Published online 1 September 2007
Published in Crop Sci 47:1985-1994 (2007)
© 2007 Crop Science Society of America
677 S. Segoe Rd., Madison, WI 53711 USA
PLANT GENETIC RESOURCES
Genetic Variability and Relationships for Adaptive, Morphological, and Biomass Traits in Chinese Bermudagrass Accessions
Y. Q. Wua,*,
C. M. Taliaferroa,
D. L. Martinb,
J. A. Andersonb and
M. P. Andersona
a Dep. of Plant and Soil Sciences, Oklahoma State Univ., Stillwater, OK 74078
b Dep. of Horticulture and Landscape Architecture, Oklahoma State Univ., Stillwater, OK 74078
* Corresponding author (yanqi.wu{at}okstate.edu).
 |
ABSTRACT
|
|---|
Bermudagrass, Cynodon dactylon (L.) Pers., is geographically widely distributed and represents the most important taxon in the genus in terms of its extensive uses for turf, forage, soil stabilization, and remediation. This warm-season, sod-forming grass is indigenous to China, but limited information is available for adaptive, morphological, and biomass traits in the Chinese germplasm. Accordingly, objectives of this study were to quantify genetic variability for 24 morphological, adaptive, and biomass-related traits and to characterize relationships among traits of 114 Chinese clonal accessions in a field experiment at Stillwater, OK. ‘Tifsport’, ‘Tifway’, ‘Midland’, and ‘Tifton 44’ bermudagrass cultivars were used as controls in the field experiment. Differences among the accessions were significant (P < 0.01 or P < 0.05) and of large magnitude for all response traits. When grouped by ploidy level, variation among accessions was far greater in tetraploids (104) than in pentaploids (3) and hexaploids (7). Response traits of plant height, leaf blade length and width, and internode length and diameter were significantly and positively correlated with each other to various degrees. Biomass yield was significantly associated with the traits of spring greenup, plant height, winter kill rate, internode, and sod density. Winter kill was positively correlated with weed prolificacy, but negatively with spring greenup. Multiple regression and path coefficient analyses indicated plant height, winter kill, greenup, sod density, and internode size to be predictive of forage yield. The large amount of genetic variability among the Chinese accessions should be a valuable resource for the development of improved turf and forage cultivars.
Abbreviations: AIL, average internode length • FLL, first leaf blade length on third node • FLW, first leaf blade width on third node • GC, genetic color • GCR, ground coverage • GUI, greenup rated on 9 Apr. 2002 and 29 Mar. 2003 • GUII, greenup rated on 19 Apr. 2002 and 16 Apr. 2003 • GUIII, greenup rated on 30 Apr. 2002 and 27 Apr. 2003 • HNS, height without seedhead • HWS, height with seedhead • SD, sod density • SID, second internode diameter • SIL, second internode length • SL, stolon length • SLL, second leaf blade length on third node • SLW, second leaf blade width on third node • TID, third internode diameter • TIL, third internode length • WA, weed abundance • WCR, winter color retention • WK, winter kill
Genetic Variability and Relationships for Adaptive, Morphological, and Biomass Traits in Chinese Bermudagrass Accessions
Y. Q. Wua,*,
C. M. Taliaferroa,
D. L. Martinb,
J. A. Andersonb and
M. P. Andersona
a Dep. of Plant and Soil Sciences, Oklahoma State Univ., Stillwater, OK 74078
b Dep. of Horticulture and Landscape Architecture, Oklahoma State Univ., Stillwater, OK 74078
* Corresponding author (yanqi.wu{at}okstate.edu).
Bermudagrass, Cynodon dactylon (L.) Pers., is geographically widely distributed and represents the most important taxon in the genus in terms of its extensive uses for turf, forage, soil stabilization, and remediation. This warm-season, sod-forming grass is indigenous to China, but limited information is available for adaptive, morphological, and biomass traits in the Chinese germplasm. Accordingly, objectives of this study were to quantify genetic variability for 24 morphological, adaptive, and biomass-related traits and to characterize relationships among traits of 114 Chinese clonal accessions in a field experiment at Stillwater, OK. ‘Tifsport’, ‘Tifway’, ‘Midland’, and ‘Tifton 44’ bermudagrass cultivars were used as controls in the field experiment. Differences among the accessions were significant (P < 0.01 or P < 0.05) and of large magnitude for all response traits. When grouped by ploidy level, variation among accessions was far greater in tetraploids (104) than in pentaploids (3) and hexaploids (7). Response traits of plant height, leaf blade length and width, and internode length and diameter were significantly and positively correlated with each other to various degrees. Biomass yield was significantly associated with the traits of spring greenup, plant height, winter kill rate, internode, and sod density. Winter kill was positively correlated with weed prolificacy, but negatively with spring greenup. Multiple regression and path coefficient analyses indicated plant height, winter kill, greenup, sod density, and internode size to be predictive of forage yield. The large amount of genetic variability among the Chinese accessions should be a valuable resource for the development of improved turf and forage cultivars.
