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Genetic variability, heritability and advances in Okra

Studienarbeit 2014 4 Seiten

Biologie - Genetik / Gentechnologie

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ABSTRACT

The present investigation “Studies on genetic variability, heritability and genetic advance in okra [ Abelmoschus esculentus (L.) Moench]” was carried out during kharif season of 2012-2013 at the Vegetable Research Farm, Department of Horticulture, College of Agriculture, J.N.K.V.V., Jabalpur (M.P.). The experimental material for the present investigation was comprised of 30 genotypes of okra. These genotypes were sown in Randomized Complete Block Design with three replications, to estimate the genetic variability. The estimates of mean sum of square due to genotypes were highly significant for all the characters, indicating the presence of genetic diversity in the existing material. The variation was highest r fruit yield per plant, followed by fruit yield per hectare, plant height at 120 DAS, plant height at 90 DAS, plant height 60 DAS and fruiting span. High heritability coupled with high genetic advance as percentage of mean for traits like uit yield per plant and fruit yield per plot suggested that the preponderance of additive genes. It also indicated higher response for selection of high yielding genotypes as these characters are governed by additive gene actions.

Key words Variability, Heritability, Genetic advance, okra and Abelmoschus esculentus

Okra [ Abelmoschus esculentus (L.) has captured a prominent position among vegetables. It is choicest fruit vegetable grown extensively in the tropical, subtropical and warm area of the world like India, Africa, Turkey and other neighbouring countries. In India, okra is one of the most important vegetable crop grown for its tender green fruits during summer and rainy seasons. Okra is known by many local names in different parts of the world. It is called lady’s finger in England, Gumbo in U.S.A. and Bhindi in India. In India, among fresh vegetables, 60 per cent share of export goes to okra. It is a hardy crop and can grow with considerable success on a wide range of soils and under variable environmental conditions. In India it is grown twice in a year for getting regular supply. In the country, a large number of okra varieties are grown, the variation occurs with regards to quantitative and qualitative traits. The plant height, number of primary branches per plant, number of fruits per plant, size of fruit i.e. length as well as weight of fruits are the yield contributing characters while, colour of fruit and fiber content determine the quality of fruit.

The foremost challenge to the existence of mankind has always been to produce adequate quantity of food form the available acreage to meet the requirements of ever expending world population. The rate of yield gain in crop improvement programme must match the rate of population growth so, as to avoid malnutrition and hunger. Attempts have been made to determine the magnitude of heritable and non-heritable components and genetic parameters such as genotypic and phenotypic coefficient of variation, heritability and genetic advance as percentage of mean in some of the quantitative characters of okra.

In any crop improvement program, basic information with respect to variability present in the crop is essential. Yield being a complex trait, is collectively influenced by various component characters, which are polygenically inherited and highly influenced by environmental variations. Genetic variability, heritability and genetic advance are pre- requisite for improvement of any crop for the selection of superior genotypes and improvement of any traits. It is very difficult to judge whether observed variability is heritable or not heritable. Moreover, knowledge of heritability is essential for selection based improvement as it indicates the extent of transmissibility of a character in future generations. The present study was, therefore aimed to study variability, heritability and genetic advance among thirty genotypes of okra.

MATERIALS AND METHODS

An experiment was conducted at Horticulture complex, Department of Horticulture, J.N.K.V.V., Jabalpur

(MP) during 2012-13 to study variability, heritability and genetic advance among thirty genotypes of okra . The soil of the experimental field was medium black, uniform texture with good drainage and medium NPK status. Jabalpur is situated on Kymore Plateau and Satpura hills agro-climatic zone of Madhya Pradesh at 23.910 North latitude, 79.50 East longitudes and on an altitude of 411.78 meters above the mean sea level. The tropic of cancer passes through the middle of the district. The climate of region is typically semi arid and sub tropical having extreme winter and summer.

Thirty genotypes of okra were grown in a randomized block design with three replications. Every genotype in each

PATEL, et al., Studies on Genetic Parameters in Okra [ Abelmoschus esculentus (L.)]

