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Genetic variability and character associations in vetiver (Vetiveria zizanioides L. Nash)
Industrial Crops and Products 49 (2013) 273–277
Contents lists available at SciVerse ScienceDirect
Industrial Crops and Products journal homepage: www.elsevier.com/locate/indcrop
Genetic variability and character associations in vetiver (Vetiveria zizanioides L. Nash) R.K. Lal ∗ , P. Gupta, V. Gupta, S. Sarkar, S. Singh CSIR – Central Institute of Medicinal and Aromatic Plants P.O. CIMAP, Lucknow, UP 226015, India
a r t i c l e
i n f o
Article history: Received 19 February 2013 Received in revised form 9 May 2013 Accepted 14 May 2013 Keywords: Direct contribution Genetic associations Genetic stocks Heritability Path coefficients
a b s t r a c t Forty genetic stocks of vetiver (Vetiveria zizanioides L. Nash) were screened for high oil yield. The considerable amount of natural and genetic variability in morpho-metric traits was recorded. The estimate of heritability (ˆh2 BS %) and corresponding genetic advance (GA), both were high for plant height (ˆh2 BS % = 98.48 and GA = 64.83). Genetic (G) and phenotypic (P) associations coefficients among the seven traits indicated that plant height was highly and significantly correlated with tillers/plant (0.399**G, 0.389**P); fresh root with dry root yield (0.905**G, 0.769**P) and oil content with oil yield (0.397**G, 0.390**P) at both genotypic and phenotypic level. The plant height with root length was also positively correlated with each other at both genetic (G) and phenotypic (P) levels (0.282*G, 0.278*P). The path coefficient under study revealed that the highest direct contribution to total oil yield was made by fresh root yield (0.514) followed by oil content (0.386), tillers/plant (0.149) and root length (0.086) in percent. © 2013 Elsevier B.V. All rights reserved.
1. Introduction The genus Vetiveria is a small genus of perennial grasses occurring mainly in tropical countries of old world. In India, only two species of vetiver are found Vetiveria zizanioides and Vetiveria lawsoni syn. Vetiveria nemoralsis belongs to family Poaceae, is native to India and is found growing wild in almost all parts of the country (Ramanujam and Kumar, 1964; Lavania, 2000; Lal, 2012). However, it is only the former, i.e. (V. zizanioides (L.) Nash), chromosome number: 2n = 20, which is of great significance as a high class perfume as well as indigenous systems of medicine since time dating back to 1103 AD (Virmani and Datta, 1975; Akhila et al., 1981; Hussain et al., 1984; Lal, 2012). Its aerial parts have other potential economic values also, such as for fodder, mulch, animal bedding, thatches, handicrafts, in paper industries, vermi compost, in making tiles, etc. (Pareek, 1994; Lal et al., 1997a,b; Lal et al., 1999a,b), thus nonpart of vetiver plants goes waste. It grows luxuriously in parts of Utter Pradesh, Madhya Pradesh, Bihar, Rajasthan and several tracts in southern and peninsular India particularly along the river banks and over marshy lands (Virmani and Datta, 1975; Hussain et al., 1984; Lal, 2012). The total world production of vetiver oil is estimated to be 300–350 tonnes per year (Lal, 2012). The annual consumption and demand is likely to increase further. In India, about 100 tonnes of oil is produced annually, which is far below
∗ Corresponding author. Tel.: +91 522 2718523; fax: +91 522 2342666. E-mail addresses: [email protected], [email protected] (R.K. Lal). 0926-6690/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.indcrop.2013.05.005
to meet our internal demand of the oil for perfumery, masticatory, attar and soap industries. In our research programme on vetiver improvement, a large number of genetic stocks/clones were assembled from different places of India. Three exotic genetic stocks were also obtained from Haiti, Reunion Island and Indonesia for genetic study. This study have planned to sort out promising genetic stock(s) suitable for high root and oil yield of better quality purpose. Since, a priori knowledge of the range of variability and character associations having great significance for further breeding, all these genetic stocks were maintained and studies for the required genetic parameters. 2. Materials and methods A large number of genetic stocks of vetiver (V. zizanioides (L.) Nash) were assembled from wild/cultivated sources of vetiver from various places in India and abroad. Out of 125 genetic stocks, a new set having forty genetic stocks of vetiver (V. zizanioides L. Nash) from Uttar Pradesh (30), Rajasthan (1), Delhi (3), Travancore (2) and Odakali (1) in India and one each from Indonesia, Haiti and Reunion Island were screened for high oil yield of better quality (Table 2, Fig. 1). The genetic stocks were grown in a randomized block design with two replications at the research farm of the CSIR–Central Institute of Medicinal and Aromatic Plants, Lucknow, India in the two consecutive years 2009–2010 and 2010–2011 under normal fertility regime (80:40:40) kg N, P2 O5 and K2 O/ha, respectively, with plot size of single row of 2.5 m each 50 cm apart. Plants were uprooted
274
R.K. Lal et al. / Industrial Crops and Products 49 (2013) 273–277
Fig. 1. Genetic variability in plants, roots and in essential oil of vetiver genetic accessions.
