Journal of Soil and Plant Interactions
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Shahrekord University
Abstract: (37 Views)
Abstract: The form of nitrogen in the nutrient solution affects the nutrients concentration and yield of the plant by influencing the uptake of cations and anions. This research was conducted to investigate the effect of different urea to nitrate ratios in the nutrient solution on the shoot and root nutrients concentration and yield of red French lettuce (Lactuca sativa L. cv. Lolla Rossa). A soilless culture experiment using completely randomized design was carried out with seven urea to nitrate ratios in the nutrient solution and four replications in the research greenhouse of Shahrekord University. The urea to nitrate ratios in the nutrient solution were: 0:100, 10:90, 20:80, 30:70, 40:60, 50:50, and 60:40. The results indicated that shoot nitrogen concentration (except for plants fed with a urea to nitrate ratio of 50 to 50) was not affected by increasing the urea to nitrate ratio in the nutrient solution. Increasing urea to nitrate ratio in the nutrient solution led to a significant increase in the concentrations of Fe and Zn in the shoot and P and Ca in the roots of lettuce. But, concentrations of P, K and Na in lettuce shoot decreased. The results indicated that root and shoot dry weights were not affected by urea to nitrate ratio in the nutrient solution. Considering the lower price of urea compared to nitrate-containing fertilizers and the useful effect of combined application of urea and nitrate in the nutrient solution for optimal lettuce growth without yield reduction, the application of a 50:50 ratio of urea to nitrate in the nutrient solution is recommended for red French lettuce production in soilless culture under the conditions of this research.
Keywords: Hydroponic, Leafy vegetables, Nitrogen form, Nutrients.
Background and Objective: Nitrate, ammonium, and urea are the main sources of nitrogen generally used for vegetable production. Urea is one of the major nitrogen fertilizers for vegetable production in soil, but it is seldom used in soilless culture. It has been reported that application of urea in the nutrient solution could affect the nutrients concentration of spinach in soilless culture (Khan et al., 1999) and also reduce the cost of production. Zhu et al., (2018) reported that compared with the full nitrate treatment, partial replacement of nitrate (20%) with urea in hydroponics significantly decreased the fresh weight of Chinese kale cultivars. This experiment was conducted to elucidate the effect of different ratios of urea to nitrate in the nutrient solution on the shoot and root nutrients concentration and yield of red French lettuce (Lactuca sativa L. cv. Lolla Rossa) in soilless culture.
Methods: A hydroponic experiment using completely randomized design was carried out with seven ratios of urea to nitrate in nutrient solution and four replications in the research greenhouse of Shahrekord University. Urea to nitrate ratios in nutrient solution were: 0:100, 10:90, 20:80, 30:70, 40:60, 50:50 and 60:40. Lettuce seedlings were grown in 2 L plastic pots containing mixture of cocopeat + perlite at the ratio of 2:1 (v/v) and were manually fertigated with nutrient solutions on a daily basis. Four weeks after transplanting, lettuce plants were harvested. The samples were dried in an oven at 60 °C and dry weights of shoot and root were measured. Then, the concentration of nutrients (N, P, K, Ca, Mg, Fe, Mn, Zn, Cu, Na) in the shoot and root was measured using common laboratory methods. Analysis of variance was done using SAS software and means comparison was conducted using the least significant difference test at 0.05 probability level.
Results: The results demonstrated that shoot nitrogen concentration (except for plants nourished with a urea to nitrate ratio of 50 to 50) was not affected by increasing the urea to nitrate ratio in the nutrient solution. This finding demonstrated that lettuce plants effectively hydrolyzed urea and efficiently used it as a nitrogen source. Increasing urea to nitrate ratio in the nutrient solution led to a significant increase in the concentrations of Fe and Zn in the shoot and P and Ca in the roots of lettuce. But, concentrations of P, K and Na in lettuce shoot decreased. These changes were due to decreased nitrate concentration in the nutrient solution. In plants nourished with nitrate, the concentration of cationic micronutrients in the plant decreases due to an increase in rhizosphere pH. Nitrate also increases the concentration of cations such as potassium and sodium in the plant by balancing the electrical charge in the cell. The results indicated that root and shoot dry weights were not affected by urea to nitrate ratio in the nutrient solution. The greatest quantity of shoot dry weight (7.31 g plant-1) was obtained in 50:50 urea to nitrate ratio; of course, it had no significant difference with shoot dry weight (6.54 g plant-1) when urea was not supplied in the nutrient solution.
Conclusions: Based on the results of this research, increasing the urea to nitrate ratio in the nutrient solution can influence the concentration of nutrients in the lettuce. Therefore, selecting the optimal ratio of urea to nitrate is essential to prevent imbalanced nutrition of lettuce. Also, combined application of urea and nitrate in the nutrient solution is useful for adequate plant growth without a reduction of the yield in lettuce. Due to the lower price of urea compared to nitrate-containing fertilizers, the application of a 50:50 ratio of urea to nitrate in the nutrient solution is recommended for red French lettuce production in soilless culture under the conditions of this experiment.
