Abstract:

The factors influencing fruiting ability and fertility of Chinese jujube (Ziziphus jujuba) were analyzed based on an investigation of 124 cultivars in the Cangxian County Jujube Repository, Hebei and 156 cultivars in the National Jujube Repository, Pomology Institute of Shanxi. The results showed that Chinese jujube germplasm resources could be classified into 3 groups, I.e. self-fruitless, self-sterile (but self-fruitful) and self-fertile. Among them, self-sterile was the basic type, and it could convert with self-fruitless and self-fertile. However, the transform between self-fertile and self-fruitless was very scarce. Under natural pollination, all the cultivars and strains tested were able to bear fruits, but they were not all fertile, accounting for 42.31%, the rest sterile. The fruiting ability and fertility changed with genotypes (cultivars or strains), years, regional conditions and orientation of the canopy, of which genotype was the most dominant factor. The percentage of fruit to bearing shoot (PFTBS) and the percentage of fruit with seed (PFWS) were respectively in a range of 0-61.54% and 0-100% under self-pollination, and 4.17%-136.84% and 0-100% under natural pollination. PFTBS and PFWS in 36 strains of cultivar ‘Jinsixiaozao’ were respectively in a range of 0.89%-163.64%, 0-6.98% under self-pollination, and 10.71%-138.89% and 0-90.00% under natural pollination. For 5 strains of cultivar 'Wuhexiaozao', the two parameters were 1.10%-81.72%, 0-100% under self-pollination, and 8.06%-137.04% and 0-2.70% under natural pollination；For the 3 strains of cultivar ‘Dongzao’ the two parameters were 25.00%-62.93%, 0-1.37% under self-pollination, and 11.32%-89.23% and 0% under natural pollination, respectively. The variation of fruiting ability was much bigger than that of fertility. Only 4.17% and 15.38% of the cultivars had stable PFTBS respectively between years and between regional conditions, while the corresponding ratio of the cultivars with stable PFWS was respectively 64.58% and 73.08%. The PFTBS under self-pollination was much higher in the south-west and north-west aspects of the canopy than in other orientations. Some excellent germplasms (with self-fruitless or self-sterile under self-pollination but fertile under cross-pollination), which were fit to be used as female parent in cross breeding, were preliminarily screened out.

Key words: Chinese jujube (Ziziphus jujuba), natural-pollination, self-pollination, fruiting ability, fertility, influncing factors