The influence of the hybrid and the duration of vernalization of tuberous roots on photosynthesis and flowering in Ranunculus asiaticus L

In Ranunculus asiaticus L., we investigated the influence of two hybrids, MBO and MDR, and three tuberous roots preparation procedures, only rehydration (Control, C), rehydration plus vernalization at 3.5°C for 2 weeks (V2), and rehydration plus vernalization at 3.5°C for 4 weeks (V4), on plant growth, leaf photosynthesis and flowering, in plants grown in pot, in a cold greenhouse. The two hybrids differently reacted to the duration of vernalization in terms of net photosynthesis: compared to Control, it did not change in V2 and increased in V4 in MBO, while it was unaffected by vernalization in MDR. Quantum yield of PSII electron transport (ɸPSII), linear electron transport rate (ETR) and non-photochemical quenching (NPQ) did not differ in the two hybrids, whereas maximal PSII photochemical efficiency (Fv/Fm) was higher in MBO than in MDR. An interaction Hybrid × Preparation procedure was found in ETR that did not change with vernalization in MBO, while decreased in MDR V2 plants. Genotype and preparation procedure significantly interacted also on total plant leaf area, which was reduced in V2 procedure only in MBO plants, while decreased in both the vernalization procedures in MDR plants. In Control plants, flowering started in 110 days in MBO and 93 days in MDR. Compared to controls, both the vernalization procedures anticipated flowering in MDR, while only the longer procedure (V4) was efficient in MBO. Vernalization always reduced the flower stem height and fresh weight in both the hybrids. In conclusion, the two hybrids showed a different response to the roots preparation procedure in terms of photosynthesis, plant growth and flowering earliness. These results highlight that specific genotype response and negative effects on flower quality should be considered in the choice of the preparation procedure in R. asiaticus L. Compared to only rehydration, the procedure V2 did non-influence flowering earliness in MBO and promoted it in MDR (-27 days than in MDR-C), while the procedure V4 anticipated flowering in both the hybrids (-25 in MBO and -59 in MDR).