Effects of different substrate addition on growth status of submerged
plants and rhizosphere microorganisms in sediments
Abstract
Sediment is an important factor affecting the growth of aquatic plants.
The effects of sediment substrate application on aquatic plants and
rhizosphere microorganisms are poorly understood. In this study, we
investigated the effects of four substrates (maifanite, vermiculite,
ceramsite, and volcanic rock gravels) on the growth and rhizosphere
microorganisms of Vallisneria natans (Lour.) Hara (V. natans) by
Illumina high-throughput sequencing technology. The results showed that
the maximum increase in plant height (20.5 cm) was observed in
vermiculite group during the whole experiment period (day 1-40). The
root activity of V. natans in the four treatment groups
(34.78~85.28 U g-1) was higher than that in CK (28.48 U
g-1). The maximum mean total chlorophyll content in maifanite group was
2.40 mg g-1, followed by vermiculite group (1.1 mg g-1). Catalase
activity in leaves in all the treatment groups except maifanite group
was significantly different during different periods (P<0.05).
The maximum mean superoxide dismutase activity in maifanite group was
273.78 U g-1 min. All four treatment groups exhibited faster reduction
in malondialdehyde content in leaves than CK group, indicating that
substrate addition could rapidly enhance plant stress adaptation.
Redundancy analysis showed that root vitality was positively correlated
with biomass, plant height, and root length, and that different
substrates had different effects on the growth of V. natans. Dominant
bacterial phyla in rhizosphere sediments in each group were roughly the
same, and the top two bacterial phyla were Proteobacteria and
Chloroflexi. Relative abundance of Desulfobacterota and Nitrospirota
were higher in four treatment groups than in CK group. Our results
showed that substrate addition, especially maifanite, into lake
sediments could promote the growth of submerged plants and improve the
rhizosphere microbial community structure. Our findings provide
theoretical basis for lake sediment improvement and aquatic vegetation
restoration.