Supplementary irrigation with ceramic emitter promotes Platycladus orientalis growth by enhancing soil bacterial α diversity under extremely high-temperature

Abstract

Although afforestation plays a crucial role in reducing global warming, the survival of forests is increasingly threatened by the regular occurrence of extremely high-temperature (EHT) events. Currently, an innovative technology known as supplementary irrigation with ceramic emitter (SICE) was developed to maintain soil moisture and promote tree growth under EHT. Nevertheless, it is still unclear how SICE affects tree growth under EHT. In this study, a field experiment was conducted to monitor the growth status of Platycladus orientalis (P.orientalis) and analyze the physicochemical properties of the rhizosphere under EHT with SICE. The α diversity of soil bacterial communities in the rhizosphere was analyzed using high-throughput sequencing of 16 S rRNA and 18 S rRNA genes. The results indicated that SICE consistently maintained the soil water content (SWC) range from 0.26 cm³ cm⁻³ to 0.54 cm³ cm⁻³ during the entire experimental period under high-temperature conditions. Furthermore, SICE marginally increased the relative abundance of Actinobacteriota, Acidobacteriota, Chloroflexi and Methylomirabilota by 1.61 %, 0.99 %, 2.33 % and 4.31 % compared with CK, respectively. In comparison, SICE significantly decreased the relative abundance of Proteobacteria by 11.93 %, including α-Proteobacteria and γ-Proteobacteria, respectively. Additionally, SICE improved the absorption of SOC and nitrogen nutrients in P.orientalis, which were 41.20 %, 41.17 % and 28.35 % higher than CK, respectively and had a significant positive effect on the conversion from SOM to SOC and accelerated the absorption of soil nutrients for P.orientalis under EHT, resulting in increasing stem diameter, tree height, crown breadth and branch length of P.orientalis by 104.80 %, 81.67 %, 47.59 % and 94.68 %. Overall, this work provides direct evidence that SICE promoted tree growth by indirectly increasing α diversity of soil bacterial communities (e.g. Chloroflexi and Methylomirabilota) in the rhizosphere and accelerating the absorption of soil nutrients under EHT during the study period, which could offer a promising implication for advancing and implementing SICE technology under EHT.