Introduction

Garden pea (Pisum sativum L.; 2n=2x=14), a member of family Leguminaceae, is one of the principal vegetable crops which is cultivated for its green pods in the temperate and sub-tropical areas of the world. Itis the second most important food legume worldwide after Phaseolus vulgaris (Jaiswal et al., 2015). Blixt (1970) indicated Mediterranean region as its principal centre of genetic diversity while the Near East and Ethiopia as its secondary habitats.

The success of any breeding programme depends upon the genetic variability present in the germplasm (Adunga and Labuschange, 2003) which provides better chances of selecting desirable types. Therefore, the genetic reconstruction of pea germplasm is first step to identify the potential genotypes for use in breeding programme. In early group of peas, only three varieties have been recommended, thus the farmers of the state have limited choice. Few early lines have been recovered in the previous study on RIL population of a cross, NDVP-250×Palam Priya. A line×tester analysis was done to determine the genetic interactions in the expression of earliness and various pod characters including pod yield. Line×tester mating design was proposed by Kempthorne (1957), offer means of obtaining useful information on differential parental combinations through an assessment of overall genetic architecture of the parental lines, in relation to the characters studied.

Materials and Methods

The experiment was conducted for three consecutive years viz., 2014-15, 2015-16 and 2016-17 at Vegetable Research Farm of the Department of Vegetable Science and Floriculture, CSK HPKV, Palampur (H.P.), India. The experimental material consisted of 21 genotypes (Table 1 and 2),

Table 1: List of lines (female parents) and testers (male parents)

Table 2: List of progenies

including five parental lines (Line 12, Line 13, Line 14, Line 15 and Line 17), three testers (Matar Ageta, Palam Triloki and Arkel) and their 15 crosses. The parents along with the hybrids were evaluated along with one standard check; Palam Triloki in randomized block design with three replications in 2014-15 with row to row and plant to plant spacing of 45 cm (in parents 30 cm) and 10 cm respectively. Each experimental plot was of 3×1.8 m²  size accommodating 6 rows. The promising genotypes were selected and evaluated along with three checks; Matar Ageta, Palam Triloki and Arkel in randomized block design with three replications during rabi, 2016-17. Ten plants per genotype per replication were randomly selected for recording the observations at appropriate stages of crop growth during both the seasons on characters viz., days to 50% flowering, days to first picking, pod length, pods plant, seeds pod^-1, pod yield plant^-1, shelling percentage, primary branches plant^-1, plant height and total soluble solids. The data were analysed for randomized block design given by Panse and Sukhatme (1984). The mean values of both the generation for each trait were subjected to statistical analysis using the model suggested by Kempthorne (1957) and Singh and Chaudhary (1977).

Results and Discussion

Analysis of variance for genotypes under study revealed significant differences among the parents for all the traits except for harvest duration in F₁ and for pods per plant, pod yield per plant and shelling percentage in F₂. This indicated that parents used in present study were genetically diverse. Gupta and Singh (2004) have reported similar results.

In F_1, when comparison was done between best cross combination and the parents involved for earliness, it was observed that for days to first picking, mean value observed for cross line 17×Palam Triloki was 116.67, which was a week earlier than parents involved (Table 3) (mean value of  123.67 was exhibited by line 17 and Palam Triloki). Mean value of cross  combination  line 17×Palam Triloki for days to 50% flowering was 84 as compared to 89 (mean value exhibited by both line 17 and Palam Triloki), which clearly indicates earliness of the cross.

Table 3: Mean performance of parents

For pod yield, best cross was line 17×T₁, with mean value of 44.43 for number of pods per plant, while it was just 14.40 for line 17 and 12.67 for Arkel. Mean pod yield per plant as exhibited by cross line 17×T₁ was 192.20 g, while it was only 69.23 g for line 17 and   60.60 g for Arkel. Thus, cross line 17× T₁ was superior in pod yield as compared to parents involved. While in F₂ when comparison was done between best cross combination and the parents involved for earliness, it was observed that for days to first picking, mean value observed for cross L₁₃×Palam Triloki was 108 days, which was 1.67 days (Table 4) later than the parent, Palam Triloki (106.33) and was ten days earlier than Line 13 (119.33). Mean value of cross combination L₁₃×Palam Triloki for days to 50% flowering was 69.67 days as compared to 90 and 69.33 (mean value exhibited by both line 13 and Palam Triloki respectively), which clearly indicates earliness of the cross. For pod yield, best cross was L₁₇×Palam Triloki, with mean value of 26.72 for number of pods per plant, while it was just 16.52 for line 17 and 15.22 for Palam Triloki.

The availability of early pea cultivars in the market fetches better prices due to less supply and high demand. Thus, ‘17×Palam Triloki’ was the most desirable genotype for early maturity among the other recommended genotypes. For improving garden pea, wide variations for pod length, seeds per plant, pods per plant and pod yield per plant are needed along with superior lines in hybridization programme (Katoch et al., 2016). Mean pod yield plant^-1 as exhibited by cross L₁₇×Palam Triloki was 134.61 g (Table 4), while it was only 83.54 g for line 17 and 75.25 g for Palam Triloki. Thus, cross L₁₇×Palam Triloki was superior in pod yield as compared to parents involved.

Table 4: Mean performance of F1 and F2 progenies

Table 4: Continue...

Conclusion

From the present study it is concluded that, for pod yield, best cross was L₁₇×T₂, with mean value of 26.72 for number of pods plant^-1. Mean pod yield plant^-1 as exhibited by cross L₁₇×T₂ was 134.61 g, whereas in F₁ line 17×T₁, with mean value of 30.87 for number of pods plant^-1 was the best. Thus, crosses L₁₇×T₁ and L₁₇×T₂ were superior in pod yield as compared to parents involved both in F₁ and in F₂, respectively.

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