Table 1. Estimates of genetic parameters in twenty characters of okra

Abbildung in dieser Leseprobe nicht enthalten

replication was grown in a plot of 3.6 m length and 3.0 m width with a spacing of 60 cm between rows and 30 cm between plants. Five plants from each replication were taken for recording observation on eighteen characters viz. plant height, leaves per plant, Branches per plant, Length of internodes (cm), Number of nodes to first flowering, Numbers of nodes were counted at the time of first flowering, Days taken to 50% flowering, Fruiting span, Number of fruits per plants, Fruit length (cm), Fruit diameter (cm), Number of ridges on fruit, Fruit weight (g) and Yield per plant (g) and their mean was obtained.

The data were statistically analyzed for computation of genetic coefficients of variation using appropriate statistical analysis. Heritability in broad sense was estimated as per the formula given by Allerd, 1960. The expected genetic advance was calculated by using formula as suggested by Johson, et al., 1995.

RESULTS AND DISCUSSION

The estimates of mean sum of square due to genotypes were highly significant for all the characters indicating the presence of genetic diversity in the existing material. Five traits viz., fruit yield per plant, fruit yield per hectare, plant height at 120 DAS, plant height at 90 DAS and plant height at 60 DAS exhibited the value of higher magnitude. The findings of Verma, et al., 2004., Mannivannarn et al., 2007, Jindal et al., 2009 are similar to that of the present findings.

The estimates of variability, heritability and genetic advance among thirty genotypes in twenty characters of okra are presented in table 1. In the present findings phenotypic coefficient of variation were observed to be higher than the corresponding genotypic coefficient of variation for all the characters studied, however the differences were narrow which implied their relative resistance to environmental variation. It also described that genetic factors were predominantly responsible for expression of those attributes and selection could be made effectively on the basis of phenotypic performance. The finding of Bendale, et al., 2003 and Senapati, et al., 2011 were similar to that of the present findings.

The present study revealed that the phenotypic coefficient of variation was higher than the corresponding genotypic coefficient of variation for all the traits, which might be due to interaction of the genotypes with the environment to some degree or other explaining environmental factors influencing the expression of these characters. High phenotypic and genotypic coefficient of variation was observed for number of branches per plant followed by fruit weight, fruit yield per plant, fruit yield per plot, fruit yield per hectare and number of leaves per plant at 60 DAS. The high values of GCV suggested greater phenotypic and genotypic variability among the genotypes and responsiveness of the attributes for making further improvement by selection. However, fruit length, fruit diameter, days to 50 per cent flowering, number of leaves per plant at 30 DAS, fruiting span, number of leaves per plant at 120 DAS, nodes to first flowering, intermodal length and number of leaves per plant at 60 DAS showed low estimates of genotypic and phenotypic coefficient of variation, indicating the potential of heterosis breeding for their amelioration.

Heritability which denotes the proportion of genetically controlled variability expressed by a programme for a particular character or a set of character is very important biometrical tool for guiding plant breeders for adoption of appropriate breeding procedures. High heritability in broad sense is helpful in identifying appropriate character for selection and enables the breeder to select superior genotypes on the basis of phenotypic expression of quantitative characters. The estimated values of heritability in broad sense were classified as high (more than 70%), edium (50-70%) and low (less than 50%). Result indicated that the heritability estimates were observed high for fruiting span, followed by plant height at 120 DAS, fruit yield per plant, fruit yield per plot and plant height at 90 DAS. The results were in close proximate to that of Chaukhande et al., 2011, Nagre et al., 2011 and Nagre et al., 2011 for plant height, Suresh Babu et al., 2004 and Nwangburuka et al., 2012 for fruit yield per plant, fruit yield per plot and plant height, Senapati, 2011 for fruit yield per plant and fruiting span. High values of broad sense heritability for the above characters expressed that they were least influenced by environmental modification. It reflected that the phenotypes were the true representative of their genotypes and selection based on phenotypic performance would be reliable.