12 months after planting of the experiments. The experimental site at the institute research farm was located at 26.5◦ N latitude and 80.50◦ E longitude, and 120 m above mean sea level. The climate is semiarid to subtropical in nature. Morpho-metric observations were recorded for seven economic traits, namely plant height (cm), tillers/plant, fresh and dry root yield (g/plot), root length (cm), oil content (%) and oil yield (g/plot). Oil content was estimated by hydro-distillation of shade dried roots of each clone for 16 h in Clevenger’s apparatus (Clevenger, 1928).
genotypic (GCV), phenotypic (PCV) levels and heritability in broad sense (h2 BS ) computed per the following formula: 2.2. Estimates of genetic parameters Heritability in broad sense (h2 BS ) %: It is the ratio of genotypic variance to the phenotypic variance = ( 2 g/ 2 p) × 100, where, 2 g = (MSg − MSe)/r and 2 p = 2 g + 2 e; MSg = mean sum of squares of genotypes; MSe = mean sum of squares of error. 2.3. Correlation coefficient (r)
2.1. Statistical analyses Statistical analyses were done using the Statistical Software 4.0 version, available in the Division of Genetics and Plant Breeding of the Institute, which is based on the standard methods in Panse and Sukhatme (1967) and Singh and Chaudhary (1979). The pooled mean values of 2 years for the all seven characters were subjected to correlation and path coefficient analyses (Dewey and Lu, 1959; Lal et al., 2001a,b). Various statistical parameters, including correlation and path coefficient, namely variance components genetic ( 2 g), phenotypic ( 2 p) and environmental ( 2 e), coefficient of variation
Analysis of variance (ANOVA). Source of variation
d.f.
Mean sum of squares (MSS)
F
Expectations
Replications Genotypes Error Total
01 (r − 1) 39 (g − 1) 39 (g − 1)(r − 1) 79 (gr − 1)
MSr MSg MSe –
– MSg/MSe –
– 2 e + r 2 g 2e
Correlation coefficients were used to measure of the associations between two or more than two variables. (i) Genotypic correlation (rg ) between two traits X and √ covariance (XY)}/ {genotypic variY = [{Genotypic ance (X) × genotypic variance (Y)}]where Genotypic and Genotypic varicovariance = (MSPg − MSPe)/r ance = (MSg − MSe)/r (ii) Phenotypic correlation (rp ) between two traits X and √ Y = [{phenotypic covariance (XY)}/ {phenotypic variance (X) × phenotypic variance (Y)}]where phenotypic covariance = (MSPg − MSPe)/r; phenotypic covariance = 2 g + 2 e; and r = number of replications. Co-heritability value of a character contribution suggests that the increases in one of the characters of those contributions will be coupled in the increasing trend in its co-heritable character. Where, Co-heritability (1, 2) = genotypic covariance/phenotypic covariance of traits 1 and 2.
R.K. Lal et al. / Industrial Crops and Products 49 (2013) 273–277
275
Table 1 Pooled ANOVA over two environments of forty genetic stocks of vetiver.
∗
Source of variation
d.f.
Replications Genotypes Error
01 39 39
Total
79
Mean sum of squares (MSS) Plant height
Tillers/plant
Fresh root yield
Dry root yield
Root length
Oil content
Oil yield
0.50 15.80∗ 15.80
63.02 8.60∗ 8.60
140.45 553.93∗ 3.27
6.01 35.32∗ 4.35
138.59 159.40∗ 5.22
0.0001 0.69∗ 0.011
0.011 0.96∗ 0.0012
P < 0.01.
2.4. Critical difference (CD) In order to compare the means of various entries, we require calculating the critical difference by following formula: CD = S.E. × ’t’ S.E. is standard error of the difference of the genotype means to be compared, and is equal to: S.E. =
2MSe 0.5 r
where MSe as error mean sum of squares and ‘t’ is the tabulated value of ‘t’ at 5% or 1% level of significance for the degree of freedom of error mean square.
be highly amenable to direct selection for their genetic improvement over a short span of time. In addition to heritability in broad sense (ˆh2 BS ) and genetic advance (GA), the associations among characters also have a direct bearing on success of selection. A critical perusal of observations/results indicates that the genotypic correlations were large than phenotypic correlations for all the traits except two traits – fresh root yield and oil yield examined (Table 3). Genotypic (G) and phenotypic (P) correlation coefficients among the seven traits revealed that plant height was highly and significantly correlated with tillers/plant (0.399**G, 0.389**P); fresh root with dry root yield (0.905**G, 0.769**P) and oil content with oil yield (0.397**G, 0.390**P) at both genotypic and phenotypic level. The plant height with root length was also positively correlated with each other at both genetic and phenotypic levels (0.282*G, 0.278*P). Hence, these traits were found to be good criteria for selection. These traits
2.5. Path coefficient analysis Path coefficients is simply a standardized partial regression coefficient and as such measures the direct influence of one variable upon another and permit the separation of correlation coefficients in to components of direct and indirect effects. Path coefficients can be defined as the ratio of standard deviation of the effect due to a given cause to the total standard deviation of the effect, i.e. if Y in the effect and x1 is the cause, the path coefficients for the path from cause x1 to the effect Y is x1 /y. 3. Results and discussion Variation among the pooled mean over 2 years of 40 diverse genetic stocks was highly significant (P < 0.01) for the all seven traits examined (Table 1). The meticulous study of analysis of variance, means, standard errors of means and critical difference (CD) revealed highly significant differences among the genotypes for all seven characters studied indicating thereby existence of considerable genetic variability among the genotypes (Tables 1 and 5). The statistical and genetic parameters for the heritable and nonheritable components of variation were computed. The sampling variance was moderate to high for nearly all the traits examined as genotypic coefficient of variation (GCV) 22.94–184.04 and phenotypic coefficient of variation (PCV) 23.11–184.27 levels. The heritable portion of phenotypic variance reflected by the size of 2 g relative to 2 p expressed as ˆh2 BS was generally very large (99.66–99.76) for the five characters except for oil content (77.86) and dry root yield (78.08) that showed moderate heritability. In other words, all characters except oil content and dry root yield were apparently only minimally influenced by environment factors (Table 5). A high heritability estimate (ˆh2 BS ) with corresponding high genetic advance (GA) is more reliable for selection than that with low genetic advance (GA). The estimate of heritability broad sense in percent (ˆh2 BS %) and corresponding genetic advance (GA), both were high for plant height (ˆh2 BS % = 98.48 and GA = 64.83), moderate heritability and high genetic advance for oil content (ˆh2 BS % = 77.86 and GA = 77.64), respectively. Therefore, these traits might
Table 2 Origin/places of collections of 40 accessions of vetiver maintained at CSIR-CIMAP, Lucknow. S.No.
