Sistemas de produção e porta-enxertos na produção de mudas de tangerineira ‘Ponkan’

Abstract

The production of healthy and vigorous seedlings is essential for the sustainability and productivity of citrus orchards. Improving the production system can lead to better quality seedlings for commercialization.An alternative for citrus seedling production is the use of the hydroponic system in a controlled environment, which can promote resource savings and improve seedling quality due to the continuous contact of the roots with the nutrient solution. The quality of seedlings also depends on the rootstocks used, as they influence various characteristics of the chosen combination, such as plant size, expected productivity, fruit quality, and a range of responses to biotic and abiotic factors. The aim of this study was to evaluate the production of ‘Ponkan’ mandarin seedlings on different rootstocks in conventional and hydroponic systems.Therefore, two experiments were set up, in which the treatments consisted of the following rootstock varieties: ‘Swingle’ citrumelo, ‘Rangpur’ lime, ‘Limeira’ and ‘Rubidoux’ trifoliate, and ‘Índio’ citrandarin. The experimental design was randomized blocks, with five treatments, four blocks, and 18 plants per plot. Growth characteristics such as height, diameter, number of leaves, root length and volume, and dry mass of the rootstocks and seedlings after grafting were evaluated.Leaf nutrient contents were also analyzed by two different methods (inductively coupled plasma optical emission spectroscopy and portable X-ray fluorescence equipment) and physiological parameters through chlorophyll fluorescence, gas exchange measurements, and leaf area.The results indicated that, for height and number of leaves, the seedlings in the conventional system performed better. The ‘Swingle’ citrumelo, ‘Rangpur’ lime, and ‘Índio’ citrandarin rootstocks provided greater growth in both systems, with the conventional system favoring seedling growth. Leaf nutrient concentrations were higher in hydroponic cultivation during the rootstock phase, while the conventional system showed higher nutrient contents in the grafted seedlings. It was observed that the hydroponic system promoted higher photochemical dissipation coefficients, especially for seedlings grafted onto ‘Swingle’ citrumelo and ‘Rangpur’ lime. Leaf area and chlorophyll content did not differ significantly among rootstocks, except for the trifoliate varieties. The hydroponic system proved to be a promising alternative for citrus seedling production; however, the conventional system provided greater growth for citrus seedlings regardless of the rootstock used.