana early tufted 18 10 n d S49 D. eriantha GL43 Botswana very late stoloniferous 36 10 n d S51 D. eriantha GL18 Botswana early decumbent 20 97 n d S62 D. eriantha 38869, cv. Premier South Africa medium-late tufted 36 129 97 S66 D. smutsii 60770 South Africa early decumbent 36 36 97 S70 D. eriantha ATF652 South Africa early stoloniferous 36 10 n d S72 D. milanjiana Mutdapilly Australia early stoloniferous 36 18 97 S74 D. milanjiana 12798 Ethiopia late stoloniferous 18 10 97 S75 D. milanjiana 12802 Ethiopia medium-late stoloniferous 18 20 93 S76 D. milanjiana 12806 Ethiopia late stoloniferous 18 10 89 S77 D. eriantha 025F South Africa late stoloniferous 36 15 90 S79 D. eriantha GL31 Botswana medium-late stoloniferous 36 53 94 S80 D. eriantha 025C South Africa late tufted 18 76 94 S82 D. eriantha 0252 South Africa medium-late tufted 18 24 90 S85 D. eriantha cv. Irene Argentina early tufted 18 129 95 S86 D. eriantha C 1 Argentina early tufted 18 18 n d S87 D. eriantha Spontaneous cross Paraguay early stoloniferous ca.36 10 95 S88 D. eriantha GL42 Botswana medium-late stoloniferous 36 26 88 S89 D. natalensis 59752, Pora late rhizo-decumbent 36 10 n d S91 D. milanjiana 34673, Kalahari Zimbabwe early stoloniferous 36 28 n d S93 D. eriantha Tip Top South Africa early tufted 18 87 97 S94 D. eriantha SSW11D South Africa medium-late tufted 18 50 93 S95 D. eriantha Variant of S51 Botswana late rhizo-decumbent ca.34 5 92 T02 D. eriantha ATF604 South Africa early stoloniferous 36 37 91 T03 D. eriantha ATF598 South Africa medium-late stoloniferous 36 10 98 T04 D. eriantha ATF2106 South Africa early decumbent 36 10 n d T05 D. eriantha 59698 South Africa medium-late tufted 36 14 93 T06 D. eriantha 41172 South Africa early tufted 36 28 97 T08 D. eriantha GL40 Botswana medium-late rhizo-decumbent 18 40 97 T10 D. eriantha GL46 Botswana late rhizo-decumbent 36 10 n d T20 D. eriantha GL5 Botswana early decumbent 36 35 95 T24 D. eriantha ATF654 South Africa early stoloniferous 36 10 n d T25 D. eriantha ATF618 South Africa early stoloniferous 36 10 n d T28 D. eriantha ATF2113 South África early stoloniferous ca.36/40 10 94 T33 D. milanjiana 59776 late stoloniferous 36+1 B 8 96 T34 D. milanjiana 59750 Zimbabwe medium-late stoloniferous 36+1 B 30 95 T36 D. eriantha GL9 Botswana early stoloniferous 36 2 90 T38 D. eriantha GL13 Botswana early rhizo-decumbent 36+1 B 56 95 T39 D. eriantha GL10 Botswana medium-late stoloniferous 36 14 96 T43 D. eriantha 59761 Zimbabwe early decumbent 36 16 96 T44 D. eriantha GL50 Botswana early stoloniferous 34 96 94 T45 D. eriantha variant of T24 South Africa early stoloniferous 34 32 84 T53 D. eriantha variant of T25 South Africa medium-late stoloniferous 36 20 75 1 S-numbers: accessions originally collected on lighter-textured soils (sandy types), or provenance is unknown. T-numbers: accessions originally collected on heavier-textured (loamy) soils. 2 Rhizo-decumbent: decumbent plus high density of below-ground rhizomes. 3 nd: not determined.

Table 2. Species and accession identification and pollen fertility.

