Effects of nanobubble in subsurface drip irrigation on the yield, quality, irrigation water use efficiency and nitrogen partial productivity of watermelon and muskmelon

. Improving crop yield and quality, as well as water and fertilizer use efficiency in a synergetic manner is a substan tial challenge. It involves limits to the sustainable development of protected agriculture. Here, we propose a new irrigation method using nanobubble water through subsurface drip irrigation to improve the agricultural performance of crops. Experiments were conducted to evaluate the effects of nanobubble water on growth, yield, quality, irrigation water use efficiency, and the nitrogen partial productivity of greenhouse watermelon and muskmelon. The results showed that in nanobubble water conditions, reducing the amount of irrigation or fertilization by 20% had no negative impacts on the tested crops, instead there were increases in the yield, quality, irrigation water use efficiency and nitrogen partial productivity of the two crops. When irrigation and fertilization were both decreased by 20%, the irrigation water use efficiency was improved by 82.6 and 70.2%, the nitrogen partial productiv ity increased by 68.9 and 30.4%, vitamin C increased by 50.1 and 66.7% which was significant. This may be because nanobubble water reduced the redundant growth of crops, and promoted the bal ance between individual development and production. Moreover, nanobubble water finally achieved increased economic benefits by reducing the input of irrigation and fertilization. Therefore, we suggest that 80% irrigation and 80% fertilization with nanobubble water could be adopted for Cucurbitaceae in greenhouse condi tions. This method also has reference significance for reducing agricultural water input.