Dr. Bijendra SinghRAJAT SINGH2023-12-272023-12-272021-08https://krishikosh.egranth.ac.in/handle/1/5810204589ABSTRACT Name: Rajat Singh Degree: Ph.D (Horticulture) Department: Horticulture Major: Horticulture Advisor: Bijendra Singh Minor: Agriculture Biotechnology ID. No- 4250 Degree awarding University: SVP University of Agriculture & Technology, (Meerut)-250110 The present investigation on “Studies on heterosis, Combining ability and molecular screening of bottle gourd (Lagenaria siceraria L.) for biotic resistance” was carried out to assess the genetic information on nature of gene action, Heterosis, combining ability and selected with sixteen lines and four tester and their 64 F1 out for 13 quantitative characters in bottle gourd at Horticulture research center (HRC), Sardar Vallabhbhai Patel University of Agriculture and Technology, Meerut (U.P) during Zaid season 2019 and 2020 in randomized block design (RBD) with three replication. The genotype exhibited significant differences for all the traits under study. A wide range of Variability along with high estimates of the phenotypic coefficient of variation (PCV) and genotypic coefficient of variation (GCV) was observed Analysis of variance of variation among the genotypes. The high heritability was observed for Days to 1st flower Initiation, Days to 1st fruit set, Vine Length (cm), Number of primary branch, Fruit Length cm, Fruit girth cm, Average fruit weight (gm), Days to 1st fruit harvest, Number of fruit per plant, Yield q/hac on these traits hence, may be useful for effective selection. The genotypes, Narendra Jyothi, NDBG-132, Narendra Rashmi, Narendra Dharidar, exhibited significant gca effects out of thirteen characters selection may be effective in segregating generation for the development of best genotype in respect to yield quintal per hacter in bottle gourd. On the basis of specific combining ability effects, of different crosses Pusa Santusti × Kashi Ganga, Punjab long × Kashi Ganga, Punjab Komal× Narendra Madhuri, IC-592210× Kashi Ganga, IC-338119× Arka Bahar, Pusa Sandesh× Pusa Naveen, IC-321747× Arka Bahar, IC-398510× Arka Bahar, Pusa Sandesh× Kashi Ganga, Pusa Sandesh× Kashi Ganga, Pusa Sandesh× Kashi Ganga were found maximum SCA effect. Yield quintal per hacter was highly exhibited significant and positive correlation with Number of fruit per plant, vine length, number of primary branch, fruit girth, number of leaf, average fruit weight, fruit length. These traits are used as selection criteria for the improvement in yield. Days to first flower initiation showed the highest positive direct effect, displayed high order of direct effect on yield q/hac followed by fruit length, vine length, fruit girth, number of leaf, duration of crop, number of primary branch, days to 1st fruit set, number of fruit per plant. The crosses IC-398510× Kashi Ganga, IC-321747×Pusa Naveen, Narendra Dharidar ×Narendra Madhuri, Punjab Komal × Narendra Madhuri, Punjab Komal × Pusa Naveen, Narendra Dharidar × Narendra Madhuri, IC-338119 × Arka Bahar, IC-592210 × Arka Bahar, Pusa Santusti × Kashi Ganga, Narendra Rashmi × Narendra Madhuri, Vallabh Saral × Narendra Madhuri, showed positive and significant better parent heterosis. These crosses may be exploited through heterosis breeding for improvement in all characters in bottle gourd. We analysed the comprehensive expression patterns of CsWRKYs genes under different biotic stresses, including powdery mildew (Podosphaera fusca) and downy mildew (Pseudoperonospora cubensis) to explore the potential functions of (BGPMR-5, CsWRKY-12, CsWRKY-46, CsWRKY-32) markers gave polymorphism between resistance and susceptible parents. CsWRKY-12 marker showed a differential amplification among powdery mildew resistance and susceptible genotypes. CsWRKY-12 marker produced an amplicon of approx 300bp in all the susceptible 253 and moderately susceptible genotypes and some bottle gourd genotypes were resistance for dm-1 and CsWRKY-47 gene specific markers were involved in responses to downly mildew (Pseudoperonospora cubensis) expression analysis of the resistant bottle gourd variety. Dr. Bijendra Singh Rajat Singh Advisor AuthorEnglishThesis