Dynamic changes in bacterial communities in the recirculating nutrient solution of cucumber plug seedlings cultivated in an ebb-and-flow subirrigation system

Abstract

Ebb-and-flow subirrigation systems are highly efficient, water-saving and environmentally friendly. However, one concern with these recirculating systems is the possible transmission of plant pathogens. Here, through 16S rRNA-targeted Illumina sequencing, the bacterial dynamics in a recirculating nutrient solution were characterized for cucumber plug seedlings cultivated in an ebb-and-flow system in summer and winter. Both the bacterial number and diversity in the nutrient solution increased immediately after the first irrigation cycle; then, these values were gradually stable with recirculating irrigation. In summer and winter, different bacterial compositions and changing patterns were observed. In summer, the predominant genera in the nutrient solution included Comamonas, Pseudomonas, Acinetobacter, Reyranella, Sphingobium, Bradyrhizobium, Sphingomonas, and Acidovorax. Of those genera, during recirculating irrigation, the relative abundance of Bradyrhizobium gradually decreased, whereas those of Pseudomonas, Reyranella, Sphingobium, Sphingomonas, and Acidovorax gradually increased. In winter, the bacterial communities were mainly composed of Nevskia, Bosea, Sphingobium, Acidovorax, Pseudomonas, and Hydrocarboniphaga. Of those genera, the relative abundance of Bosea, Sphingobium, and Acidovorax showed an increasing trend, whereas those of Nevskia and Hydrocarboniphaga decreased overall. Furthermore, in both summer and winter, no plant pathogenic bacteria on cucumber could be detected; however, some potentially beneficial bacteria, including Comamonas testosteroni, Acinetobacter baumannii, Pseudomonas aeruginosa, P. koreensis and Sphingobium yanoikuyae, colonized the nutrient solution and exhibited increased relative abundances during irrigation. The colonization of these bacteria might facilitate the plant growth promotion. Inoculation of the microbes from the effluent nutrient solution also promoted the growth of cucumber seedlings, but did not lead to any disease. The present data elucidate the bacterial dynamics in a cucumber cultivation ebb-and-flow system and provide useful information for biological control during cucumber seedling production.

Ebb-and-Flow Subirrigation Improves Seedling Growth and Root Morphology of Tomato by Influencing Root-Softening Enzymes and Transcript Profiling of Related Genes

“…These responses have been ascribed to a more uniform watering [52], lower water stress, and to an improved nutrition status due to a higher nutrient retention in the growing medium [53] in sub-irrigated when compared to top sprinkle-irrigated tomato plants. Recent studies on tomato and cucumber show that under ebb-and-flow irrigation, the plant growth potential is strong, the growth period is advanced, and the bottom water supply can enhance the quality of plug seedlings [54,55]. In this experiment, it was found that compared with the traditional top sprinkle irrigation, the ebb-and-flow irrigation treatment could significantly increase the stem diameter, as well as the root dry and fresh weight of tomato seedlings, indicating the importance of the ebb-and-flow irrigation strategy.…”

Proper irrigation amount for eggplant cultivation in a solar greenhouse improved plant growth, fruit quality and yield by influencing the soil microbial community and rhizosphere environment

“…Studies have shown that an ebb-and-flow subirrigation system can be used to increase water use efficiency in greenhouse cucumber planting; the enrichment of specific fungi increases under the nutrient solution, but it does not increase the cucumber disease rate (Dong et al, 2020). Specific microorganisms can promote crop resistance to water loss (Rajabi-Khamseh et al, 2020) but may also affect plant root development (Bennett and Klironomos, 2019).…”

Effect of Cucumber Continuous Monocropping on Traditional Chinese Medicine Residue through Analysis of Physicochemical Characteristics and Microbial Diversity

“…Soilless plant cultures, such as those of Plagiomnium acutum [1], cucumber [2], slippery mushroom [3], cherry tomato [4], and lettuce [5], are widely applied in vegetable production. The advantages of soilless plant culture include not only increasing yield but also satisfying specific nutrient requirements [6,7].…”