Abbreviations: AIL, average internode length • FLL, first leaf blade length on third node • FLW, first leaf blade width on third node • GC, genetic color • GCR, ground coverage • GUI, greenup rated on 9 Apr. 2002 and 29 Mar. 2003 • GUII, greenup rated on 19 Apr. 2002 and 16 Apr. 2003 • GUIII, greenup rated on 30 Apr. 2002 and 27 Apr. 2003 • HNS, height without seedhead • HWS, height with seedhead • SD, sod density • SID, second internode diameter • SIL, second internode length • SL, stolon length • SLL, second leaf blade length on third node • SLW, second leaf blade width on third node • TID, third internode diameter • TIL, third internode length • WA, weed abundance • WCR, winter color retention • WK, winter kill
|
INTRODUCTION
|
|---|
BERMUDAGRASS [Cynodon dactylon (L.) Pers.] is a polymorphic warm-season, sod-forming, perennial species widely used for turf, forage, soil stabilization, and remediation in warmer regions of the world (Harlan and de Wet, 1969; Beard, 1973; Taliaferro, 1995, 2003). The grass belongs to the tribe Cynodonteae Dumort., subfamily Chloridoideae Rouy, and family Gramineae Juss. (Poaceae Barnh.) (Clayton and Renvoize, 1986). The species is found on every continent and most islands between about 45°N and S latitudes. It penetrates to approximately 53°N in Europe and is found up to 3000 m elevation in South Asia and below sea level in West Asia and North Africa (Harlan and de Wet, 1969; Harlan et al., 1970). Variety dactylon is the cosmopolitan and ubiquitous taxon, and provides the most important and diverse genetic resources in the species for its use as forage and turf (Harlan, 1970; Taliaferro, 1995).
There is enormous genetic variability available in bermudagrass, ranging from very small, fine-textured plants used for turf to large, leafy robust plants used as pasture grasses (Harlan and de Wet, 1969; Kneebone, 1973). The variability within C. dactylon var. dactylon was thought to have resulted from its interaction with two taxonomic varieties, C. dactylon var. aridus and var. afghanicus (Harlan and de Wet, 1969). In the United States, many superior turf bermudagrass cultivars were derived from bermudagrass germplasm imported primarily from Africa during the last century (Taliaferro, 1995; 2003). Juska and Hanson (1964) reported substantial variation among bermudagrass cultivars for morphological characteristics related to general turf use. Wofford and Baltensperger (1985) and Coffey and Baltensperger (1989) reported that variation in bermudagrass for various morphological and turf performance characters was heritable, and several traits including leaf length and leaf width had moderate to high narrow sense heritability values. Bermudagrass is the principal species used for turf in the southern United States, and other regions in the world with similar climatic conditions.
Burton (1947) reported a correlation coefficient of 0.80 between first year hay yield after establishment and the four-year total yield indicating that the hay yield for the first year should give an excellent index of later yield performance. De Silva (1991) observed significant amounts of genetic variation for shoot dry weight among populations collected in Sri Lanka. Avis et al. (1980) reported significant genotype x environment interactions for bermudagrass forage yield suggesting the necessity to use multiple environment testing through time (years) and space (locations) to characterize relative genotypic differences. Bermudagrass is grown on an estimated 10 to 12 million hectares in the southern United States for forage (Taliaferro et al., 2004).
The full range of genetic variability in C. dactylon is likely not represented in current germplasm collections and much potential exists to add valuable new germplasm to the collected pool (Taliaferro, 2003). Harlan (1970) noted that only a tiny fraction of the total germplasm that exists in the taxon had been studied and even less used in breeding improvement programs up to that time. The situation remains essentially the same, especially with respect to Asian germplasm.
