Effects of drought stress on the physiology, photosynthesis, and anatomical structure of container and bareroot plants of two Camellia oleifera cultivars

Abstract

Background Oil-tea tree (Camellia oleifera Abel) is an important high-quality edible oil tree species in China and is also a pioneer afforestation tree species in hilly red soil areas in southern China. It can grow and bear fruit on relatively barren mountains. Although C. oleifera has strong adaptability, long-term drought still affects its normal growth and even causes plant death, which has a serious impact on the afforestation industry. Results Under drought stress, the leaf edge of the C. oleifera curled, and the leaf yellowed, drooped, and even withered and died. Moreover, the accumulation of catalase (CAT), soluble sugar (SS) and abscisic acid (ABA) gradually increased, and the CAT activity and SS content increased more in the bareroot-stage seedlings than in the container-stage seedlings. We observed that, compared with the CK treatment, the drought treatment (10 DAT) significantly reduced the net photosynthetic rate (Pn), transpiration rate (E), maximum photochemical efficiency (Fv/Fm), and actual photochemical and quantum efficiency (FPSII). The Pn in the ‘HS-CS’, ‘HS-BS’, ‘HJ-CS’ and ‘HJ-BS’ treatments decreased by 126.68%, 112.33%, 126.08% and 117.22%. We also found that the drought resistance of bareroot-stage plants was greater than that of container-stage plants. After rewatering under drought stress, multiple indices of C. oleifera were greater than normal, and physiological characteristics and anatomical structure were positively related to compensation or overcompensation. At the same time, we also found that the recovery ability of C. oleifera ‘Huashuo’ was greater than ' C. oleifera ‘Huajin’. Conclusion The results showed that drought led to yellowing and shrinkage of C. oleifera leaves, reduces photosynthetic efficiency, and ultimately affected the normal growth of C. oleifera materials. In order to prevent this situation, C. oleiferashould reduce drought stress or timely rehydration to maintain the stability of leaf structure, morphology and function. In addition, we found that the drought resistance of bareroot seedlings was greater than that of container seedlings, and the recovery ability of C. oleifera ‘Huashuo’ was stronger than that of C. oleifera ‘Huajin’.