References:
Keywords: Hydroponic, Leafy vegetables, Nitrogen form, Nutrients.
Background and Objective: Nitrate, ammonium, and urea are the main sources of nitrogen generally used for vegetable production. Urea is one of the major nitrogen fertilizers for vegetable production in soil, but it is seldom used in soilless culture. It has been reported that application of urea in the nutrient solution could affect the nutrients concentration of spinach in soilless culture (Khan et al., 1999) and also reduce the cost of production. Zhu et al., (2018) reported that compared with the full nitrate treatment, partial replacement of nitrate (20%) with urea in hydroponics significantly decreased the fresh weight of Chinese kale cultivars. This experiment was conducted to elucidate the effect of different ratios of urea to nitrate in the nutrient solution on the shoot and root nutrients concentration and yield of red French lettuce (Lactuca sativa L. cv. Lolla Rossa) in soilless culture.
Methods: A hydroponic experiment using completely randomized design was carried out with seven ratios of urea to nitrate in nutrient solution and four replications in the research greenhouse of Shahrekord University. Urea to nitrate ratios in nutrient solution were: 0:100, 10:90, 20:80, 30:70, 40:60, 50:50 and 60:40. Lettuce seedlings were grown in 2 L plastic pots containing mixture of cocopeat + perlite at the ratio of 2:1 (v/v) and were manually fertigated with nutrient solutions on a daily basis. Four weeks after transplanting, lettuce plants were harvested. The samples were dried in an oven at 60 °C and dry weights of shoot and root were measured. Then, the concentration of nutrients (N, P, K, Ca, Mg, Fe, Mn, Zn, Cu, Na) in the shoot and root was measured using common laboratory methods. Analysis of variance was done using SAS software and means comparison was conducted using the least significant difference test at 0.05 probability level.
Results: The results demonstrated that shoot nitrogen concentration (except for plants nourished with a urea to nitrate ratio of 50 to 50) was not affected by increasing the urea to nitrate ratio in the nutrient solution. This finding demonstrated that lettuce plants effectively hydrolyzed urea and efficiently used it as a nitrogen source. Increasing urea to nitrate ratio in the nutrient solution led to a significant increase in the concentrations of Fe and Zn in the shoot and P and Ca in the roots of lettuce. But, concentrations of P, K and Na in lettuce shoot decreased. These changes were due to decreased nitrate concentration in the nutrient solution. In plants nourished with nitrate, the concentration of cationic micronutrients in the plant decreases due to an increase in rhizosphere pH. Nitrate also increases the concentration of cations such as potassium and sodium in the plant by balancing the electrical charge in the cell. The results indicated that root and shoot dry weights were not affected by urea to nitrate ratio in the nutrient solution. The greatest quantity of shoot dry weight (7.31 g plant-1) was obtained in 50:50 urea to nitrate ratio; of course, it had no significant difference with shoot dry weight (6.54 g plant-1) when urea was not supplied in the nutrient solution.
Conclusions: Based on the results of this research, increasing the urea to nitrate ratio in the nutrient solution can influence the concentration of nutrients in the lettuce. Therefore, selecting the optimal ratio of urea to nitrate is essential to prevent imbalanced nutrition of lettuce. Also, combined application of urea and nitrate in the nutrient solution is useful for adequate plant growth without a reduction of the yield in lettuce. Due to the lower price of urea compared to nitrate-containing fertilizers, the application of a 50:50 ratio of urea to nitrate in the nutrient solution is recommended for red French lettuce production in soilless culture under the conditions of this experiment.
References:
- Khan, N.K., Watanabe, M., Watanabe, Y., 1999. Effect of different concentrations of urea with or without nickel addition on spinach (Spinacia oleracea E.) growth under hydroponic culture. Soil Sci. Plant Nutr. 45(3), 569-575. https://doi.org/10.1080/00380768.1999.10415820
- Zhu, Y., Li, G., Liu, H., Sun, G., Chen, R., Song, S., 2018. Effects of partial replacement of nitrate with different nitrogen forms on the yield, quality and nitrate content of Chinese kale. Commun. Soil Sci. Plant Anal. 49(11), 1384-1393. https://doi.org/10.1080/00103624.2018.1464179
Type of Study: Research |
Subject:
Availability of soil water and nutrients for plant
Received: 2025/06/7 | Accepted: 2025/08/12
Received: 2025/06/7 | Accepted: 2025/08/12
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Journal of Soil and Plant Interactions by http://jspi.iut.ac.ir is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.
This work is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported License which allows users to read, copy, distribute and make derivative works for non-commercial purposes from the material, as long as the author of the original work is cited properly.
This work is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported License which allows users to read, copy, distribute and make derivative works for non-commercial purposes from the material, as long as the author of the original work is cited properly.
