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K. JOHN* AND P. RAGHAVA REDDY
Regional Agricultural Research Station, Tirupati-517502, Andhra Pradesh, India
Line × tester analysis was performed using six lines and four testers for yield and water use efficiency traits in groundnut. The gca variances were highly significant for all the characters studied except specific leaf weight. The parent ICGV-91114 proved to be a good general combiner for root length and pod yield per plant. TAG-24 is also a good general combiner for SPAD chlorophyll meter reading at 60 DAS, specific leaf area at 60 DAS, relative water content at 40 DAS and harvest index. The crosses viz., TAG-24 × TMV-2 for SPAD chlorophyll meter reading at 60DAS, Prasuna × Dharani for SPAD chlorophyll meter reading at 40 DAS. Among the hybrids, Narayani × Dharani had recorded superior sca effect for pod yield per plant. This cross was derived from high × low (or) high × medium gca parents. Hence, these cross would be used for further selection to obtain high yielding seggregants.
General combining ability, Specific combining ability, Water use efficiency, Groundnut
Groundnut is an important oilseed crop is grown under rain-dependent production conditions in India. Due to erratic rainfall and frequent drought, and also lack of high yielding adapted cultivars, groundnut yields are gradually low and unstable under rain-dependent conditions. Though, groundnut is known for its relative ability to withstand periods of water limited conditions still produce biomass and kernels requires thorough investigations to increase water use efficiency (WUE), to assure sustained food security for the benefit of resource poor farmers in the semi arid regions. Blum (1988) and Lawn (1989) have considered the value of physiological or morphological attributes in breeding improved cultivars of crop species. Therefore, sustaining crop productivity under water limited conditions and saving irrigation water are the most important aspects that needs to be addressed immediately. The information on the combining ability status of the genotypes will give an indication as to how well they combine with a given genotype to produce potential and productive populations and also on the nature of gene action involved. This helps the breeder to decide upon the choice of parents for hybridization and to isolate promising genotypes from the segregating populations. An investigation was taken up in groundnut involving a set of six lines and four testers were crossed in a line ×
tester mating design, to study the general and specific combining ability and the gene action determining the yield and water use efficiency traits in this crop.
Twenty four F1 crosses were obtained by making crosses in L × T analysis. The lines viz., TAG-24, Prasuna, Rohini, Narayani, K-6 and Greeshma and testers viz., Dharani, TMV-2, TCGS-1416 and ICGV-91114. Twenty four F1s along with eight parents were sown in a Randomised Block Design (RBD) in three replications during kharif 2014. Each parent was sown in 3 rows of 3 m length while F1s were raised in a single row of 3 m length. Ten random plants per replication were sampled in case of parents and F1s per replication were tagged at random for recording observations. Observations were recorded on ten random plants in parents and F1 in each treatment per replication. The experiment was conducted in a red sandy loam soil with a neutral pH, low in organic carbon. Recommended agronomic and plant protection measures were adopted for the conduct of experiment. Data were obtained for water use efficiency traits and yield viz., days to 50 per cent flowering, days to maturity, SPAD chlorophyll meter reading (40 and 60 DAS), specific leaf area (40 and 60 DAS), specific leaf weight (40 and 60 DAS), relative water content (40 and 60 DAS), root length (cm), dry haulms weight per plant (g), harvest index (%)
and pod yield per plant (g). The water use efficiency traits were measured on all four leaflets of third leaf from the top on main axis at 40 and 60 DAS.
The combining ability analysis was carried out according to Model I and Method II of Griffing (1956). The fixed effect model (Model I) was considered to be more appropriate in the present investigation since the study was restricted to the parents and direct crosses only.
The analysis of variance indicated that variance due to line and testers for all the characters were significant except days to maturity and specific leaf weight at 40 days after sowing and 60 days after sowing indicating differences among the combining ability. Obviously due to the diverse nature of the lines and testers the crosses between them were also found to be significant for all the characters except days to maturity and specific leaf weight at 40 days after sowing and 60 days after sowing. Significant variance of line × tester interaction indicated the importance of combining ability.
The magnitude of specific combining ability variances was much greater than those of general combining ability variances for all the characters except specific leaf weight at 40 days after sowing and 60 days after sowing, which indicated the preponderance of non additive gene action.
The per se performance and general combining ability analysis effects are presented in Table 2. The parent TAG-24 recorded high specific leaf weight at 40 days after sowing and 60 days after sowing. This parent has recorded higher relative water content at 60 days after sowing. Early flowering and maturity was observed in line Rohini and higher relative water content at 40 days after sowing. The highest pod yield per plant was registered by Narayani. The tester Dharani has shown highest mean value for specific leaf weight at 40 days after sowing and 60 days after sowing. TMV-2 had recorded the higher mean value for root length. TCGS-1416 had recorded highest mean for SPAD chlorophyll meter reading at 40 days after sowing and 60 days after sowing, specific leaf weight at 40 days after sowing and 60 days after sowing, dry haulms yield per plant, low mean value for specific leaf area at 40 days after sowing and 60 days after sowing.