Cynodon dactylon is indigenous to and widely distributed in China. The species is common in the southern region, ranging from tropical Hainan Island to a line connecting the northern edge of Sichuan province eastward to Shanghai. Cynodon dactylon is also found in northern China, especially in the region south of the Yellow River (Anonymous, 1990). In the far northwest China, C. dactylon is sparsely distributed in the southern and northern oasis plains in Xinjiang (Abulaiti et al., 1998). In southwestern China, it is present in natural settings including sites at approximately 3000 m in elevation in Yunnan, and in some valleys of Tibet. The wide geographic distribution suggests the potential for large variation in Chinese native C. dactylon germplasm. However, little information exists on genetic variation for agronomic and biological characters in native Chinese bermudagrass. In a previous study (Wu et al., 2006b), we reported significant variability among Chinese Cynodon accessions for seed yield and its components. This paper reports the results of research designed to assess genetic variation in traits related to vegetative growth and forage accumulation among 114 C. dactylon accessions from China. Specific objectives of the study were to (i) quantify genetic variability for morphological, adaptive, and biomass-related traits; and (ii) characterize relationships among traits.
|
MATERIALS AND METHODS
|
|---|
The Chinese C. dactylon accessions used in this study consisted of 114 clonal accessions described by Wu et al. (2006b). Bermudagrass cultivars ‘Tifsport’ (Hanna et al., 1997), ‘Tifway’ (Burton, 1966), ‘Midland’ (Hein, 1953), and ‘Tifton 44’ (Burton and Monson, 1978) were included as standards in the field study. The Chinese accessions comprised 104 tetraploids (2n = 4x = 36), three pentaploids (2n = 5x = 45), and seven hexaploids (2n = 6x = 54) (Wu et al., 2006a).
The experimental design and methods of establishing and managing the field plots were reported by Wu et al. (2006b). Briefly, greenhouse-grown clonal plants of each accession were transplanted to field plots on the Agronomy Research Station, Oklahoma State University, Stillwater, OK, in 2001. The experimental design was a randomized complete block with three replications. Plot size was 2.5 by 2.5 m separated by 0.5-m alleys between plots. The soil type was a Renfrow loam (fine, mixed, superactive, thermic Udertic Paleustoll). Fertilization and weed control practices were as reported by Wu et al. (2006b).
Response traits are listed in Table 1
, along with information on time and method of evaluations. Ground coverage, winter color retention, greenup, genetic color, sod density, slime mold, leaf spot (caused by Bipolaris cynodontis Marignoni), and weed abundance were assessed by visual ratings of field plots. Stolon length (plant establishment rate), plant height with seedhead, and height without seedhead were measured in the field. In August of 2002 and 2003, five full-length stems were collected randomly in each plot and placed in a plastic bag, and then stored in a freezer at –20°C for subsequent measurements of morphological traits. The traits were (i) length of second and third internodes from the terminal end, and average over all internodes of each stem, (ii) diameter of second and third internodes, and (iii) lengths and widths of first and second leaf blades originating from the third node (Table 1). After collection of individual stems, aboveground biomass (subsequently referred to simply as biomass) samples were harvested from each plot by hand clipping a 0.3 by 0.3 m area. The biomass samples were dehydrated at 55°C (130°F) in forced air ovens for 72 h. The biomass yield (Mg ha–1) was calculated from the dried sample weight (g m–1) by multiplying a coefficient of 0.1111.
View this table:
[in this window]
[in a new window]
|
Table 1. Duration and date of data collection, and methods of trait evaluations on 114 Chinese Cynodon accessions and four cultivars.
|
|
Plot means were used for statistical analyses for traits with multiple measurements. A randomized complete block design was used with entry, year, and replication as random effects, while entry was the main effect. The SAS/MIXED procedure was used for analysis of variance (ANOVA) and to obtain REML estimates of the variance components (SAS Institute, 2003). A test was conducted for differences within and among the ploidy levels, and unequal variance methods were used if heterogeneity of variances among ploidy levels was detected. The PROC CORR procedure was used to perform phenotypic correlation (subsequently referred to simply as correlation) analyses. Multiple regression with stepwise procedure was used to select significant traits at 0.05 probability level for biomass. Path coefficient analyses were performed using standard methods (Dewey and Lu, 1959; Das et al., 2004).
