Multivariate analysis on blackgram genotypes for bruchine (Callosobruchus maculatus F.) resistance towards selection of parental lines

Black gram (Vigna mungo (L.) Hepper) is one of the most important pulse crops in daily diets. However, black gram production and post-harvest preservation are still tedious due to the losses caused by the storage pest bruchine, Callosobruchus maculatus (F.), both quantitatively and qualitatively. Hence, the present study involves the utilization of the multivariate analysis by effectively understanding variation among the genotypes based on their level of bruchine infestation. The multivariate studies indicated that the traits viz., the total number of adult emergence (AE), seed damage % (SD) and seed weight loss % (SWL) had more variation and with more significant correlation among them. Also, these traits are the most influential principal component traits governing 88% of the variation among genotypes. The divergence analysis showed that the genotype TU 68 found in cluster II would have the potential to create the variation for bruchine infestation among the black gram genotypes involved in the study. As it has scored lesser adult emergence (AE) (7 adults), seed damage % (SD) (14 %) and seed weight loss % (SWL) (17.79 %) than the other genotypes. It shows the resistant nature of the genotype against bruchine beetles. Hence, TU 68 could be utilized in the future hybridization programme as a donor for bruchine resistance.

Assessment of Genetic Diversity for Yield and its Attributing Traits in Tomato (Solanum lycopersicum L.) Genotypes for Protected Conditions

Background: Tomato plant has high yield potential, although the yield is very low because of non-availability of superior cultivars for protected cultivation. Presence of diversity is an important for variety development. Hybridization among divergent parents is probably produce ample variability and helps to isolate superior recombinants. So, the study was carried out to assess of genetic diversity in tomato for choosing promising and genetically diverse parents for improvement in yield for protected cultivation. Methods: Fourteen genotypes of tomato were planted inside naturally ventilated polyhouse during September 2018 to May 2019. The data were recorded for twenty-one characters from randomly five tagged plants from each genotype and genetic diversity was computed by utilizing Mahalanobis D2 analysis. Result: All genotypes were arranged into five highly divergent clusters in which cluster I contain maximum genotypes followed by cluster II. The intra cluster distance was highest in cluster I and inter-cluster distance was highest among cluster-II and V. Cluster means indicated that cluster II had high mean values for maximum traits. The highest contribution towards genetic diversity was shown by fruit yield/plant followed by number of fruits per plant. Based on breeding objectives, potential lines are selected as parents for utilization in hybridization programme.

Screening of Mango Landraces for Polyembryony and Confirmation of Seedling Origin using Microsatellite Markers

Background: The introduction of polyembryonic rootstocks in the area of propagation is of great importance since they produce one zygotic and several nucellar plantlets. Proper identification of sexual embryo from each hybrid seed is necessary in order to preserve only the nucellar seedlings, which would help to maintain the rootstock’s genetic characteristics as well as to overcome the major constraints in the area of fruit breeding especially in hybridization programme by eliminating the nucellar ones to advanced generations. Contrasting reports exists regarding the vigour of zygotic seedlings of polyembryonic mango genotypes. It is necessary to identify/ distinguish the zygotic seedling from the nucellar population at an early stage, for which, microsatellite analysis could be a reliable tool. Methods: The experiment was laid out in completely randomized design (CRD) with 20 treatments replicated thrice. The twenty local mango landraces from Thiruvananthapuram (Kerala) were screened for polyembryony and were geo-referenced. Germination studies were conducted. Microsatellite analysis of all the plantlets from two varieties which exhibited the highest polyembryony were done using SSR primers and their banding patterns were compared with those of their respective mother plants. Result: Out of twenty mango varieties screened, seventeen were polyembryonic. Kappa Manga recorded the highest germination, germination index and seedling vigour index-I. Kotookonam Varikka recorded the highest polyembryony and followed by Kochu Kilichundan. Microsatellite analysis revealed that all the seedlings obtained from the respective stones of Kotookonam Varikka and Kochu Kilichundan had identical SSR profile to the mother plant, which indicated nucellar origin of seedlings having similar genetic composition to the mother plant.