Accessions
Origin/places of collection
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40
RZA-1 RRZA-10 SEL-1 BRT-5 GHG-1 RI-1 OD-1 KS-1 KS-2 IN-1 Gulabi TC-1 TC-2 MTR-1 K-15 K-18 K-20 K-25 K-27 K-29 K-62 AR-56 BBH-1 Haiti-1 DS-1 KH-8 CIM Vriddhi PH-8 BB-18 Dharini Kesari DOR-1 J-15 MD-1 BG-1 BKT-1 KH-30 KH-40 KH-41 MUSA-25
Razaganj, Lakhimpur (Kheri), UP, North India Razaganj, Lakhimpur (Kheri), UP, North Ind CIMAP, Lucknow, North India Bharat Pur, Rajasthan, North India Ghaghraghat, UP, North India Reunion, Island Odakkali, South India CIMAP, Lucknow, North India CIMAP, Lucknow, North India Indonesia CIMAP, Lucknow, North India Travencore, India Travencore, UP, India Mathura, UP, India Kanpur, UP, India Kanpur, UP, India Kanpur, UP, India Kanpur, UP, India Kanpur, UP, India Kanpur, UP, India Kanpur, UP, India Agra, UP, India New Delhi, India Haiti New Delhi, India Kanpur, UP, India CIMAP, Lucknow, India New Delhi, India Barabanki, UP, India CIMAP, Lucknow, India CIMAP, Lucknow, India Deoria, UP, North India Jhansi, UP, India Moradabad, UP, India Kukra/Bankey Ganj, Lakhimpur (Kheri), UP, India Bakshi-Ka-Talab Lucknow, UP, India Kanpur, UP, India Kanpur, UP, India Kanpur, UP, India Musanagar, UP, India
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Table 3 Genetic and phenotypic associations/correlations and co-heritability amongst seven economic traits of forty genetic stocks of vetiver. Genetic correlations
Characters Plant height
Plant height
– −0.073 1.004 −0.205 0.982 0.049 1.019 0.224 0.975 0.190 0.981 0.0002 0.051
Tillers/plant Fresh root yield Dry root yield Root length Oil content Oil yield
Tillers/plant 0.399∗∗ 0.389∗∗ – +0.029 1.011 −0.206 2.283 0.128 0.958 −0.075 1.015 −0.232 1.011
Fresh root yield
Dry root yield
Root length
Oil content
Oil yield
-0.149 −0.150 0.053 0.051 –
−0.177 −0.152 0.034 0.012 0.905∗∗ 0.769∗∗ –
0.282∗ 0.278∗ 0.135 0.134 −0.204 −0.199 −0.098 −0.065 –
0.215 0.214 0.161 0.154 −0.041 −0.037 −0.083 −0.059 0.135 0.131 –
−0.0001 0.004 0.181 0.176 0.225 0.223 0.134 0.119 0.040 0.036 0.397∗∗ 0.390∗∗ –
−0.512 1.034 −0.108 0.986 0.167 1.087 −0.044 1.001
0.161 1.294 0.154 1.215 0.039 0.993
0.063 0.979 −0.208 1.071
0.019 0.999
Values in upper diagonal belongs to genetic and phenotypic correlations and below diagonal relates to environmental correlation and co-heritability in broad sense: * P < 0.05 ** P < 0.01. Table 4 Direct (bold) and indirect effects on seven economic traits related to path analysis in vetiver genotypes. Traits
Plant height
Plant height Tillers/plant Fresh root yield Dry root yield Root length Oil content
−0.1472 −0.059 0.022 0.026 −0.042 −0.032
Tillers/plant 0.060 0.149 0.008 0.005 0.020 0.024
Fresh root yield
Dry root yield
Root length
Oil content
Oil yield (rg )
−0.081 0.029 0.544 0.492 −0.111 −0.022
0.0616 −0.012 −0.316 −0.349 0.0341 0.029
0.024 0.012 −0.018 −0.008 0.086 0.012
0.083 0.062 −0.016 −0.032 0.052 0.386
−0.00001 0.181 0.225 0.134 0.040 0.397
Residual effects = 0.7405903. Table 5 Estimates of variance components and allied genetic parameters obtained by different methods for diverse traits of forty genetic stocks in vetiver. S. No.
Characters
1 2 3 4 5 6 7
Plant height Tillers/plant Fresh root yield Dry root yield Root length Oil content Oil Yield
Genetic parameters 2g
2p
2e
GCV
PCV
CD5%
CD1%
CV (%)
SEM
h2 BS %
GA
1021.26 277.73 275.33 15.48 77.09 0.41 0.477
1017.07 286.33 278.59 19.83 82.31 0.35 0.479
15.80 8.60 3.27 4.35 5.22 0.011 0.0012
22.94 53.48 48.95 27.88 27.44 76.64 184.04
23.11 54.30 49.24 31.56 28.35 77.87 184.27
8.03 5.92 3.65 4.21 4.62 0.21 0.07
10.73 7.92 4.88 5.63 6.17 0.28 0.09
2.85 9.41 5.33 14.78 7.14 13.78 9.04
2.81 2.07 1.28 1.47 1.62 0.07 0.02
98.48 96.99 98.83 78.08 93.66 77.86 99.76
64.83 33.30 33.78 6.33 16.94 77.64 1.42
ˆ 2 g, ˆ 2 p, 2 e – variance due to genotype, phenotype and environment; GCV, PCV – genetic and phenotypic coefficient of variation; ˆhBS – heritability in broad sense; GA – genetic advance; CD – critical difference; SEM – standard error mean, respectively.
