Paspalum Accessions Research Articles

Cattle preference in Paspalum atratum and its relationship with morphological and anatomical leaf characteristics

AbstractNew atra paspalum (Paspalum atratum Swallen) accessions were found to be differentially grazed by cattle, without differences in herbage accumulation and nutritive value. This study aimed to evaluate cattle preference, morphological and anatomical leaf traits, and their relationships at four sampling events. Five new atra paspalum accessions and the cultivar Cambá were used. The experimental unit was a 2 m × 2 m plot. Treatments were replicated four times in a completely randomized design. Cattle preference was determined in spring (December 2016 and 2017), summer (March 2017), and autumn (May 2017) using six steers Bos spp. that grazed the plots for 4 h on two consecutive days. Plant height, leaf‐blade length, leaf‐blade width, and the proportions of five leaf tissues at three leaf regions were measured at each date. The proportion of the leaf that is curved was measured in December 2017. Cattle preference was variable among accessions and sampling events. Some accessions were shorter, with shorter and more flexible leaves than Cambá (p < 0.05). The proportion of lignified tissues was greater during the spring (2016 and 2017) and summer (7%–23%) than in the autumn. One accession had the lowest proportion of lignified tissue in the warm season (8%–12%) but the highest during the fall (around 15%). The same accession had the fewest primary vascular bundles in the warm season. Cattle preference was negatively correlated with the proportion of lignified tissues, the number of primary vascular bundles, plant height, and leaf‐blade length. Cattle preference was affected by the growing season and reduced by greater presence of leaf structural tissue.

Assessment of turf quality in Paspalum vaginatum Sw. accessions of Sumatra, Java, and Bali (Indonesia) with clay and amended sand growing media

Abstract. Rahayu, Ariyanto DP, Usrotin AH, Hatami FR, Mo YG. 2023. Assessment of turf quality in Paspalum vaginatum Sw. accessions of Sumatra, Java, and Bali (Indonesia) with clay and amended sand growing media. Biodiversitas 24: 1650-1658. Seashore paspalum (Paspalum vaginatum Sw.) is a selected turfgrass species in the FIFA football world cup Qatar 2022. The choice considers its turf quality, growth habit, quick recovery from damage, tolerance in warm conditions, and low water consumption. Since the breeding program of seashore paspalum worldwide still needs to be improved and is yet to start in Indonesia, we suppose that in the future, seashore paspalum will become a favorite turfgrass industry. Previous studies showed that Indonesia has many accessions to the germplasm of seashore paspalum. This study aimed to find superior mother lines of Indonesian germplasm accession by select of visual and functional quality using clay soil of vertisol and vertisol-amended sand as growing media for quality evaluation. This study was a wild-type collection followed by a plot experiment using Randomized Complete Block Design. In this experiment, the control was using a commercialized cultivar. Seashore paspalum accessions were collected from Java, Bali, and Sumatra Indonesian islands. Observation of variables were visual qualities, i.e., tiller density, color, leaf texture, uniformity, and functional quality, i.e., surface covering, recoverability, clippings dry weight, root length, root dry weight. The National Turfgrass Evaluation Program (NTEP) rated those qualities by scoring. The quality index of turfgrass used a rating score formulated from a visual and functional quality score. The data were analyzed using DMRT and T-test. Results showed that growing paspalum in clay-amended sand media showed a better recovery rate than the accessions grown in vertisol media. Mowing the grass can reduce plant height and leaf texture, and increases the clipping dry weight. Sand amendment to vertisol soil can improve the seashore paspalum visual qualities, i.e., leaf texture, tiller density, color score, and functional quality, such as root length. Seashore paspalum accessions vary in quality, i.e., visual and functional. Native accessions have a better recovery rate, higher tiller density, and uniformity than the control but a higher clipping yield. Bogor accession had faster soil surface coverage, Siak accession had a high recovery rate. Rumbei accession was the highest clipping dry weight, fast land cover, and high root dry weight. The accessions of Siak and Rumbei have higher quality index than the control after mowing. Siak accession performed better in vertisol, whereas Rumbei accession performed better in vertisol-amended sand. The performance of Rumbai and Siak accessions showed that seashore paspalum from Sumatra has better characteristics than Java and Bali and is promising for further cultivar development.

