Determination of characteristic properties of some guava genotypes and investigation of hybridization possibilities

Trends in the cultivation of tropical fruit species have started to increase in our country in recent years. In the adaptation studies carried out in our country in relation to these fruit species, guava was identified as the species that stands out with its cold resistance property. This situation has led to the conclusion that guava cultivation in our country conditions can be done more risk-free than other species. In our country, there are not orchards specifically established for guava cultivation. Also, significant part of the genotypes used to produce guava were grown with seed and showed heterozygosity. This caused differences in genotypes in terms of ripening time, size, fruit shape and color. Therefore, in this planned study, in order to turn this difference into advantage, selection of genotypes in different districts of Mersin and Antalya, evaluation of their characteristic features and determination of commercial genotypes according to weighted grading were aimed. In addition, the effects of hybridization, self-pollination and open pollination on fruit set were examined by including hybridization studies. Seed germination studies were carried out according to color of flesh in fruit obtained as a result of hybridization combination. In the conducted research to evaluate the characteristics of guava genotypes, some of the UPOV criteria were taken into consideration. These are including 10 criteria for morphological characteristics (tree branch status and leaf characteristics) and 18 criteria for pomological characteristics (physical and chemical properties of fruit). Promising genotypes were evaluated through weighing them and pomological characteristics were taken into consideration in this weighing. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) were used to determine the relationship of genotypes. In the study carried out by crossing, hybridization, self-pollination and open pollination studies were performed among genotypes with pink and white fruit flesh. Fruit set were determined according to hybridization combinations. In seed germination studies, germination rate, duration, energy and index were determined according to fruit flesh color. More than 550 guava genotypes have been followed and among them 28 genotypes thought to have commercial values have been selected for further evaluation. in different locations of Mersin and Antalya. When genotypes were examined, tree branch conditions were found to be 45% vertical in terms of morphological features and 40% in the leaves were the most spear-shaped. In fruit pomological characteristics, the most striking features were found to be fruit weight and number seeds in fruit. It was noted that pomological features were more prominent than morphological features in determining the commercial value of the types. According to the principal component analysis (PCA), 28 genotypes were clustered into four different groups. In hybridization studies using pink flesh fruited genotypes as a parent was found to be more successful than white ones. The highest success rate in hybridization combinations was determined in the open pollination study with 90%. In seed germination studies, germination rate of seeds extracted from pink genotypes was the highest in hybridization study. This rate was recorded as 71% (1505 units) in pink genotypes and 29% (615 units) in white genotypes. In seed germination studies, germination rate, duration, energy and index of seeds obtained from hybridization were determined according to fruit flesh color of female parent. The results of the study, germination rate of seeds extracted from pink types was higher (71%) than that determined on seeds from white types (29%). Based on PCA results, the top five types that are promising to have commercial value are P2-S1-A3 (74 points), AHR-A10 (71 points), P1-S13-A1 (70 points), P3-S7-A2 (68 points) and P1- S12-A1 (66 points). Among them, first two types (P2-S1-A3 and AHR-A10) were fell into independent group in PCA and HCA analyzes.