Low estimation of heritability was recorded for fruit length, plant height at 30 DAS, nodes to first flowering and number of leaves per plant at 30 DAS. This is indicative of the fact that these characters are rather more influenced by the environment and may not respond much to selection. While, it was moderate for fruit weight, number of leaves per plant at 90 DAS, number of fruits per plant, number of leaves per plant at 120 DAS, plant height at 60 DAS, days to 50 per cent flowering, intermodal length, fruit diameter, number of branches per plant, number of leaves per plant at 60 DAS and fruit yield per hectare which indicated that selection based on phenotypic performance would be rewarding. The results were in close proximate to that of Hazra and Basu, 2000 for number of branches per plant, number of leaves per plant, days to 50 per cent flowering and number of fruits per plant, Dhankar and Dhankar 2002 for number of fruits per plant and plant height.

Heritability however, indicates only the effectiveness with which selection of a genotype can be based on phenotypic performance, but fails to indicate the genetic progress. Heritability estimates along with genetic gains are more effective and reliable in predicting the improvement through selection Johnson et al., 1955. Estimates of genetic advance helps to predict the extent of improvement that can be achieved for improving the different characters. The estimated values of genetic advance as percent of mean were classified as high (more than 20%), moderate (11- 20%) and low (less than 11%).

Genetic advance as percentage of mean ranged between 3.74% for number of leaves per plant at 30 DAS to 31.80% for number of branches per plant. The highest estimate of genetic advance as percentage of mean was recorded for number of branches per plant, fruit weight, fruit yield per plant and fruit yield per plot. The results were in consonance with (4) and Nagre et al. (10) for fruit yield per plant, (11) for yield per plant and number of branches per plant.

According to assume scale for classification (as above), fruit yield per hectare, number of leaves per plant at 60 DAS, plant height at 120 DAS, plant height at 60 DAS, number of fruits per plant, plant height at 90 DAS, number of leaves per plant at 90 DAS and plant height at 30 DAS showed moderate value of genetic advance as percentage of mean. The findings were in agreement to the findings of Dhankar and Dhankar, 2002. for number of fruits per plant, plant height. Low estimates were observed for internodal length, number of leaves per plant at 120 DAS, fruiting span, nodes to first flowering, days to 50 per cent flowering, fruit diameter, fruit length and number of leaves per plant at 30 DAS. The findings were in agreement to Chaukhande, et al., 2011 for fruit diameter

High heritability coupled with high genetic advance for traits like fruit yield per plant and fruit yield per plot. Suggested that the preponderance of additive genes. It also indicated higher response for selection of high yielding genotypes as these characters are governed by additive gene actions. The findings were in agreement to the findings of Singh and Singh, 2006 and Naidu et al., 2007

High heritability supplemented with moderate genetic advances as percentage of mean were manifested by plant height at 120 DAS and plant height at 90 DAS which might be attributed to additive gene action conditioning their expression and phenotypic selection for their amenability

PATEL, et al., Studies on Genetic Parameters in Okra [ Abelmoschus esculentus (L.)]

can be brought about. These findings corroborated the earlier findings of Kumar, et al., 2011 . High heritability coupled with low genetic advance as percentage of mean was observed for fruiting span. This revealed the predominance of non-additive gene action in the expression of these characters. Low estimates of heritability coupled with low genetic advances as percentage of mean were displayed by nodes to first flowering, fruit length and number of leaves per plant at 30 DAS that indicated that this character was highly influenced by environmental effects and consequently its selection would be ineffective.

On the basis of present investigation, it is concluded that the different characters have the influence of both additive and non additive gene action hence, the breeder should adopt suitable breeding methodology to utilize both additive and non additive gene effects simultaneously, since varietal and hybrid development will go a long way in the breeding programmes, especially in case of okra.

