Agromorphological characteristics of nero and viking aronia (Aronia melanocarpa (Michx) Elliot) varieties and quality parameters at different maturity levels

The study was carried out at the Aronya Plantation, Pomology Laboratory and the Food Technology Laboratory of Atatürk Horticultural Central Research Institute, and at the Cytology Laboratory of the Bursa Uludağ University Faculty of Agriculture Department of Horticulture, and at the Scanning Electron Microscopy Laboratory of Bursa Uludağ University Faculty of Science and Literature in 2017-2018. Agromorphological properties of 'Nero' and 'Viking' cultivars of aronia berry (Aronia melanocarpa (Michx) Elliot), a new berry in our country, have been defined and yield characteristics of both cultivars have been determined. Flower structures and fertilization biologies were examined in detail using stereo microscope, light microscope and Scanning Electron Microscope (SEM). The growth curve of the fruit was determined by regular measurements from fruit set to harvest. At the same time, chemical contents and morphological changes of both cultivars were determined during the fruit development and ripening stages. Harvesting was carried out at six different times in order to determine the optimum harvest times for various utilizations, and both fruit pomology and biochemical content were revealed. Phenological periods of the aronia cultivars have been defined, and the number of days from the full bloom to the harvest has been determined as 136-140 days for 'Nero' and 139-144 days for 'Viking'. The plant morphological properties and yield characteristics of the cultivars were determined, and it was observed that 'Viking' cultivar was ahead of 'Nero' cultivar in terms of both vegetative and yield characteristics. In the full and economic yield year, the average yield per scrub was recorded as 12.86 kg in 'Nero' cultivar and 14.91 kg in 'Viking' cultivar. In the examinations made in the flower structures, it was determined that the size of the petals, female and male organs were different between the cultivars. It was determined that ovaries of both cultivars generally have five carpels and two ovules in each carpel. Stigma surface morphology was investigated in SEM in detail, and papilla cells were defined. There was no significant difference between the cultivars in terms of stigma surface morphology. It has been recorded that the average number of male organs in a flower varies between 24-25. While the difference between the cultivars in terms of anther sizes was found to be significant, it was found to be insignificant in terms of pollen sizes. It was observed that 'Nero' cultivar had larger anthers, and 'Viking' cultivar had larger pollens. The pollens of both cultivars had three colporates, and their pollen shapes were subprolate. In the conditions of self-pollination and free pollination, the development of pollen tubes in the tubular pipes was examined by the squash method, and it was observed that pollen tubes reached the ovary 48 hours after pollination in 'Nero' cultivar and 72 hours after pollination in 'Viking' cultivar. The fruit growth curve in both aronia cultivars was determined as a single sigmoid. In the examination of fruit sections, it was observed that the formation of anthocyanins started in the placenta, and although it accumulates in pericarp and hippocampus in large amounts, its presence was also detected in mesocarp tissues. It was determined that the formation of anthocyanins starts earlier in 'Nero' cultivar. In order to determine the impact of the harvest time on fruit quality, the berry weight (g), berry sizes (mm), berry firmness (g mm-1), soluble solid content (%), pH, titratable acidity (g 100 ml-1), total dry weight (%), total anthocyanin content (mg 100g1), condensed tanin content (mg 100g-1), total soluble tannin (ppm), total phenolic contents (mg GA 100 g -1), total antioxidants (µm TE 100 g FW-1), total and reducing sugar (%) in both aronia cultivars have been determined in six different harvest times. Hence, the optimum harvest times for various utilizations were identified. Accordingly, it has been determined that the fruits can be harvested between 10-20 of September if they will be utilized for fresh consumption, in juice industry and food coloring, and between 20 September and 20 October if they will be utilized for dry consumption. Key words: Aronia, fruit, fertilization biology, pollen, anther, anthocyanin, antioxidant, harvest time