|
RESULTS AND DISCUSSION
|
|---|
Variability of 24 Adaptive, Morphological, and Biomass Traits
Significant (P < 0.01 or 0.05) differences among accessions were detected for all traits (Table 2
). Effects of year, replication, and accession by year interaction were significant (P < 0.01 or 0.05) respectively in 16, 15, and 16 of the 19 traits with two- or three-year data (Table 2). Replication effects were also significant (P < 0.01 or 0.05) in the five one-year data traits (Table 2). The ANOVA results clearly indicated different magnitudes of variation among accessions within the three ploidy levels (Tables 3–5
). For the 104 tetraploids, significant effects (P < 0.01 or 0.05) were attributable to accessions for 22 of the 24 traits, third internode length (TIL) and winter color retention (WCR) being exceptions. Additionally, year and the accession x year interaction were significant (P < 0.01 or 0.05) for 17 of the 19 traits with two- or three-year data (Table 3). The three pentaploid accessions did not differ (P > 0.05) for any trait, though year and the accession x year interaction were significant (P < 0.01 or 0.05) for some traits (Table 4). Differences among the seven hexaploid accessions were significant (P < 0.01) for four traits, with year and the year x accession interaction also being significant for certain traits (Table 5).
View this table:
[in this window]
[in a new window]
|
Table 2. Analyses of variance on 24 adaptive, morphological and biomass traits for 114 Chinese Cynodon accessions.
|
|
View this table:
[in this window]
[in a new window]
|
Table 3. Analyses of variance on 24 adaptive, morphological, and biomass traits for 104 tetraploid Chinese Cynodon accessions.
|
|
View this table:
[in this window]
[in a new window]
|
Table 5. Analyses of variance on 24 adaptive, morphological, and biomass traits for seven hexaploid Chinese Cynodon accessions.
|
|
View this table:
[in this window]
[in a new window]
|
Table 4. Analyses of variance on 24 adaptive, morphological, and biomass traits for three pentaploid Chinese Cynodon accessions.
|
|
Means and ranges for all traits of the 114 Chinese accessions and the four standard cultivars are presented by year in Table 6
, because significant entry x year interactions were present for most traits in Table 2. For two establishment rate descriptors, stolon length (SL) and ground coverage (GCR), the ranges were larger in the Chinese collection than in the four cultivars. Among Chinese accessions, pentaploid and hexaploid plants tended to have a faster establishment rate than tetraploid accessions, though the SL and GCR ranges for tetraploids were greater (Table 6). This indicates that some tetraploid accessions were superior in establishment rate to either pentaploid or hexaploid accessions. The four standard cultivars generally had better winter color retention than the Chinese accessions, though there was variation among the latter. The ranges for the three spring greenup ratings (greenup rated on 9 Apr. 2002 and 29 Mar. 2003 [GUI], greenup rated on 19 Apr. 2002 and 16 Apr. 2003 [GUII], and greenup rated on 30 Apr. 2002 and 27 Apr. 2003 [GUIII]) were larger than those for the standard cultivars, indicating some Chinese accessions initiated growth earlier than the standard cultivars. Among the three ploidy levels, the hexaploids had highest GU averages, the pentaploids lowest, while the tetraploids had the largest ranges both years. The winter kill (WK) ranges were larger in the 114 Chinese accessions compared to the four cultivars over the two years. The hexaploids on average had the lowest WK rates, while the tetraploids had the largest ranges, and the pentaploids had the highest WK averages. Variability for genetic color (GC) was greater among Chinese accessions compared to control cultivars. Interestingly, the hexaploids had higher GC means in each of the two years, while the tetraploids had larger ranges. For sod density (SD), the Chinese accessions had a larger range than the four cultivars in 2002, while Tifsport and Tifway showed better SD values than any of the Chinese accessions in 2003. The pentaploid Chinese accessions had higher average sod density than the other two ploidy levels in 2002, but its average value was the lowest in 2003, probably due to greater winter injury. For the 11 morphological descriptors (height with seedhead [HWS], height without seedhead [HNS], average internode length [AIL], second internode length [SIL], third internode length [TIL], second internode diameter [SID], third internode diameter [TID], first leaf blade width on third node [FLW], first leaf blade length on third node [FLL], second leaf blade width on third node [SLW], and second leaf blade length on third node [SLL]), the forage-type cultivars Tifton 44 and Midland had larger mean values than the Chinese accessions for most traits, while some Chinese accessions were similar to or smaller than the turf type cultivars Tifsport and Tifway in certain traits. Hexaploid and pentaploid accessions had mean morphological trait values generally similar in size, and generally larger than those for Chinese tetraploid accessions. However, some large tetraploids were similar to pentaploids and hexaploids in size. For the two diseases leaf spot and slime mold, the Chinese accessions had mean ratings ranging from 1 to 9. In 2003, weeds occurred in significant numbers in some plots. Again, the Chinese accessions had a large range in weed abundance (WA) ratings, while WA ratings for the standard cultivars were relatively low. For the Chinese accessions, the mean and range of biomass was higher in 2002 than in 2003. Compared to the four standards, the Chinese accessions had larger ranges for biomass yield in both years. Among the three ploidy levels of the Chinese accessions, the tetraploids had largest range, while hexaploids had highest yearly averages.
