Effects of Tree Shape on the Microclimate and Fruit Quality Parameters of Camellia oleifera Abel

Abstract

Tree shape can affect microclimate, which may directly influence fruit growth and development. Open center and round head are two tree canopy shapes that are generally used in Camellia oleifera Abel. cultivation. To study the effects of the two canopy shapes on the microclimate and fruit quality parameters inside the canopy and investigate the correlations between microclimate and oil yield characteristics, microclimates in different developmental periods and fruit quality parameters at maturity at different positions in the two canopy shapes were determined. In this study, the open-center shape increased the light intensity and temperature, and reduced the relative humidity within the canopy, and the microclimate was more uniformly distributed within the open-center canopy. Fruit quality parameters of open-center canopied trees were also significantly increased and had more uniform distributions, especially the oil yield parameters. The content ratio of the dry seed, oil content ratio of the fresh fruit, and oil yield increased by 43.55%, 59.30% and 79.01%, in the lower layer, respectively, and 27.33%, 41.75%, and 55.43%, in the inner canopy, respectively, compared to those of round-head canopied trees. For both canopy shapes, oil yield parameters had positive correlations with light intensity and temperature, but negative correlations with relative humidity, and the correlation coefficients between light intensity and temperature at different developmental stages and oil yield parameters in round-head canopies were greater than in the open-center canopies. Additionally, regression equations between the single microclimatic factor in different developmental periods and oil yield parameters could be used to estimate the latter in the two canopy shapes. The optimum light conditions for open-center and round-head canopy shapes were 916–1893 and 1108–1259 μmol·m2·s−1, respectively. Overall, the open-center canopy had a more desirable microclimate and a more uniform microclimate distribution, especially the light intensity, which contributes to high uniform fruit quality parameters. Thus, an open-center canopy is the desirable shape in C. oleifera production.