Plant number1 Species Accession Origin Pollen viability (%)

S06 D. eriantha ATF2102 South Africa 90 S19 D. eriantha ATF2094 South Africa 95 S22 D. eriantha ATF2108 South Africa 95 S24 D. eriantha ATF2116 South Africa 98 S30 D. eriantha GL 49 Botswana 91 S41 D. eriantha ATF605 South Africa 100 S42 D. eriantha ATF612 South Africa 97 S46 D. eriantha GL28 Botswana 93 S69 D. eriantha ATF631 South Africa 90 S78 D. eriantha 025F South Africa 94 S81 D. eriantha 025C South Africa 92 T52 D. eriantha Variation of S89 Zimbabwe 92 1 S-numbers: accessions originally collected on lighter-textured soils (sandy types), or provenance is unknown. T-numbers: accessions originally collected on heavier-textured (loamy) soils. Chromosome number of Digitaria eriantha sensu lato 161

Figure 1. Metaphase in a root-tip cell with 2n = 18 Figure 4. Diakinesis with 17 bivalents (2n = 34). chromosomes.

Figure 2. Diakinesis with 9 bivalents (2n = 18). Figure 5. Diakinesis with 18 bivalents (2n = 36).

Figure 3. Metaphase I with 10 bivalents (2n = 20). Figure 6. Diakinesis with 18 bivalents plus 1 B-chromosome (arrowhead). in some individuals of a given population and frequently deleterious, especially in odd num- species. They are widespread among flow- bers. However, as no effect is usually detected, ering plants and tend to be maintained along they may remain totally undetected unless by the generations by a strong non-disjunction cytological examination (Jones 1995; Schifino- at meiosis or mitosis. At meiosis, they dis- Wittmann 2004). Their widespread distribution play a typical behaviour, remaining as univa- in nature and their until now unexplained prop- lents, when only one is present. If there are erties make B-chromosomes a most fascinating more than one, they may pair among them- genetic enigma (Jones 1995). selves, forming bi- or multivalents, but never The small extra-chromosomes found in 3 pair with the normal chromosomes. Their pres- of the accessions, exclusively tetraploid ones, ence cannot be detected qualitatively and is are most likely B-chromosomes, as they look 162 M.T. Pozzobon, A. Glatzle, I.F. Conterato, M.T. Schifino-Wittmann and V.G. Smiderle smaller than the normal chromosomes, and at In three cases, plants S51 and S95, T24 and meiosis are observed as univalents (Figure 6), T45, T25 and T53, the second plant of each pair never pairing with any other chromosome of the was a variation observed in the original acces- complement. B-chromosomes, common in many sion, which is most likely due to a mixture of grasses, have also been reported in some Digi- genotypes, although at the collection sites seed taria species, e.g. D. eriantha (Goldblatt and had been collected from 10–30 individual plants Johnson 1994). Shambulingappa (1968) reported within an area usually not exceeding 500 m2. the occurrence of B-chromosomes in D. decum- Chromosome numbers confirm that S51 (2n = 20) bens and D. pentzii (now joined as D. eriantha) and S95 (2n ca. 34), T24 (2n = 36) and T45 and in D. valida, describing them as small and (2n = 34) are different genetically. No difference heterochromatic. in chromosome number was observed for T25 Table 1 shows that the tetraploid, or 2n = 34 and T53 (both 2n = 36) but they differed in flow- chromosome number, is predominant (almost ering habit and leaf colour (bluish with T53). 75%) among the plants analysed. When trying to Meiotic behaviour was generally regular in correlate chromosome numbers with agronomic most of the 47 plants examined, in spite of the characteristics, there is a clear predominance varying numbers of chromosomes: chromosome of stoloniferous plants among the tetraploid or pairing was almost always in bivalents (Figures 2 2n = 34 genotypes (69%, with only 9 % of tufted to 5) and chromosome disjunction at anaphases plants), whereas 59% of the diploid or 2n = 20 and telophases I and II (Figure 7). Sporadically, genotypes have a tufted growth habit. The only some meiotic irregularities such as multivalents 3 diploid accessions, which are stoloniferous (Figure 8) and bridges (Figure 9) were observed. (25%), were provided by ILRI Ethiopia (S74– Gupta et al. (1974) verified a generally regular S76) and are similar in appearance with strongly meiosis in some Digitaria species, the exception pilose leaves and stems, but differ somewhat in being two aneuploid 2n = 39 and 2n = 45 acces- flowering time. Of these, no passport data are sions of D. glauca, where several meiotic irregu- available. The proportion of decumbent plants is larities were detected. similar among both diploid and tetraploid gen- The percentage of viable pollen grains otypes (about 20%). Flowering behaviour and (Figure 10) was high, almost always exceeding presence of abundant below-ground rhizomes 90% in all plants examined (Tables 1 and 2), (about 10% of the accessions) are independent despite the number of chromosomes or pres- of chromosome number (ploidy level). All except ence of accessory chromosomes, showing that one accession originally collected on heavier- these plants are potentially male-fertile to textured (loamy) soils (95%) were tetraploid or be used in crosses. According to Theunissen had 2n = 34 chromosomes, and all accessions (1997), Digitaria eriantha ecotypes with (T33, T34, T38) with accessory chromosomes pollen fertility above 70% produced normal were derived from loamy soils. sexual embryo sacs, a character associated with