Agronomic, nutritive value, reproductive, cytogenetic, and molecular aspects of Paspalum accessions: Contribution to the development of new forage cultivars

AbstractThis study investigated the agronomic, nutritive value, cytogenetic, molecular, and reproductive aspects of twenty‐five Paspalum accessions to support breeding programs. The agronomic aspects and the nutritive value were evaluated in a randomized block experimental design with four replications, and with monthly repeated measures for 2 years. For the molecular characterization 16 microsatellite markers developed for different Paspalum species in previous works were used. The number of chromosomes was determined by visualizing the meiotic cells and the DNA content was determined by flow cytometry. The embryo sac clarification technique was used to characterize the reproductive system. The results indicated genetic variability for all the variables related to yield and nutritive value. For almost all variables, the values of Paspalum accessions were higher than those of the commercial cultivars Megathyrsus maximus cv. Tanzania and Urochloa brizantha cv. Marandu, used as references. However, the accessions showed in vitro dry matter digestibility values lower than the mean value presented by the references. The groups formed in the molecular analysis showed correspondence to the groups observed in the principal components analysis, considering the variables related to yield and nutritive value. Most accessions were revealed to be tetraploid with 40 chromosomes and most accessions belonging to the Virgata group displayed a sexual embryo sac structure. Some crosses can be indicated for genetic breeding, due to a superior genomic affinity between the accessions and the higher probability of heterosis in the progeny. These results provide subsidies to genetic plant breeding programs that use these accessions.

Correlation of shear strength and physicochemical properties as a criterion for the selection of accessions of Paspalum grasses

The present study aimed to evaluate the application of shear strength and its correlations with leaf blade morphological and chemical variables as a tool capable of detecting differences between species and accessions of the genus Paspalum in the early stages of a forage plant breeding programme. A total of 13 Paspalum accessions from two species (Paspalum atratum and Paspalum regnellii) were subjected to analyses of shear strength, which also analysed the neutral detergent fibre, acid detergent fibre, lignin, and digestibility. Morphological measurements were also performed to standardize the shear strength per unit of leaf tissue. The experimental design consisted of complete randomized blocks, with four replications and eight cuts performed over 2 years. Shear strength was evaluated for its potential usefulness for detecting differences between accessions of the same species and the correlations of accessions. It was possible to use the shear strength measured with the texturometer to detect differences between species and accessions of the Paspalum genus. The results showed significant correlations of shear strength and neutral detergent fibre (r = 0.49), and negative correlations were found between digestibility and shear strength (r = -0.55). These correlations were maintained when the strength variables were standardized according to the morphological variables. Thus, shear strength can be used in the initial stages of the selection of species of the genus Paspalum.

Reproductive mode and DNA content of Paspalum accessions from Plicatula group: Reproduction and DNA content of Paspalum

This study aims the reproductive and DNA content characterization of ten different Paspalum species from the Plicatula group (P. atratum, P. compressifolium, P. guenoarum, P. lenticulare, P. lepton, P. oteroi, P. plicatulum, P. rhodopedum, P. rojasii and P. wrightii), contributing to the determination of the best breeding and conservation method to be used. The DNA content of 150 accessions was estimated by flow cytometry using foliar tissues. The reproductive mode of 135 accessions was characterized by flow cytometric seed screening, and five accessions were determined by cytoembryological ovary analysis. DNA content ranged from 1.50 pg (BGP 380) to 4.27 pg (BGP 193), both from P. compressifolium species. Most of the accessions were compatible to the tetraploid level, except for BGP 281 (P. lenticulare), BGP 272 (P. rojasii), and BGP 380 (P. compressifolium), which were diploids. Accessions with tetraploid DNA content presented apomictic reproduction, whereas the three diploid accessions were sexual. These results contribute to the reproductive knowledge of species of the Plicatula group. The diploid sexual accessions identified represent important material to overcome the apomictic barrier in crosses and can be used after polyploidization as female parents in crosses with apomictic accessions in Paspalum breeding programs.

Genetic diversity and morphological characteristics of native seashore paspalum in Indonesia

