A hydroponic experiment was conducted to study the effect of partial replacement of NO-3-N by NH4+-N on the seedling growth and organic acid content of tomato (Lycopersicon esculentum Mill.). A completely randomized d...A hydroponic experiment was conducted to study the effect of partial replacement of NO-3-N by NH4+-N on the seedling growth and organic acid content of tomato (Lycopersicon esculentum Mill.). A completely randomized design was established with three replications and five treatments, i.e., NO-3-N/NH4+-N of 100/0, 75/25, 50/50, 25/75 and 0/100. Results showed that 25% replacement of NO3--N by NH4+-N significantly (P = 0.05) improved fresh and dry weight, revealing that a proper percentage of NH4+-N was important for tomato nitrogen nutrition. This could increase the plant growth even though tomato was a crop that preferred nitrate nutrition. Also an increase in the proportion of NH4+-N in the nutrient solution led to a significant decrease (P = 0.05) in malate, citrate and fumarate. However, the 25% NH4+-N plus 75% NO3--N treatment had no significant effect (P = 0.05) on the 2-ketoglutarate, succinate or oxalic acid content, showing that only some organic acids in tomato plants were affected. Only pyruvate increased significantly (P = 0.05), and it only increased for 25% and 50% replacement of NO3--N by NH4+-N. Metabolism of these organic acids, especially malate, citrate and fumarate, should be further studied at the molecular level in vegetables applied with different nitrogen forms.展开更多
Field lysimeter method was employed to investigate the downward movement and leaching of N applied to summer corn (Zea may L.) on dryland soil in Beiling. A N-fertilizer (120 kg N hm-2) and a control treatment were ar...Field lysimeter method was employed to investigate the downward movement and leaching of N applied to summer corn (Zea may L.) on dryland soil in Beiling. A N-fertilizer (120 kg N hm-2) and a control treatment were arranged for the study. Soil solution was collected at depths of 20, 40, 60, 120 and 170 cm,while leachate was collected at the bottom (200 cm) of the lysimeter. The results showed that the downward movement of NO3-N in soil profile was greatly affected by rainfall pattern. The peak of leached NO3-N from both treatments coincided with the peak of the rainfall. In addition, leached NO3-N from both treatments and rainfall were significantly correlated (P<0.05). The amount of leached NO3-N was not great in the N-fertilizer treatment. The results also suggested that N fertilization could cause NO3-N contamination of groundwater during the rainy season.展开更多
基金Project supported by the National Natural Science Foundation of China (No. 30270790) and National Post-doctoral Foundation of China (No. 2003033494).
文摘A hydroponic experiment was conducted to study the effect of partial replacement of NO-3-N by NH4+-N on the seedling growth and organic acid content of tomato (Lycopersicon esculentum Mill.). A completely randomized design was established with three replications and five treatments, i.e., NO-3-N/NH4+-N of 100/0, 75/25, 50/50, 25/75 and 0/100. Results showed that 25% replacement of NO3--N by NH4+-N significantly (P = 0.05) improved fresh and dry weight, revealing that a proper percentage of NH4+-N was important for tomato nitrogen nutrition. This could increase the plant growth even though tomato was a crop that preferred nitrate nutrition. Also an increase in the proportion of NH4+-N in the nutrient solution led to a significant decrease (P = 0.05) in malate, citrate and fumarate. However, the 25% NH4+-N plus 75% NO3--N treatment had no significant effect (P = 0.05) on the 2-ketoglutarate, succinate or oxalic acid content, showing that only some organic acids in tomato plants were affected. Only pyruvate increased significantly (P = 0.05), and it only increased for 25% and 50% replacement of NO3--N by NH4+-N. Metabolism of these organic acids, especially malate, citrate and fumarate, should be further studied at the molecular level in vegetables applied with different nitrogen forms.
文摘Field lysimeter method was employed to investigate the downward movement and leaching of N applied to summer corn (Zea may L.) on dryland soil in Beiling. A N-fertilizer (120 kg N hm-2) and a control treatment were arranged for the study. Soil solution was collected at depths of 20, 40, 60, 120 and 170 cm,while leachate was collected at the bottom (200 cm) of the lysimeter. The results showed that the downward movement of NO3-N in soil profile was greatly affected by rainfall pattern. The peak of leached NO3-N from both treatments coincided with the peak of the rainfall. In addition, leached NO3-N from both treatments and rainfall were significantly correlated (P<0.05). The amount of leached NO3-N was not great in the N-fertilizer treatment. The results also suggested that N fertilization could cause NO3-N contamination of groundwater during the rainy season.
