Effects of Foliar Spraying with Different Concentrations of Selenium Fertilizer on the Development, Nutrient Absorption, and Quality of Citrus Fruits

Abstract

Selenium (Se) fertilizer has a good effect on many field crops, but there are few reports on the application of Se fertilizer on citrus. We investigated the effects of 0 mg/L (CK, water treatment), 50 mg/L, 100 mg/L, 150 mg/L, and 200 mg/L sodium selenite aqueous solutions on the growth, nutrition, and fruit quality of 15-year-old citrus unshiu (Citrus reticulata Blanco cv. Succosa). The results showed that a low concentration of Se fertilizer promoted the growth and development of the citrus plan, and a high concentration of Se fertilizer was found to slightly inhibit the growth and development of the plant. Among the different treatment groups, 150 mg/L selenium fertilizer showed have the best effect on these evaluated parameters. The results thus suggest that 150 mg/L of Se fertilizer promotes the formation of chlorophyll in the leaves of the test plant and increases the longitudinal and transverse diameter of the fruits and weight of single fruit, significantly enhancing the activity of antioxidant enzymes in the leaves, promoting the absorption of nutrients in the leaves, increasing the contents of total sugar and vitamin, and decreasing the acidity in the fruits and the pericarp thickness. It also promoted the accumulation of the total selenium content in the leaves and fruits and consequently improved the quality of the fruits. These results showed that appropriate concentration of Se treatment can improve the activity of antioxidant enzymes to enhance plant stress resistance, regulate the content of sugar and acid in fruits, and improve the quality of fruits.

Enrichment characteristics and dietary evaluation of selenium in navel orange fruit from the largest navel orange-producing area in China (southern Jiangxi)

“…Meanwhile, the fruit shape index (H/D) and vitamin C content of Se-rich navel oranges were higher than those of ordinary navel oranges, but the titratable acid content was lower than that of ordinary navel oranges ( Table 1 ). This is consistent with the findings of Wen et al (2021) , who demonstrated that exogenous application of Se fertiliser (150 mg⋅L –1 Se) significantly promoted citrus growth and development, increasing single fruit weight, horizontal and longitudinal diameter, and vitamin C content, while reducing acidity ( p < 0.05). This is mainly attributed to the fact that the application of Se fertiliser promotes an increase in chlorophyll content in the plant body and promotes photosynthesis ( Zhang M. et al, 2014 ; Wen et al, 2021 ).…”

“…This is consistent with the findings of Wen et al (2021) , who demonstrated that exogenous application of Se fertiliser (150 mg⋅L –1 Se) significantly promoted citrus growth and development, increasing single fruit weight, horizontal and longitudinal diameter, and vitamin C content, while reducing acidity ( p < 0.05). This is mainly attributed to the fact that the application of Se fertiliser promotes an increase in chlorophyll content in the plant body and promotes photosynthesis ( Zhang M. et al, 2014 ; Wen et al, 2021 ). The assimilates of photosynthesis are the material basis of plant cell activity, and the accumulation of photosynthates directly affects a range of metabolic activities ( Matsoukas et al, 2012 ; Wen et al, 2021 ).…”

“…In this study, the average content of medium and massive elements (Mg, P, K, and Ca) was higher in Se-rich navel oranges than in ordinary navel oranges ( Table 1 ), indicating that Se can promote the co-uptake of the above elements ( Bañuelos et al, 2020 ). This is consistent with the findings of Wen et al (2021) , and this phenomenon has been confirmed in other crops, such as tea and pear trees ( Liu et al, 2015 ; Qin et al, 2019 ). Meanwhile, this study found a significant coupled positive correlation ( p < 0.05) between P, K, and Mg elements in Se-rich navel oranges ( Figure 4 ).…”

“…This is mainly attributed to the fact that the application of Se fertiliser promotes an increase in chlorophyll content in the plant body and promotes photosynthesis ( Zhang M. et al, 2014 ; Wen et al, 2021 ). The assimilates of photosynthesis are the material basis of plant cell activity, and the accumulation of photosynthates directly affects a range of metabolic activities ( Matsoukas et al, 2012 ; Wen et al, 2021 ). Meanwhile, Se fertilisation application significantly promoted the activity of antioxidant enzymes in leaves and fruits, facilitated the absorption of nutrients ( Motesharezadeh et al, 2019 ), increased vitamin C content, reduced acidity, promoted the accumulation of total Se content in fruits, and improved fruit quality ( Ardebili et al, 2014 ; Wen et al, 2021 ).…”

Selenium species transforming along soil–plant continuum and their beneficial roles for horticultural crops

“…A proper dose of Se fertilizer enhances Se accumulation in different plant parts but reduces the accumulation of heavy metals [ 64 ]. The application of Se promotes concentrations of nitrogen, phosphorus, potassium, calcium, and magnesium in citrus leaves [ 99 ] and also increases potassium and calcium concentrations of grape berries [ 100 ]. The nitrogen, potassium, and calcium uptake of wheat seedlings ( Triticum aestivum L.) was enhanced by the application of 5 μM Na 2 SeO 4 but the nitrogen uptake was significantly declined by10 μM Na 2 SeO 4 [ 101 ].…”