Abstract. Rahayu, Fatimah, Bae EJ, Mo YG, Choi JS. 2020. Genetic diversity and morphological characteristics of native seashore paspalum in Indonesia. Biodiversitas 21: 4981-4989. Seashore paspalum (Paspalum vaginatum) is a warm-season turfgrass indigenous to tropical and coastal areas worldwide. The objectives of this study were to measure the genetic diversity and genetic variation of Indonesian seashore paspalum germplasm. Three turf quality, six morphological characters, and ten SSR (microsatellite) markers were used to assess genetic relationships and genetic variation among 22 germplasm resources from Indonesia and one commercial variety (Salam) from United States of America. The results showed significant variation for five morphological characters among 23 tested seashore paspalum accessions. The cluster analysis of morphological characters of 23 seashore paspalum accessions using 0,6 cut off divided into three morphological types: tall high-density, intermediate, and dwarf low-density ecotype. The genetic variation revealed 22 alleles with average number of alleles per locus was 2 and polymorphism information content (PIC) values average was 0.33. The microsatellite marker cluster analysis showed that 23 seashore paspalum accessions were grouped into two major groups, with a genetic similarity coefficient was 0,72. The low level of genetic diversity occurred among Indonesia natural grass germplasm and the genetic distance was relatively low between Indonesian germplasm and Salam variety. The genetic diversity and morphological characteristics will be useful for further study and utilization of Indonesian seashore paspalum germplasm.

Sanitary quality of seed of Paspalum species

Abstract Brazil has been developing research for selection of native species of Paspalum for use as turfgrass, nevertheless little is known about the sanitary quality and pathogens associated to the seeds, being the aims of this study. Subsamples of 100 seeds of two accessions of Paspalum notatum Flügge (PN 01 and PN 04) and one accesses of Paspalum lepton Schult. (PL 01) were submitted to the blotter test at 20 °C with a 12-h photoperiod for 7 days. The Penicillium and Curvularia genus incidence were highest in the three accessions of Paspalum. The seed health quality was variable between accessions, with more than 56% of incidence of the fungus Curvularia on the seeds. This study reported for the first time the occurrence of Curvularia spp. and Cladosporium herbarium in seeds of P. lepton, in the Northeast region of Brazil.

Measurement of Genetic Diversity of Chinese Seashore Paspalum Resources through Morphological and Sequence-related Amplified Polymorphism Analysis

Seashore paspalum (Paspalum vaginatum) is a notable warm-season turfgrass. Certain germplasm resources are distributed in the southern regions of China. The objectives of this study were to investigate the genetic diversity and genetic variation of Chinese seashore paspalum resources. Morphological characteristics and sequence-related amplified polymorphism (SRAP) markers were used to assess genetic relationships and genetic variation among 36 germplasm resources from China and six cultivars from the United States. The results showed significant variation for 13 morphological characteristics among 42 tested seashore paspalum accessions, and that the phenotypic cv was, in turn, turf height > turf density > internode length > inflorescence density > leaf width > reproductive branch height > spikelet width > leaf length > spikelet number > inflorescence length > internode diameter > inflorescence width > spikelet length. According to the morphological characteristics and cluster analysis, 42 seashore paspalum accessions were divided into six morphological types. In total, 374 clear bands were amplified using 30 SRAP primer combinations; among these bands, 321 were polymorphic with 85.83% polymorphism. SRAP marker cluster analysis showed that 42 seashore paspalum accessions were grouped into seven major groups, with a genetic similarity coefficient ranging from 0.4385 to 0.9893 and genetic distance values ranging from 0.0108 to 0.8244. The high level of genetic diversity occurred among Chinese germplasm, and the genetic distance was relatively high between Chinese germplasm and cultivars introduced from the United States. The patterns in morphological trait variations and genetic diversity will be useful for the further exploitation and use of Chinese seashore paspalum resources.

First Report of Phyllachora sp. Causing Tar Spot on Seashore Paspalum in South China