Figure 7. Normal early anaphase I with a 9/9 chromosome Figure 8. Metaphase I, 16 bivalents plus a quadrivalent distribution. (arrowhead). Chromosome number of Digitaria eriantha sensu lato 163

Figure 9. Anaphase I with bridge. Scale bar = 10 µm Figure 10. Full, stained, possibly viable pollen grains and an empty, sterile one. Scale bar = 10 µm (Figures 1–9, same magnification)

successful sexual reproduction. He observed that 95% of accessions originally collected under that tufted ecotypes displayed the worst vege- loamy conditions (according to their pass- tative reproduction potencies and the best seed port data) are tetraploid (2n = 36) or have 2n = 34 germination as compared with stoloniferous chromosomes. Furthermore, diploid (2n = 18) or ecotypes. Under Chacoan conditions, the first 2n = 20 genotypes are much more likely to have a statement (poor vegetative reproduction) was tufted (almost 60%), and the tetraploid or 2n = 34 confirmed, the second one (better sexual repro- ones a stoloniferous (about 70%) growth habit. duction of tufted ecotypes), however, was not As preliminary on-farm observations suggest obvious, particularly since stoloniferous eco- (data not shown), accessions which display sim- types quickly covered the soil surface, even ilar persistence to common Pangola grass under with a fairly low density of established plants. a wide range of environmental conditions belong to the groups with 2n = 36, 2n = 34 and 2n = 18 Conclusion chromosomes. We conclude that agronomic characters do not, The Chaco collection of seed-producing Digi- or only to a limited extent, seem to be predeter- taria eriantha sensu lato accessions shows a mined by chromosome numbers. The presence of wide range of variation of morphological and considerable ecotype (pheno- and genotype) var- agronomic characters. There are strongly stolo- iation and a wide geographic distribution imply niferous, tufted and intermediate decumbent phe- that an extensive genetic adaptability for persist- notypes, with half of the decumbent ones forming ence, even under fierce environmental conditions, abundant below-ground rhizomes. Observations exists within Digitaria eriantha sensu lato. at the collection sites suggest that the rhizoma- tous types are highly tolerant of grazing. Fur- thermore, pilosity, leaf colour, robustness of Acknowledgements inflorescences and flowering behaviour differ a lot between accessions. As the cytogenetic anal- We thank Dr Harold Ospina, Universidade Federal ysis shows, there is wide variation in chromo- do Rio Grande do Sul, for his help with the transpor- some numbers: 2n = 18 in 25%, 2n = 20 in 2%, tation of plants; FAPERGS (Fundação de Amparo à 2n = 36 in 61%, 2n = 34 in 5% and 2n = 36 plus Pesquisa do Estado do Rio Grande do Sul), CNPq accessory chromosomes in 7% of the 44 acces- (Conselho Nacional de Desenvolvimento Cientí- sions examined which gave clear results. fico e Tecnológico), AVINA Foundation, Antonio No consistent correlations between phenotype Espinoza, Cord Kelly, Gandera 63, Miguel Serrati or agronomic characters and chromosome num- and Pedro Zucolillo for financial support, and all bers could be detected. However, it is remarkable persons and institutions who provided germplasm. 164 M.T. Pozzobon, A. Glatzle, I.F. Conterato, M.T. Schifino-Wittmann and V.G. Smiderle

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(Received for publication January 9, 2006; accepted March 30, 2006)