Effects of Dung Beetle-Amended Soil on Growth, Physiology, and Metabolite Contents of Bok Choy and Improvement in Soil Conditions

The role of dung beetles has been extensively reported in successful plant growth, soil quality improvement, and soil reclamation. Still, its effects on plant physiology and metabolism are seldomly reported. This research evaluates the dung beetle’s ( Catharsius molossus L.) effects on the growth, physiology, and metabolite content of bok choy and subsequent improvement in soil physicochemical properties. A 6 months pot experiment was carried out on silty-clay type soil which contained three soil-applied amendment groups, i.e., dung + beetles, cow dung, and control (unamended). Various soil and plant-related parameters were measured with UV, SEM, EDS, etc. using standard methods. Results showed that the dung + beetles group improved soil nutrient status, including nitrogen, phosphorous, potassium, magnesium, and calcium, and drastically decreased soil density, pH, and electrical conductivity compared with the cow dung and control groups. Plants under dung + beetles– and cow dung–amended soil significantly increased total leaf sugar, vitamin C, polyphenols, total protein, and amino acids compared with control plants. A significant increase in IAA, GA3, and ZR, while a significant decrease in ABA was also noted in the dung + beetles and cow dung group, as compared with the control. Furthermore, dung + beetles applications significantly increased the net photosynthetic rate, stomatal conductance, and chlorophyll content when compared with the cow dung and control group. It is concluded that dung + beetles has significantly enhanced the growth, physiological process, and metabolite contents of bok choy. Application of this amendment can be an effective and sustainable strategy to improve crop yields and nutrient status.