were also reinforced by high values of co-heritability. Since higher co-heritability value of a character contribution suggests that the increases in one of the characters of those contributions will be coupled in the increasing trend in its co-heritable character (Singh, 1988; Lal et al., 1999b, 2010a,b; Srivastava and Lal, 2012). Low environmental and week positive and negative associations were also noted between number of traits at both genetic and phenotypic levels (Table 3). Plant height with tillers/plant, fresh root yield with dry root yield and oil content with oil yield also exhibited high co-heritability with each other, hence may form a good selection criterion for valuable economic traits. The path coefficient under study revealed that the highest direct contribution to total oil yield was made by fresh root yield (0.544) followed by oil content (0.386), tillers/plant (0.149) and root length (0.086) in percent. Direct contribution of other two traits plant height and dry root yield to oil yield was negative but their indirect contribution was invariably large via dry root yield and fresh root yield, tillers/plant and oil content, plant height and fresh root yield, plant height and fresh root yield although residual effect was 0.740 (Table 4). These traits were also reinforced by high values of co-heritability (Table 3). Therefore, the choice of most economic
traits, root yield and oil content, tillers/plant followed by plant height may be used as a better selection criterion for improvement of oil yield. Dry root yield might be a rewarding proposition in vetiver, though nothing is as dependable as is selection for oil yield per se. Notwithstanding, however, improvement of oil yield is not only factor in vetiver. High essential oil yield coupled with oil quality is of great importance in trade. Thus, while selection for essential oil yield, the quality parameters should also be considered in the vetiver crop improvement programme. 4. Conclusions Genetic improvement and development of high yielding varieties is dependent upon genetic variability, we examined genetic variation for seven traits of 40 genetic stocks in order to understand genetic variability, genetic, phenotypic and environmental associations and contribution of various yield components in vetiver. Genotypic and phenotypic coefficient of variations was largest for essential oil yield followed by oil content. It is evident from the path coefficient study that the traits fresh root yield (0.514) followed by
R.K. Lal et al. / Industrial Crops and Products 49 (2013) 273–277
oil content (0.386%), tillers/plant (0.149) and root length (0.086) were the highest direct contributors to total oil yield in vetiver. All these traits also expressed high heritability (ˆh2 BS ) and medium to high genetic advance and positive correlations. Oil content and oil yield/plot (g) was also positively correlated with each other at both genetic and phenotypic levels. References Akhila, A., Nigam, M.C., Virmani, O.P., 1981. Review article vetiver oil – a review of chemistry. CROMAP 3, 195–221. Clevenger, J.F., 1928. Apparatus for determination of volatile oils. J. Am. Pharm. Assoc. 17, 345. Dewey, D.R., Lu, K.H., 1959. A correlation and path coefficient analysis components of crested wheat grass seed production. Agron. J. 51, 515–518. Hussain, A., Sharma, J.R., Puri, H.S., Tayagi, B.R., 1984. Vetiveria zizanioides (L.) Nash Vetiver or Khus. Status Report on Genetic Resources on Important Medicinal and Aromatic Plants in South Asia>. CIMAP, Lucknow, India, pp. 273–304 (behalf of International Board of Plant Genetic Resources Rome). Lal, R.K., 2012. On genetic diversity in germplasm of vetiver (Vetiveria zizanioides L Nash). Ind. Crop Prod. 43, 93–98. Lal, R.K., Chandra, R., Chauhan, H.S., Misra, H.O., Singh, A.K., Krishna, S., Shankar, H., Singh, H.P., Singh, S.P., Kumar, B., Yadav, A., Shasany, A.K., Dhawan, S.S., Gupta, A.K., 2010a. A high yielding variety of lemongrass (Cymbopogon khasianus) CIMAP Suwarna suitable for water stress/rainfed/marginal land conditions. J. Med. Aromat. Plant Sci. 32, 61–63. Lal, R.K., Chandra, R., Ram, M., Ram Yadav, A., Shanker, H., Misra, H.O., Kalra, A., Kumar, B., Gupta, A.K., 2010b. High oil yielding variety CIMAP Harsh of palmarosa (Cymbopogon martinii Roxb. (Wats.) var. Motia). J. Med. Aromat. Plant Sci. 32, 148–149. Lal, R.K., Sharma, J.R., Misra, H.O., Kumar, S., Shukla, N., Sharma, S., 1999a. Influence of variability and associations on economic traits in isabgole (Plantago species). J. Med. Aromat. Plant Sci. 21, 361–372.
