Influence of Paclobutrazol on the Growth and Photosynthesis of Sequoia sempervirens Seedlings

Abstract

Paclobutrazol (PAC), as a commonly used plant regulator, has the important function of improving the plant’s stress resistance. Sequoia sempervirens Endl. is a large caliber, fast-growing timber species and one of the world’s five major landscaping tree species. This study researched the effects of spraying PAC on the growth and photosynthetic activity of S. sempervirens seedlings. The results showed the plant height and the plant crown diameter were decreased significantly with the increase in PAC concentration (500 – 3,000 mg·dm−3). However, the ground shoot diameter, net photosynthetic rate, stomatal conductance, inter-cellular CO2 concentration, transpiration rate, actual photochemical quantum yield, and photosynthetic electron transport rate all showed the trend of increasing first reaching the maximum at 2,000 mg·dm−3 and then decreased. Water use efficiency showed the opposite trend. Spraying 2 times was better than once. The conclusion suggests that PAC can protect the photosynthetic activity and improve the resistance of S. sempervirens seedlings under natural cooling and draught in autumn and winter.

Application of Paclobutrazol to Mitigate Environmental Stress of Urban Street Trees

“…Application of paclobutrazol can reduce tree water loss, resulting in improved tree water status based on reduced leaf area [12][13][14]. The production of smaller leaves and more compact tree crowns often results in increased foliar chlorophyll concentration (measured directly or through Soil Plant Analysis Development chlorophyll index (SPAD index)) and increased photosystem efficiency or photosynthetic rate [15][16][17][18][19][20][21][22]. Recent studies have also shown that paclobutrazol can enhance production of secondary pigments and molecules that can reduce the impacts of oxidative stresses such as drought or exposure to salinity [23,24].…”

Dynamic Changes in Endogenous Hormones in Terminal Buds from Different Crown Positions in Sequoia sempervirens (Lamb.) Endl

“…Practices have also proved this point in reverse. The application of the growth inhibitor paclobutrazol and calcine during autumn could inhibit significantly the growth of redwood branches and improve the cold resistance of the tree (Ju et al, 2019(Ju et al, , 2020.…”

“…During the process of cultivation in autumn and winter, its terminal buds were lost and, the next spring, the lateral buds sprouted into new branches. Considering the habitable environment of S. sempervirens and the living environment in Xuzhou (Ju et al, 2019;Zhang et al, 2015), the causes of terminal bud death were analyzed. There are three possible explanations.…”