Effects of Drought Stress on the Morphological Structure and Flower Organ Physiological Characteristics of Camellia oleifera Flower Buds

Investigations on the impact of drought stress on the reproductive growth of C. oleifera have been relatively limited compared to the extensive research conducted on its nutritional growth. To study the effects of drought stress on the growth and development of C. oleifera flower buds, we investigated the effects of drought stress on the bud anatomical structure, relative water content, relative electrical conductivity, antioxidant enzyme activity, osmoregulation substance content, and hormone contents of C. oleifera using 4-year-old potted plants (‘Huaxin’ cultivar) as experimental materials. We observed C. oleifera flower bud shrinkage, faded pollen colour, shortened style length, decreased relative water content, increased relative electrical conductivity, and decreased pollen germination rate under drought stress. As the stress treatment duration increased, the malondialdehyde (MDA), soluble sugar (SS), soluble protein (SP), and proline (Pro) contents, as well as peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT) activities increased. Moreover, the levels of the plant hormones indole acetic acid (IAA) and cytokinin (CTK) increased, whereas those of salicylic acid (SA) and jasmonic acid (JA) decreased, and those of abscisic acid (ABA) and gibberellin a(3) (GA(3)) first increased and then decreased. Compared to the control group, the drought treatment group exhibited stronger antioxidant capacity, water regulation ability, and drought stress protection. These results indicate that C. oleifera is adaptable to drought-prone environments. The results of this study provide a theoretical basis for the evaluation of drought resistance in C. oleifera, as well as the development of water management strategies for cultivation.