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Lal, R.K., Sharma, J.R., Misra, H.O., Sharma, S., Naqvi, A.A., 2001a. Genetic variability and relationship in quantitative and qualitative traits of Java Citronella (Cymbopogon winterianus, Jowitt). J. Essent. Oil Res. 13, 158–162. Lal, R.K., Sharma, J.R., Misra, H.O., 1997a. Genetic diversity in germplasm of vetiver grass, Vetiveria zizanioides (L.) Nash. J. Herbs Spices Med. Plant. 5, 1–12. Lal, R.K., Sharma, J.R., Misra, H.O., 1997b. Varietal selection for high root and oil analysis in vetiver Vetiveria zizanioides (L.) Nash. J. Med. Aromat. Plant Sci. 19, 1–4. Lal, R.K., Sharma, J.R., Naqvi, A.A., 1999b. Genetic variability and exploitation in vetiver grass, Vetiveria zizanioides (L.) Nash. JMAP 21, 963–968. Lal, R.K., Sharma, J.R., Singh, N., Misra, H.O., Naqvi, A.A., 2001b. Genetic associations and diversity in the genetic resources of curry neem (Murraya koenigii). J. Med. Aromat. Plant Sci. 22/4A and 23/1A, 216–221. Lavania, U.C., 2000. Primary and secondary centres of origin of vetiver and its dispersion. In: Second International Proceedings on Vetiver and the Environment Conference, Vetiver, Phetchaburi Province Thailand, 18–22 January, pp. 432–434. Panse, V.G., Sukhatme, P.V., 1967. Statistical Methods for Agricultural Workers, 2nd ed. Indian Council of Agricultural Research, New Delhi. Pareek, S.K., 1994. Germplasm collection and evaluation of vetiver. In: Rana, R.S., Singh, B., Kopar, M.N., Mathur, R., Kochar, S., Dahoon, S.S. (Eds.), Plant Genetic Resources Exploration, Evaluation and Maintenance. NBPGR, New Delhi, pp. 275–281. Ramanujam, S., Kumar, S., 1964. Metroglyph analysis of geographical complexes in Indian vetiver. Indian J. Genet. 24, 144–150. Singh, R.K., Chaudhary, B.D., 1979. Variance and covariance analysis. In: Biometrical Methods in Quantitative Genetic Analysis. Kalyani Publisher, New Delhi, India, pp. 57. Singh, S.P., 1988. Genetic divergence over environments in pearl millet (Pennisetum typhoides). Genet. Agric. 42, 35–41. Srivastava, N.K., Lal, R.K., 2012. Variations among commercial cultivars of Vetiveria zizanioides (L.) in the photosynthetic and metabolic characters associated with essential oil accumulation. Int. J. Med. Plant Res. 1, 45–49. Virmani, O.P., Datta, S.C., 1975. Vetiveria zizanioides (L.) Nash. Indian Perfumer 19, 73–95.
Contents lists available at SciVerse ScienceDirect
Industrial Crops and Products journal homepage: www.elsevier.com/locate/indcrop
Genetic variability and character associations in vetiver (Vetiveria zizanioides L. Nash) R.K. Lal ∗ , P. Gupta, V. Gupta, S. Sarkar, S. Singh CSIR – Central Institute of Medicinal and Aromatic Plants P.O. CIMAP, Lucknow, UP 226015, India
a r t i c l e
i n f o
Article history: Received 19 February 2013 Received in revised form 9 May 2013 Accepted 14 May 2013 Keywords: Direct contribution Genetic associations Genetic stocks Heritability Path coefficients
a b s t r a c t Forty genetic stocks of vetiver (Vetiveria zizanioides L. Nash) were screened for high oil yield. The considerable amount of natural and genetic variability in morpho-metric traits was recorded. The estimate of heritability (ˆh2 BS %) and corresponding genetic advance (GA), both were high for plant height (ˆh2 BS % = 98.48 and GA = 64.83). Genetic (G) and phenotypic (P) associations coefficients among the seven traits indicated that plant height was highly and significantly correlated with tillers/plant (0.399**G, 0.389**P); fresh root with dry root yield (0.905**G, 0.769**P) and oil content with oil yield (0.397**G, 0.390**P) at both genotypic and phenotypic level. The plant height with root length was also positively correlated with each other at both genetic (G) and phenotypic (P) levels (0.282*G, 0.278*P). The path coefficient under study revealed that the highest direct contribution to total oil yield was made by fresh root yield (0.514) followed by oil content (0.386), tillers/plant (0.149) and root length (0.086) in percent. © 2013 Elsevier B.V. All rights reserved.
1. Introduction The genus Vetiveria is a small genus of perennial grasses occurring mainly in tropical countries of old world. In India, only two species of vetiver are found Vetiveria zizanioides and Vetiveria lawsoni syn. Vetiveria nemoralsis belongs to family Poaceae, is native to India and is found growing wild in almost all parts of the country (Ramanujam and Kumar, 1964; Lavania, 2000; Lal, 2012). However, it is only the former, i.e. (V. zizanioides (L.) Nash), chromosome number: 2n = 20, which is of great significance as a high class perfume as well as indigenous systems of medicine since time dating back to 1103 AD (Virmani and Datta, 1975; Akhila et al., 1981; Hussain et al., 1984; Lal, 2012). Its aerial parts have other potential economic values also, such as for fodder, mulch, animal bedding, thatches, handicrafts, in paper industries, vermi compost, in making tiles, etc. (Pareek, 1994; Lal et al., 1997a,b; Lal et al., 1999a,b), thus nonpart of vetiver plants goes waste. It grows luxuriously in parts of Utter Pradesh, Madhya Pradesh, Bihar, Rajasthan and several tracts in southern and peninsular India particularly along the river banks and over marshy lands (Virmani and Datta, 1975; Hussain et al., 1984; Lal, 2012). The total world production of vetiver oil is estimated to be 300–350 tonnes per year (Lal, 2012). The annual consumption and demand is likely to increase further. In India, about 100 tonnes of oil is produced annually, which is far below
∗ Corresponding author. Tel.: +91 522 2718523; fax: +91 522 2342666. E-mail addresses: [email protected], [email protected] (R.K. Lal). 0926-6690/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.indcrop.2013.05.005
to meet our internal demand of the oil for perfumery, masticatory, attar and soap industries. In our research programme on vetiver improvement, a large number of genetic stocks/clones were assembled from different places of India. Three exotic genetic stocks were also obtained from Haiti, Reunion Island and Indonesia for genetic study. This study have planned to sort out promising genetic stock(s) suitable for high root and oil yield of better quality purpose. Since, a priori knowledge of the range of variability and character associations having great significance for further breeding, all these genetic stocks were maintained and studies for the required genetic parameters. 2. Materials and methods A large number of genetic stocks of vetiver (V. zizanioides (L.) Nash) were assembled from wild/cultivated sources of vetiver from various places in India and abroad. Out of 125 genetic stocks, a new set having forty genetic stocks of vetiver (V. zizanioides L. Nash) from Uttar Pradesh (30), Rajasthan (1), Delhi (3), Travancore (2) and Odakali (1) in India and one each from Indonesia, Haiti and Reunion Island were screened for high oil yield of better quality (Table 2, Fig. 1). The genetic stocks were grown in a randomized block design with two replications at the research farm of the CSIR–Central Institute of Medicinal and Aromatic Plants, Lucknow, India in the two consecutive years 2009–2010 and 2010–2011 under normal fertility regime (80:40:40) kg N, P2 O5 and K2 O/ha, respectively, with plot size of single row of 2.5 m each 50 cm apart. Plants were uprooted
274
R.K. Lal et al. / Industrial Crops and Products 49 (2013) 273–277
Fig. 1. Genetic variability in plants, roots and in essential oil of vetiver genetic accessions.
