Morphological, cytological and nutritional changes of autotetraploid compared to its diploid counterpart in Chinese jujube (Ziziphus jujuba Mill.)

Polyploidization plays an important role in plant breeding because polyploid plants often show better agronomic characteristics related to growth, yield and quality. The autotetraploid Chinese jujube, ‘Riguang’, was induced from diploid ‘Dongzao’ by colchicine in 2004, but systematic comparative study on its characteristics has not been done. The morphological, cytological and nutritional differences between ‘Riguang’ and ‘Dongzao’ were comparatively analyzed. The autotetraploid displayed relatively slower growth and significant dwarfing characteristics as compared to the diploid counterpart. Compared with its diploid donor, ‘Riguang’ exhibited darker green leaves and much bigger stomata, pollens, flowers and fruits. The average fruit weight of ‘Riguang’ was 40.56% heavier; The contents of ascorbic acid, titratable acids, soluble sugar and cyclic adenosine monophosphate in ‘Riguang’ fruits were significantly higher than those in ‘Dongzao’ fruits. The significant higher chlorophyll content in ‘Riguang’ leaves led to the increased photosynthetic efficiency in the autotetraploid plants. In brief, the autotetraploid ‘Riguang’ exhibited some superior agronomic characteristics that include less vigor, but higher photosynthetic capacity, higher yield per tree, bigger and more nutritious fruit. This is the first systematic comparative study on the characters of autotetraploid and its diploid counterpart in Chinese jujube, which can provide reference for in-depth study of autotetraploid in fruit tree