View this table:
[in this window]
[in a new window]
|
Table 6. Means, standard deviations, and ranges for 24 trait descriptors of adaptation, morphology, and biomass in 2001 through 2003 on 114 Chinese Cynodon accessions and four standard cultivars.
|
|
Estimates of variance components and associated standard errors for the 24 traits examined in 114 Chinese accessions are presented in Table 7
. Genotypic variance estimates (
G2) were significant (P < 0.01) for all traits, and accession x year interaction variance estimates (GxY2) were significant (P < 0.01 or 0.05) for all traits but FLW and SLW (Table 7). For the 104 tetraploids, G2 was significant for all traits except GUI, and GxY2 was significant for 16 of 19 traits (data not provided). For the pentaploids, G2 was significant for TID and SLW (P < 0.01). For the hexaploid accessions, G2 was significant (P < 0.01 or 0.05) for GUII and WA, and GxY2 significant (P < 0.05) for FLL only.
View this table:
[in this window]
[in a new window]
|
Table 7. Estimates of variance components and their associated standard errors for 24 adaptive, morphological, and biomass traits in 114 Chinese bermudagrass accessions.
|
|
The results clearly indicated the presence of substantial genetic variation among the 114 Chinese accessions for the 24 descriptor traits. Such variation was expected based on previous reports of variation among C. dactylon accessions from geographic areas other than China (Burton, 1947, 1965; Juska and Hanson, 1964; Harlan and de Wet, 1969; Kneebone, 1973; Harlan, 1970). Genetic variation in bermudagrass for many forage and turf performance traits has been demonstrated to be heritable and useful in breeding improvement (Burton, 1947, 1951, 1956, 1959, 1965; Wofford and Baltensperger, 1985; Coffey and Baltensperger, 1989).
Trait Relationships and Biomass Component Analysis
Significant (P < 0.05 or 0.01) correlation coefficients among the adaptive, morphological, and biomass trait descriptors are presented in Table 8
. Highly positive relationships (r > 0.70) were respectively found for all pairings of HWS and HNS, GUIII and GUII and GUI, AIL and SIL and TIL, SID and TID, FLW and SLW, and FLL and SLL. Highly negative correlations were found between WK rate and GU descriptors, indicating that accessions with early spring growth had better winter survival. Most of the correlation coefficients between the various morphological traits were significant and substantial, indicating, for instance, that accessions with longer and wider leaves also had internodes that were longer and of greater diameter, and that such accessions were generally taller. The relatively high correlation (r = 0.57, P < 0.0001) between WA and WK simply reflected the opportunity for weed encroachment in accessions with substantial winter kill. The slime mold and leaf spot occurrence were not correlated (r = –0.04, P = 0.42), suggesting that simultaneous selection for resistance may be possible.