12 months after planting of the experiments. The experimental site at the institute research farm was located at 26.5◦ N latitude and 80.50◦ E longitude, and 120 m above mean sea level. The climate is semiarid to subtropical in nature. Morpho-metric observations were recorded for seven economic traits, namely plant height (cm), tillers/plant, fresh and dry root yield (g/plot), root length (cm), oil content (%) and oil yield (g/plot). Oil content was estimated by hydro-distillation of shade dried roots of each clone for 16 h in Clevenger’s apparatus (Clevenger, 1928).
genotypic (GCV), phenotypic (PCV) levels and heritability in broad sense (h2 BS ) computed per the following formula: 2.2. Estimates of genetic parameters Heritability in broad sense (h2 BS ) %: It is the ratio of genotypic variance to the phenotypic variance = ( 2 g/ 2 p) × 100, where, 2 g = (MSg − MSe)/r and 2 p = 2 g + 2 e; MSg = mean sum of squares of genotypes; MSe = mean sum of squares of error. 2.3. Correlation coefficient (r)
2.1. Statistical analyses Statistical analyses were done using the Statistical Software 4.0 version, available in the Division of Genetics and Plant Breeding of the Institute, which is based on the standard methods in Panse and Sukhatme (1967) and Singh and Chaudhary (1979). The pooled mean values of 2 years for the all seven characters were subjected to correlation and path coefficient analyses (Dewey and Lu, 1959; Lal et al., 2001a,b). Various statistical parameters, including correlation and path coefficient, namely variance components genetic ( 2 g), phenotypic ( 2 p) and environmental ( 2 e), coefficient of variation
Analysis of variance (ANOVA). Source of variation
d.f.
Mean sum of squares (MSS)
F
Expectations
Replications Genotypes Error Total
01 (r − 1) 39 (g − 1) 39 (g − 1)(r − 1) 79 (gr − 1)
MSr MSg MSe –
– MSg/MSe –
– 2 e + r 2 g 2e
Correlation coefficients were used to measure of the associations between two or more than two variables. (i) Genotypic correlation (rg ) between two traits X and √ covariance (XY)}/ {genotypic variY = [{Genotypic ance (X) × genotypic variance (Y)}]where Genotypic and Genotypic varicovariance = (MSPg − MSPe)/r ance = (MSg − MSe)/r (ii) Phenotypic correlation (rp ) between two traits X and √ Y = [{phenotypic covariance (XY)}/ {phenotypic variance (X) × phenotypic variance (Y)}]where phenotypic covariance = (MSPg − MSPe)/r; phenotypic covariance = 2 g + 2 e; and r = number of replications. Co-heritability value of a character contribution suggests that the increases in one of the characters of those contributions will be coupled in the increasing trend in its co-heritable character. Where, Co-heritability (1, 2) = genotypic covariance/phenotypic covariance of traits 1 and 2.
R.K. Lal et al. / Industrial Crops and Products 49 (2013) 273–277
275
Table 1 Pooled ANOVA over two environments of forty genetic stocks of vetiver.
∗
Source of variation
d.f.
Replications Genotypes Error
01 39 39
Total
79
Mean sum of squares (MSS) Plant height
Tillers/plant
Fresh root yield
Dry root yield
Root length
Oil content
Oil yield
0.50 15.80∗ 15.80
63.02 8.60∗ 8.60
140.45 553.93∗ 3.27
6.01 35.32∗ 4.35
138.59 159.40∗ 5.22
0.0001 0.69∗ 0.011
0.011 0.96∗ 0.0012
P < 0.01.
2.4. Critical difference (CD) In order to compare the means of various entries, we require calculating the critical difference by following formula: CD = S.E. × ’t’ S.E. is standard error of the difference of the genotype means to be compared, and is equal to: S.E. =
2MSe 0.5 r
where MSe as error mean sum of squares and ‘t’ is the tabulated value of ‘t’ at 5% or 1% level of significance for the degree of freedom of error mean square.
