The Effect of Rotational Cropping of Industrial Hemp (Cannabis sativa L.) on Rhizosphere Soil Microbial Communities

Abstract

Crop rotation affects soil properties and soil microbial diversity and structure. Currently, it is not well understood how soil microbial diversity changes following different crop rotation systems of industrial hemp, an ancient and economically important crop. Therefore, these changes were analyzed in this study. Our results showed that different rotation systems significantly affected the wilt disease incidence, plant height, yield, soil physicochemical properties and soil microbial communities in the greenhouse. The rotation systems used in this study significantly reduced the plant mortality and increased the yield compared with a monoculture system. The levels of alkaline hydrolysis and available phosphorus in the soil decreased significantly compared with a monoculture cropping system. Using MiSeq high-throughput sequencing, we showed that the soil diversity and number of bacteria and fungi were significantly higher for rotation systems and controls compared to the monoculture system. The relative abundance of pathogens increased with a monoculture system. Redundancy analysis suggests that soil properties may also affect the soil microbial composition. Taken together, different rotation systems used in this study significantly decreased the disease incidence, increased plant yields and increased soil microbial diversity compared with monoculture for industrial hemp. We believe that applying these rotation systems is an efficient and eco-friendly approach to control soil borne pathogenic diseases and increase floral yields.

Microbiome Diversity and Variations in Industrial Hemp Genotypes

“…Similarly, Sphingomonas and Methylobacterium are highly associated with hemp cultivars and have been shown to promote plant growth and pathogen resistance 6 . Sphingomonas is highly abundant in hemp plants ( Barnett et al 2020, Tang et al 2022) and in some cases speci cally the phyllosphere 56 . Recently, a potentially novel strain of Sphingomonas was isolated from Cannabis sativa 57 .…”

Changes in Rhizosphere Soil Nutrients, Enzyme Activities, and Microbial Communities at Different Stages of Industrial Hemp Development

“…The first part was air-dried and passed through 1 and 0.25 mm sieves to determine the pH, SOM, AN, AP, AK, electrical conductivity (EC), and copper (Cu) and zinc (Zn); the second part was stored at 4 • C for the analysis of soil enzyme activity and the number of microorganisms within one week; the third part was stored at −20 • C for DNA high-throughput sequencing within one month. After grinding the soil sample and passing it through a 2 mm sieve, its physicochemical properties were obtained using the earlier research methods [19]. A calibrated pH meter was used to measure the pH value; the K 2 Cr 2 O 7 colorimetric method was used to measure SOM; the alkali diffusion method was used to measure AN; a spectrophotometer was used to measure AP after extraction with 0.5 mol/L NaHCO 3 ; the ammonium acetate extraction flame photometric method was utilized to measure AK; the conductivity method was utilized to measure EC.…”

“…In contrast, the microecological imbalance in the rhizosphere is the primary reason for the increase of pathogenic bacteria, thus reducing crop yield [17,18]. Currently, the research on rhizosphere microorganisms of industrial hemp mainly focuses on how the various tillage measures impact the soil microbial community and its diversity [19,20]. However, rhizosphere nutrients primarily come from soil supply, and rhizosphere microorganisms participate in the nutrient demand of crops in different growth periods, essentially a process of interaction of soil, microorganisms, and yield [21,22].…”