Influence of biostimulants on root dynamics and possible citrus post-harvest quality
When considering nutrient uptake in citrus, uptake occurs naturally and primarily through the roots. For this reason, soil applications and management of the root to optimize nutrient uptake is important (Raath, 2021).
The roots of a plant, collectively, form the root system. The two principal functions of the root system are anchorage and absorption (Weier et al., 1982). Absorption of nutrients by plants involves movement of ions from the soil to root surfaces by diffusion and mass flow, ion accumulation in root cells, radial movement of ions from root surfaces into the xylem, and translocation of ions from roots to shoots. Appreciable amounts of carbohydrates may accumulate in the fine roots (Pallardy, 2008). Furthermore, in heavy-fruiting trees, a very strong inter-sink competition between roots and fruit for carbohydrates inhibited root, and resulted in death of feeder roots (Loeschner et al., 1990).
A biostimulant treatment was applied at different rates on Mandarin cv. Tango at fruitset and observations of root biomass was visually recorded. Also fruit was submitted to a certified laboratory for nutrient analysis at harvest. As can be seen in Figure 1, there were large differences between treatments and control trees on a visual basis. When looking at the data analysis of nutrients in the fruit, Calcium stands out, and was 30% higher than control trees (Figure 2). Nutrients like Ca, Mg and Fe are mainly absorbed by young roots in which the cell walls of the endodermis are not yet suberised. The ability of trees to utilize these nutrients depends largely on the number of active root tips (Raath, 2021).
The importance of Calcium fruit content has been well documented in relation to post-harvest quality and extended cold chain storage life (Chen Z. et al. 2024).
Marina Schoeman and Chris Burbidge
