STUDIES ON COMBINING ABILITY AND HETEROSIS IN FIELD PEA (PISUM SATIVUM L.)

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1 Legume Res., 32 (4) : , 2009 AGRICULTURAL RESEARCH COMMUNICATION CENTRE / indianjournals.com STUDIES ON COMBINING ABILITY AND HETEROSIS IN FIELD PEA (PISUM SATIVUM L.) H.K. Borah Regional Agricultural Research Station, Assam Agriculture University, Shillongani, Nagaon , India. ABSTRACT Combining ability analysis carried out for ten characters using six diverse parents in field pea revealed that variance due to gca and sca were highly significant for days to maturity, plant height, number of pods per plant, number of seeds per pod, 100 seed weight and seed yield per plant, indicating the importance of both the additive and non-additive genetic components of variation. The parents DDR-44 and Rachna were good general combiners for grain yield and biological yield; HUP-2 for 100 seed weight and maturity; DMR-7 for number of pods per plant; HUDP-6 and DMR-41 for plant height; and HUP-2 and DDR-44 for protein content. The cross combinations viz., HUP-2 x DDR-44, Rachna x DDR-44, HUDP-6 x DMR-41 and DMR-7 x DMR- 41 were the best with significant sca effects and high per se performance for seed yield. Heterosis over standard check (SC) was studied for ten characters in 15 hybrids. Considering the values of standard check, high heterotic effects were observed for days to maturity, protein content and 100 seed weight; moderate for days to flowering, number of seeds per pod, plant height and number of branches per plant. High heterotic response for seed yield per plant was mainly due to pods per plant, number of seeds per pod and 100 seed weight. Key words : Field pea, Combining ability, Heterosis. INTRODUCTION Field pea (Pisum sativum L.) is a highly nutritive rabi season legume with high yield levels. It is generally grown in the char or reverine areas of Assam, where the soil is light. Therefore, varieties suitable for light textured soil are required. Varieties suitable for relay cropping are also needed, as this is a common practice in Assam. In this regard, selection of suitable parents with appropriate characteristics is important for successful breeding programme. Combining ability analysis on the basis of diallel mating system is one of the most appropriate methods to identify the best combiners, which can be utilized for hybridization programme. It gives information about the nature of gene action and the relative magnitudes of fixable (additive) and non-fixable (non-additive/dominance) genetic variations. Keeping this in view, the present investigation was undertaken in field pea. On the other hand, exploitation of heterosis is a cheap and easy method for increasing yield in many crops. Cross combinations showing heterotic vigour can be utilized for developing high yielding pure lines of field pea. Therefore, in the present investigation analysis for heterosis was also done for yield and its components. MATERIAL AND METHODS Diallel analysis was carried out with 6 parents, viz., HUP-2, Rachna, DMR-7, HUDP-6, DDR-44 and DMR-41. The 15 F 1 s, excluding reciprocals were grown along with 6 parents and a standard check (T-163) in a randomized block design with three replications at Regional Agricultural Research Station, Shillongani, Assam during rabi, The row length was kept as 4.0 m with spacing between and within rows as 40.0 cm and 10.0 cm respectively. Observations were recorded on 10 randomly selected plants from each of the parents and F 1 s for different characters studied. Combining

2 256 LEGUME RESEARCH Table 1. Analysis of variance for combining ability for different characters in 6-parent diallel of field pea Source of d.f. Days to Days to Plant Branches Pods/ Pod Seeds 100 seed Seed yield/ Protein variation flowering maturity height /plant plant length /pod weight plant content GCA ** 36.56** ** ** ** 68.98** 9.34** 0.45 SCA ** 16.78* ** * ** 32.65** 16.89** 2.54 Error s 2 g s 2 s s 2 g /s 2 s ability analysis was done according to the method 2 and model 1 of Griffing (1956). Heterosis over standard check (T-163) was calculated and tested for significance as per Panse and Sukhatme (1967) procedure. RESULTS AND DISCUSSION Analysis of variance revealed significant differences among parents and F 1 s for all the characters studied. This showed the presence of sufficient genetic diversity in the material. Analysis of variance for combining ability revealed that variance due to general combining ability (gca) and specific combining ability (sca) were highly significant for days to maturity, plant height, number of pods per plant, number of seeds per pod, 100 seed weight and seed yield per plant, while nonsignificant for number of branches/plant, pod length and protein content, indicating the importance of both the additive and non-additive genetic components of variation for these characters (Table 1). However, the estimates of sca variance were much higher than the gca variance for all the characters, indicating predominance of non-additive variance in controlling the expression of these characters. These findings are in conformity with the findings of Sharma et al (2000) and Singh et al (1994). The per se performance of the parents was good indicator for their gca effects (Table 2). The parents Rachna and DDR-44 were good general combiners for seed yield; HUP-2 for 100 seed weight and maturity; DMR-7 for number of pods per plant; HUDP-6 and DMR-41 for plant height; and HUP-2 and DDR-44 for protein content. The breeders may utilize the good general combiners in specific breeding programme for getting high yielding varieties as high gca effects are mostly due to additive gene effect, or additive X additive interaction effects as reported by Griffing(1956). The superior specific cross combinations for seed yield per plant viz., HUP-2 x DDR-44, Rachna x DDR-44, DMR-7 x DMR-41 and Rachna x HUDP- 6 had positive gca effects for at least one of their parents. The crosses HUP-2 x DDR-44 and HUP-2 x DMR-7 exhibited desirable significant sca effect for protein content (Table 3). All these crosses had positive and significant sca effects for 5-7 attributes in F 1 generation. These crosses would produce

