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Open Access
GENETIC VARIATION AND NATURE OF GENE ACTION IN ASSAM RICE FOR GRAIN ZINC CONCENTRATION AND BIOFORTIFICATION POTENTIAL
(2023) Bhuyan, Nabajyoti; Pathak, Prasanna K.
The cultivated gene pool of rice is deficient in most of the required micronutrients. Zinc is one of the most important among these to mention about. Twenty (20) percent of the world population is at risk of Zn deficiency resulting from inadequate dietary Zn intake that causes stunted growth (Brown et al., 2009). Genetic and agronomic manipulations for biofortification to raise the concentration of the nutrients in the grain are suggested to overcome the problem. The present investigation was undertaken to study genetic diversity for grain Zn in Assam rice germplasm and also to explore the possibility of bifortification potential. A set of 29 ahu genotypes randomly collected from different places along with the high yielding sali rice variety Shraboni, known to be rich in Zn, were evaluated in 4 different micro-environments created by differential application of Zn fertilizer in ahu season of 2019. Among these, 6 were randomly selected for combining ability studies through diallel mating system without the reciprocals. Observations were taken on different morphological and quality characters and the recorded data were subjected to different statistical analyses following standard procedures. Out of 30 genotypes, 9 were grouped as low (<20 mg 1000g-1), 12 medium (20-30 mg 1000g-1) and 9 others were grouped as high (>30 mg 1000g-1) grain Zn genotypes as per their grain Zn content. Grain Zn content was found highest (52.35 mg 1000g-1) in Shraboni and lowest (11.73 mg 1000g-1) in Basantabahar. GCV, PCV and heritability were high for grain Zn for the genotypes. Grain Zn showed a significant positive correlation with panicle length, grains per panicle and spikelet fertility. Highest grain Zn was recorded in the environment which had relatively high initial soil Zn and was then further added with fertilizer Zn while the lowest grain Zn was recorded in the environment which had low initial soil Zn and no further Zn was added with Zn fertilizer. However, increase in grain Zn with the addition of fertilizer Zn was not uniform across the tested genotypes. The genotypes - Shraboni, Dehangi, Kopouguni, Laishanka and Negilai recorded high grain Zn content across all the environments. Inglongkiri, Panimudi, Arpang and Ranga Ahu showed good grain Zn content in low Zn environment while Begungutia, Kolong, Disang and Ikhajoy showed good grain Zn content in high Zn environment. The results suggest the possibility of identifying high Zn genotypes and also the possibility of agronomic biofortification as most of the genotypes showed increase in grain Zn with addition of external Zn to soil. The genotypes exhibited significant variation in the individual environments as well as over environments for most of the characters studied including yield and grain Fe. Based on D2 analyses the genotypes were grouped in 5 different clusters of which 4 were mono-genotypic and the rest one was with 26 genotypes. Significant variation among the genotypes as well as tested environments was also reflected in the stability analysis. Shraboni, Dikhow and Rangadaria for grain yield and Shraboni, Dehangi, Kopouguni, Laishanka and Negilai for grain Zn showed high mean performance with average stability. There is significant variation among the crosses both in low and high Zn environments for almost all the characters. Significant positive GCA effects were found for grain yield and grain Zn for Inglongkiri and Kolong in both high and low Zn environments. Heterosis over mid parent was seen for grain Zn in Kasalath×Inglongkiri and for grain yield in Kasalath×Ikhojoy and Ikhajoy×Kolong. Heterobeltiosis was recorded for grain Zn in Kasalath×Kolong in high Zn environment.
