Production systems for ‘Ponkan’ mandarin nursery plants grafted onto different rootstocks

ABSTRACT One of the main challenges in citrus nursery plant production under protected environments is the space required for plant growth due to the large volume of containers and substrates, along with nutritional management demands. Hydroponics emerges as a promising alternative, offering more precise nutrient supply, efficient water use, reduced space requirements, and better control of growth conditions. This study aimed to evaluate the production of ‘Ponkan’ mandarin nursery plants in conventional cultivation and hydroponics systems, using five rootstocks: ‘Swingle’ citrumelo, ‘Rangpur’ lime, ‘Limeira’ and ‘Rubidoux’ trifoliate, and ‘Índio’ citrandarin. Two experiments were conducted in randomized blocks with five treatments, four replicates, and 18 plants per plot. One hundred and 50 days after grafting, growth and physiological parameters were measured, including scion length,plant height, stem diameters, number of leaves, root length, root volume, dry mass, Dickson quality index, leaf traits, photosynthetic pigments, chlorophyll a-fluorescence, gas exchange, and water use efficiency. The joint analysis of experiments was performed, and the means were compared using the Tukey’s test. In the conventional system, plants were produced in 3.2 dm3 bags with commercial substrate, while in the hydroponic one they were produced in 280 cm3 tubes with vermiculite placed in pools supplied with nutrient solution. Higher growth of ‘Ponkan’ mandarin nursery plants was obtained in the conventional system with ‘Swingle’ citrumelo, ‘Rangpur’ lime, and ‘Índio’ citrandarin rootstocks. Photosynthetic parameters showed no significant differences between rootstocks and production systems, except for photochemical dissipation coefficient, which was higher in hydroponics for plants grafted onto ‘Swingle’ citrumelo and ‘Rangpur’.