Profiles of citrus orchard nutrition and fruit quality in Hunan Province, China

ABSTRACT Understanding of orchard nutrition status can facilitate the proper management of orchards for higher fruit yield and quality. From 2011 to 2019, the nutrition status of orchards in Hunan Province, a major citrus-producing area in china, were assessed. A total of 361 soil samples, 378 leaf samples and 285 fruit samples of sweet oranges including navel orange (citrus sinensis l. Osbeck ‘newhall’) and common sweet orange (citrus sinensis l. Osbeck ‘bingtangcheng’), and mandarins including satsuma mandarin (citrus unshiu marc. ‘miyagawa’) and ponkan (citrus reticulata blanco ‘xinnu’) were collected. These samples were from112 sweet orange orchards and 140 mandarin orchards. Parameters of soil, leaf and fruit nutrition and fruit quality were analyzed based on these samples. The results revealed that soil acidification occurred in 79.0% of sweet orange orchards (ph 3.56 to 8.12) and 74.7% of mandarin orchards (ph 2.75 to 8.15). Soil organic matter (om) was abundant in both sweet orange orchards (21.3 g/kg on average) and mandarin orchards (19.77 g/kg on average). Nutrient analysis demonstrated deficiencies of nitrogen (n), potassium (k) and boron (b) in soils and leaves of sweet orange and mandarin orchards. Zinc (zn) was abundant in soils but deficient in leaves, suggesting a low zn utilization efficiency in these orchards. Besides, excessive iron (fe), magnesium (mn) and copper (cu) were found in sweet orange and mandarin leaves, which may be associated with low soil ph and fungicides application in this area. The average contents of n, phosphorus (p) and k in the fruit were about 0.80%, 0.11% and 0.51%, respectively, with a ratio close to 1:0.14:0.6. Multiple linear regression (mlr) analysis revealed that leaf npk and molybdenum (mo) significantly affect fruit fresh fruit weight (ffw) and total soluble solids (tss), and leaf p is closely correlated with fruit titratable acid (ta).