View this table:
[in this window]
[in a new window]
|
Table 8. Significant (P < 0.05) correlations between the adaptive, morphological, and biomass traits with 2-yr data in 114 Chinese Cynodon accessions.
|
|
Biomass yield was significantly (P 
0.05) positively and negatively correlated with 11 and one trait descriptors, respectively (Table 8). Multiple regression analysis with stepwise selection procedures showed that GUI, HNS, SD, SID, WK, HWS, and AIL were significant (P < 0.05) in a model to predict biomass yield, although they collectively accounted for only 29.6% of total biomass variation. Path analysis data for biomass and the seven selected traits are given in Table 9
. Among the seven path coefficients (direct effects), the highest value was 0.39 for plant HNS, indicating its large effect on biomass yield. However, GUI, SD, SID, and AIL had similar coefficients in magnitude indicating that they were important contributors to biomass yield. The WK had a predicted negative effect on biomass yield, indicating its importance to adaptation to temperate regions. The HWS contributed to biomass yield via HNS (Table 9). Therefore, selection for taller plants with better winter survival, earlier spring greenup, denser sod, and bigger internodes should improve the biomass yield.
View this table:
[in this window]
[in a new window]
|
Table 9. Path analysis of direct and indirect effects of seven traits on biomass for 114 Chinese Cynodon dactylon accessions.
|
|
|
CONCLUSIONS
|
|---|
Substantial genetic variation was found among 114 C. dactylon accessions from China for each of 24 adaptive, morphological, and biomass yield descriptor traits. Variation was greatest among tetraploid accessions, which constituted 91% (104) of the collection. Variation among pentaploid (3) and hexaploid (7) accessions for the 24 traits was evident, but of low magnitude compared to the tetraploid accessions. Some accessions exhibited traits either uniquely or rarely expressed in existing bermudagrass collections, such as dark green foliage color. Significant accession x year interactions for many of the descriptor traits indicated the failure of accessions to respond similarly over the two years. Winter kill was positively correlated with weed prolificacy, but negatively with spring greenup and biomass yield. Morphological traits were significantly and positively correlated with each other at varying magnitudes. Biomass yield was significantly associated with numerous traits. Multiple regression and path coefficient analyses both indicated selection for height, adaptation, spring greenup, sod density, and internode size in introduced bermudagrass germplasm should be favorable for increased forage yield. The high degree of polymorphism in C. dactylon germplasm indigenous to China is of potential value in breeding improved turf and forage bermudagrass cultivars.
|
NOTES
|
|---|
All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Permission for printing and for reprinting the material contained herein has been obtained by the publisher.
Received for publication January 24, 2007.
|
REFERENCES
|
|---|
- Abulaiti, D.S. Shi, and G. Yang. 1998. Preliminary research report on the native Cynodon dactylon in Xinjiang. (In Chinese.) J. Xinjiang Agric. Univ. 21:124–127.
- Anonymous. 1990. Cynodon Rich. p. 82–85. In Chinese floral acta. Vol. 10. (In Chinese.) Science Press, Beijing, China.
- Avis, J.D., C.M. Taliaferro, and D. Holbert. 1980. Genotype x interaction study of bermudagrass yields in Oklahoma. Proc. Okla. Acad. Sci. 60:69–74.
- Beard, J.B. 1973. Turfgrass science and culture. Prentice Hall, Englewood Cliffs, NJ.
- Burton, G.W. 1947. Breeding bermuda grass for the southeastern United States. Agron. J. 39:551–569.[Free Full Text]
- Burton, G.W. 1951. Intra- and inter-specific hybrids in bermudagrass. J. Hered. 42:153–156.[Free Full Text]
- Burton, G.W. 1956. Utilization of heterosis in pasture plant breeding. p. 3–12. In G.J. Neale (ed.) Proc. Int. Grassl. Congr., 7th, Palmerston North, New Zealand. 6–12 Nov. 1956. Wright and Carman, Wellington, New Zealand.
- Burton, G.W. 1959. Principles of breeding vegetatively propagated plants. p. 661–670. In Proc. Congr. Int. Soc. Sugarcane Technologists, 10th, Honolulu, HI. 3–22 May 1959. Elsevier, Amsterdam, the Netherlands.
- Burton, G.W. 1965. Breeding better bermudagrasses. p. 93–96. In L.P. Jordao et al. (ed.) Proc. Int. Grassl. Congr., 9th, Sao Paulo, Brazil. 7–20 Jan. 1965. Dep. Nacl. de Producao Anim., Sao Paulo, Brazil.
