Abstract
Rhizosphere microbiota are conducive to soil nutrient cycling for plant growth. Long-term and excessive application of chemical fertilizer is harmful to agriculture. Seaweed extract is a good organic substitute for rhizosphere ecosystem and plant growth. We supplemented 5‰ seaweed extract powder to chemical fertilizer, and then studied its effect on rhizosphere bacteria of japonica rice (Oryza sativa L. subsp. japonica). In a short-term experiment, we compared the changes in rhizosphere bacteria among four treatments, i.e., no fertilizer (T1), chemical fertilizer only (T2), chemical fertilizer with 5‰ seaweed extract (T3), and less chemical fertilizer with 5‰ seaweed extract (80% of that of T3) (T4). Results show that seaweed extract supplement could affect the bacterial community in tillering and heading stages; the α-diversity of rhizosphere bacteria in the heading stage was obviously improved. In addition, seaweed extract supplement improved significantly the content of nitrate nitrogen (N), available phosphorus (P), and available potassium (K) in rhizosphere soil in the tillering stage, and, finally, increased the rice yield and quality mildly. Therefore, the seaweed extract supplement is shown to be a potential strategy to enrich the diversity of rhizosphere bacteria, which enhanced soil nutrient level, increased rice yield and quality, and also saved the use of chemical fertilizer.
Highlights
The rhizosphere is an important supporting area for complicated interaction among the plant, soil, and microorganism
1,240,607 effective tags were obtained from 27 samples, clustered with 97% identity, and had chimeric sequences removed to produce 9813 operational taxonomic units (OTUs)
Compared to that of T2, soils that were treated with seaweed extract supplement (T3) showed increases in relative abundance of Actinobacteria, Firmicutes, and Chloroflexi by 41.42%, 21.17%, 12.59%, respectively, while there was a decrease in Acidobacteriota by 19.76%
Summary
The rhizosphere is an important supporting area for complicated interaction among the plant, soil, and microorganism. Rhizosphere microorganisms contribute to the release of organic acids, amino acids, carbohydrates, and secondary metabolism products [1,2]. It is reportedly responsible for the degradation and transformation of organic matter and concomitant release of nutrient [3], the generation of plant hormone [4], and the improvement of plant mineral nutrition and formation of soil aggregate [5]. Nutrient inputs to cultivated soils could alter microbial community structure and activities, which could greatly influence their environmental fate [9]. It is important to study the effect of fertilization on rhizosphere microbes
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