Banca de DEFESA: GABRIELE DIAS DA SILVA

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STUDENT : GABRIELE DIAS DA SILVA
DATE: 26/02/2025
TIME: 09:00
LOCAL: Webconferência
TITLE:

Pollen Viability and Genetic Divergence among Genotypes of Cucurbita spp.

KEY WORDS:

Cucurbita máxima; Cucurbita moschata; Cucurbita pepo; morphological characterization; molecular markers.

PAGES: 77
BIG AREA: Ciências Agrárias
AREA: Agronomia
SUBÁREA: Fitotecnia
SPECIALTY: Melhoramento Vegetal
SUMMARY:

Pumpkins and zucchinis belong to the Cucurbitaceae family and, due to the great genetic variability of the family, they stand out for the production of fruits that are consumed in Brazil and worldwide. The genetic divergence of pumpkins and zucchinis (Cucurbita spp.) is manifested in characteristics such as: size and weight of the fruit and from this divergence, genetic improvement programs are dedicated to obtaining more productive cultivars that better meet the needs of the consumer market. The objectives of this work were the morphological characterization, evaluation of pollen viability and estimation of genetic divergence between genotypes of Cucurbita spp. aiming to obtain genotypes with better productive performance and fruit quality. All experiments were conducted at the Federal Rural University of Rio de Janeiro, in the municipality of Seropédica/RJ and divided into five stages: 1st) evaluation of morphological characteristics of fruit of genotypes Brazilian zucchini (Cucurbita moschata); 2) evaluation of pollen viability; 3) study of genetic divergence via morphological markers; 4) evaluation of the best genotypes identified in the first experiment under field conditions; and 5) study of genetic divergence via molecular markers. In the first stage, four genotypes of Brazilian zucchini (Cucurbita moschata) were evaluated to evaluate fruit characteristics and productivity under Seropédica conditions and to compare the genotypes. The genotype “Abobrinha Luso Brasileira” stood out among the commercial ones with the highest quality and fruit weight. In the second stage, the pollen viability of two genotypes of C. moschata and two of C. pepo was evaluated in five storage periods and at anthesis. From the regression analysis and Tukey test at 5% probability for comparison of means, it was not possible to observe means below the ideal of 70% described in the literature. Statistical analyses were performed in the RBio program. In the third stage, an experiment was carried out to evaluate the genetic divergence of 12 Cucurbita spp. genotypes, aiming at the selection of 5 genotypes with the best performance in relation to morphological characteristics and fruit quality. Principal component analysis was performed and the Squared Euclidean distance was used to obtain the dissimilarity matrix. The genotypes were grouped using the hierarchical method UPGMA (Unweighted Pair Group Method using Arithmetic Averages), and from these analyses, 5 genotypes with the best performance were selected. Statistical analyses were performed in the R 4.2.3 program. In the fourth stage, the 5 genotypes with the best performance (“Híbrido F₁ Caserta”, “Abobrinha Bavette”, “Abobrinha Pádua”, “Abobrinha Redonda Clara” and “Abobrinha de Tronco Branca”) chosen from stage 3 were evaluated in the field. Six morphological characteristics were evaluated and analysis of variance (ANOVA) was performed. The means were compared by Tukey's test at 5% probability. Estimates of genetic parameters were also performed. These statistical analyses were performed using the Genes program. The traits CIR, DF, DC and CF indicated greater heritability and consequently suffered less environmental influence. This result indicates the possibility of successful selection based on these traits. Finally, the 12 genotypes evaluated in the genetic divergence experiment were subjected to molecular analysis. DNA extraction was performed and the samples were subjected to PCR analysis with molecular markers of the ScoT type. Genetic divergence among 15 genotypes of Cucurbita spp. was estimated using the Nei & Li distance. The genotypes were grouped using the Tocher Optimization method and the UPGMA hierarchical method. These statistical analyses were performed using the Genes program. Eight primers were tested, totaling 89 bands, of which 74 were polymorphic (83%) and 15 were monomorphic (17%). By the Optimization method, 8 groups were formed, while by the UPGMA method, 9 groups were formed. The results obtained in the present study will serve as a basis for the selection of parents and for carrying out controlled crosses between genotypes of Cucurbita spp.

COMMITTEE MEMBERS:
Presidente - 2271445 - BRUNA RAFAELA DA SILVA MENEZES
Externa ao Programa - 2147409 - MARILENE HILMA DOS SANTOS - UFRRJExterna à Instituição - DANIELE LIMA RODRIGUES