be highly amenable to direct selection for their genetic improvement over a short span of time. In addition to heritability in broad sense (ˆh2 BS ) and genetic advance (GA), the associations among characters also have a direct bearing on success of selection. A critical perusal of observations/results indicates that the genotypic correlations were large than phenotypic correlations for all the traits except two traits – fresh root yield and oil yield examined (Table 3). Genotypic (G) and phenotypic (P) correlation coefficients among the seven traits revealed that plant height was highly and significantly correlated with tillers/plant (0.399**G, 0.389**P); fresh root with dry root yield (0.905**G, 0.769**P) and oil content with oil yield (0.397**G, 0.390**P) at both genotypic and phenotypic level. The plant height with root length was also positively correlated with each other at both genetic and phenotypic levels (0.282*G, 0.278*P). Hence, these traits were found to be good criteria for selection. These traits
2.5. Path coefficient analysis Path coefficients is simply a standardized partial regression coefficient and as such measures the direct influence of one variable upon another and permit the separation of correlation coefficients in to components of direct and indirect effects. Path coefficients can be defined as the ratio of standard deviation of the effect due to a given cause to the total standard deviation of the effect, i.e. if Y in the effect and x1 is the cause, the path coefficients for the path from cause x1 to the effect Y is x1 /y. 3. Results and discussion Variation among the pooled mean over 2 years of 40 diverse genetic stocks was highly significant (P < 0.01) for the all seven traits examined (Table 1). The meticulous study of analysis of variance, means, standard errors of means and critical difference (CD) revealed highly significant differences among the genotypes for all seven characters studied indicating thereby existence of considerable genetic variability among the genotypes (Tables 1 and 5). The statistical and genetic parameters for the heritable and nonheritable components of variation were computed. The sampling variance was moderate to high for nearly all the traits examined as genotypic coefficient of variation (GCV) 22.94–184.04 and phenotypic coefficient of variation (PCV) 23.11–184.27 levels. The heritable portion of phenotypic variance reflected by the size of 2 g relative to 2 p expressed as ˆh2 BS was generally very large (99.66–99.76) for the five characters except for oil content (77.86) and dry root yield (78.08) that showed moderate heritability. In other words, all characters except oil content and dry root yield were apparently only minimally influenced by environment factors (Table 5). A high heritability estimate (ˆh2 BS ) with corresponding high genetic advance (GA) is more reliable for selection than that with low genetic advance (GA). The estimate of heritability broad sense in percent (ˆh2 BS %) and corresponding genetic advance (GA), both were high for plant height (ˆh2 BS % = 98.48 and GA = 64.83), moderate heritability and high genetic advance for oil content (ˆh2 BS % = 77.86 and GA = 77.64), respectively. Therefore, these traits might
Table 2 Origin/places of collections of 40 accessions of vetiver maintained at CSIR-CIMAP, Lucknow. S.No.
Accessions
Origin/places of collection
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40
RZA-1 RRZA-10 SEL-1 BRT-5 GHG-1 RI-1 OD-1 KS-1 KS-2 IN-1 Gulabi TC-1 TC-2 MTR-1 K-15 K-18 K-20 K-25 K-27 K-29 K-62 AR-56 BBH-1 Haiti-1 DS-1 KH-8 CIM Vriddhi PH-8 BB-18 Dharini Kesari DOR-1 J-15 MD-1 BG-1 BKT-1 KH-30 KH-40 KH-41 MUSA-25
Razaganj, Lakhimpur (Kheri), UP, North India Razaganj, Lakhimpur (Kheri), UP, North Ind CIMAP, Lucknow, North India Bharat Pur, Rajasthan, North India Ghaghraghat, UP, North India Reunion, Island Odakkali, South India CIMAP, Lucknow, North India CIMAP, Lucknow, North India Indonesia CIMAP, Lucknow, North India Travencore, India Travencore, UP, India Mathura, UP, India Kanpur, UP, India Kanpur, UP, India Kanpur, UP, India Kanpur, UP, India Kanpur, UP, India Kanpur, UP, India Kanpur, UP, India Agra, UP, India New Delhi, India Haiti New Delhi, India Kanpur, UP, India CIMAP, Lucknow, India New Delhi, India Barabanki, UP, India CIMAP, Lucknow, India CIMAP, Lucknow, India Deoria, UP, North India Jhansi, UP, India Moradabad, UP, India Kukra/Bankey Ganj, Lakhimpur (Kheri), UP, India Bakshi-Ka-Talab Lucknow, UP, India Kanpur, UP, India Kanpur, UP, India Kanpur, UP, India Musanagar, UP, India
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Table 3 Genetic and phenotypic associations/correlations and co-heritability amongst seven economic traits of forty genetic stocks of vetiver. Genetic correlations
Characters Plant height
Plant height
– −0.073 1.004 −0.205 0.982 0.049 1.019 0.224 0.975 0.190 0.981 0.0002 0.051
Tillers/plant Fresh root yield Dry root yield Root length Oil content Oil yield
Tillers/plant 0.399∗∗ 0.389∗∗ – +0.029 1.011 −0.206 2.283 0.128 0.958 −0.075 1.015 −0.232 1.011
Fresh root yield
Dry root yield
Root length
Oil content
Oil yield
-0.149 −0.150 0.053 0.051 –
−0.177 −0.152 0.034 0.012 0.905∗∗ 0.769∗∗ –
0.282∗ 0.278∗ 0.135 0.134 −0.204 −0.199 −0.098 −0.065 –
0.215 0.214 0.161 0.154 −0.041 −0.037 −0.083 −0.059 0.135 0.131 –
−0.0001 0.004 0.181 0.176 0.225 0.223 0.134 0.119 0.040 0.036 0.397∗∗ 0.390∗∗ –
−0.512 1.034 −0.108 0.986 0.167 1.087 −0.044 1.001
0.161 1.294 0.154 1.215 0.039 0.993
0.063 0.979 −0.208 1.071
0.019 0.999
Values in upper diagonal belongs to genetic and phenotypic correlations and below diagonal relates to environmental correlation and co-heritability in broad sense: * P < 0.05 ** P < 0.01. Table 4 Direct (bold) and indirect effects on seven economic traits related to path analysis in vetiver genotypes. Traits
Plant height
Plant height Tillers/plant Fresh root yield Dry root yield Root length Oil content
−0.1472 −0.059 0.022 0.026 −0.042 −0.032
Tillers/plant 0.060 0.149 0.008 0.005 0.020 0.024
Fresh root yield
Dry root yield
Root length
Oil content
Oil yield (rg )
−0.081 0.029 0.544 0.492 −0.111 −0.022
0.0616 −0.012 −0.316 −0.349 0.0341 0.029
0.024 0.012 −0.018 −0.008 0.086 0.012
0.083 0.062 −0.016 −0.032 0.052 0.386
−0.00001 0.181 0.225 0.134 0.040 0.397
Residual effects = 0.7405903. Table 5 Estimates of variance components and allied genetic parameters obtained by different methods for diverse traits of forty genetic stocks in vetiver. S. No.