Open Access
MORPHO-MOLECULAR PROFILING OF INDUCED VISIBLE MUTANTS OF JOHA RICE (ORYZA SATIVA L.) FOR sd1 AND BADH 2 GENES AND THEIR PHENOTYPIC STABILITY
(2023) Dutta, Lonishree; Sarma, Kishore Kumar
Mutation breeding offers a simple, fast and efficient way to rectify major defects without altering their original identity. The present study deployed radiation (gamma rays @ 200 and 300Gy)-induced mutation for the improvement traditional aromatic rice landraces namely Kon Joha. Among the various putative mutants identified in the M 2 generation, only sixtysix rice mutants were advanced to M3 generation. In the present study 28 mutants of Kon Joha from M3 generation were raised in M4 generation along with their parents and four checks for evaluations based on 16 agro-morphological and 9 grain quality traits. Interestingly, all the mutants showed a reduction in plant height as compared to their parents in all the three generations. The reduction in plant height varies from 35 to 45% . Furthermore, mutants of Kon Joha have increased their yield potential over their parents. Interestingly, JKOJM-300-1007-14(3.5 ton/ha) and JKOJM-200-1512-1 (3.2 ton/ha) exhibited the highest yield advantages over their parents. Study on DUS characterization showed variability among the cultivars studied, showing monomorphism for 33 traits and polymorphism for 23 traits. Thus, the phenotypic characterization of the aromatic cultivars established distinctiveness for their utilization in breeding programmes. UNJ clustering based on usual Euclidean distances for the polymorphic traits grouped the cultivars into four multi-genotypic clusters. Further, a pooled analysis of variance based on a randomized complete block design revealed ample variations among the genotypes for the studied traits. The differences observed between genotypic and phenotypic coefficients of variation were low for days to 50% flowering, days to maturity, culm height (cm), culm length (cm), thousand-grain weight (g) and grain yield per hectare (kg), which facilitate selection in the presence of sufficient genetic variability for the traits studied. Mahalanobis D2 analysis revealed three multi-genotypic and one mono-genotypic clusters of the cultivars. Moreover, in the association analysis, grain yield plant -1 is significantly and positively correlated both at genotypic and phenotypic levels with culm height, culm length, panicle length, filled grains panicle-1, chaffy panicle, spikelet fertility, straw yield plant -1 , biological yield plant-1 and harvest index. JKOJM-300-186-14 exhibited the highest amylose 13.05 and highest crude protein was exhibited by JKOJM-200-1512-1 (8.65). The aroma score of the Kon Joha mutants were higher than the checks like Kon Joha, Keteki Joha, Badshah Bhog and Kola Joha. As per sensory evaluation JKOJM-300-158-11, Kon Joha mutant has the overall acceptability. The SSR marker-based genome similarity in rice mutants and corresponding parents ranged from 98.91 to 93.48% indicating the trueness of the mutants. Moreover, the UPGMA algorithm and Gower distance-based dendrogram, neighbour joining tree and PCA scatter diagram assured that mutants were grouped with their respective parents and fell into separate clusters showing high similarity between mutants and parents and dissimilarity among the checks. Three genotypes were identified for nitrogen responsiveness. There was absence of sd1 gene in the mutants. Therefore, it can be concluded that some other genes are responsible for dwarf varieties. BADH2 gene was present in all the genotypes. Four mutants along with four checks were send for multi-location trial . Eberhart and Russel model found JKOJM-300-584-5 (Xi = 3141.9, bi = 1.01 and S2di=0.02) followed by JKOJM-300-158-11 (Xi = 3131.1, bi = 1.04 and S2di=0.09), JKOJM-300-1353-8 (Xi = 2987.29, bi = 1.11 and S2di=0.15) JKOJM-300-1007-14 (Xi = 2845.76, bi = 0.97 and S2di=0.03) exhibited stability under all the environment. Shukla’s stability model also concluded JKOJM-300-584-5 as the most stable genotype. Two-dimensional GGE biplot was generated using the first two principal components (axis 1 and axis 2), which accounted for 69.9% and 18.04 % difference in GEI for yield per hectare, respectively. Locations were found to be the most significant causes of yield heterogeneity, accounting for 75.73 % of overall G + E + G × E variation, respectively, according to the combined study of variance. All the GGE biplots for the grain yield revealed G3 (JKOJM-300-1007-14) as the most stable genotype. AMMI 1 biplot for GYH indicated that G1, G4, G2 and G3 as the high yield genotypes however, only G1 and G3 can be considered as the stable genotypes among them. AMMI 2 biplot was also analysed which revealed that the G8 (E2), G5 (E2), G7 (E6, E5), G6 (E5), G2 (E7, E3) and G4 (E7 and E3) as the high yielding genotypes for GYH for the mentioned environments. Based on ideal genotype ranking genotype G2 followed by G1 was the best performer, with a high mean yield and high stability in the tested environment. According to the AEC line, genotypes G2 and G4 were extremely stable with a high average yielding per hectare. Overall, the information and materials generated from the current study will be very useful and informative for students, researchers and plant breeders. Additionally, our results also showed that irradiation could generate a considerable amount of genetic variability and provide new avenues for crop improvement and diversification.
