Correlation Coefficients and Factor Analysis for Morpho-physiological and Biochemical Attributes Affecting the Yield and Yield Components of Desi-type Chickpea (Cicer arietinum L.) Genotypes

IntroductionChickpea (Cicer arietinum L.) is one of the most important crops in the human food basket worldwide. It is a highly nutritious pulse crop with low digestible carbohydrates, protein, essential fats, fiber, and a range of minerals and vitamins. As the human population grows, the demand for this protein source increases and various approaches to its sustainable products are being developed. Autumn cultivation of chickpea in cold regions requires the introduction of cultivars tolerant to freezing stress. The ability of plants to overwinter depends on the biochemical and physiological responses induced by their cold acclimation duration. Cold acclimation mechanisms in the plant are a fundamental reason for plant tolerance increase in autumn cultivation. Hence, investigating the mentioned traits can help identify cold-tolerant genotypes. Identifying attributes that provide a suitable description of the diversity between genotypes is critical through canonical correlation analysis, cluster analysis, and determining the genetic distance.Materials and MethodsThis experiment was conducted during the 2017-18 growing season in the research field of Ferdowsi University of Mashhad, Iran (Lat 36° 15′ N, Long 59° 28 E; 985 m Altitude). Chickpea germplasm, including 29 Desi-type chickpea genotypes and one cold tolerant cultivar (cv. Saral), was studied in terms of morpho-physiological and biochemical attributes and their relationship with yield and yield components. Chickpea seeds were provided from the Mashhad chickpea collection at the Research Center for Plant Science. Following seedbed preparation by ridge tillage in October 2017, chickpea seeds were sown with a density of 40 plant m-2. Irrigation was conducted three times during the growth period: immediately after sowing, two weeks after the first irrigation and flowering stage. Hand-weeding was done three times during the growth stage in early March, early April, and early May. Data were analyzed using the SAS 9.4 software, and the mean comparison was performed by the Duncan Multiple Range Test (DMRT) at a 5% probability level. Statistica software also performed a cluster analysis (based on Euclidean distance) and principal component analysis (PCA).Results and DiscussionEvaluating the morpho-physiological performance of chickpea genotypes is valuable for breeding programs that integrate chickpea cold tolerance. Based on Pearson's correlation coefficient results, a significant positive correlation was observed between the survival of chickpea germplasm with seed yield and biological yield. Also, a significant negative correlation between survival with photosynthesis pigment content and Fv'/Fm' revealed a high relationship between these parameters. Traits with the highest canonical discriminate coefficients had the best effect on the diversity across the studied genotypes. Based on the factor analysis results, the first factor with 22.8%, and the second with 12.1% explained the most differences. In the first factor, the most critical traits with a positive charge are Fv'/Fm', the total content of photosynthetic pigments, starch, the number of fertile pods, and the number of seeds, and the critical trait with a negative charge was the survival. The genotypes of the five cluster analysis groups had a higher mean in 54% of the traits compared to the total mean. The crossing of genotypes of group one due to higher survival and seed yield and genotypes of group five due to plant height and first pod height (compared to the total mean), which also have a considerable genetic distance, can lead to the release of new varieties. Also, the genotypes of the three cluster analysis groups (MCC32, MCC34, MCC155, MCC194, MCC199, and MCC291) have high-priority traits for selection by breeders and can be used in breeding programs for autumn cultivation.ConclusionAccording to the results of the present study, selection for successful overwintering of desi-type chickpea genotypes in cold regions is recommended based on the mentioned characteristics in breeding programs. The group three chickpea genotypes of cluster analysis (MCC32, MCC34, MCC155, MCC194, MCC199, and MCC291) and morpho-physiological and biochemical attributes affecting the yield and yield components determined from this study may be helpful for genetic engineering and breeding programs that integrate chickpea cold tolerance..