Rhizosphere water and nitrogen regulation in early growth stage of cucumber

Improving water and nitrogen (N) management for reducing water and N losses, and enhancing water and N use efficiency (NUE), is very important for vegetable production, especially in early growth stage when the crop roots are not well developed. In this study, controlled release fertilizers (CRFs) and superabsorbent gel were used in seedling substrate of cucumber as a strategy of rhizosphere water and N management. The effects of such management on plant growth, water and nutrients uptake in both seedling nursery period and post-transplanting vegetative growth stage were investigated. The results indicated that CRFs applied in seedling substrate, not only significant improved the growth of cucumber seedlings, but also increased substrate nutrient content during transplanting period. Measured data shown that each seedling could carry 186.4－201.9 mg N into rhizosphere at transplanting time while controlled N release account for 90.0%－93.6%. Because of these high content of controlled release nitrogen in the rhizoshpere, compare with conventional practice, rhizosphere water and nitrogen management could save 80% of basal N fertilizer application at transplanting without any reduction of plant growth during vegetative period, meanwhile, N leaching loss was reduced significantly. Superabsorbent gel applied into seedling substrate obviously decreased water leakage in seedling nursery period, but no significant effects on N leaching mitigation and plant dry matter accumulation were observed. In conclusion, rhizosphere regulation which using CRFs and superabsorbent gel in seedling substrate was demonstrated to be a simple and efficient approach for N and water management in early growth stage of transplanted-vegetable.