Comparison between the vegetative and fruit characteristics of 'Orah' (Citrus reticulata Blanco) mandarin under different climatic conditions

Abstract

There is little information on the impact of agrometeorological factors on late-maturing citrus varieties. Here, several indices of the agronomic and physiological quality of ‘Orah’ mandarin fruit during three consecutive years were studied along with the metabolic traits under different climatic conditions. The average yield was high in the dry-hot valleys. However, the yield and yield efficiency were the lowest in areas with humid-sparse sunlight. The fruit in the dry-hot valleys and south subtropical regions were large and had seed number beyond 15.38, while the fruit in areas with humid-sparse sunlight were reddish and had few seeds. A statistical analysis of the total soluble solids (TSS) within three years showed that the fruit with highest amounts were in the mid-subtropical regions (≥ 14.03%), followed by the dry-hot valleys. The fruit of tropical rainforest areas (titratable acid ≥ 0.67%) were considered to contain the highest percentage of acid. A metabolic analysis showed that the contents of several metabolites, such as malic acid and proline, varied noticeably across different climatic regions. Correlation and factor analyses of the agronomic, physiological and metabolic indices with meteorological parameters revealed that the fruit yield and quality in the dry-hot valleys were superior to those observed in other regions and that temperature, in particular at the degreening and overwintering stages, along with the hours of sunshine significantly resulted in a considerable degree of variation in the indicators of fruit heterogeneity, such as weight, TSS, malic acid and proline.