Genetic variability, heritability, genetic advance and correlation studies among F7 populations of chickpea (Cicer arietinum L.)

Genetic variability is the main basis of improvement in crops. The experiment was conducted at The University of Agriculture Peshawar to estimate genetic variability, heritability, genetic advance and correlation studies among F7 populations of chickpea. The experimental material comprised 35 chickpea genotypes Viz. 33 F6 populations of chickpea and two check varieties i.e., NIFA-2005 and Karak-1. The genotypes were sown in RCB design with two replications. Data were collected on eight yield contributing traits viz. Secondary branches plant, pods plant, seed pod, 100-grain weight, grain yield plant and harvest index. The analysis of variance showed significant differences (p≤0.01) among F6 populations of chickpea for all the traits studied. Maximum number of secondary branches plant (23.50), seeds pod (1.80) and seed yield plant (22.76 g) revealed by C1-P2-1-2. Maximum pods plant 1 (58.60), 100-seed weight (30.64 g) and harvest index (42.55%) were recorded for C1-P1-1-1, C1-P16-4 and karak-1, respectively. Pods plant exhibited high heritability (0.93) followed by seed yield plant (0.86), secondary branches plant (0.85, 100-seed weight (0.75), plant height (0.73) and harvest index (0.68). High genetic advance was noticed for seed yield plant (33.21), pods plant (29.61%) and secondary branches plant (22.73%). The genotypic and phenotypic correlation of seed yield plant was positive and highly significant with secondary branches plant, pods plant and harvest index. Chickpea genotypes C1-P2-1-1, C1-P1-6-2, C1-P2-1-2, C1-P1-6-4, C1-P2-3-3 and C1-P2-3-1 showed best performance than local checks Karak-1 and NIFA-2005 for pods plant and seed yield plant and should be further tested at multi-location for possible release as a new cultivars.


Introduction
Chickpea is the third most important pulse crop in the word after dry bean and dry peas Chickpea is an important annual rabi season crop.On the basis of photoperiod and photosynthesis it is C3 (inefficient) and long days crop respectively.It is a deep tap rooted crop and adapted to water stress condition.The crop is sensitive to excess of water and yield best on sandy loam soils [4].Nutritionally, the importance of chickpea in human food from the high protein contents of its seeds, a better protein digestibility than several other pulses, no hemaggulutinating activity and low antitrypsic activity.It contain protein (23%), carbohydrates (645%), starch (47%) and fats (5%), crude fiber (6%) [5].On the basis of area and production India, Pakistan and Turkey are the major chickpea growing countries.Among these, India is leading the world in chickpea production, producing 5980 thousand tons annually followed by Pakistan 845 thousand tons and then Turkey 525 thousand tons.In Pakistan, the area under chickpea cultivation is about 1054 thousand hectares with an average yield of 472 kg ha -1 .In Khyber Pakhtunkhwa chickpea is growing on an area of 39.7 thousand hectares, production of 22.9 thousand tons with an average of 577.0 kg ha - 1 [6].Chickpea is cultivated on approximately 75% rain fed area of Khyber Pakhtunkhwa i.e.Karak, Bannu, Lakki Marwat, Dera Ismail Khan and Tank [7].Genetic variation is important in breeding programs for traits and for picking desirable genotypes.
Analysis of the correlation among parameters is essential for determining selection criteria [8].Plant breeders are continuously trying to improve yield of chickpea to feed an ever-increasing population.For this purpose improvement in chickpea production need information on nature and extent of genetic variation in quantitative traits and their interrelationship in population including diverse genotypes, which are pre-requisites for efficient breeding program [9].As genetic variability and correlation are essential in breeding programs, therefore the present study was aimed to study genetic variability, heritability, genetic advance and genotypic and phenotypic correlation in F6 populations of chickpea for yield attributing traits.

Materials and methods
The contemporary investigations were carried out at The University of Agriculture Peshawar with aims to explore genetic variability, heritability, genetic advance and correlation coefficient among F7 populations of chickpea.35 chickpea genotypes including 33 crosses derived from the cross of parents ICC-19181 × NDC-4-20-4 and 2 check varieties (Table 1) were evaluated in RCB design with two replications during rabi season 2016-17.Row length was 2 m, row to row distance was 30 cm and plant spacing was 10 cm.Standard cultural practices were followed throughout the growing season including hand weeding, irrigation and at the time of pods formation insecticide (Emamectin benzoate) was sprayed.The biometrical data were recorded from randomly selected five plants on Secondary branches Plant -1 , Pods plant -1 , seed pod -1 , 100-Grain Weight, Grain yield plant -1 and harvest index.

Statistical analysis
Data recorded on each traits were analyzed using Statistix 8.1 software.The genotype means of each traits were compared using least significant differences test at 5% level.Heritability (h 2 BS) was worked out according to [10].

Secondary branches plant -1
The mean square showed significant (p≤0.01)differences among F7 populations for secondary branches plant -1 (

100-Seed weight (g)
Mean squares displayed significant (p≤0.01)differences among F7 populations for 100-Seeds weight (Table 2).The said trait ranged from 16.81 to 30.64 g among all the F6 populations.The mean values indicated that maximum 100-Seeds weight 30.64 g was noticed for CI-P1-6-4 and minimum 16.81 g was recorded for C1-P1-6-5 (Table 3).Genotypic, environmental and phenotypic variances for 100-Seeds weight was 3.99, 1.31 and 5.30 respectively.Heritability and genetic advance for the said trait was 0.75 and 11.55% (Table 4).Our heritability estimates for the mention trait are in accordance with [1, 24,25].The correlation of 100-seed weight and seed yield plant -1 (rg = 0.295*, rp = 0.234 ns ) was positive and significant at genotypic level but positive and non-significant at phenotypic level, while with rest of traits 100 seed weight had nonsignificant association (Table 5).[14, 26, 27] also noted positive correlation between grain yield and 100-Seeds weight.
[34] also observed positive association between grain yield and harvest index.

Conclusions and recommendations
The genotypes used in present studies were of diverse nature and produced more yield.High heritability and genetic advance were recorded for most of the traits which is the room for improvement.The genotype C1-P2-1-2 followed by C1-P2-1-1 exhibited better performance than local checks Karak-1 and NIFA-2005 in terms of seed yield plant -1 and should be further tested at multi-location for possible release as a new cultivars.Seed yield plant -1 showed highly significant positive genotypic and phenotypic correlation with primary branches plant -1 , secondary branches plant -1 , pods plant -1 , seeds pod -1 , seeds plant - 1 , biological yield plant -1 and harvest index showed that these traits are important for selection in chickpea.

[ 1 ].
It contribution to world pulses production is 12% .The Asian region contributes 70% to the total world's chickpea production [2].It is probably originated in the area of present day Southeastern Turkey and adjoining Syria.Chickpea is an important food legume providing protein in human diet.It has the ability to fix atmospheric nitrogen and improve soil fertility with low added cost of production [3].

Table 5 . Genotypic correlation (above diagonal) and phenotypic correlation (below diagonal) among yield attributing traits of F6 populations of chickpea
= Significant at 5% and 1% probability level respectively whereas NS = Non-significant