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
In this study, exogenous pre-harvest treatment of tomato plants with MeJA （Methyl Jasmonate） and chitosan was used to elicit lycopene biosynthesis and stimulate plant growth. Lycopene is a bright red carotene and ca...In this study, exogenous pre-harvest treatment of tomato plants with MeJA （Methyl Jasmonate） and chitosan was used to elicit lycopene biosynthesis and stimulate plant growth. Lycopene is a bright red carotene and carotenoid pigment found in tomatoes, carrots and other red fruits and vegetables. It is a powerful antioxidant that protects cells from damage and blocks cancerous cell growth. Many studies suggest eating lycopene-rich foods may be directly linked to reducing risk of several cancers, heart disease and stroke, hence there is a need to enhance its levels in tomatoes. Tomato seeds were soaked in MeJA and chitosan solutions of varying concentrations and then planted. The resulting plants were irrigated with the solutions used to soak the seeds, accordingly. The heights of the plants were recorded on a tri-weekly basis and HPLC （High Performance Liquid Chromatography） was used to analyze the effects of the MeJA and chitosan solutions on lycopene yields in the tomato fruits. Analysis of chromatograms obtained from tomato samples in the MeJA and chitosan-treated groups showed enhanced levels of lycopene. Plant growth was not significantly affected by treatment ofMeJA. Chitosan, however, noticeably increased plant growth over 7 weeks.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In this study, exogenous pre-harvest treatment of tomato plants with MeJA （Methyl Jasmonate） and chitosan was used to elicit lycopene biosynthesis and stimulate plant growth. Lycopene is a bright red carotene and carotenoid pigment found in tomatoes, carrots and other red fruits and vegetables. It is a powerful antioxidant that protects cells from damage and blocks cancerous cell growth. Many studies suggest eating lycopene-rich foods may be directly linked to reducing risk of several cancers, heart disease and stroke, hence there is a need to enhance its levels in tomatoes. Tomato seeds were soaked in MeJA and chitosan solutions of varying concentrations and then planted. The resulting plants were irrigated with the solutions used to soak the seeds, accordingly. The heights of the plants were recorded on a tri-weekly basis and HPLC （High Performance Liquid Chromatography） was used to analyze the effects of the MeJA and chitosan solutions on lycopene yields in the tomato fruits. Analysis of chromatograms obtained from tomato samples in the MeJA and chitosan-treated groups showed enhanced levels of lycopene. Plant growth was not significantly affected by treatment ofMeJA. Chitosan, however, noticeably increased plant growth over 7 weeks.