- Burton, G.W. 1966. Tifway (Tifton 419) bermudagrass. Crop Sci. 6:93–94.[Free Full Text]
- Burton, G.W., and W.G. Monson. 1978. Registration of ‘Tifton 44’ bermudagrass. Crop Sci. 18:911.[Free Full Text]
- Clayton, W.D., and S.A. Renvoize. 1986. Genera Graminum: Grasses of the world. Kew Bulletin Additional Series 13. Her Majesty's Stationery Office, London.
- Coffey, B.N., and A.A. Baltensperger. 1989. Heritability estimates for selected turfgrass characteristics of bermudagrass evaluated under shade. p. 117–119. In H. Takatoh (ed.) Proc. Int. Turfgrass Res. Conf., 6th, Tokyo, Japan. 31 July–5 Aug. 1989. Intl. Turfgrass Soc. and Japan Soc. Turfgrass Sci., Tokyo.
- Das, M.K., R.G. Fuentes, and C.M. Taliaferro. 2004. Genetic variability and trait relationships in switchgrass. Crop Sci. 44:443–448.[Abstract/Free Full Text]
- de Silva, P.H.A.U. 1991. The ecological genetics of Cynodon dactylon (L.) Pers. in Sri Lanka. Ph.D. diss. Univ. of Reading. UK.
- Dewey, D.R., and K.H. Lu. 1959. A correlation and path-coefficient analysis of components of crested wheatgrass seed production. Agron. J. 51:515–518.[Abstract/Free Full Text]
- Hanna, W.W., R.N. Carrow, and A.J. Powell. 1997. Registration of (Tift 94) bermudagrass. Crop Sci. 37:1012.[Free Full Text]
- Harlan, J.R. 1970. Cynodon species and their value for grazing or hay. Herbage Abstr. 40:233–238.
- Harlan, J.R., and J.M.J. de Wet. 1969. Sources of variation in Cynodon dactylon (L.) Pers. Crop Sci. 9:774–778.[Abstract/Free Full Text]
- Harlan, J.R., J.M.J. de Wet, and K.M. Rawal. 1970. Geographic distribution of the species of Cynodon L.C. Rich (Gramineae). East Afric. Agric. For. J. 36:220–226.
- Hein, M.A. 1953. [Cynodon dactylon (L.) Pers.] Registration of varieties and strains of Bermuda grass, II. Agron. J. 45:572–573.[Free Full Text]
- Juska, F.V., and A.A. Hanson. 1964. Evaluation of bermudagrass varieties for general purpose turf. USDA Agric. Res. Ser. Agric. Handbook No. 270. U.S. Gov. Print. Office, Washington, DC.
- Kneebone, W.R. 1973. Breeding seeded varieties of bermudagrass for turfgrass use. Proc. Scotts Turfgrass Res. Conf. 4:149–153.
- SAS Institute. 2003. SAS proprietary software version 9.1. SAS Inst., Cary, NC.
- Taliaferro, C.M. 1995. Diversity and vulnerability of bermuda turfgrass species. Crop Sci. 35:327–332.[Abstract/Free Full Text]
- Taliaferro, C.M. 2003. Bermudagrass (Cynodon (L.) Rich). p. 235–256. In M.D. Casler and R. Duncan (ed.) Turfgrass biology, genetics, and breeding. Sleeping Bear Press, Chelsea, MI.
- Taliaferro, C.M., F.M. Rouquette, Jr., and P. Mislevy. 2004. Bermudagrass and stargrass. In L.E. Moser et al. (ed.) Warm-season (C4) grasses. ASA Monogr. 45. ASA, CSSA, and SSSA, Madison, WI.
- Wofford, D.S., and A.A. Baltensperger. 1985. Heritability estimates for turfgrass characteristics in bermudagrass. Crop Sci. 25:133–136.[Abstract/Free Full Text]
- Wu, Y.Q., C.M. Taliaferro, G.H. Bai, D.L. Martin, J.A. Anderson, M.P. Anderson, and R.M. Edwards. 2006a. Genetic analyses of Chinese Cynodon accessions by flow cytometry and AFLP markers. Crop Sci. 46:917–926.[Abstract/Free Full Text]
- Wu, Y.Q., C.M. Taliaferro, D.L. Martin, C.L. Goad, and J.A. Anderson. 2006b. Genetic variability and relationships for seed yield and its components in Chinese Cynodon accessions. Field Crops Res. 98:245–252.[CrossRef]
TOP
ABSTRACT
INTRODUCTION
