6 research outputs found
EVALUATION OF EGGPLANT ACCESSIONS BASED ON THEIR QUANTITATIVE AND QUALITATIVE TRAITS PERFORMANCE UNDER TROPICAL CLIMATE
No full textAgro-morphological genetic variation on yield and yield-related traits plays an important role in varietal development in eggplant. The present study assessed different genetic variations of 27 eggplant accessions using yield and yield- related morphological traits. The experiment was laid out in a randomized complete block design with three replications. All collected data on nine qualitative and eleven quantitative traits were subjected to analysis of variance using SAS 9.4 software, while variance components were estimated. All the studied traits (quantitative) exhibited high significant variation (p ‰ 0.01). The quantitative traits such as number of primary branches per plant, fruit diameter, fruit length, fruit girth, average fruit weight, number of fruits per plant, fruit length to width ratio, and fruit yield per plant can be exploited through selection as these traits have high PCV, GCV, h2B and GAM. Considering diversity patterns and other agronomic traits, the accessions BB1 from group I, accessions BT13, BM9, BB26, BB31, BM5 from group II, BB23 from group III, BT17 from group IV, BB12 and BT6 from group V and BT15 from group VI was taken into consideration as better parents for an effective hybridization program
Half Diallel Analysis for Biochemical and Morphological Traits in Cultivated Eggplants (<i>Solanum melongena</i> L.)
No full textEleven morphologically diverse cultivated eggplant accessions were used for hybridization following half diallel mating design to obtain 55 hybrids. Evaluation of hybrids along with the parents was conducted over two locations followed by randomised complete block design with three replications to study gene action and combining ability of 15 morphological and biochemical traits. The analysis of variance indicated highly significant differences among the environments and interaction of genotype and environment, except for fruit length to width ratio. Additive gene effects were significant for the inheritance of these traits and expression of these additive genes were greatly affected by environments. The general combining ability (GCA) was greater than their respective specific combining ability (SCA) for all traits except for fruit yield per plant. High values of GCA and SCA effects for characters of interest were dispersed among different genotypes. From this study it was observed that the best parental line was BT15 based on days to first flowering, total number of fruits per plant, total soluble solids and total phenol content. Besides, the parent BM5 showed good general combining ability effects for fruit yield per plant, fruit length and fruit length to width ratio and the parent BB1 performed good general combining ability for fruit diameter, fruit girth and fruit weight. Besides, other parents showed the best performance for only one trait. On the other hand, the hybrid BT6 × BT15 was reported bearing early flowering with high total phenol content and the hybrid BM9 × BB26 has high fruit yield with high soluble solids. Besides, the hybrid BM9 × BB1 has a high fruit diameter and fruit weight. All other hybrids except for these three (BT6 × BT15, BM9 × BB26 and BM9 × BB1) were shown the best performance for only one trait. Hence, based on the desired trait, the hybrid can be selected for future use after large scale evaluation
Flooding tolerance in rice: adaptive mechanism and marker-assisted selection breeding approaches
No full textNatural and man-made ecosystems worldwide are subjected to flooding, which is a form of environmental stress. Genetic variability in the plant response to flooding involves variations in metabolism, architecture, and elongation development that are related with a low oxygen escape strategy and an opposing quiescence scheme that enables prolonged submergence endurance. Flooding is typically associated with a decrease in O2 in the cells, which is especially severe when photosynthesis is absent or limited, leading to significant annual yield losses globally. Over the past two decades, considerable advancements have been made in understanding of mechanisms of rice adaptation and tolerance to flooding/submergence. The mapping and identification of Sub1 QTL have led to the development of marker-assisted selection (MAS) breeding approach to improve flooding-tolerant rice varieties in submergence-prone ecosystems. The Sub1 incorporated in rice varieties showed tolerance during flash flood, but not during stagnant conditions. Hence, gene pyramiding techniques can be applied to combine/stack multiple resistant genes for developing flood-resilient rice varieties for different types of flooding stresses. This review contains an update on the latest advances in understanding the molecular mechanisms, metabolic adaptions, and genetic factors governing rice flooding tolerance. A better understanding of molecular genetics and adaptation mechanisms that enhance flood-tolerant varieties under different flooding regimes was also discussed
Genetic Diversity Analysis among Capsicum annuum Mutants Based on Morpho-Physiological and Yield Traits
