Effect of Biparental Mating on Association Pattern Among Quantitative Characters in Okra ( Abelmoschus esculentus  (L.) Moench)

Guddadamath S.G.; Mohankumar H.D.; Salimath P.M.

Research Report

Effect of Biparental Mating on Association Pattern Among Quantitative Characters in Okra (Abelmoschus esculentus (L.) Moench)

Guddadamath S.G.

, Mohankumar H.D.

, Salimath P.M.

Department of Genetics and Plant Breeding, UAS, Dharwad-5 Karnataka, India

Author

Correspondence author
International Journal of Horticulture, 2012, Vol. 2, No. 5 doi: 10.5376/ijh.2012.02.0005
Received: 17 Dec., 2012 Accepted: 24 Dec., 2012 Published: 31 Dec., 2012

This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Preferred citation for this article:

Guddadamath S.G., Mohankumar H.D., and Salimath P.M., 2012, Effect of Biparental Mating on Association Pattern Among Quantitative Characters in Okra (Abelmoschus esculentus (L.) Moench), International Journal of Horticulture, 2(5): 21-24 (doi: 10.5376/ijh.2012.02.0005)

Abstract

An experiment was undertaken to study relationship between various economically important traits in three populations of the okra viz, biparental (BIP) F₂, single cross (SC) F₂, and double cross (DC) F₂ populations for the purpose of genetic improvement. The analysis of variance revealed highly significant differences for the populations under study for the characters. The association studies revealed the characters fruits length, average fruit weight, number of fruits per plant (0.929**), number of branches per plant and plant height showed significant positive association with fruit yield per plant, and also showed significant positive association among themselves. This suggested that these characters should be considered while selecting plants for yield improvement in segregating populations of okra. It was also revealed that intermating in early segregating generations of different individuals lead to release of additional variability.

Keywords

Okra; Abelmoschus esculentus (L.) Moench; Biparental mating; GCV; PCV

Okra [Abelmoschus esculentus (L.) Moench.] is an important vegetable crop cultivated in tropical and sub-tropical parts of the world. Tender fruits are used as vegetable, eaten boiled or in culinary preparation as sliced and fried pieces. It is also used for thickening soups and gravies, because of its high mucilage content. Okra fruits are also sliced and sun dried or canned and pickled for off-season use. It has good nutritional value, particularly vitamin-C (30 mg/100 g), calcium (90 mg/100 g), Iron (1.5 mg/100 g) rich in Iodine (97 mg/100 g).

Generally amount of variability generated is more in the early segregating generations as compared to later generations. Bhendi is one vegetable crop where heterosis has been exploited successfully. Yield plateau seems to have been reached in heterotic hybrids. In order to break this barrier there is a need to develop truly potential inbreed line which in combination can produce really novel hybrids with desirable maximum heterosis. Among the various approaches for developing inbred lines, selection in potential segregating population is an important one. But then, the key to success lies in developing the really promising potential segrega- ting populations. If we attempt intermating in early segregating generations of different individuals additional variability will be released, since biparental mating among the segregates in the F₂ of a cross may provide more opportunity for the recombination to occur, mop up desirable genes and as a result release concealed variability. In view of the above facts, an attempt has been made in the present study to improve the yield and yield contributing characters by releasing more variability which in turn available for selection in segregating generations of okra.

Materials and Methods

The present investigation was carried out at Horticulture Research Station, Devihosur, Haveri, Karnataka during 2008 and 2009. The experimental material was derived from three okra lines L-1, L-2 and L-3. In summer 2008 single cross (L-1×L-2) and double cross of [(L-1× L-2) × (L-2 × L-3)] F₁ populations were developed and in next season (kharif, 2008), these populations were selfed to get their respective F₂populations. Biparental progenies were (BIP F₂) developed by random mating selected superior plants in the F₂ segregating population (Kearsay, 1965). The experimental material comprised of two BIP, three single cross and two double cross F₂’s populations. In 2009 all these F₂populations (800 plants in each F₂ populations) were grown in RBD with two replications and observations were recorded on 5 randomly selected plants in each F₂population for twelve characters. The plot size was four rows each of 5 m length with spacing of 60 cm×30 cm.

The correlation coefficient was computed according to the method suggested by Weber and Moorthy (1952) as given below: r =Cov xy/(ÖVx Vy), Cov xy =Covariance between the characters x and y; Vx= Variance of the character x; Vy=Variance of the character y.

Results and Discussions

Analysis of variance for the characters studied, indicated highly significant for all the three types of populations suggested the existence of sufficient amount of genetic variability in the parents selected for study (Table 1).

Table 1 Analysis of variance for twelve quantitative characters in BIP F₂ population of okra

All the fruit and fruit related characters showed significant positive association with fruit yield per plant and also among themselves except the characters days to 50 % flowering, and fruit diameter, internodal length in all the three populations studied (Table 2). In present study, high association was observed for all the traits in the biparental (BIP) and low associations in single cross (SC) and double cross (DC) F₂ populations. Among the BIP’s populations, number of fruits per plant (0.929**), 100 seed weight (0.871**), average fruit weight (0.859**), number of nodes per plant (0.611**), number of branches per plant (0.916**) and plant height (0.912**) exhibited positive significant association with fruit yield per plant. These findings are in conformity with the results of (Singh, 2006) in okra.

Table 2 Genetic association among twelve different characters in different F₂ populations of okra

A comparison of direction and magnitude of association among characters between all the F₂ populations (Table 3) indicated that, several new associations in terms of direction and magnitude of association was observed. For example association of plant height with average fruit weight (0.756**); and number of fruits per plant with average fruit weight (0.625**), which was non-significant in case of SC and DC F₂ populations but changed to significant and positive in BIP populations under study (Figure 1), indicates the breakage of undesirable linkage between these traits. Such changes in magnitude and direction may occur due to gene reshuffling and breakage of linkage due to intermating in the early segregating populations. Similar type of shift in association was seen between plant height and seed yield; number of branches and seed yield; number of capitula per plant and seed yield in safflower (Parameshwarappa, 2009).

Table 3 Comparison of magnitude and direction of association among yield attributing character in different populations of okra

Figure 1 Graphs showing the association of number of fruits per plant with other yield related traits in three different F₂populations

In general in all the crop plants negative associations do exists between the two important yield components. For example boll number and boll weight in cotton, pod number and pod length in pulses, and grain number per spike and grain size in cereals. Breeders tend to break these undesirable negative associations between yield components.

References
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Paramesharappa K.G., Rudra Naik V., and Bentur M.G., 2009, Impact of biparental mating on genetic variability and path analysis in safflower, Karnat. J. Agric. Sci., 22(1):44-46

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Shanthakumar G., and Salimath P.M., 2010, Studies on variability, heritability and genetic advance for fruit yield and its component traits in early segregating generation in bhendi [Abelmoschus esculentus (L.) Moench], Indian J. Plant Genet. Resour., 23(3): 296-302

Singh B., Pal A.K., and Sanjay S., 2006, Genetic variability, correlation analysis in okra [Abelmoschus esculentus (L.) Moench], Indian J. Hort., 63(3)

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