3 desirable trangressive segregants, if the additive genetic system present in the good combiner and the complementary epistatic effects in the F 1 act in the same direction to enrich the desirable plant characters. The best crosses, mainly HUP-2 x DDR-44, Rachna x DDR-44, DMR-7 x DMR-41 and Rachna x HUDP-6 were the best with desirable and significant sca effects with high per se performance for seed yield per plant. The present study revealed that breeders can improve upon the seed yield of field pea varieties, if they give proper attention to such type of genotypes in the available materials for crossing programme. Heterosis : Heterosis over standard check (SC) was studied for all the characters in 15 hybrids. Only Vol. 32, No. 4, Table 2. Estimates of GCA effect for parents along with their mean performance for 10 characters Parent Days to flowering Days to maturity Plant height Branches /plant Pods/plant GCA Mean GCA Mean GCA Mean GCA Mean GCA Mean HUP ** ** Rachna 0.56* * DMR * ** ** ** HUDP ** ** ** DDR ** DMR ** Mean SE(gi) SE(gi-gj) Table 2. Contd. Parents Pod length Seeds/ pod 100 seed weight Seed yield/plant Protein content GCA Mean GCA Mean GCA Mean GCA Mean GCA Mean HUP * ** ** * ** Rachna * ** ** DMR ** ** * * HUDP ** * DDR ** ** DMR ** * Mean SE(gi) SE(gi-gj) two hybrids viz., HUP-2 x DDR-44 and Rachna x DDR-44 exhibited significant heterosis over standard check (T-163) for seed yield. Considering the values of standard check, high heterotic effects were observed for days to maturity, protein content and 100 seed weight; moderate for days to flowering, number of seeds per pod, plant height and number of branches per plant. High heterotic response for seed yield per plant was mainly due to pods per plant, number of seeds per pod and 100 seed weight. The range of heterosis for different characters over standard check were from to percent for seed yield, to percent for days to flowering, to percent for days to maturity, to 4.98 percent for plant height, to percent for branches/plant, to 39.42

4 258 LEGUME RESEARCH Table 3. Estimates of SCA effects and mean performance for different attributes of 5 best crosses derived from 6 parent diallel crosses Crosses Days to flowering Days to maturity Plant height Branches /plant Pods/plant SCA Mean SCA Mean SCA Mean SCA Mean SCA Mean HUP-2 x DDR * ** 43.9 Rachna x DDR ** ** ** * 35.0 DMR-7 x DMR * ** ** ** Rachna x HUDP * * 38.2 HUP-2 x DMR * ** * * 37.1 Mean SE(gi) SE(gi-gj) Table 3. Contd. Crosses Pod length Seeds/ pod 100 seed weight Seed yield/plant Protein content SCA Mean SCA Mean SCA Mean SCA Mean SCA Mean HUP-2 x DDR ** ** ** ** 24.6 Rachna x DDR ** * ** ** DMR-7 x DMR ** * ** ** 22.7 Rachna x HUDP ** * ** * 23.0 HUP-2 x DMR ** ** ** ** ** 25.8 Mean SE(gi) SE(gi-gj) Table 4. Best crosses for different characters showing heterosis over standard check (SC) Characters Best crosses Days to flowering Rachna x DDR-44 Days to maturity Rachna x DDR-44 Plant height Rachna x DDR-44 Number of branches/plant DMR-7 x DMR-41 Number of pods /plant HUP-2 x DDR-44 Pod length Rachna x DDR-44 Number of seeds/pod HUP-2 x DDR seed weight HUP-2 x DMR-7 Seed yield/plant HUP-2 x DDR-44 Protein content HUP-2 x DMR-7 percent for pods/plant, to 4.99 percent for pod length, to percent for seeds/pod, to 5.11 percent for 100 seed weight and to percent for protein content respectively. Similar results were reported by Pant and Bajpai (1991) and Sharma et al (1998) in field pea. The list of best crosses for different characters showing heterosis over standard check (SC) is given in Table-4. Most of the hybrids showed negative heterosis for days to 50 percent flowering and days to maturity indicating that they had the tendency to flower and mature early. High magnitudes of heterosis were observed for protein content and 100 seed weight. Plant breeders can give emphasis on yield contributing characters for the improvement of seed yield in field pea.

5 Vol. 32, No. 4, REFERENCES Griffing, B. (1956). Aust.J. Biol. Sci., 9: Panse, V.G. and Sukhatme, P.V. (1967). Statistical Methods for Agricultural Workers. ICAR, New Delhi. Pant D.C. and Bajpai, G.C. (1991). Indian J. Pulses Res., 4: Sharma, M.K. et al. (2000). Crop Res., Hisar, 19: Sharma, R.N.et al. (1998). Ann. Agric.Res., 19: Singh, V. P.et al. (1994). Indian J. Pulses Res. 7:11-14.