Marker-Assisted Pyramiding of Downy Mildew-Resistant Gene Ppa3 and Black Rot-Resistant Gene Xca1bo in Popular Early Cauliflower Variety Pusa Meghna

Cauliflower is an important extensively grown cool season vegetable in India. Black rot and downy mildew are major devastating diseases reducing yield and quality of the crop. To tackle these through host plant resistance, a marker-assisted backcross breeding method was followed to pyramid a black rot-resistant gene (Xca1bo) and a downy mildew-resistant gene (Ppa3) from donors BR-161 and BR-2, respectively, into the background of Pusa Meghna cauliflower cultivar. Marker-assisted backcross breeding was followed up to BC2 generation using SCAR marker ScOPO-04833 and SSR marker BoGMS0624 for black rot and downy mildew resistance genes in foreground selection, respectively. In background selection, at each stage of backcrossing, 47 parental polymorphic SSR markers were used. The graphical genotyping of the five two-gene (Xca1boXca1boPpa3Ppa3) homozygous BC2F2 plants showed an average recovery of 85.44% of the Pusa Meghna genome with highest genome recovery of 91.7%. The genome contribution of donor parents (BR-161 and BR-2) was 8.26 with 6.34% of residual heterozygousity. The backcross derived pyramided lines BC2F2:3-7-16 and BC2F2:3-7-33 showed high resistance to both the diseases and exhibited higher yield and vitamin C content as compared with recipient parent Pusa Meghna. It is, therefore, evident from this study that resistant genes can be introgressed successfully into a Pusa Meghna cultivar without any yield penalty, benefitting farmers with reduced input cost and consumers with chemical residue free produce. Besides, the pyramided lines carrying dominant resistant genes can be exploited in a hybridization programme to develop hybrid(s) in cauliflower.

Assessment of Chickpea (Cicer arietinum L.) Genotypes under Normal and Late Sown Environments using Stress Indices

Background: Heat stress is a major restrain in chickpea (Cicer arietinum L.) productivity. Developing tolerant chickpea genotypes contributes breeding materials for hybridization programme. Stress indices related to abiotic stresses are found effective in screening of genotypes for high temperature tolerance in chickpea. Methods: An experiment with 24 genotypes under two different environments i.e., timely and late sown conditions was planned to identify the chickpea genotypes tolerant to heat stress, using thirteen stress indices. Stress Susceptibility Index (SSI) is the cardinal index to group genotypes based on their tolerance level. Stress indices Mean Productivity (MP), Geometric Mean Productivity (GMP), Harmonic Mean (HM) Index, Heat Resistant Index (HRI) and Modified Heat Tolerance Index (MHTI) are very effective in identifying stress tolerant genotypes. Result: The result indicated that genotypes H 04-75, H 08-75, H 12-26, H 09-96, ICCV 92944, DCP 92-3 and GNG 2226 are tolerant to heat stress. The identified genotypes can be used as parents in hybridization programme for breeding chickpea cultivars tolerant to high temperature environments.

Combining Ability of Selected Soybean [Glycine max (L.) Merrill] Parental Lines

Background: The success of hybridization programme depends on the combining ability of parental lines. Methods: Seven soybean genotypes and all their partial diallel crosses in the F2 generation were evaluated in a randomized complete block design at two locations in Nigeria, during the 2017-2018 growing season. Result: Analysis of variance showed that both environments and genotypes were significantly different for all measured traits. The genotype TGx 1988-5F was the best general combiner for earliness in flowering and poding, while TGx 1448-2E was the best general combiner for number of pods/plant and seed yield/plant. Crosses having significant and positive specific combining ability effect for number of pods/plant and seed yield/plant were TGx 1485-1D × TGx 1448-2E and TGx 1988-5F × TGx 1989-19F, respectively. Genotypes TGx 1988-5F and TGx 1448-2E exhibiting good general combining ability for earliness and seed yield/plant, are thus, promising for utilization in the future hybridization programme for soybean improvement.

Assessment of Genetic Diversity in Morphological Traits of Mango Genotypes Using D2 Statistics

An experiment was conducted during 2018-2020 to study the genetic diversity in 24 morphological traits using D2 statistics in mango genotypes of eastern tropical region of India. Present study reveals that the clustering pattern based on D2 statistics grouped 40 genotypes of mango into 7 clusters, out of which cluster VI (7397.45) shows the highest intracluster value followed by cluster III (5346.99) and cluster V (4130.4), indicating considerable genetic divergence among the accessions of this cluster. While maximum inter- cluster distance was observed between the cluster VI and VII (300180) followed by cluster II and VI (289267.7) and cluster I and VI (214380.5) indicated that the accessions belonging to these groups were genetically most diverse and can be used as a parent in hybridization programme. Wide range of genetic diversity observed among cluster VI and cluster VII, can either be utilized for breeding programmes for genetic improvement in mango or directly adopted as a variety. Fruit yield exhibited significant contribution towards the genetic divergence (60.77%) followed by fruit weight (26.79%), stone percentage (4.74%), peel percentage (2.31%) and pulp percentage (2.05%).

