Characterisation of brinjal (solanum melongena L.) and its wild relatives

Abstract

The study entitled “Characterization of brinjal (Solanum melongena L.) and its wild relatives” was carried out at the Department of Plant Breeding and Genetics, College of Agriculture, Padannakkad during 2018-2020. The main objectives of the study was to characterize the brinjal genotypes and its wild relatives based on morphological characters; analyze the genetic variability in collected accessions and to develop selection index for cultivated types. The experimental meterial consisted of 25 S. melongena accessions and five wild relatives (S. mammosum, S. macrocarpon, S. insanum, S. incanum and S. gilo) collected from North Kerala (Malappuram-11, Kozhikode-5, Kannur-4, Kasaragod- 3, Wayanad-1) and Regional station, NBPGR, Thrissur (6). The passport data of thirty accessions were prepared and these were evaluated for 17 qualitative and 22 quantitative characters based on IPGRI descriptor in field experiment laid out in Randomized Block Design with three replications. The morphological characterization based on qualitative characters showed wide variation for stem colour, leaf lobing, fruit shape and fruit colour. The results of analysis of variance indicated significant differences for all the quantitative characters indicating presence of high genetic variability. The mean performance of genotypes revealed distinct variation between cultivated and wild accessions for most of the characters. The wild accessions recorded lower values for fruit yield and fruit weight but longer duration for flowering and fruit set. Eight S. melongena accessions (SM 27, SM 25, SM 23, SM 20, SM 10, SM 23, SM 24 and SM 8) had high fruit yield per plant (more than 1000 g). The accession SM 27 had shown superiority for important yield component traits like fruit yield, fruit diameter and fruit weight. Among all accessions, the green fruited S. melongena accession SM- 25 showed lesser incidence of shoot and fruit borer. Three wild accessions S. mammosum (SM 22), S. gilo (SM 29) and S. insanum (SM 30) showed no incidence of fruit and shoot borer. The variance component analysis revealed high heritability coupled with high genetic advance as per cent of mean for all flowering and fruit characters indicatingthat most likely the heritability is due to additive effects making selection effective based on these characters. Association analysis revealed that plant height, days to first flowering, number of long styled flowers, fruit diameter, fruit weight and number of fruits per plant shown significant genotypic correlation and direct effect showing true association of these characters with fruit yield. Selection based on all these characters will help to achieve efficient improvement in fruit yield. The UPGMA clustering of 30 eggplant accessions for qualitative traits revealed three groups based on anthocyanin pigmentation of plant parts and leaf prickliness, traits important for stress tolerance. The genetic diversity analysis based on Mahalanobis D 2 statistics for 22 quantitative characters grouped 30 accessions into eight clusters. The clustering patern showed the S. melongena accessions collected from North Kerala grouped under cluster I (22) and cluster III (2). All the five wild accessions were grouped in five different clusters (III, IV, VI, VII and VIII). The green fruited accessions SM 25 and SM 27 collected from NBPGR were placed in cluster III and cluster V indicating their distinctness. The character fruit yield per plant, leaf blade width, number of fruits per plant and leaf blade length hade made major contribution towards genetic divergence with maximum by fruit yield per plant. The maximum intra-cluster distance was reported in cluster I, followed by cluster III. The remaining are solitary clusters. The highest inter- cluster distance was recorded between solitary clusters V and VIII, V and IV and V and III providing scope for hybridization between genotypes of these highly divergent cluster especially involving wild accession SM 30 for fruit and shoot borer resistance. Selection index involving discriminant functions based on relative economic importance of various characters showed a combination of four characters (Fruit yield per plant + Number of long styled flowers + Fruit diameter + Fruit weight) with maximum relative efficiency. Based on high selection index score involving four character combination and overall cluster ranking for three yield attributes two green fruited accessions SM 25 and SM 27 and six purple fruited accessions SM-8, SM- 10, SM-18, SM-20, SM-23 and SM 24 are identified as promising. Among these,the green fruited accession SM 25 had shown very low incidence of fruit and shoot borer. Based on selection index score and cluster divergence (high inter-cluster distance) the SM-27 is identified as promising parent in intra-specific hybrid involving of SM-27 x SM-25 and inter-specific hybrids involving SM-27 x S. insanum and SM-27 x S. macrocrpon. These crosses may be attempted in future breeding program for obtaining progenies superior for yield as well as shoot and fruit borer and bacterial wilt resistance.