LITERATURE CITED

llard, R.W. 1960. Principles of Plant Breeding. Jhon Wiley and Sons Inc, New York, USA. pp. 485. endale, V.W.; Kadam, S.R.; Bhave, S.G.; Mehta J.L. and Pethe U.B. 2003. Genetic variability and correlation studies in okra. Orissa J.Hort. 31 (2): 1-4. haukhande, Pooja; Chaukhande, P.B. and Dod, V.N. 2011. Genetic variability in okra. Abstracts of National Symposium on Vegetable

Biodiversity, held at JNKVV, Jabalpur, during April. 4-5:30-32. hankar, B.S. and Dhankar S.K. 2002. Study on variability in okra.

Haryana J. of Hort. Sci., 31 (1&2): 82-84. azra, P. and Basu, D. 2000. Genetic variability, correlation and path analysis in okra. Annals of Agricultural Research. 21(3): 452- 453.

Jindal, S. K.; Deepak Arora and Ghai, T. R. 2009. Genotype x environment interactions for fruit traits in okra (Abelmoschusesculentus L. Moench). Crop Improvement. 36 (2): 72-79.

Johnson, H.W.; Robinson, H.F. and Comstock, R.E. 1955. Estimates of genetic and environmental variability in soybean. Agron. J. 47: 314-318.

Manivannan, M. I.; Rajangam, J. and Geetharani, P. 2007. Variation studies in okra. Asian Journal of Horticulture. 2 (2): 188-191. Nagre, P.K.; Sawant, S.N.; Wagh, A.P.; Paithankar, D.H. and Joshi, P.S. 2011. Genetic variability and correlation studies in okra. Abstracts of National Symposium on Vegetable Biodiversity, held at JNKVV, Jabalpur, during April 4-5, pp 4.

Naidu, A.K., Verma, B.K. and Raut, R.L. 2007. Genetic variability studies of yield and its attributing traits in okra [ Abelmoschus esculentus (L.) Moench]. Abstract of International Conference on sustainable Agriculture for food, Bio-energy and livelihood security. Feb 14-16, Vol. II: 467.

Nwangburuka, C. C. Denton, O. A. Kehinde, O. B. Ojo, D. K. Popoola, A. R. 2012. Genetic variability and heritability in cultivated okra [ Abelmoschus esculentus (L.) Moench]. Spanish Journal of Agricultural Research. 10 (1): 123-129.

Prashant Kumar; Vikas Singh and Dubey, R. K. 2011. Potential of genetic improvement for pod yield and yield related traits in okra Abelmoschus esculentus (L.) Moench. Environment and Ecology. 29 (4A): 2067-2069.

Senapati, N. Mishra, H. N. Beura, S. K. Dash, S. K. Prasad, G. Patnaik, A. 2011. Genetic analysis in Okra hybrids. Environment and Ecology. 29 (3A): 1240-1244.

Singh, S. P. and Singh, J. P. 2006. Variability, heritability and scope of improvement for yield components in okra (Abelmoschus esculentus (L.) Moench). International Journal of Plant Sciences (Muzaffarnagar). 1 (2): 154-155.

Sureshbabu, K.V.; Gopalakrishnan, T.R. and Mathew, Saly K. 2004. Genetic variability, correlation studies, path analysis and reaction to yellow vein mosaic virus (YVMV) in Abelmoschus caillei (A. cher.). Abstracts of first Indian Horticulture Congress, New Delhi. pp 85-86.

Verma, B.K., R.K. Shrivastava; B.R. Sharma and Amarchandra 2004. Variability studies of yield components in okra. Abstracts of first Indian Horticulture Congress, New Delhi. pp. 84-85.

Details

Seiten
4
Jahr
2014
Dateigröße
459 KB
Sprache
Englisch
Katalognummer
v308061
Institution / Hochschule
Jawaharlal Nehru University – JNKVV Jabalpur MP
Note
Schlagworte
genetic variability heritability genetic advance okra Abelmoschus esculentus

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Titel: Genetic variability, heritability and advances  in Okra