Open Access
A Comparative Study of Vegetable and Grain-type Soybean [Glycine max (L.) Merr.]
(2023) Kurrey, Vivechana; Goswami, P.K.
Soybean (Glycine max (L.) Merrill) is one of the most important leguminous oilseed crops and known for its useful nutrients like protein (32-43%) oil content (14-16%), carbohydrate content (23-38 mg/g), and many other useful minerals including vitamin A, B and D and also rich in lysine. Global awareness of the use and benefits of vegetable soybean has been increased through the efforts of the Asian vegetable research and development center (AVRDC). The present investigation was carried out at ICR Farm, AAU Jorhat during 2022-23, using 28 genotypes consisting of both vegetable and grain-type. It was laid out in RBD with two replications. Analysis of variance for various traits revealed significant differences among all the genotypes for traits studied. GCV and PCV were high for primary branches per plant, total chlorophyll content and seed yield per plant indicating high variation among the genotypes. High broad sense heritability coupled with high genetic advance showed for primary branches per plant, total chlorophyll content, protein content, carbohydrate content and seed yield per plant implies predominant role of additive gene action. The Correlation study revealed that seed yield per plant had strong positive correlations with plant height, days to maturity and total chlorophyll content. Further, the Path coefficient analysis demonstrated that the character days to maturity, followed by plant height and pods per plant showed maximum direct effect on seed yield per plant. The result of field evaluation revelled that pod blight, anthracnose caused by Colletotrichum truncatum. Rhizoctonia aerial blight and hypocotyl rot caused by Rhizoctonia solani. Fusarium wilt and root rot caused by Fusarium oxysporum were found as major diseases that affected the soybean genotypes. A precise screening was done by utilising artificial inoculation technique in vegetable soybean genotypes, the result evident that no genotype was found immune or completely resistant. The only genotype AVSB 2009 among vegetable-type showed moderately resistant against all the diseases studied on the basis of field and artificial inoculation. Among all the genotypes PS 1670 (grain-type) is the highest yielder with moderate resistance against major disease on the basis of field screening.
