Genetic Diversity Studies and Fusarium Wilt Screening in Chickpea ( Cicer arietinum L.) Germplasm

increasing the genetic divergence of chickpea has been a major goal for breeders. The assessment of genetic diversity of chickpea germplasm can provide a valuable information to the breeder for parental selection strategies in plant breeding programs. Methods: Two hundred and eighty chickpea germplasm including two checks (JG-11 and SA-1) were tested with an objective to explore the genetic divergence by using Mahalanobis D 2 statistics. Among the 280 germplasm lines, 269 germplasm lines were selected from ICRISAT core set chickpea germplasm and 11 advanced breeding lines and varieties from AICRP, scheme from ZARS Kalaburagi . The field experiment was carried out in augmented block design (ABD) during Rabi 2021-22. The magnitude of genetic divergence was studied using data obtained from five quantitative traits. Result: The 280 genotypes including checks were divided into seventeen clusters based on their D 2 values. Out of seventeen clusters, cluster II (89 genotypes) was the largest followed by cluster I (83 genotypes), cluster III (31 genotypes), cluster VIII (29 genotypes), cluster VII (24 genotypes), cluster VII (15 genotypes). Same set of germplasm were also screened for fusarium wilt in wilt sick plot, 30 germplasm lines showed resistant (10.71%), 83 moderately resistant (29.64%), 44 moderately susceptible (15.71%), 31 susceptible (11.07%) and 92 highly susceptible reaction to fusarium wilt. Clusters XIV and XVI had extreme genetic distance and the germplasm lines in these cluster also showed moderate resistance to fusarium wilt (ICC 1098, ICC 11284 and ICC 10466).

selection strategies in plant breeding programs.Chickpea wilt (Fisarium oxysporum f. sp.Ciceri) is a very important disease and the pathogen in association with other soilborne pathogens like root rots and foot rot also causes extensive damage to chickpea.It causes around 10% yield loss in India but under certain conditions and specific locations, the losses may go up to 60%.Thus, the present Genetic Diversity Studies and Fusarium Wilt Screening in Chickpea (Cicer arietinum L.) Germplasm study was commenced to estimate the extent of genetic diversity present and field screening for fusarium wilt among 280 chickpea germplasm.

MATERIALS AND METHODS
Two hundred and eighty chickpea germplasms including two checks (JG-11 and SA-1) were evaluated during Rabi 2020-21 at Zonal Agricultural Research Station (ZARS), Kalaburagi.Sowing was carried out by hand dibbling method and approximately 40 seeds were sown per genotype.Sowing was done on 6th October, 2021 for germplasm characterization and the field experiment was carried out in Augmented Block Design (ABD) with two checks in each block.Each entry was planted in one row of 4-meter length having a spacing of 30 cm between the rows and 10 cm between the plants respectively.The data was noted for five polygenic traits viz., days to 50 per cent flowering, plant height (cm), days to maturity, 100 seed weight (grams) and seed yield/plant (grams) (Plate 1).The data were analysed with the technique of D 2 statistics (Mahalanobis 1936), as advocated by Rao (1952)
Plate 2: Field screening of 280 chickpea germplasm for Fusarium wilt.

RESULTS AND DISCUSSION
Analysis of variance (ANOVA) is an important tool to determine the variability present among the genotypes.The analysis (ANOVA) revealed the presence of considerable variability among 280 genotypes including checks (JG-11 and SA-1) for all the five polygenic traits (Table 1).The results show ample scope incorporating the promising genotypes in the breeding programmes aimed improvement in seed yield and its component characters.

Group constellations by tocher method
On the basis of D 2 values, two-hundred and eighty genotypes including two checks (JG-11 and SA-1) were clustered into 17 clusters based on Tocher's method (Rao, 1952) et al (2020).The solitary clusters are obtained due to the fact that they exhibit some distinctive characters which make them diverse from the other clusters.

Intra-cluster and inter-cluster distances among the chickpea germplasm
Intra-cluster and inter-cluster distances were calculated using D 2 values.Out of 17 clusters, intra cluster distances were lower than inter-cluster distances indicating that genotypes included in different clusters are more diverse compared to the genotypes included in the same clusters.
The mean intra-cluster D 2 values were ranged from 0 to 425.66.Cluster VII logged highest intra-cluster distance (425.66),followed by cluster VIII (401.40),indicating that wide genetic divergence was existing among the genotypes within these clusters.So, more emphasis will be given to the genotypes included in these clusters while selecting parents for future crop improvement.The clusters viz., cluster VI (260.71),cluster III (221.62),cluster II (176.78),cluster I (148.70)had moderate intra cluster distance.Whereas, no intra cluster distance was observed in nine clusters IV, V, IX, X, XI, XII, XIII, XIV, XV, XVI, XVII as they are monogenotypic with one genotype per cluster (Table 3).

