Nitrogen and phosphorus uptake kinetics by two blackberry genotypes grown in Florida

H. Liu, M. Curtis Gluck, G. Liu
This study aimed to investigate N and P acquisition efficiency of two selected blackberry (Rubus fruticosus) cultivars, ‘Natchez’ and ‘Osage’, for Florida’s rapidly expanding commercial production. The seedlings were purchased from a commercial supplier and grown in an aeroponic system with 10% strength Hoagland solution at pH 6.5 for two weeks. After being washed with DI water four times, the seedlings were individually placed in a container with 0.1 mmol L‑1 CaSO4 solution for starvation for 72 h. Three individual single-seedling tests were then conducted with three corresponding measuring solutions, each with three replications, containing 0.071 mmol L‑1 NH4+, 0.071 mmol L‑1 NO3-, and 0.016 mmol L‑1 H2PO4-, respectively, with 0.1 mmol L‑1 Ca2+ added. The temperature was 23±1°C, relative humidity was 55±3%, and photosynthetic photon flux density (PPFD) was 69 µmol s‑1 m‑2. The data were calculated via the nutrient depletion method. The results showed that ‘Osage’ was significantly faster than ‘Natchez’ in influx of each of NH4+, NO3-, and H2PO4-, with respective Imax values of 9.37 and 3.09 µmol g‑1 DW h‑1 for NH4+, 1.86 and 0.92 µmol g‑1 DW h‑1 for NO3-, and 1.86 and 0.32 µmol g‑1 DW h‑1 for H2PO4-. The corresponding Km values of ‘Osage’ and ‘Natchez’ were 17.2 and 169.1 µmol L‑1 for NH4+, 74.5 and 73.7 µmol L‑1 for NO3-, and 4.2 and 18.4 µmol L‑1 for H2PO4-, respectively. These results indicate that ‘Osage’ has significantly better Michaelis-Menten kinetics coefficients for influx of NH4+, NO3-, and H2PO4- than ‘Natchez’.
Liu, H., Curtis Gluck, M. and Liu, G. (2024). Nitrogen and phosphorus uptake kinetics by two blackberry genotypes grown in Florida. Acta Hortic. 1388, 331-338
DOI: 10.17660/ActaHortic.2024.1388.48
ion absorption, nutrient uptake, root system, Rubus fruticosus

Acta Horticulturae