Open Access
Diversity study of Greengram [Vigna radiata (L.) Wilczek] with morphological and SSR markers
(2023) Sonowal, Santosh; Zaman, Shazmira
Greengram [Vigna radiata (L.) Wilczek] belongs to the family ‘Fabaceae’ and subfamily ‘papilionaceae’ is an important grain legume crop in the world. It is the third important pulse crop after chickpea and pigeon pea in India. Although, India is the leading producer of green gram globally but its production and productivity levels are very low to meet the nutrient status of people due to many reasons including lack of superior varieties or hybrids. Evaluation and characterization for genetic variability and identification of diverse genotypes is the first and foremost step in any crop improvement programme. Genetic parameters like GV, PV, GCV, PCV, hbs and GA were estimated in 30 genotypes of greengram collected from NBPGR. A high extent of variability was found for quantitative characters like plant height, number of cluster per plant, pods per plant, seeds per pod & harvest index. Estimates of GCV & PCV were high for characters viz., seed yield per plant, pods per cluster, pods per plant and harvest index. High heritability coupled with high genetic advance as per cent of mean was observed for characters viz., harvest index, yield per plant, pods per plant, cluster per plant, pod per cluster, seed per pod, 100 seed weight, number of primary branches and plant height indicating the role of additive gene action and highlighting the importance of those traits as efficient selection criteria. High extent of variability was found also for qualitative traits like terminal leaf shape, seed colour, seed shape etc. among the genotypes studied. Diversity study using quantitative characters depicted 6 clusters out of which 3 are solitary. Among all the characters studied, 100 seed weight exhibited maximum contribution towards divergence. Cluster II and cluster VI exhibited maximum inter-cluster distance. Hence, it can be suggested that hybridization among the genotypes of these two clusters might give better heterotic combination. Again on the basis of qualitative traits studied, genotypes were grouped into 3 main clusters and 4 solitary clusters applying Jaccard’s similarity coefficient. Accordingly, maximum divergence was observed between the genotype IC-148403 and IC-282094 suggesting their utility in crossing to get better segregant. Out of 30 genotypes, 15 were subjected to SSR (already reported) based polymorphism analysis. Out of the total 22 SSR screened, 10 were polymorphic across fifteen genotypes. The maximum PIC was revealed by primer GMES4400, cp06039 and cp8304 (0.375 each) while minimum PIC among polymorphic markers was shown by primer DMBSSR038 (0.2772). The average value of PIC was found to 0.35744. Accordingly, the genetic diversity pattern of these 15 greengram germplasm under study was estimated by the Jaccard similarity coefficient. The dendrogram using unweighted neighbour-joining (UPGMA) drawn from the analysis divided 15 genotypes into 3 clusters. Maximum divergence was observed between the genotype IC-76544 and IC-39548 indicating the usefulness of these genotypes in hybridization programme. More number of polymorphic SSR primers will be required for further investigation to get a clear picture of diversity pattern at molecular level. Genotypes viz., IC-76544 and IC-121232 were grouped in the same cluster for quantitative, qualitative as well as SSR studies. Although the diversity at both morphological and genomic level was studied, there is need of further statistical analysis to measure the degree of relationship between the dissimilarity matrixes generated from qualitative, quantitative and SSR marker data.
Open Access
MORPHO-PHYSIOLOGICAL EVALUATION AND DNA FINGERPRINTING OF DROUGHT QTL INTROGRESSED RICE GENOTYPES
(2023) Adhikari, Pragyan; Chetia, Sanjay Kumar
Rice (Oryza sativa L.) holds a significant position as one of the world's most crucial cereal crops, serving as a staple food for a vast majority of the global population. In India, it plays a vital role, contributing around 45 percent to the total cereal production and serving as the primary food source for over 60 percent of the population. Developing countries, particularly in Asia, Africa, and Latin America, contribute more than 90% to the world's total rice production. However, around 40% of the world’s rice is produced under rainfed environment, making it vulnerable to the adverse effects of low rainfall. Drought stands out as a major abiotic stress factor that leads to reduced yields. Rice faces even greater challenges due to its semi-aquatic nature and high-water requirement. Keeping the significance of drought stress in mind, an effort to introgress drought QTLs into some of the popular rice varieties of Assam was made at AAU – Assam Rice Research Institute, Titabar. In the present study, morpho-physiological evaluation of 17 drought QTL introgressed lines along with 4 checks (IR64 drought, Sahbhagi Dhan, Luit and Lachit) was carried out in a field experiment laid out in Randomised Block Design with three replications under irrigated and drought stress conditions. 