Seashore paspalum is an indigenous, warm-season turfgrass that is often used on golf courses, sport fields, and other recreational sites, especially where salt is an issue (Guo et al. 2016). One hundred forty-six accessions or cultivars collected from south China and the United States currently are planted in the Danzhou campus of Hainan University. In 2017, there was an outbreak of typical tar-spot symptoms on leaves of 94 accessions or cultivars of seashore paspalum. The tar spots, 0.3 to 1.5 mm in diameter, were composed of irregular brown spots surrounded by yellowish halos on the infected leaves. Pseudostromata were subglobose with 0.3 to 1.5 mm diameter, slightly papillate, epiphyllous, shiny black, and immersed in the host leaves. Perithecia (268 to 320 μm in diameter) had paraphyses and asci (80 to 110 × 11 to 17 μm) with eight ascospores (5.5 to 8.5 × 8 to 13 μm). Ascospores were ellipsoid, single celled, hyaline, with a central concave depression present or absent. Morphologically, the pathogen was a member of Phyllachorales (Dayarathne et al. 2017). Total DNA from leaf spots was extracted from three seashore paspalum accessions: SP17, SP40, and SP64. The rDNA internal transcribed spacer (ITS) sequences were amplified with the primer pair ITS1f (5′-CTTGGTCATTTAGACGAAGTAA-3′) and ITS4 (5′-TCCTCCGCTTATTGATATGC-3′). The results showed that three ITS sequences, 511 bp, were totally identical, and the ITS sequence was deposited in NCBI (MG897306). BLAST analysis revealed that the ITS sequence displayed no high similarity with known Phyllachora species and showed 89% identity with Phyllachora sp. (MG881848.1) and 88% identity with Phyllachora sp. (MG881846.1), confirming that the pathogen was Phyllachora sp. To verify the pathogenicity of the pathogen, healthy stolons of three accessions (SP17, SP40, and SP64) were planted in sterilized sand in an incubation box, which was kept for 2 weeks to confirm that the plants were healthy and without disease. Leaves were then inoculated by a sterilized toothpick with ascospores from mature stromata of infected seashore paspalum planted in the Danzhou campus of Hainan University. Two weeks after inoculation, 80% of inoculated plants showed symptoms of disease, and the fungus from the inoculated leaves was morphologically and molecularly identical to the samples collected in the field. Controls remained without tar-spot symptoms. Tar spot has been reported on several plant species (McCoy et al. 2018); however, this is the first report of Phyllachora sp. on seashore paspalum in south China.

Morphological and physiological responses and the recovery ability of Paspalum accessions to water deficit and waterlogging

AbstractLimited knowledge about the agronomic potential of Paspalum species from the Americas hinders their use in pastures. The response mechanisms to water deficit and waterlogging were studied in five accessions of Paspalum sp. (P. regnellii cv. BRS Guará and BGP 397, P. conspersum BGP 402 and P. malacophyllum BGP 289 and BGP 293) and Urochloa brizantha cv. Marandu. Morphological and physiological traits at the end of the stress and after the recovery period were measured. All Paspalum accessions, especially BGP 289, BGP 402 and BGP 397, and also cv. Marandu, showed survival mechanisms to water deficit. BRS Guará showed adaptive features to waterlogging, although had with a low survival rate to water deficit. Under waterlogging, BGP 289 and cv. Marandu showed reduced growth, and after the recovery period, they presented low plant survival and root recovery. Although growth of BGP 293 was reduced during waterlogging, it presented high tiller survival rate. BGP 293, BGP 402 and BGP 397 showed adaptive potential strategies for waterlogging and water deficit. There is genetic variability among the evaluated accessions for water deficit and waterlogging stresses, suggesting that they may be used per se or as progenitors in crosses with other genotypes in breeding programmes.

Evaluation and strategies of tolerance to water stress in Paspalum germplasm

The evaluation of genetic resources in germplasm banks of Paspalum can contribute to their use in breeding programs and for advanced research in biotechnology. This study evaluated the tolerance of 11 Paspalum accessions to abiotic stress caused by soil water deficit in a greenhouse experiment at Embrapa Pecuaria Sudeste, Sao Carlos, state of Sao Paulo, Brazil. The variables analyzed were: dry biomass of green matter, dead matter and roots; leaf area; leaf water potential; number of days to lose leaf turgor (wilting); soil moisture at wilting; and number of tillers per pot. The results showed high genetic variability for all traits, not only among species but also within species, and also reflected the existence of different strategies of response and potential adaptation to water deficit events. For breeding programs, when the aim is to produce materials better adapted to the occurrence of prolonged drought, 5 accessions from this group seem to have good potential: P. malacophyllum BGP 289, P. quarinii BGP 229, P. regnellii BGP 112, P. conspersum BGP 402 and P. urvillei x P. dilatatum BGP 238. Conversely, when the goal is to select materials for short-term water stress conditions, 6 accessions stand out: P. atratum BGP 308, P. regnellii BGP 215, 248 and 397, P. dilatatum BGP 234 and P. malacophyllum BGP 293.

