การคัดเลือกพันธุ์คะน้าฮ่องกงต้นเล็กโดยวิธีการคัดเลือกต้นต่อแถวต่อต้นประยุกต์

Abstract

Chinese kale is an important produce of the Royal Project Foundation. Breeding programs for various characters of the produce were set up. The objectives of this breeding program were to select Chinese kale with 1.00-1.50cm stem diameter and early harvesting date. This selection process had been conducted from November 2015 to August 2018 at the Royal Project Foundation Vegetable Research and Development Station, Mae Rim district, Chiang Mai. Modified Ear to Row to Ear method was done for 4 generations. In the first generation, characterization and distribution of traits in the initial population base on stem shape, stem diameter, and plant height were studied. The plants that meet the stem diameter criteria and have a suitable plant height for harvesting within 15-20 days after transplanting were selected. Each selected plant was then pollinated with mixed pollens from selected plants in the same group. Seeds of each selected plant were collected separately for growing and selection in the next generation. The results showed that average stem diameter and plant height of the base population were 0.52 and 11.94 cm, respectively. The selected plants were divided by the stem shape into 2 groups. When the plants had been selected for 3 generations by modified Ear to Row to Ear method, the offspring of group A (S3A) with very elongated stem had an average stem diameter of 0.76 cm and an average plant height of 12.09 cm. The coefficient of variance values (C.V. = 29.32 and 26.81%) were less than those of the first generation (C.V. = 70.81 and 44.19 %) and the proportion of plants with very elongated stem was higher. The results of the study show that the selection of baby Chinese kale by modified Ear to Row to Ear method for 4 generations earned 8 selected lines with very elongated stem. They had stem diameter and plant height that meet the standard as the extension variety. Moreover, the selected lines had smaller leaves than the extension variety. Thus, the yields after standard post-harvest trimming were not different from that of the extension variety. However, the selection with only two selection criteria made the selected lines had low uniformity of leaf traits. For the next breeding program, S3 -3-2-1, S3 -3-2-2 and S3 -6-2-1 lines should be selected using leaf traits as one criterion to improve uniformity of qualitative characteristics.