Effects of Oxygation with Micro-nano Air Bubbles on Yield, Fruit Quality and Irrigation-water Use Efficiency of Muskmelon

Abstract

【Background】Intensive facility agriculture production could densify soil and create hypoxia, thereby toxifying roots and ultimately leading to yield reduction. Aerating subsurface drip irrigation can oxygenate subsoil and improve soil ventilation to ameliorate such detrimental impacts. However, traditional mechanically aerated subsurface irrigation and chemically aerated subsurface irrigation could produce large air bubbles in soils, which can escape the soil along pores adjacent to the roots, compromising oxygation efficiency as a result. Improving aerating irrigation efficiency is an issue remaining to be resolved, one way in which is to fertigate using water rich in micro-nano air bubbles. Its efficacy, however, is impacted by many factors. 【Objective】The purpose of this paper is to study the effects of fertigation frequency and fertilizer amount used in fertigation on yield and quality of muskmelon under surface-drip oxygation with micro-nano air bubbles (MNBW), from which we proposed a suitable MNBW for facility cultivation of muskmelon. 【Method】The experiment consisted of two irrigations: one was MNBW and the other one was conventional irrigation with groundwater (CGW). Added to the MNBW were three irrigation frequencies: once every three days (P3), one every seven days (P7) and once every 15 days (P15), and two fertilizations: 100% (F100) and 80% (F80) of the fertilizers used by local farmers. In each treatment, we measured the fruit quality and irrigation-water use efficiency (IWUE) of the muskmelon. 【Result】The MNBM can reduce fertilizer application by 20% while in the meantime improving the yield by up to 54.6% and the IWUE by up to 67.6%. It also increased the content of soluble sugar, vitamin C and soluble solids in the fruits all at significant level. Irrigation frequency affected the efficacy of MNBW too, with the frequency P3 improving fruit quality. Compared to P15, P3 increased soluble solid and vitamin C by 21.5%~28.0% and 11.6%~14.8%, and stem thickness by 8.6%~14.2%, respectively. 【Conclusion】The optimal MNBW for the muskmelon is irrigating after every three days coupled with a fertigation using 80% of the fertilizer applied in the conventional fertigation. It is worth pointing out that if incomplete composted manure is used as base fertilizer, MNBW could inhibit muskmelon growth and reduce its yield, quality and IWUE as a result. Our results have important implications for facility production of muskmelon.

Keywords

• oxygation micro-nano air bubbles
• subsurface drip irrigation
• facility muskmelon production
• fruit yield and quality
• irrigation water use efficiency