Jujube, also called Chinese date, originated in China and has been cultivated there for 4000 years (Guo and Shan, 2010). There are over 800 cultivars in China (Liu and Wang, 2009), whereas in the United States, less than 10 cultivars are commercially available (Yao, 2013). Both commercial jujube growers and home gardeners in the United States demand a wider choice of cultivars to expand the maturation season and for different end uses.
Jujubes grow and produce well in a wide range of areas in the United States, especially in the semiarid southwest (Yao, 2013). But, commercial growers and home gardeners are affected by poor fruit set in some cases because of non-self-fruiting cultivars and lack of pollinizers.
To meet the cultivar demands in the United States, we have built a collection of over 50 cultivars: some collected in the United States and the majority directly imported from China (Yao, 2013). We have been evaluating them since acquisition. For cultivars, self-fertile, partial self-fertile, and self-sterile all exist and cross-pollination always increases fruit set and fruit size over self-pollination (Yao et al., 2015). Cultivars for different purposes and pollinizer recommendations are needed. There are several studies regarding pollen amount and pollen germination from China (Guo and Shan, 2010; Han et al., 2008; Liu and Peng, 1992), but no such studies in the United States.
Phenology provides basic information about a fruit species introduction and is helpful for planting region expansion, especially marginal regions. Adding phenological data and pollen germination information to our knowledge of cultivars would greatly assist cultivar recommendation for particular growing areas in North America. We have reported jujube cultivar flowering and fruiting habits, cultivar vitamin C profile, and sugar composition dynamics in the past (Huang et al., 2017; Yao et al., 2015). The objectives of this study were to observe jujube phenology and pollen germination of different jujube cultivars collected in New Mexico. The two unique germplasm resources of ‘Zaocuiwang’ and ‘Yu’ were identified during the phenology observation and pollen study process.
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