Growth response and ion regulation of seashore paspalum accessions to increasing salinity

Seashore paspalum (Paspalum vaginatum Swartz) is an important warm-season turfgrass indigenous to tropical and coastal areas worldwide. The objectives of this study were to investigate the growth response and ion regulation of Chinese seashore paspalum germplasm under salinity stress. Twenty-seven seashore paspalum accessions and one check cultivar “Sea Isle 2000” were grown in solution culture in a glasshouse, with NaCl added to achieve salinities of 0 (control), 340 and 510mmol/L. Compared with the nonsaline controls, the salinity stressed accessions showed significantly increased leaf firing, decreased shoot growth, and an increase or decrease in root growth. Significant genetic variations in the leaf firing (LF), relative shoot weight (RSW) and relative root weight (RRW) were found among the different accessions, with coefficients of variation ranging from 19.54% to 37.84%. The P40 accession had the best salinity tolerance with little leaf firing under salinity stress, followed by Sea Isle 2000, P29 and P14. For the control, the average K+ concentration was 1161.69mmol/kg in the shoots and 383.73mmol/kg in the roots. Compared to the control, the salinity treatment showed that the K+ concentration treatment decreased in both the shoots and roots; however, the percentage of the reduction in the shoots was significantly lower (26.20%) than that in the roots (69.68%). The Na+ concentration was very low in both the shoots and roots of the seashore paspalum, with an average of 65.90mmol/kg and 39.50mmol/kg, respectively, under the treatment of nonsalinity. Compared to the nonsalinity control, the Na+ concentration greatly increased in both the shoots and roots; however, the percentage of the increase in the shoots was lower (15-fold) than in the roots (25-fold). The results indicate that taking up more of the K+, maintaining a high K+ concentration in the shoots and reducing the Na+ being transferred from the roots to the shoots could be the mechanisms for Na+ and K+ regulation for salinity tolerance in seashore paspalum.

CHARACTERIZATION OF PASPALUM ACCESSIONS AS ORNAMENTAL LAWN

CHARACTERIZATION OF PASPALUM ACCESSIONS AS ORNAMENTAL LAWN

Development and Characterization of Seashore Paspalum SSR Markers

ABSTRACTThe increasing use of secondary water sources for irrigation, which is highly linked to salinization, creates a demand for salt tolerant turf. Seashore paspalum (Paspalum vaginatum Swartz) is a warm‐season turfgrass that survives in sand dunes along coastal sites, brackish ponds, and in estuaries. Some seashore paspalum accessions and cultivars are far more salt tolerant than others. To identify genetic regions that are associated with salt tolerance, molecular tools must be developed. In this study, genomic libraries, enriched for microsatellites, were generated using the salt tolerant accession HI33. High throughput sequencing and subsequent assembling of these libraries resulted in 18,967 contigs and 158,595 singletons. The number of simple sequence repeats (SSR) detected in contigs and in singletons was 3511 and 31,949, respectively, and the number of primer sets designed within each group was 937 and 1667. A total of 80 SSR markers, including five markers previously developed, were used to assess genetic relationships among 18 Paspalum accessions. Two major clusters were identified from the seashore paspalum accessions. Accessions that are likely polyploids, all with coarse leaves, grouped together whereas accessions with fine‐to mid‐fine leaves formed a second group. Furthermore, 33 seashore paspalum SSR markers cross‐amplified in bahiagrass (Paspalum notatum Flugge) and these markers can be a useful tool in this species.

Cytological and reproductive aspects in the Caespitosa group of Paspalum

Somatic chromosome numbers are reported for thirty four germplasm accessions of Paspalum, Caespitosa group, representing five different species. All five species have shown x=10 as the basic chromosome number. The diploid 2n=20 chromosome number was confirmed for P. chacoense and P. indecorum, as well as sexuality for the latter. This is the first report of the chromosome number and cytological behavior for P. ligulare (2n=20 and 40), P. pleostachyum (2n=20, 30 and 40) and P. redondense (2n=20 and 40). The present results document regular meiosis in diploid accessions, with primarily bivalent pairing at diakinesis and metaphase I. Polyploids of these species had irregular meiosis, with univalent, trivalent, and quadrivalent chromosome associations. Diploid accessions of P. pleostachyum and P. ligulare have shown a single meiotic embryo-sac, indicating sexual reproduction, while the triploid and one of the tetraploid accessions of P. pleostachyum have shown aposporic embryo-sacs of nucelar origin, and a few meiotic sacs, suggesting facultative apomixis. Identification of the new diploid accessions may prove useful for phylogenetic studies of Paspalum, as well as for breeding programs focusing on the forage potential of species of the Caespitosa group.

