Chinese jujube (Ziziphus jujuba Mill.) is a drought-tolerant, nutrient-rich fruit crop with a long cultivation history, but its breeding progress remains limited. Natural fruit set is extremely low, embryo abortion is frequent, and manual emasculation is difficult because the flowers are only a few millimeters wide. Indian jujube (Ziziphus mauritiana Lam.) carries valuable traits, including large fruit size, high yield, and resistance to jujube witches’ broom disease and fruit cracking. However, its flowering period does not normally overlap with that of Chinese jujube, and stored pollen loses viability quickly. Due to these challenges, there is a need to conduct in-depth research on flowering-time synchronization and efficient pollination strategies in jujube breeding.
In an article published (DOI: 10.1093/hr/uhag066) on 7 March 2026 in Horticulture Research, researchers from Hebei Agricultural University, Binzhou Academy of Agricultural Sciences, Wudi Inspection and Testing Center, Shandong Institute of Pomology, and Hebei Agricultural University’s College of Foreign Language reported a dual-regime strategy for improving reproductive success in Ziziphus. The study combined flowering-time regulation with in vitro pollination to overcome barriers that have long restricted interspecies hybridization between Chinese jujube and Indian jujube.
The researchers first tested how temperature control and pruning could shift the flowering schedule of Indian jujube cultivar ‘Niunaidaqingzao’. A treatment that retained five to six primary branches, each with one secondary branch, advanced flowering by about two months, allowing Indian jujube to bloom in April together with Chinese jujube ‘Dongzao’ and wild Chinese jujube ‘Suanzao’. The team then tracked flower-opening stages, pollen viability, stigma receptivity, pollen tube elongation, and ovary expansion. They found that pollen viability peaked before the stigma reached its most receptive stage, confirming a key internal timing mismatch. Triple artificial self-pollination (TAS) increased pollen tube emergence to 59%–87% across the three genotypes, outperforming in vitro spontaneous self-pollination (SSP) and single artificial self-pollination (AS). Triple artificial cross-pollination (TAC) also improved crossing outcomes, raising pollen tube emergence to 54%–72% in key cross combinations and increasing ovary expansion to 26%–39%.
The authors said the study shows that jujube hybridization can be made more predictable by managing both the flowering calendar and the pollination window. By first bringing two species into bloom at the same time, and then applying viable pollen at multiple stages of stigma development, breeders can give pollen tubes more opportunities to grow successfully. They said this strategy turns a difficult field-based crossing problem into a more controllable in vitro process, creating a practical foundation for using Indian jujube as a genetic resource in Chinese jujube improvement.
The findings provide a useful framework for breeders seeking to introduce new traits into jujube without relying on transgenic transformation, which remains technically challenging in this crop. By improving flowering synchronization and pollination efficiency, the method could help develop hybrid populations carrying useful alleles for disease resistance, stress tolerance, fruit size, yield, and quality. With further optimization, this dual-regime approach may support more precise breeding in Ziziphus, broaden the genetic base of cultivated jujube, and help produce cultivars better suited to changing production environments and market demands.
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References
DOI
10.1093/hr/uhag066
Original Source URL
https://doi.org/10.1093/hr/uhag066
Funding information
This work was supported by the National Key R&D Program of China (2024YFD2200600), the Key R&D Program of Shandong Province, China (No. 2025LZGC049), the Shandong Provincial Standardization Pilot Project (2023-SD-146), and the Key R&D Program of Shandong Province, China (2020LZGC008).
About Horticulture Research
Horticulture Research is an open access journal of Nanjing Agricultural University and ranked number one in the Horticulture category of the Journal Citation Reports ™ from Clarivate, 2023. The journal is committed to publishing original research articles, reviews, perspectives, comments, correspondence articles and letters to the editor related to all major horticultural plants and disciplines, including biotechnology, breeding, cellular and molecular biology, evolution, genetics, inter-species interactions, physiology, and the origination and domestication of crops.