The estimates of gca effects showed that among the lines TAG-24 was found to be superior as it showed significant and positive gca effect for SPAD chlorophyll meter reading at 60 days after sowing, higher relative water content at 40 days after sowing, harvest index and significant negative gca effect for specific leaf area at 60 days after sowing. The parent Prasuna was a good combiner as it had registered significant positive gca effect for SPAD chlorophyll meter reading at 60 days after sowing and dry haulms yield per plant. Rohini was good general combiner for early flowering and Narayani for early maturity. The line, Greeshma had shown significant negative gca effect for specific leaf area at 40 days after sowing and significant positive gca effect for specific leaf weight at 40 days after sowing and 60 days after sowing.
Among the tester’s TMV-2 was good combiner for harvest index. The best general combiner for relative water content at 60 days after sowing was TCGS-1416 as it showed significant positive gca effect.ICGV-91114 recorded significant positive gca effect for root length and pod yield per plant. Since, high gca effect is attributed to additive and additive × additive type of gene actions, these parents could be used in breeding programme for yield improvement through pedigree breeding.
The mean performance and sca effects of the crosses are presented in Table 3. The cross Narayani × Dharani came to flowering early and recorded high mean value for root length. Similar results were also reported by Adamu et al. (2008), Sharma and Gupta (2008), Rekha et al. (2009) and Savithramma et al. (2010). High SPAD chlorophyll meter reading at 40 days after sowing was registered by Prasuna × Dharani. TAG-24 × TMV-2 recorded higher mean for SPAD chlorophyll meter reading at 60 days after sowing. TAG-24 × ICGV-91114 had showed lower mean value for specific leaf area at 60 days after sowing. The cross Greeshma × TCGS-1416 recorded highest mean for specific leaf weight at 40 days after sowing and 60 days after sowing, harvest index pod yield per plant and lower mean for specific leaf area at 40 days after sowing. TAG-24 × Dharani showed higher mean value for specific leaf area at 40 days after sowing, K-6 × ICGV-91114 for relative water content at 60 days after sowing and Prasuna × TMV-2 for dry haulms yield per plant.
The cross Narayani × Dharani showed significant sca effect in the desirable direction for days to 50 per cent flowering, root length and pod yield per plant. Nadaf et al. (1988) reported importance of additive gene action for pod yield per plant. On the contrary, the importance of non-additive gene action for this trait was mentioned by Dwivedi et al. (1989). Both additive and non-additive gene actions were reported for this trait by Makne and Bhale (1989), Parmar et al. (2000), Jogloy et al. (2005), Venkateswarlu et al. (2007), Sharma and Gupta (2008), Manivannan et al. (2008), Adamu et al. (2008), Jivani et al. (2009), Rekha et al. (2009), Savithramma et al. (2010), Motilal and Ezhil (2010) and Ganesan et al. (2010). Since, high gca effect is attributed to additive and additive × additive type of gene action, these parents could be used in breeding programme for yield improvement through pedigree method.
The cross K-6 × TMV-2 was found to be desirable for days to maturity. Prasuna × Dharani exhibited significant sca effect for SPAD chlorophyll meter reading at 40 days after sowing and non significant sca effect for specific leaf weight at 60 days after sowing. TAG-24 × TMV-2 showed significant positive sca effect for SPAD chlorophyll meter reading at 60 days after sowing and TAG-24 × ICGV-91114 also exhibited significant sca negative effect for specific leaf area at 40 days after sowing. The cross K-6 × TCGS-1416 had performed significant sca effect specific leaf area at 60 days after sowing. Greeshma × TCGS-1416 had showed significant sca effect for specific leaf weight at 40 days after sowing and harvest index. The best specific combiner for relative water content at 40 days after sowing and 60 days after sowing was TAG-25 × Dharani. Prasuna × TMV-2 had showed significant sca effect for dry haulms yield per plant. These results are in agreement with the findings of Adamu et al. (2008).
It could be concluded from the results of the present study that the parents viz, TAG-24, Rohini, Prasuna, Narayani, Greeshma, TMV-2, ICGV-91114 and TCGS-1416 were considered as desirable parents could be used in breeding programme. Among the hybrids, Narayani × Dharani had recorded superior sca effect for pod yield per plant. This cross was derived from high × low (or) high × medium gca parents. Hence, these crosses would be used for further selection to obtain high yielding seggregants. Prasuna × Dharani and TAG-24 × TMV-2 were recorded superior per se for SPAD chlorophyll meter reading, these crosses were derived from high and low for SPAD chlorophyll meter reading in the segregating generation.
This research was supported under the UGC Research award to the first author by the University Grants Commission (UGC), New Delhi is gratefully acknowledged.