Effect Of Chilling Temperature On Chlorophyll Florescence, Leaf Anatomical Structure, And Physiological And Biochemical Characteristics Of Two Camellia Oleifera Cultivars

Camellia oleifera Abel. is an economically important tree that produces edible oils and flowers and fruits in late autumn and early winter. However, low temperatures lead to low yields because of the absence of normal pollination and fertilization. In this study, a pot experiment was conducted to understand the effects of temperature (6 degrees C, 25 degrees C, and control) on florescence, photosynthesis, physiological response, and anatomical structure in two Camellia cultivars (Hua Shuo and Hua. Xin) for 25 days. Low-temperature stress (6 degrees C) decreased net photosynthetic rate, transpiration rate, stomatal conductance, chlorophyll content, and maximum quantum yield of PSII photochemistry of the two cultivars. Initial fluorescence, leaf thickness, and soluble sugar and malondialdehyde contents increased in the low-temperature treatment compared to the normal temperature (25 degrees C). Low-temperature stress (6 degrees C) destroyed chloroplast morphology and structure. In addition, it inhibited the normal opening of Hua Xin and normal temperature promoted the growth of young fruits. However, the flowers of Hua Shuo bloomed, the stamens and pistils withered but did not fall off, and for the first time it was discovered that a significant amount of mucus appeared at the base of the flower under low temperature. The mechanism of secretion of the mucus is unknown and merits further investigation. In summary, these results suggest that C. oleifera has a high fruit setting rate under normal temperature. Low temperature, even 6 degrees C, significantly reduced photosynthetic efficiency and the fruit setting rate. In addition, Hua Shuo had better cold tolerance than Hua Xin, but young fruit of Hua Xin grew faster than Hua Shuo at the normal temperature. (C) 2020 Friends Science Publishers