Effect of rhizosphere aeration by subsurface drip irrigation with tanks on the growth of 'Red Globe' grape seedling and its absorption, distribution and utilization of urea-15N

Aerated irrigation can promote plant growth, increase yield and improve fruit quality, but the study on the effect of aeration irrigation on the absorption and metabolism of plant urea is relatively few. In this study, subsurface drip irrigation (SDI) with tanks technique and 15N tracer techniques were utilized to investigate the effect of the rhizosphere aeration treatment on plant growth and urea absorption, distribution and utilization of 'Red Globe' grape seedlings. The results indicated that the net photosynthetic rate, stomatal conductance and transpiration rate of the leaves increased with the aeration treatment in the same irrigation period. Soil urease and nitrate reductase of the aeration treatment were significantly higher than those from the no aeration treatment at the first, third, and fifth day after irrigation, but the difference was not significant between seedlings of the two treatments at the seventh and ninth day after irrigation. However, experiments that determined the absorption and utilization of the urea-15N in plants indicated that the Ndff values of the plant parts were significantly lower with aeration than those without aeration (CK).The distributions of 15N in these two treatments in the same parts were distinctly different except for the leaves, and the 15N utilization rate (3.46%) of plants with aeration was noticeably obviously lower than that of the CK plants (9.63%).The results showed that when urea was used as the nitrogen source, the rhizosphere aeration treatment performed by SDI with tanks reduced the ability of the organs to absorb nitrogen, and altered the distribution of nitrogen in the different parts of the grape plants. Therefore, we concluded that rhizosphere aeration could improve plant photosynthesis and soil urease and nitrate reductase activity, but it had negative effects on urea uptake, indicating that rhizosphere aeration and urea application did not have synergistic effects.These results suggest that it is not suitable for aeration irrigation when urea is used as nitrogen fertilizer.