Interactive effects of water and fertilization on biomass translocation and nitrogen uptake and utilization of winter wheat

Objectives In order to improve water and nitrogen use efficiencies of winter wheat, a research was conducted to examine photosynthetic partitioning and translocation in plant organs as well as the nitrogen uptake under different water–nitrogen levels.

Methods A field experiment was conducted for two years in Xinxiang City, Henan Province. Water supply was regulated as light, moderate and severe deficit levels, with corresponding water contents of 60%–65%, 50%–55%, and 40%–45% of the field capacity. Nutrient input levels were setup as high (N 240 kg/hm², P₂O₅ 240 kg/hm², K₂O 240 kg/hm²), middle (N 180 kg/hm², P₂O₅ 180 kg/hm², K₂O 180 kg/hm²) and low (N 120 kg/hm², P₂O₅ 120 kg/hm², K₂O 120 kg/hm²), respectively. Labeled ¹⁵N method was used to analyze the uptake, utilization and distribution of nitrogen in wheat plants as affected by water and fertilizer treatments.

Results A moderate level of water deficit could increase the remobilization of nitrogen from pre-anthesis reserves in vegetative organs to the grains under high fertilizer rate. The transfer amount of the pre-anthesis reserves for the light water deficit was the largest under middle nutrient input level. Under low fertilization level, the transfer rate and amount of pre-anthesis reserves in vegetative organs increased with the increase of the water deficit. Under all the three levels of fertilization, the contribution rates of the transfer amount from pre-anthesis reserves to grain yield increased with the increase of water deficit.

Conclusions The deficit irrigation could improve the redistribution of nitrogen and dry matter stored in vegetative organs before anthesis. The coupling of the deficit irrigation and fertilization could effectively control the nitrogen uptake and accumulation of winter wheat. The low N–P₂O₅–K₂O rate (120–120–120 kg/hm²) and light water deficit (60%–65% of field water capacity) is the optimum scheme for saving water and fertilizer, and achieving high yield and high efficiency under the experimental condition.