Plantation quality assessment of Camellia oleifera in mid-subtropical China

Abstract

Camellia oleifera is a woody shrub widely cultivated on subtropical acid soil regions, and its oil is considered to be an “oriental olive oil”. It was once believed that soil is the most important site factor limiting the yield of oil from C. oleifera. However, in addition to soil factors, topography and weather factors have been shown to be correlated with C. oleifera fruit yield. To identify soil factors, topography factors and weather factors, which are the main factors that affect fruit yield and assess the quality of C. oleifera plantations from different regions in mid-subtropical China, four types of sites, namely a basin, a plain, low hills, and high mountains were selected in China’s Hunan Province. Twenty eight parameters – totalling 180 sites and 540 standard plots – were statistically analysed. Water-holding porosity, pH, available phosphorus, mean annual precipitation, year round sunshine hours, soil organic matter (SOM), soil water storage and aspect were selected as components of a minimum data set so that the quality of a C. oleifera plantation could be predicted. The highest weighting was given to aspect, and the results indicated that topography and soil physical properties played a greater role than SOM and nutrient concentrations. The plantation quality index (PQI) for each type of region was as follows: basin, 0.89 ± 0.03; plain, 0.71 ± 0.06; low hills, 0.63 ± 0.05; and high mountains, 0.57 ± 0.06. Along with the PQI, the grey relational analysis equation coefficients confirmed that the basin had the highest quality of C. oleifera plantations, followed, in that order, by the plains, the hills, and the mountains. The results provide that topography and soil physical properties will be essential for evaluating quality of a C. oleifera plantation and that the C. oleifera planted in the basin will obtain higher economic benefits than plain, low hills and high mountains.