Changes in growth and soil microbial communities in reciprocal grafting clones between Populus deltoides males and females exposed to water deficit conditions

Abstract

& Key message Our findings highlight that male-rooted clones (M/M and F/M) of Populus deltoides are more water-deficit tolerant than female-rooted clones (F/F and M/F), as shown by a smaller decrease in total biomass and net photosynthetic rate in the male-rooted clones. & Context It has been reported that graft clones (female scion and male rootstock) in poplars may be an option to mitigate the effects of water deficit on plants. However, the extent to which grafting mitigates the effect of soil water deficit on soil microorganisms remains poorly understood. & Aims The research was designed to investigate the effects of soil water deficit on plant growth, soil microbial communities, and soil enzymatic activities of the reciprocal graft clones of P. deltoides. & Methods Four different graft clones (female shoot scion and female rootstock, F/F; male shoot scion and female rootstock, M/F; male shoot scion and male rootstock scion, M/M; and female shoot scion and male rootstock, F/M) in P. deltoides were used. Two watering regimes, irrigation and soil water deficit (i.e., non-irrigation conditions, natural levels of precipitation) were included in the experiments. The microbial community structure was quantified using phospholipid fatty acid. & Results Under water deficit, the decreases in total biomass, net photosynthetic rates, and leaf nitrogen content were more evident in M/M and F/M than in F/F and M/F. Bacterial phospholipid fatty acids (PLFAs) and actinomycetal PLFAs remained unaffected in the four graft clones. In contrast, during soil water deficit, fungal PLFAs were higher in M/M and F/M soil coincided with higher extracellular activities of β-1,4-N-acetyl-glucosaminidase and leucine aminopeptidase. & Conclusion Male-rooted clones (M/M and F/M) are more tolerant to water deficit than female-rooted clones (F/F and M/F). It is possible that the better performance of M/M and F/M, when exposed to water deficit, is associated mainly with higher fine root activity, greater specific root length and root/shoot ratio as well as increased fungal PLFAs.

Effects on major edaphic properties across various contexts: light drought vs. extreme drought

“…Extreme drought diminished the diffusion of soluble substrates in the soil and degraded the microbial migration rate, which could lead to diminish the microbial activity and enzyme activity (Bastida et al, 2006;Tietema et al, 2008). Furthermore, drought lowed acidic soil pH levels (Liu et al, 2019), and elevated alkaline soil pH levels (Deng et al, 2021), soil pH drove spatial distribution of soil bacteria (Chu et al, 2010;Fierer and Jackson, 2006;Jesus et al, 2009), whereas fungi were more adaptable to pH changes (Lauber et al, 2008). Our research proposed that droughts enhanced the soil F:B ratio and soil pH, and they had a signi cant positive correlation.…”

Grafting enhances plants drought resistance: Current understanding, mechanisms, and future perspectives

“…Therefore, aquaporins and their related genes need further exploration in grafted plants under drought stress. Furthermore, the root’s water and nutrient uptake ability was improved in the grafted poplars, which may be related to the high relative abundance of rhizosphere fungi ( Liu et al., 2019 ).…”