No full textIt is crucial to assess genetically superior parents when developing novel hybrids. This experiment was conducted to find out the diversity of 27 Capsicum annuum mutant lines derived from two varieties.To achieve the objective, 23 morpho-physiological and yield traits were recorded through two planting seasons. Highly significant differences (p < 0.01) were recorded among the studied traits. There was a strong to moderately positive phenotypic association between yield and all other morphological traits except first bifurcation length, stem diameter, pedicle length, flowering date, and maturity date. A higher Genotypic Coefficient of Variation (GCV) and Phenotypic Coefficient of Variation (PCV), combined with moderate to high heritability and high hereditary progress, have been found in the number of fruits per plant, fruit yield per plant, and number of seeds per fruit. High heritability was found in yield characteristics, vis-à-visnumber of seeds per fruit, number of fruits per plant, and indicated high genetic advance. The studied genotypes were divided into six groups after the cluster analysis. Based on the correlation matrix of 23 quantitative characteristics, principal component analysis revealed that the percentage of variation for PC1 and PC2 is 28%and 19%, respectively, andPC1 represents the largest percentage of the overall total variation. The calculated genetic distance also explains the potential of heterosis breeding. The revealed findings might be helpful for breeders to target quantitative characters and the parental lines of C. annuum during the execution of their future breeding programmes for developing high-yielding and climate-resilient chilli varieties
Recent Advances in Rice Varietal Development for Durable Resistance to Biotic and Abiotic Stresses through Marker-Assisted Gene Pyramiding
No full textAbiotic and biotic stresses adversely affect rice growth, development and grain yield. Traditional rice breeding techniques are insufficient in modern agriculture to meet the growing population’s food needs on a long-term basis. The development of DNA markers closely linked to target genes or QTLs on rice chromosomes, and advanced molecular techniques, such as marker-assisted selection (MAS), have encouraged the evolution of contemporary techniques in rice genetics and breeding, such as gene pyramiding. Gene pyramiding refers to the act of combining two or more genes from multiple parents into a single genotype, which allows the overexpression of more than one gene for broad-spectrum abiotic and biotic stress resistance. Marker-assisted pedigree, backcrossing and pseudo-backcrossing methods can increase the conventional breeding speed by reducing the number of breeding generations in order to enhance the pyramiding process. Pyramiding is affected by several factors: the number of transferred genes; the range within gene and flanking markers; the number of chosen populations in every breeding generation; the features of genes and germplasms; and the potentiality of breeders to identify the target genes. Modern breeding methods, such as the marker-assisted backcrossing approach, have made gene pyramiding more precise and reliable for the development of stress-tolerant rice varieties in the coming decades. This review presents up-to-date knowledge on gene pyramiding schemes, marker-assisted gene pyramiding techniques, the efficiency of marker-assisted gene pyramiding and the advantages and limitations of gene pyramiding methods. This review also reports on the potential application of marker-assisted selection breeding to develop stress-tolerant rice varieties that stabilize abiotic and biotic stresses. This review will help rice breeders to improve yields by increasing rice productivity under abiotic and biotic stress conditions
Advanced Breeding Strategies and Future Perspectives of Salinity Tolerance in Rice
No full textRice, generally classified as a typical glycophyte, often faces abiotic stresses such as excessive drought, high salinity, prolonged submergence, cold, and temperature, which significantly affects growth, development, and ultimately, grain yield. Among these negative impacts of abiotic factors in rice production, salinity stress is a major constraint, followed by drought. There is considerable research on the use of marker-assisted selection (MAS), genome editing techniques, and transgenic studies that have profoundly improved the present-day rice breeders’ toolboxes for developing salt-tolerant varieties. Salinity stresses significantly affect rice plants during seedling and reproductive stages. Hence, greater understanding and manipulation of genetic architecture in developing salt-tolerant rice varieties will significantly impact sustainable rice production. Rice plants’ susceptibility or tolerance to high salinity has been reported to be the result of coordinated actions of multiple stress-responsive quantitative trait loci (QTLs)/genes. This paper reviews recent literature, updating the effects of salinity stress on rice plants and germplasm collections and screening for salinity tolerance by different breeding techniques. Mapping and identification of QTLs salt tolerance genes are illuminated. The present review updates recent breeding for improvement in rice tolerance to salinity stress and how state-of-the-art tools such as MAS or genetic engineering and genome editing techniques, including mutagenesis and conventional breeding techniques, can assist in transferring salt-tolerant QTLs genes into elite rice genotypes, accelerating breeding of salt-resistant rice cultivars
