Genetic Variability and Inter-relationships Among Grain Physical and Hydration Traits in Chickpea

Pulses play a vital role in providing daily protein dietary requirement of largely vegetarian population in the Indian sub-continent. Chickpea, being the major pulse crop, provides bulk of this requirement through dal and other preparations. It accounted for nearly 43% (10.13 MT) of the total pulse production and 80% of total pulse export during 2018-19 (Anonymous, 2019). It is a good source of carbohydrates and protein and constitutes an important component of diet of largely vegetarian Indian masses (Chibbar et al., 2010). In general, large-seeded kabuli chickpeas fetch a higher price and the price premium increases as the seed size increases (Gaur et al., 2007). Hydration capacity and volume expansion (after soaking in water) are important cooking quality traits in chickpea, particularly in kabuli type which are mostly cooked as ‘whole grain’ without decortication. Chickpea breeding in India has been focussed on yield improvement along with incorporation of stress resistance and quality improvement has often been neglected (Srivastava et al., 2017). Limited information is available on these properties of chickpea based on breeding lines (Tripathi et al., 2012), mini-core collection (Sastry et al., 2019) etc. and such information on recently released varieties is not available. Hence, present study was undertaken to assess the genetic variability and inter-relationships among grain physical and hydration traits in chickpea varieties.

Fifty-nine chickpea (Cicer arietinum L.) varieties including 46 desi type and 13 kabuli type (Table 1). These varieties are popular in different parts of the country and are in breeder seed production chain based on indents from various state agencies.  The material was grown at ICAR-IIPR New Research Campus during 2017-18 in randomized block design with three replications. In each replication, four rows of a variety were planted in 4m row with row to row spacing of 30 cm and plant to plant spacing of 10 cm. The harvested seeds were evaluated for their grain physical and hydration traits viz., 100-seed weight, seed density, hydration capacity, hydration index, swelling capacity and swelling index. Three random samples of 100 seeds from each cultivar per replication were weighed and the values were converted into grams per 100 seeds. The seed volume was determined by transferring 100 seeds into a 100 ml measuring cylinder containing 50 ml of distilled water. The gain in volume was taken as the volume occupied by the seed. Seed density was calculated as seed weight divided by seed volume. Hydration capacity was recorded as gain in weight after overnight (12h) soaking in distilled water. Hydration index was calculated as hydration capacity divided by the original seed weight. Swelling capacity was determined as gain in volume after overnight soaking in water. Swelling index was calculated as swelling capacity divided by the original seed volume. The data was subjected to analysis of variance (ANOVA) for testing the significance of variation due to varieties for six seed quality traits as described by Gomez and Gomez (1984). Mean values were calculated and compared using F-test at 5% level of significance. Correlation between these quantitative characters was estimated according to the method given by Singh and Chaudhary (1977).



The analysis of variance (ANOVA) for seed quality traits indicated significant variation for all the traits (Table 1). The seed weight ranged from 11.00 to 51.50 g/100 seeds with mean of 21.8 g/100 seeds, seed density ranged from 1.19 to 1.88 with mean of 1.37, hydration capacity ranged from 0.05 to 0.62 with mean of 0.24, hydration index ranged from 0.33 to 1.51 with mean of 1.10, swelling capacity ranged from 0.08 to 0.60 with mean of 0.25 and swelling index ranged from 0.62 to 2.33 with mean of 1.59 (Table 2). Among desi types, the 100 seed weight ranged from 11.0 g (Bidisha) to 30.0 g (Virat) while among kabuli types, it ranged from 15.0 g (GPF 2) to 51.5 g (Kripa). The seed density among desi types ranged from 1.19 g/ml (PBG 5) to 1.88 g/ml (Phule Vikram) and among kabuli types ranged from 1.27 g/ml (GNG 1969) to 1.5 g/ml (GPF 2). The hydration capacity among desi types ranged from 0.05 g/seed (PBG 7) to 0.34 g/seed (Virat) and among kabuli types ranged from 0.16 g/seed (GPF 2) to 0.62 g/seed (Kripa). The hydration index among desi types ranged from 0.33 (PBG 7) to 1.51 (JG 11) and among kabuli types ranged from 1.03 (GPF 2) to 1.42 (GNG 1969). The swelling capacity among desi types ranged from 0.08 ml/seed (Pant G 186) to 0.38 ml/seed (Virat) and among kabuli types ranged from 0.17 ml/seed (GPF 2) to 0.60 ml/seed (Kripa). The swelling index among desi types ranged from 0.62 (Pant G 186) to 2.33 (Phule Vikram) and among kabuli types ranged from 1.35 (PKC 1) to 1.79 (HK 4). Similar range for seed weight (16 to 39 g/100 seeds), seed density (0.87 and 1.33 g/ml), hydration capacity (0.14–0.37 g/seed), hydration index (0.01–0.02), swelling capacity (0.02–0.34 ml/seed) and swelling index (0.06–2.4) have been reported by Singh et al., (2010). The magnitude of PCV was slightly high than the GCV for seed quality traits indicating moderate influence of environment on expression of these traits. Similar findings have been reported earlier (Lokare et al., 2007; Malik et al., 2011). High heritability coupled with high genetic advance was recorded for 100-seed weight, hydration capacity and swelling capacity in both desi and kabuli genotypes. These findings are in agreement with those of Pandey et al., (2007) and Malik et al., (2010). These results indicate that high heritability of these traits is predominantly due to additive gene action and hence direct selection for these traits is expected to be effective. The 100-seed weight showed significant positive correlations with hydration capacity and swelling capacity among both desi and kabuli types (Table 3). Muller (1967) reported the role of cell wall structure, seed composition and cell compactness on water absorbing capacity of seeds. Larger seed size and thinner seed coat facilitate water absortion by seeds (Sefa-Dedeh and Stanley, 1979). Many researchers have reported positive correlation between seed weight and hydration capacity (Khattak et al., 2006; Nizakat et al., 2006; Ozer et al., 2010 et al.,) and seed weight and swelling capacity (Kaur et al., 2005). Seed density showed negative correlation with hydration capacity and hydration index in both desi and kabuli types. Cultivars with high seed density have compact endosperm which results in lower hydration (Singh et al., 2010) and subsequently lower swelling capacity. Hydration capacity was positively correlated with hydration index, swelling capacity and swelling index in both desi and kabuli types. Similar findings have been reported by Kaur et al., (2005) and Ozer et al., (2010).

The present study estimates the genetic variability and inter-relationship between chickpea seed quality traits viz., 100-seed weight, seed density, hydration capacity, hydration index, swelling capacity and swelling index among recently released and popular chickpea varieties. The results indicate high heritability of these traits, predominantly due to additive gene action with possibility of direct selection for improving these traits. Chickpea seed volume and swelling capacity are important traits for consumers, particularly when whole grains are consumed after soaking and cooking. Enough variability exists for seed quality traits among desi and kabuli chickpea types. Since most of these traits are positively correlated with seed size among both desi and kabuli types, indirect selection for seed size in breeding population may be effective for simultaneous improvement in physical and hydration traits. It is high time that concerted efforts should be made for developing chickpea varieties possessing consumer preferred quality traits.