Phosphorus fertilization rate and dynamics in early development of three giant reed (Arundo donax L.) ecotypes

Abstract

Recently, biomass crops attracted considerable attention as a possible alternative to fossil fuels; nevertheless, the interest in its agronomic practices such as irrigation and fertilization is still unclear. This study aims at determining the appropriate phosphorus (P) fertilization management in the early development stage of giant reed (Arundo donax L.). The uptake, transportation, and fertilization use efficiency of P were reported in three ecotypes of giant reed, i.e., STM (Hungary), BL (the USA), and ESP (Spain). Somatic embryo-derived plantlets were developed under glasshouse environment in clean sand (quartz) augmented with 0, 25, 50, 100, and 150 mg P kg−1, added as monosodium phosphate. P-treated plants possessed a fibrous root system characterized by many lateral roots, while control plants (received no P) had a root system distinguished with long axial roots with very few lateral branches. Phosphorus uptake significantly varied according to plant ecotype, plant parts, and applied P concentration. Giant reed ecotypes showed different responses to uptake and accumulation of P, where P contents in the STM, ESP and BL ecotypes were 392, 413, and 445 μg g−1, respectively. The accumulation of P in different plant parts was as follows: leaf blade > culm > root. The treatment of 50 mg P kg−1 displayed the highest P content in all plant parts. The BL and STM ecotypes showed the same translocation factor (TF) of 4.96, while the ESP ecotype exhibited a lower TF of (4.03). The treatment of 50 mg P kg−1 revealed the highest TF (5.94). The BL ecotype showed P use efficiency (PUE) of 7.08 compared with 6.49 and 5.85 for the ESP and STM ecotypes, respectively. The 50 mg P kg−1 exhibited the highest PUE (13.37). The BL ecotype displayed the highest CO2 assimilation rate (12.46 μmol photons m−2 s−1). Also, the rate of CO2 assimilation increased upon increasing the rate of the applied P. Our results reveal that the appropriate P fertilization rate of the ESP, STM, and BL ecotypes is 25, 25, and 50 mg P kg−1, respectively.