Abstract:[Objective] The objective of the study is to explore the effect of monosodium glutamate wastewater manure(hereinafter referred to as manure) mixed with inorganic fertilizer on the root absorption characteristics and humus composition of rhizosphere soil of watermelon(Citrullus lanatus).[Methods] The present study was conducted to determine the effects of different treatments, i.e. CK(control, no fertilization); N100(pure urea, hereinafter referred to as inorganic fertilizer); M10N90(the proportion of manure and inorganic fertilizer is 10% and 90%); M30N70(the proportion of manure and inorganic fertilizer is 30% and 70%) and M50N50(the proportion of manure and inorganic fertilizer is 50% and 50%) on root activity, construction levels of root system, root morphological characteristics and root exudates, as well as humus composition in the rhizosphere soil of watermelon.[Results] The results indicated that in comparison to N100 treatment, M30N70 treatment significantly increased root activity, and promoted the root growth of watermelon. At the same time, M30N70 treatment also increased the total root length, root surface area, specific root surface area, root volume and root tip number, while the root average diameter obviously decreased. The total root length in the M30N70 treatment increased by 74.63%, 40.84%, 28.41% and 19.37%, and the specific root surface area was increased by 39.42%, 30.82% and 20.89% compared to the treatments of CK, N100, M10N90 and M50N50, respectively. In addition, M30N70 treatment obviously increased the contents of root exudates and humic acid, and increased the ratio of humic acid to fulvic acid, showing 137.36%, 47.95% and 33.33% increase in humic acid content compared with the treatments of CK, N100 and M10N90, respectively. However, in M10N90 and M50N50 treatments, less effects was observed than that in M30N70 treatment.[Conclusion] Monosodium glutamate wastewater mixed with inorganic fertilizer, especially M30N70 treatment, is beneficial to the root absorption characteristics and humus composition in the rhizosphere soil of watermelon, and it is recommended as the suitable fertilization proportion in the practice.