Unusual chromosome numbers in Paspalum L. (Poaceae: Paniceae) from Brazil

Somatic chromosome numbers were determined for 20 new germplasm accessions of Paspalum, belonging to 17 species collected in Brazil. Chromosome number is reported for the first time for P. reduncum (2n = 18), P. cinerascens (2n = 20), P. cordatum (2n = 20), P. filgueirasii (2n = 24), P. ammodes (2n = 36), P. bicilium (2n = 40), P. heterotrichon (2n = 40), and P. burmanii (2n = 48). New cytotypes were confirmed for two germplasm accessions of P. carinatum (2n = 30) and P. trachycoleon (2n = 36), one of P. clavuliferum (2n = 40) and one of P. lanciflorum (2n = 40), indicating variability in these species. The remaining chromosome numbers reported here confirm previous counts. The unexpected chromosome numbers 2n = 18, 24, 36, and 48 in Paspalum species, which are usually shown to be multiples of 10, suggest that much more collection and cytogenetic characterization are necessary to assess the whole chromosomal and genomic multiplicity present in the genus, which seems to be much more diverse than currently thought to be.

Characterization of Seashore Paspalum (Paspalum vaginatum Swartz) Germplasm by Transferred SSRs from Wheat, Maize and Sorghum

One hundred and thirty SSR markers from wheat, maize and sorghum were screened for the transferability to Paspalum. The transfer rate was 67.5, 49.0 and 66.8% respectively. This would be a very efficient approach for DNA marker development for species which are not well studied molecularly. The polymorphism level for transferred SSR markers was 51.5% within species (Paspalum vaginatum) and 87.1% among Paspalum species. The high level of polymorphism is directly related to the high degree of heterozygosity maintained by its way of reproduction, i.e. self-incompatibility. Forty transferred polymorphic SSR markers were selected and used for characterization and evaluation of seventy-three Paspalum accessions. In total, 209 polymorphic bands were detected from these 40 SSR markers, with an average of five polymorphic bands per marker. The Paspalum accessions clustered into three major groups. Two very similar dendrograms can be generated from either 109 or 209 polymorphic bands. This led us to determine that 18 of the transferred SSR markers were sufficient for genetically differentiating the investigated germplasm accessions. The number of SSR markers required for germplasm characterization and evaluation is discussed. This is the first report of the transfer of SSR markers from major field crops to newly emerged environmental turfgrasses.

Chromosome numbers and meiotic behavior of some Paspalum accessions

Chromosome number and meiotic behavior were evaluated in 36 Brazilian accessions of the grass Paspalum (which had never previously been analyzed) to determinate which accessions might be useful in interspecific hybridizations. The analysis showed that one accession of Paspalum coryphaeum was diploid (2n = 2x = 20) and one accession of Paspalum conspersum hexaploid (2n = 6x = 60), the remaining 34 accessions being tetraploid (2n = 4x = 40). The pairing configuration was typical for the ploidy level i.e. in the diploid, chromosomes paired as 10 bivalents, in tetraploids as bi-, tri- and quadrivalents, and in hexaploid as 30 bivalents. A low frequency of meiotic abnormalities (less than 10%) was observed in the diploid, hexaploid and some tetraploid accessions, although the majority of tetraploid accessions showed a high frequency of meiotic irregularities. The use of accessions with a low frequency of meiotic abnormalities in breeding programs is discussed.

Cytogenetic characterization of Brazilian Paspalum accessions.

Chromosome number, pairing relationship and meiotic behavior were evaluated in 24 Brazilian accessions of different Paspalum species as an initial screening to determine which of them might be useful in an interspecific hybridization program. The analysis showed that six were diploids, 16 tetraploids and two hexaploids. The pairing relationship was typical for the ploidy level and agreed with reported data. However, the meiotic behavior after diakinesis was much more abnormal than expected considering the pairing relationship. There was a high frequency of abnormal tetrads in the majority of accessions.

Failure of cytokinesis and 2n gamete formation in Brazilian accessions of Paspalum

Cytological analysis on 112 Brazilian accessions of Paspalum showed that 52 were affected by failure of first or second cytokinesis during microsporogenesis. When the failure of cytokinesis occurred only in the first division and in the second division the cytokinesis was normal, a dyad of microspores was formed. In most of them the two cells remained binucleate, but in some a restitutional nucleus was observed. When the first division was normal and the failure of cytokinesis occurred only in the second division, dyads and triads were observed. A restitutional nucleus in one or both cells of the dyad, or in the binucleate cell of the triad was also observed. The percentage of dyads and triads varied among accessions, reaching 15.75 of the sporads in some. The absence of cytokinesis indicates the possibility that the widespread occurrence of polyploidy in the genus Paspalum originates from 2n pollen grains.