Cluster mean values of seventeen clusters
Cluster mean value ranged from 31 days (cluster XIV) to 83 days (cluster XVI) for the trait days to 50 per cent flowering.
Cluster XIV genotypes exhibited early flowering habit with average number of days taken to flowering were 31, indicating that the Cluster XIV composed of early flowering genotypes.Cluster mean for the trait days to maturity ranged from 90 (cluster XI) to 130 days (cluster XVI).The genotypes of Cluster XI demonstrated a unique early maturing   100 seed-weight was ranged from 8 g (cluster XI) to 56.8 g (cluster XVII), the genotypes of the cluster XVII showed the highest 100 seed-weight followed by cluster III (31.7 g) which shows that the genotypes of this cluster have bold seed characters which are preferred by the consumers.The genotype MNK-1 (56.80 g) showed the highest 100 seedweight and the genotype ICC-14077 (4.8 g) has the lowest 100 seed-weight.Cluster mean for seed yield/plant values   ranged from 2.38 g (cluster XII) to 8.13 g (cluster XVII), with genotypes from cluster XVII had the highest seed yield/plant (8.13 g) suggesting that the genotypes of this cluster are preferred for the seed yield improvement of chickpea (Table 4).
Fusarium wilt screaning in chickpea (Cicer arietinum L.) germplasm Among the two hundred and eighty-two chickpea genotypes along with two checks screened against wilt, there was a significant variation between genotypes for their disease reaction.

CONCLUSION
In this current divergence study, the relative contribution of each character towards genetic divergence will provide effective data to assist the plant breeders in selecting superior genotypes from available germplasm collection to use them as parents in the future crop improvement programme.The maximum intra cluster distance (425.66) was observed in the cluster VII, followed by cluster VIII (401.40),indicating the existence of wide genetic diversity among the genotypes within these cluster.The maximum inter cluster distance was observed between cluster XIV and cluster XVI (4352.70),followed by cluster X and cluster XIV (3578.44),cluster XVI and cluster XVII (3383.30),cluster XIV and cluster XV (3063.34),cluster VI and cluster XVI (3050.80),revealing that genotypes included in these clusters are genetically diverse and is vital for future hybridization programme.The field screening for Fusarium wilt of two hundred and eighty chickpea genotypes in the wilt sick plot yielded thirty resistant genotypes, of which ICCV 16116 (0.44) followed by ICC 9942 (1.77), ICC 4657 (3.48), ICC 9872 (5.50) showed significantly higher level of resistance for wilt as they produced narrow range of per cent disease incidence (PDI) value.The characters which contributed more to genetic divergence may be given more weightage in future plant breeding programmes to improve the yield through selection.The Fusarium wilt resistant genotypes which were screened using sick plot can be directly released as variety or choice of parents for hybridization programme.
. The software package INDOSTAT version 8.5 was used to analyse the statistical data.Experimental layout for screening Fusarium wilt was laid out on National W ilt Sick Plot maintained at Agricultural Research Station, Kalaburagi [Latitude (N) 170 35' and Longitude (E) 760 81'].The sick plot is maintained since 1985-86 to till date.It is one of the national sick plot for screening AICRP and local genotypes.The wilt sick plot was maintained by adding chopped plants of Fusarium oxysporum f. sp.ciceris infested chickpea plants every year.All the genotypes were sown in single row along with wilt susceptible (JG-62) and resistant check varieties (W R-315) during the rabi 2019 season.A row length of 4 meters each was maintained with a spacing of 30 cm and 10 cm between the rows and plants respectively (Plate 2).The observations on per cent disease incidence was recorded at 30, 60, 90 days after sowing by counting the number of diseased and dead plants (due to Fusarium wilt) among Plate 1: Diverse chickpea germplasm for mojor traits Plant he ight Se ed size and colour

Fig 2 :
Fig 2: Diagrammatic representation of per cent contribution of each character towards divergence in genotypes.
Genetic Diversity Studies and Fusarium Wilt Screening in Chickpea (Cicer arietinum L.) Germplasm the total number of plants present per genotype and per cent disease incidence was estimated.Disease rating was categorized as per the standard wilt scoring format of All India Coordinated Research Project (AICRP) on chickpea, IIPR, Kanpur.

Table 1 :
Summary of analysis of variance (ANOVA).

Table 2 :
Clustering pattern of chickpea genotypes based on D 2 analysis.

Table 3 :
Intra (diagonal)and inter cluster distances (D 2 value) of 280 genotypes along with checks of chickpea.Genetic Diversity Studies and Fusarium Wilt Screening in Chickpea (Cicer arietinum L.) Germplasm

Table 4 :
Cluster means of 17 clusters for yield and its related traits in chickpea genotypes.

Table 5 :
Laxuman et al. (2022)fied as resistant against fusarium wilt under field condition.Fusarium wilt.Similar results were also reported byShah et al. (2015)andKumar et al. (2015),Ayana et al. (2019).Laxuman et al. (2022)used various wilt resistant chickpea genotypes and breeding lines for evaluating yield response in different environments.They observed higher average yields of KCD-11 and ICCV 191106 with wilt resistance.