Identification of superior genotypes for yield and quality in red gram[Cajanas cajan (L.)Millsp.] suitable for Kerala

Abstract

Red gram [Cajanus cajan (L.) Millsp.], commonly known as pigeonpea, is an important tropical and subtropical legume valued for its edible seeds. It serves as both a green vegetable and a split pulse (‘dhal’), being a rich source of protein, carbohydrates, vitamins, minerals, and essential amino acids such as lysine, methionine, and tryptophan. In combination with cereals, pigeonpea provides a nutritionally balanced diet and contributes to food security and sustainable smallholder farming systems. India is the largest producer of pigeonpea. It ranks second among pulses after chickpea, with major cultivation in Maharashtra, Karnataka, Madhya Pradesh, Uttar Pradesh, and Gujarat. In Kerala, however, despite being an integral part of the diet, commercial cultivation of pigeonpea is meagre. Therefore, the present research entitled “Identification of superior genotypes for yield and quality in red gram [Cajanus cajan (L.) Millsp.] suitable for Kerala” was undertaken in the Department of Genetics and Plant Breeding, College of Agriculture, Vellayani, during 2021-2025. In the first experiment, thirty genotypes originating from ICRISAT (Hyderabad), TNAU (Coimbatore), and IARI (New Delhi) were collected and evaluated in the field to study variability parameters and genetic divergence (D2). Analysis of variance revealed highly significant differences among genotypes for all 16 traits studied, indicating substantial genetic variability. The genotypic and phenotypic coefficients of variation (GCV and PCV) exhibited high values for traits such as the number of primary branches per plant, number of pods per plant, seed yield per plant, biological yield, and the content of total phenol, tannin, and methionine, indicating a strong potential for improvement through selection. High heritability coupled with high genetic advance as a percentage of the mean was observed for most traits, indicating the predominance of additive gene action, making direct selection effective. Correlation analysis revealed that seed yield per plant was positively and significantly associated with number of pods per plant, biological yield, harvest index, primary branches, and seeds per pod, while phenol content showed a significant negative correlation. Path analysis indicated that biological yield, flowering traits, and harvest index exerted strong positive direct effects on seed yield, whereas days to bud initiation and plant height contributed negatively. All thirty genotypes were assembled into six clusters using D² analysis. Cluster III had the highest number of genotypes (9), followed by cluster IV (5 genotypes), and clusters I, II, V, and VI each had one genotype. The highest intra-cluster distance was recorded in cluster IV and the lowest in cluster II, whereas the highest inter-cluster distance was observed between clusters I and VI, followed by clusters IV and V. Molecular diversity analysis among the 30 genotypes was conducted using 30 Simple Sequence Repeat (SSR) markers. Of these, 14 were polymorphic, 9 were monomorphic, and 7 markers failed to amplify. The Polymorphic Information Content (PIC) values of polymorphic SSR markers ranged from 0.12 (ASSR 363) to 0.50 (ASSR 281). The lowest Jaccard’s similarity coefficient was observed between genotypes ICPL 300 and ICPL 22081 (0.167). UPGMA cluster analysis grouped all 30 pigeonpea genotypes into six clusters, with Cluster I being the largest (12 genotypes), followed by Cluster III (11 genotypes), Cluster V (3 genotypes), Cluster IV (2 genotypes), and Clusters II and VI with one genotype each. Principal Coordinate Analysis (PCoA) confirmed the presence of considerable genetic diversity among the 30 red gram genotypes. Ten superior genotypes, viz., ICPL 11259, ICPL 11300, ICPL 11318, ICPL 11326, ICPL 20327, ICPL 22045, ICPL 22084, ICPL 22081, APK 1, and Pusa Arhar 16, were selected based on seed quality attributes and seed yield per plant. Phenological evaluation of these genotypes was conducted in the field for three seasons (Rabi, Summer, and Kharif). Seasonal evaluation revealed that seed yield per plant was highest during Kharif, though with high variability, whereas Rabi showed relatively stable but lower yields, and Summer provided balanced performance with moderate yield consistency. Among the ten genotypes, APK 1 and Pusa Arhar 16 consistently recorded high seed yield across all three seasons along with good quality traits and are suitable for cultivation in Kerala. Genotypes grouped in different clusters with maximum inter-cluster distances indicate high genetic diversity, which can be exploited in future breeding programmes to manifest heterosis and develop superior hybrids. Genotypes with high molecular diversity can serve as parental lines for making crosses with a broad genetic base, thereby enhancing the scope of genetic improvement.