10 traits; 7 morphological viz., leaf rolling, days to 50% flowering, ear bearing tillers, panicle length, spikelets per panicle, spikelet fertility and grain yield per plant and 3 physiological traits viz., chlorophyll content, relative leaf water content, excised leaf water loss were studied. Significant variation was observed among the genotypes for all the 10 traits evaluated under drought stress conditions, while under irrigated conditions, significant variation was observed for all traits except relative leaf water content and spikelet fertility. Highest GCV and PCV values were observed for spikelets per panicle (19.46 and 20.12 respectively) under irrigated conditions and leaf rolling (70.30 and 74.17 respectively) under drought stress conditions. High heritability coupled with high genetic advance as percentage of mean were exhibited by 3 traits, viz., chlorophyll content, ear bearing tillers and spikelets per panicle under both irrigated and drought stress conditions, while leaf rolling and grain yield per plant displayed high heritability coupled with high genetic advance as percentage of mean under drought stress conditions. Genotyping was done using the linked SSR markers to confirm the presence of the QTLs and the study revealed that 4 lines out of the 17 lines evaluated contained all three introgressed QTLs (qDTY 1.1, qDTY 2.2 and qDTY 4.1). DNA fingerprinting was also carried out for the lines under study using 50 SSR panel markers selected from Gramene, out of which 11 were found to be polymorphic. The PIC content of the markers varied from 0.0023 (RM152) to 0.7460 (RM154). A dendrogram constructed from the dissimilarity index grouped the population into 3 clusters. Based on the evaluation, the four best-performing lines Luit x IR64 Drought (4.13-1), Kolong x IR64 Drought (4.4-2), Kolong x IR64 Drought (12.1-4) and Kopilee x IR64 Drought (2.1-2) were identified which may be sent for multilocation trials and subsequently be released and notified. These lines hold promise in assisting farmers to better manage and mitigate the impact of drought stress.
Open Access
EVALUATION AND DIVERSITY ANALYSIS OF CHILLI GENOTYPES (Capsicum spp.)
(2023) Khargharia, Palki Priya; Das, Reecha.T.
In the present investigation, 31 genotypes of chilli were evaluated in a Randomized Block Design at Experimental Farm, Department of Horticulture, Assam Agricultural University, Jorhat-13 during Rabi, 2022-23. The investigation was oriented to assess the genetic variability parameters, character association, cause-effect relationships and clustering of genotypes based on the existing variation. Analysis of variance revealed presence of significant variation among all the genotypes for the concerned traits under study. Based on mean performance, the genotypes Chilli Sel-1, Krishna Selection, Kashi Abha, Mem chilli, Kharika Selection, Local Collection-5 and 2021/CHIVAR-4 were found to be superior. GCV and PCV were high for the characters total chlorophyll content, ascorbic acid content, fruit length, fruit diameter, pericarp thickness and average fruit weight indicating high variation among the genotypes. Total chlorophyll content, ascorbic acid content, fruit length, fruit diameter, pericarp thickness, plant height and average fruit weight disclosed high heritability coupled with high genetic advance which implies role of additive gene action. Correlation studies revealed that fruit yield per plant was significantly and positively correlated with relative leaf water content, fruit length and average fruit weight. Genotypic path analysis showed that days to first red ripe fruit harvest followed by relative water content and average fruit weight exhibited positive direct effect on yield. Pertaining to this, selection for these characters should be functional for improvement in yield. Mahalanobis D2 statistics divided the thirty one genotypes into eight clusters among which cluster I had maximum numbers of genotypes i.e. 10. The maximum intra-cluster distance was recorded in cluster VI signifying wide range of variation among the genotypes of that cluster.. The superior genotypes Local collection-5 and Kashi Abha were included in cluster II and Cluster V respectively which had highest inter-cluster distance. Hence hybridization of genotype Local collection-5 with Kashi Abha can result in improved varieties with high heterosis. This study has revealed scope for further detailed research works to improve the chilli genotypes with regards to the major characters.
Open Access
EVALUATION OF SOME RICE VARIETIES UNDER NORMAL SOWN AND DELAYED TRANSPLANTING SITUATION IN SALI WITH LOW LEVEL OF FERTILIZER INPUT
(2023) DAS, OLYMPICA; Kalita, U.C.
