Cost analysis of apple hybrid breeding

【Objective】This study is based on the practice of apple hybrid breeding, in which the various expenses incurred during the breeding process were statistically analyzed. By organizing the expenses at different stages and of different types during the apple hybrid breeding process, this research aims to provide a statistical overview of the costs associated with the process from hybrid pollination to the selection of superior lines, with the intention to offer a reference for optimizing breeding procedures, reducing breeding costs, and improving breeding efficiency.【Methods】A statistical analysis of the expenses incurred from pollination to the selection of superior lines in hybrid breeding is conducted. The overall process of apple hybrid breeding includes hybrid pollination, obtaining hybrid seeds, sand stratification storage, sowing, greenhouse seedling cultivation, field transplantation, management of seedlings, preparation of scions and dwarf rootstocks, grafting, management of the selection nursery, evaluation of hybrid offspring and selection of superior lines, final selection, regional trials, and variety approval. This study integrates the breeding process with the practical breeding activities of the research group, dividing the process from hybrid pollination to the selection of superior lines into four stages: the stage of obtaining hybrid seeds, the greenhouse seedling stage, the seedling stage, and the superior line selection stage after grafting. Additionally, expenses related to labor, materials, and land use are analyzed to calculate the costs of hybrid breeding at different stages and types based on the expenditures from apple hybrid pollination to the selection of superior lines.【Results】Among different stages, the first stage is the hybrid seed acquisition stage, which lasts from April of the first year to January of the second year, encompassing the process from hybrid pollination to seed acquisition, prior to seed stratification storage. The second stage is the greenhouse seedling stage, occurring from January to April of the second year, which includes the greenhouse seedling process from seed storage until the planting of seedlings. A total of 12 500 hybrid seeds are sown in plug trays and placed in the greenhouse for cultivation. The third stage is the seedling stage, from April of the second year to August of the third year, which includes the process from field transplanting to the acquisition of scions. This primarily involves completing field transplanting of seedlings, field management, and the collection and sorting of scions. The fourth stage is the selection of superior lines after grafting, from August of the third year to December of the eighth year, which includes the planting of rootstock seedlings, grafting of hybrid seedlings, management of hybrid offspring, investigation and evaluation of fruit traits of hybrid offspring, and the selection of superior lines. The work involved in the hybrid seed acquisition stage, from hybrid pollination to the selection of superior lines, includes pollen preparation, hybrid pollination, management and harvesting of hybrid fruits, and extraction of hybrid seeds, with costs for this stage accounting for approximately 0.7% of total expenditures. The main tasks in the greenhouse seedling stage include seed storage, sowing, and seedling management, with expenditures for this stage accounting for 0.9%. The seedling stage includes field transplanting, management, and collection of scions, which requires significant labor input for various breeding tasks, resulting in a higher number of hired workers, with expenditures for this stage accounting for 3.2% of total costs. The selection of superior lines after grafting involves planting rootstock seedlings, grafting, and managing hybrid offspring, with this stage having the highest costs, accounting for as much as 95.2% of total costs. In different categories, statistics are conducted on three types of expenditures: labor costs, material costs, and land use fees, analyzing the breeding costs from hybrid pollination to the selection of superior lines. Among these, labor costs primarily consist of labor expenditures and the salaries of technical personnel. Material costs include expenses for rootstock seedlings, agricultural inputs, and field machinery usage fees. Land costs encompass the usage and maintenance fees of greenhouses as well as land rental fees. In the hybrid breeding process from pollination to the selection of superior lines, labor costs account for the largest expenditure, reaching a proportion of 49.9%. This is followed by material costs, which account for 37.9%, while land use fees are relatively lower, making up 12.2%. Furthermore, in the case of a hybrid scale of 10 000 plants, the average cost per plant from pollination to the selection of superior lines is approximately 122.2 yuan. 【Conclusion】The total cost from hybrid pollination to selecting superior lines in hybrid breeding is 1 221 973.5 yuan, with an average cost of 122.2 yuan per plant. Among the different breeding stages, the cost of selecting superior lines after grafting is the highest, making up a significant portion at 95.2%; the costs for the seedling stage, obtaining hybrid seeds, and greenhouse seedling stage are lower, accounting for 3.2% , 0.7% , and 0.9% respectively. In terms of different types of expenses, labor costs are the highest, reaching 55.3% , while material costs and land use fees account for 33.9% and 10.8% of the breeding costs respectively.