Characters
1 2 3 4 5 6 7
Plant height Tillers/plant Fresh root yield Dry root yield Root length Oil content Oil Yield
Genetic parameters 2g
2p
2e
GCV
PCV
CD5%
CD1%
CV (%)
SEM
h2 BS %
GA
1021.26 277.73 275.33 15.48 77.09 0.41 0.477
1017.07 286.33 278.59 19.83 82.31 0.35 0.479
15.80 8.60 3.27 4.35 5.22 0.011 0.0012
22.94 53.48 48.95 27.88 27.44 76.64 184.04
23.11 54.30 49.24 31.56 28.35 77.87 184.27
8.03 5.92 3.65 4.21 4.62 0.21 0.07
10.73 7.92 4.88 5.63 6.17 0.28 0.09
2.85 9.41 5.33 14.78 7.14 13.78 9.04
2.81 2.07 1.28 1.47 1.62 0.07 0.02
98.48 96.99 98.83 78.08 93.66 77.86 99.76
64.83 33.30 33.78 6.33 16.94 77.64 1.42
ˆ 2 g, ˆ 2 p, 2 e – variance due to genotype, phenotype and environment; GCV, PCV – genetic and phenotypic coefficient of variation; ˆhBS – heritability in broad sense; GA – genetic advance; CD – critical difference; SEM – standard error mean, respectively.
were also reinforced by high values of co-heritability. Since higher co-heritability value of a character contribution suggests that the increases in one of the characters of those contributions will be coupled in the increasing trend in its co-heritable character (Singh, 1988; Lal et al., 1999b, 2010a,b; Srivastava and Lal, 2012). Low environmental and week positive and negative associations were also noted between number of traits at both genetic and phenotypic levels (Table 3). Plant height with tillers/plant, fresh root yield with dry root yield and oil content with oil yield also exhibited high co-heritability with each other, hence may form a good selection criterion for valuable economic traits. The path coefficient under study revealed that the highest direct contribution to total oil yield was made by fresh root yield (0.544) followed by oil content (0.386), tillers/plant (0.149) and root length (0.086) in percent. Direct contribution of other two traits plant height and dry root yield to oil yield was negative but their indirect contribution was invariably large via dry root yield and fresh root yield, tillers/plant and oil content, plant height and fresh root yield, plant height and fresh root yield although residual effect was 0.740 (Table 4). These traits were also reinforced by high values of co-heritability (Table 3). Therefore, the choice of most economic
traits, root yield and oil content, tillers/plant followed by plant height may be used as a better selection criterion for improvement of oil yield. Dry root yield might be a rewarding proposition in vetiver, though nothing is as dependable as is selection for oil yield per se. Notwithstanding, however, improvement of oil yield is not only factor in vetiver. High essential oil yield coupled with oil quality is of great importance in trade. Thus, while selection for essential oil yield, the quality parameters should also be considered in the vetiver crop improvement programme. 4. Conclusions Genetic improvement and development of high yielding varieties is dependent upon genetic variability, we examined genetic variation for seven traits of 40 genetic stocks in order to understand genetic variability, genetic, phenotypic and environmental associations and contribution of various yield components in vetiver. Genotypic and phenotypic coefficient of variations was largest for essential oil yield followed by oil content. It is evident from the path coefficient study that the traits fresh root yield (0.514) followed by
R.K. Lal et al. / Industrial Crops and Products 49 (2013) 273–277
oil content (0.386%), tillers/plant (0.149) and root length (0.086) were the highest direct contributors to total oil yield in vetiver. All these traits also expressed high heritability (ˆh2 BS ) and medium to high genetic advance and positive correlations. Oil content and oil yield/plot (g) was also positively correlated with each other at both genetic and phenotypic levels. References Akhila, A., Nigam, M.C., Virmani, O.P., 1981. Review article vetiver oil – a review of chemistry. CROMAP 3, 195–221. Clevenger, J.F., 1928. Apparatus for determination of volatile oils. J. Am. Pharm. Assoc. 17, 345. Dewey, D.R., Lu, K.H., 1959. A correlation and path coefficient analysis components of crested wheat grass seed production. Agron. J. 51, 515–518. Hussain, A., Sharma, J.R., Puri, H.S., Tayagi, B.R., 1984. Vetiveria zizanioides (L.) Nash Vetiver or Khus. Status Report on Genetic Resources on Important Medicinal and Aromatic Plants in South Asia>. CIMAP, Lucknow, India, pp. 273–304 (behalf of International Board of Plant Genetic Resources Rome). Lal, R.K., 2012. On genetic diversity in germplasm of vetiver (Vetiveria zizanioides L Nash). Ind. Crop Prod. 43, 93–98. Lal, R.K., Chandra, R., Chauhan, H.S., Misra, H.O., Singh, A.K., Krishna, S., Shankar, H., Singh, H.P., Singh, S.P., Kumar, B., Yadav, A., Shasany, A.K., Dhawan, S.S., Gupta, A.K., 2010a. A high yielding variety of lemongrass (Cymbopogon khasianus) CIMAP Suwarna suitable for water stress/rainfed/marginal land conditions. J. Med. Aromat. Plant Sci. 32, 61–63. Lal, R.K., Chandra, R., Ram, M., Ram Yadav, A., Shanker, H., Misra, H.O., Kalra, A., Kumar, B., Gupta, A.K., 2010b. High oil yielding variety CIMAP Harsh of palmarosa (Cymbopogon martinii Roxb. (Wats.) var. Motia). J. Med. Aromat. Plant Sci. 32, 148–149. Lal, R.K., Sharma, J.R., Misra, H.O., Kumar, S., Shukla, N., Sharma, S., 1999a. Influence of variability and associations on economic traits in isabgole (Plantago species). J. Med. Aromat. Plant Sci. 21, 361–372.
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