Rainfed lowland rice cultivation holds significant importance, but it faces various challenges due to its heterogeneous ecosystem and unpredictable rainfall patterns, especially for farmers in flood-affected regions. Severe floods can lead to complete damage of seedlings in the main fields. However, some seedlings may survive in the seedbeds, offering an opportunity for farmers to replant their fields once the floodwaters recede, using overaged seedlings (60-70 days old). Therefore, the present investigation was carried out during the Sali season (July) of 2022 at the ICR Farm, Assam Agricultural University, Jorhat. The study followed a 3-replicated Randomized Block Design (RBD). The main objective of the trial was to assess the performance of various genotypes under normal sowing and delayed transplanting situations with 70day old seedlings. Considerable variation was observed among the grain yield and its associated component traits. The analysis of mean sum of squares for 18 quantitative characters indicated significant differences attributed to various sources of variation, particularly for grain yield and its component traits. The estimates of genotypic coefficient of variation (GCV) and phenotypic coefficient of variation (PCV) were found high for chaffs per panicle, grains per panicle, number of panicles per hill, grain yield per hill (g/hill), spikelets per panicle, grain yield (kg/ha), straw yield (kg/ha) and biological yield (kg/ha). The present study evaluated traits such as chaffs per panicle, grains per panicle, spikelets per panicle, biological yield (kg/ha), straw yield (kg/ha), grain yield (kg/ha), grain yield per hill (g), and number of panicles per hill to exhibit high heritability, genotypic coefficients of variation, and genetic advance as a percentage of the mean. These findings suggest that selecting these traits could effectively lead to improvements under normal sown and delayed transplanting conditions with 70days old seedlings. Among the genotypes evaluated in this study, Gandhari stood out as the top yielder, showcasing a remarkable yield of 4201.5 kg/ha. This exceptional performance can be attributed to its significantly higher values for grains per panicle (172), spikelet fertility (89%), grain yield (18.7 g/hill), straw weight (6420.8 kg/ha), biological yield (10622.4 kg/ha) compared to Gitesh, grains per panicle (161.4), spikelet fertility (76.9%), grain yield (12.3 g/hill), straw yield (4691.7 kg/ha) and biological yield (7383.8 kg/ha) respectively. Furthermore, Gandhari showed moderate performance for the remaining evaluated characters. The analysis revealed a significant positive correlation of grain yield (kg/ha) with grain yield per hill (g/hill), biological yield (kg/ha), and straw yield (kg/ha) at both the genotypic and phenotypic levels. Other noteworthy genotypes, such as JR-16(3752.2 kg/ha) and JR-21(3670 kg/ha), also had higher yields compared to the check variety Gitesh (2691.6 kg/ha) and exhibited commendable performance in other traits. These genotypes showed promise for recommendation under normal sown and delayed transplanting situations, provided the investigation is extended for another 2-3 years followed by on-farm trials. Additionally, they could serve as potential parental material in hybridization programs aimed at developing suitable rice varieties for normal sowing and delayed transplanting situations specifically targeting flood-affected farmers of Assam in Sali season.
Open Access
Study of genetic diversity of few drought tolerant rice varieties using morphological and molecular markers
(2023) Kalita, Mridusmita; Baruah, Aiswarya
Rice (Oryza sativa L.) is one of the most important cereal crops. Increasing rice production is constrained by various stress and drought is one of the major limiting factors. For future food security assessments of genetic resources are necessary. North east India is the home of many indigenous rice varieties that are traditionally cultivated and maintained by farmers. Indigenous varieties contain a high level of genetic diversity and can serve as potential genetic resources for improving yield, and resistance to various biotic and abiotic stress conditions. The genetic architecture of diverse germplasm can be precisely estimated by assessing the structure of the population using molecular markers. Simple sequence repeat (SSR) markers are highly informative, codominant and reproducible. The first objective of this study was to assess the genetic diversity of a few indigenous rice germplasm using SSR markers. Out of the total of 28 SSR markers screened, 16 were polymorphic across twenty-seven genotypes with PIC values ranging from 0.076 to 0.499. The genetic diversity of rice germplasm under study was estimated by the Jaccard similarity coefficient. The phylogenetic tree, using unweighted neighbor-joining (UPGMA) drawn from the analysis divides 27 genotypes into 3 clusters. In the second objective, 9 genotypes were further characterized by exposure to drought stress compared to the control condition. Plants were grown in PVC pipes and subjected to drought by withdrawing water at 45 days after showing (DAS) for 25 days. After that plants were uprooted and a comparative study was done for a few morphophysiological parameters i.e. root length, root biomass, root-shoot ratio, root length density, chlorophyll content etc. It was observed that genotype Dehangi followed by N22 and Shahabhagi showed the best performance for all parameters under drought stress. This information will help in the selection of varieties with better root characteristics for drought tolerance in future breeding programs.