Multivariate Analysis of Quantitative Traits in Field Pea (Pisum sativum var. arvense)

Background: Field pea is one of the important cool season grain legume crops cultivated in India. In this investigation, experimental material i.e. eighty germplasm lines of field pea with four checks (IPF 4-9, Adarsh, Ambika and IPFD 10-12) were evaluated to determine the estimates of genetic diversity in the test genotypes.Methods: The data were recorded on thirteen quantitative characters for the study of genetic diversity. The mean data of each characters were subjected to cluster analysis by using D2 Mahalanobis clustering method. The principle component analysis (PCA) for measuring genetic divergence was done by XLSTAT and R 4.0 statistical package. Result: Eighty-four germplasms including checks were categorized into five distinct clusters, indicates the occurrence of high genetic diversity in the evaluated set of germplasm. Between cluster III and IV highest inter-cluster distance was observed, indicates the maximum diversity among genotypes of these clusters. Considerable differences were observed for cluster mean among different distinct clusters for all the thirteen characters. The hybridization programme involving genotypes from cluster III and cluster IV may be used to isolate suitable segregants. Principal component analysis grouped different traits under study into thirteen principal components (PCs) in which only five PCs with eigen value greater than 1 accounted 70.97% of total variation present in genotypes. The traits falling to these five PCs may be given due importance in field pea improvement programmes.

An Analysis of Pollen Parameters, Fruit Set and Fruit Development During Attempts on Intergeneric Hybridization of Papaya (Carica papaya L.)

Research was conducted at the University Orchard, Horticultural College and Research Institute, to investigate the extent of pollen production, pollen fertility, fruit set, fruit growth and seed set as well as seedling vigour when two wild relatives of papaya (Vasconcellea cauliflora and Vasconcellea candamarcensis) are involved in the hybridization programme as male parents with three papaya cultivars (CO 7, TNAU Papaya CO 8 and Pusa Nanha) as female parents. Among the two wild relatives, V. candamarcensis was more polleniferous but with significantly lesser pollen viability and germination than V. cauliflora. Among the six intergeneric crosses, although the fruit set ranged from 60.00% to 93.33% the fruit retention till harvest was only 30.77 per cent to 35.71 per cent. The study also revealed metaxenic influence of wild parent on the growth of the fruits derived after crossing. Seed set was observed only with CO 7 as female parent but the seed size and weight, germination and seedling vigour recorded by intergeneric crosses of CO 7 with Vasconcellea were found to be low. The implications of the observations are discussed in relevance to employing the wild relatives for improvement of papaya.

Evaluation of staygreen sunflower lines and their hybrids for yield under drought conditions

The experimental material for the present study comprised of 28 inbred lines (including two checks) which were developed by mutation and hybridization among the lines from AICRP trials MARS, UAS, Dharwad and on the basis of SPAD readings and stay green nature, they were considered as drought tolerant lines. These lines were used for the present experiment and were evaluated under both normal and moisture stress condition in rain out shelter to study their root characteristics. Among 28 inbreds evaluated, eight inbred lines i.e. DSR-13, DSR-19, DSR-23, DSR-24, DSR-37, DSR-66, DSR-107 and DSR-132 were identified as drought tolerant nature which exhibited least reduction in their yield under moisture stress condition. Simultaneously hybridization programme was also initiated during summer 2018 using these 28 inbred lines as testers (males) and 5 CMS lines as female lines in Line × Tester fashion. Among 140 hybrids developed, only 40 F1 hybrid combinations were further analyzed for heterosis and combining ability studies along with four checks RHA 6D-1, RHA 95C-1, KBSH-53 and Cauvery Champ. Most of the hybrid combinations showed significant negative heterosis for flowering indicating earliness, and also all the combinations showed a positive heterosis for plant height indicating tallness dominant over dwarf checks. The combinations CMS 7-1-1 A × DSR-37 (624 kg/ha), CMS-853A × DSR-19 (624 kg/ha), and CMS-853A × DSR-23 (619 kg/ha) exhibited significant maximum heterosis for seed yield (kg ha−1) over the checks KBSH-53 (496.50 kg/ha) and Cauvery Champ (486.50 kg/ha) showing maximum seed yield per hectare.