International Journal of Aquaculture, 2025, Vol.15, No.4, 208-220 http://www.aquapublisher.com/index.php/ija 210 one type from Fuzhou, Jiangxi Province was independent groups, and the other varieties were from another major category. These works provide reference for the identification of water chestnut germplasm resources and inference of kinship. 2.3.2 Case: results of the project of conservation and innovation of water chest germplasm resources of Chinese academy of agricultural sciences The scientific research team represented by the Vegetable and Flower Research Institute of the Chinese Academy of Agricultural Sciences systematically collected and preserved domestic water chestnut germplasm with the support of the national germplasm resource protection project. They organized detoxification and rejuvenation of the core germplasm, established a water chestnut germplasm resource garden, and preserved more than 50 pieces of materials including Guangxi's "Guilin Horseshoe" and Guangdong's "Black Taro". Virus removal through stem tip tissue culture improves the vitality and consistency of the germplasm. On this basis, researchers used molecular markers to analyze the kinship relationship of the main germplasm, screened out hybrid parent combinations with strong complementarity, and carried out artificial hybrid breeding exploration (He et al., 2023). For example, a large-grained variety in Guangxi was hybridized with early-mature varieties in Guangdong, and a batch of F1-generation hybrid seedlings were successfully obtained. Although the flowering and fruiting rate of water chestnuts is low, a small number of new varieties with hybrid advantages have been cultivated through measures such as hormone treatment and distant hybridization in other places. The project also used modern molecular technologies, such as simplified genome sequencing (RAD-seq), to develop large-scale polymorphic SSR markers, and conducted preliminary analysis of genomic mutations in main varieties such as "Guizushi" and "Guizushi". 3 Innovation in Breeding and Seedling Cultivation Technology 3.1 Traditional tuber breeding methods and bottlenecks Water chestnuts are traditionally reproduced by nutrition, that is, they are used as seeds for breeding with small bulbs harvested in the last season, commonly known as "seed shepherd" or "female shepherd". This method is simple in technology, but there are obvious bottlenecks: the reproduction coefficient is low, and 200 to 300 kilograms of seed balls need to be left per mu of water chestnut, accounting for more than 10% of the total output, and the reproduction rate is limited, making it difficult to rapidly expand and reproduce new varieties (Lü et al., 2011; Gao et al., 2015). Seed potatoes are degenerated and diseased, and their asexual reproduction for many years can easily lead to species degradation, resulting in a decrease in yield and quality. In addition, pathogenic bacteria often lurk in the epidermis and inside the seedlings, such as Tilletia spp. (smut fungus) and Fusariumspp. (wilt fungus) of water chestnu, and diseases with bacterial seed potatoes are spread, which makes the incidence rate in the seedling stage high. The storage loss is large. The water chestnut seed balls must be stored in low temperature and wet sand until the spring of the following year. During storage, it is prone to germination, weight loss or mold, rotten and deterioration, and the loss can reach about 20%. Planting and land preparation is complicated, and planting tubers requires fine field preparation and digging and point-planting. The degree of mechanization is low and the workload of people is large. These problems have to a certain extent limited the expansion of water chestnut planting scale and the promotion speed of new varieties. 3.2 Tissue culture and tibs rapid generation system Tissue culture technology provides water chestnuts with new ways to detoxify and reproduce quickly. As early as the late 1990s, Guangxi scientific research institutions began to explore the stem tip tissue culture detoxification technology of water chestnuts, and used virus-carried germplasm to obtain virus-free test tube seedlings through ex vivo culture, and then used for purification and revitalization. In recent years, the introduction of intermittent immersion bioreactors (TIBS) has greatly improved the rapid breeding efficiency of water chestnut tissue culture. TIBS uses liquid culture medium to regularly soak the cultures to achieve automatic feeding and ventilation. Studies have shown that under the TIBS system, the average proliferation multiple of water chestnut test tube seedlings per generation can exceed 40 times, which is far higher than 8 to 10 times that of traditional semi-solid culture. The seedlings in TIBS have many tillers, thick leaf-like stems, fast rooting, and the transplant survival rate
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