Open Access
GENETIC VARIABILITY ANALYSIS IN F3 POPULATION DERIVED THROUGH INTRASPECIFIC HYBRIDIZATION IN OILSEED BRASSICA
(2023) Ullah, Masuma Farhana; Phukan, Rumjhum
Brassica juncea is an allotetraploid with the genomes AA and BB from Brassica rapa and Brassica nigra, respectively. It belongs to the Brassicaceae/Cruciferae family. It is world’s third most important source of edible oil after soybean and oil palm. Indian mustard has the genetic potential for higher yield and is the predominant oilseed Brassica in India. But due to its longer crop duration, the harvesting time coincides with the pre-monsoon showers resulting in crop loss. Therefore, the development of short-duration high-yielding Indian mustard varieties that can be incorporated into the rice-based cropping sequence of Assam will play a crucial, role in increasing the average yield of rapeseed-mustard in Assam. The genetic diversity found in the available germplasm of a particular crop is wholly responsible for the success of any breeding strategy. The current study revealed significant variation for all the 17 yield attributing characters. All the characters under study have demonstrated high broad sense heritability. Plant height, number of primary branches, number of secondary branches, number of seeds per siliqua, 1000 seed weight, number of siliqua on main shoot, seed yield per plant, seed yield per hectare, biological yield per plant, harvest index, lesion size, number of lesions on infected leaves number of infected leaves per plant and number of infected plants per plot demonstrated high heritability coupled with high genetic advance. Correlation coefficients and path coefficients together provide more reliable information that may be used to effectively create crop improvement strategies. Results of the correlation studies demonstrated that seed yield per hectare had a strong positive correlation with days to maturity, biological yield per plant, and seed yield per plant. Path analysis of the current study revealed that the character, and number of infected plants per plot followed by seed yield per plant had the maximum direct effect on seed yield per hectare. Alternaria blight caused by Alternaria brassicae (Berk) Sacc. is one of the important diseases of rapeseed-mustard affecting the quality and quantity of seed. In the 25 populations that were assessed for disease incidence in field, five genotypes, PM-22, PHR-2 X PM-21, PM-21 X PM-22, PM-21 X Pusa Karishma and PM-27 were shown to have a moderate level of disease resistance. The Artificial inoculation of test genotypes is necessary to produce a more uniform disease occurrence for precise screening. Out of the 10 genotypes that were assessed for disease incidence through artificial inoculation the genotype PM-22, exhibited moderate resistance. Molecular markers are effective, precise, and reliable than other types of markers for genetic study of plants in distinguishing closely related species and cultivars. In the current study, 15 SSR markers were evaluated, and 12 of them were shown to be polymorphic. Therefore, the experimental findings revealed that the analysis of variance components will assist in the selection of the parents to develop better recombinants for use in future breeding projects to develop early maturing mustard genotypes that are appropriate for Assam's agroclimatic condition and have a maximum impact on traits that affect yield. The genotypes that exhibited resistance to Alternaria blight can be used for additional in-depth investigation regarding the host-resistance mechanism to develop resistant mustard varieties to Alternaria blight.

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