Genus Begonia is prominent ornamental bedding and potted flower crop, encompassing types such as Rieger Begonia (Begonia × hiemalis), Tuberous Begonia (Begonia tuberhybrida), and B. semperflorens, which are extensively cultivated. Building upon the breeding methodology of Rieger Begonia, this study endeavors to utilize Tuberous Begonia as the maternal parent and integrate the attributes of B. semperflorens to develop innovative interspecific hybrid varieties. Interspecific hybridization was accomplished by using Tuberous Begonia 'Fortunate' as the female parent and B. semperflorens as pollen donor through embryo rescue techniques, resulting in successful interspecific offsprings. Flow cytometry analysis revealed the expected DNA content combination in the hybrids. Furthermore, Random Amplified Polymorphic DNA (RAPD) analysis confirmed the authenticity of the interspecific hybrids by exhibiting specific bands of both parents. The plant type, basal branching habit, and leaf shape of the hybrids resembled those of the male parent, B. semperflorens, while the double flower characteristic inherited from the female parent. Additionally, the hybrids exhibited year-round flowering without requiring photoperiod treatment and showed no apparent dormancy, rendering them suitable for continuous production. These hybrids are also exhibiting robust branching habits and possess distinctive plant traits compared to commercially available Rieger Begonias. They are particularly suited for cultivation in hot and humid regions. Evaluation of production and growth advantages indicated their capability for year-round supply and commercial production. Applications for Plant Variety Rights have been submitted for these hybrids in Taiwan.
This study presents a groundbreaking field breeding strategy for Lantana camara, a plant celebrated for its ornamental value yet criticized for its invasive tendencies. Traditional hand pollination techniques for lantana are labor-intensive, as each flower produces only one seed, making the generation of significant populations time-consuming. Although open pollination represents an alternative for seed production, the reliability of generating sterile triploids through interploidy crosses has been questionable. Addressing these challenges, this research innovatively employs open-pollinated breeding between diploid and tetraploid populations to efficiently produce sterile triploid cultivars. The method leverages male-sterile tetraploids for open pollination with female-sterile, male-fertile diploids, yielding 544 triploid seeds within five weeks and proving the effectiveness of interploidy hybridization. Moreover, diploid populations in an all-by-all cross setup produced over 2,000 seeds in the same period, eliminating the need for hand pollinations. Nonetheless, the development of tetraploid breeding lines encountered obstacles due to insufficient pollen transfer, likely resulting from low pollen production, although selfing within hybrid lines remained feasible in an open-pollinated field setting. These findings significantly advance the fields of ornamental breeding and invasive species management, providing fresh perspectives on the cultivation and control of Lantana camara. Demonstrating the capability to rapidly produce large volumes of sterile triploid lines with minimal labor, this study lays the groundwork for the broader availability of non-invasive Lantana camara alternatives in the future.
Many legume trees are notorious for their prolific production of seedpods, which are usually large and in many cases stink when cracked open. Such pods affect both the beauty and sensory perception of the tree, and may be slippery and hazardous on walking surfaces. For example, Samanea (Albizia) saman, which has naturalized in many tropical and subtropical places and is commonly known in Hawaii as monkey pod tree, is a favorite landscape tree in Hawaii for its large canopy, especially in parking lots and parks. Unfortunately, this species produces a large amount of sticky pods that stick to shoes and tires, and can create an objectionable mess, a high volume of green waste and high maintenance of parking lots. The seedpods are heavy to rake and can cause damage to lawn mower blades. Seedless cultivars would have no potential to become invasive and their maintenance cost would be much lower. Seed-bearing ornamental plants can be converted to triploid, non-seed-bearing forms, and thereby eliminate their invasiveness and reduce their maintenance. Triploid plants rarely produce functional gametes, because they do not undergo normal meiosis, and the resulting sterility accounts for the economically valuable seedlessness of triploid bananas, limes, and seedless watermelons. Sterile nursery plants can be used for landscaping virtually without any possibility to become invasive. In a field trial at the University of Hawaii Waimanalo Research Station, it was observed that tetraploid plants of Samanea (Albizia) saman on diploid roots grew similarly to mixoploid and diploid plants on diploid roots. These tetraploid plants were developed by treating the apical meristem of diploid seedlings with 0.1% colchicine for 48h. Therefore, the root system remained diploid, while the above ground portion of the plants were tetraploid. However, tetraploid plants on tetraploid roots, grown from seeds harvested from tetraploid induced plants, were inferior to triploid plants on triploid roots. Triploid plants were almost double in size (67% taller, had 109% wider canopy, and 90% larger DAB, n=8). This is the first time that this phenomenon has been documented in Samanea spp.
