Journal of Soil and Plant Interactions

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Phosphorus (P) is an essential element for plant growth and it is responsible for various functions in the plant. That is why it has been dubbed as the key of plant life. However, its excessive consumption disturbs uptake of micronutrients and reduces plant performance. To investigate the effect of application of P, in calcareous soils containing different amounts of native P, on growth and uptake of micronutrients in cucumber, a greenhouse experiment was carried out as a factorial in a completely randomized design with three replications, at University of Jiroft, Iran. Treatments consisted of five levels of native P (11, 28, 51, 78 and 97.1 mg P/kg soil) and two levels of P fertilizer (0 and 20 mg/kg). Leaf dry weight and concentration of P, Fe, Zn Cu and total uptake of these nutrients by leaves were measured after 6 weeks of plant growth. Results showed that the highest dry weight was related to P fertilizer use, which, as compared to no P-fertilizer application, showed an increase of about 14.61%. Also, treatments which used P fertilizer had the highest concentration of P, and the higher cucumber yield could be justified by P application. On the other hand, micronutrient elements such as Fe, Zn and Cu reached their highest amount in treatments with no use of P fertilizer. However, in case of using P fertilizer, the concentration of these micronutrients in plants was reduced by 25, 16 and 30.41 percent, respectively.

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An experiment was conducted to select the optimum nutrient solution for growing lettuce (Lactuca sativa L.) under hydroponic conditions (open system) and Shahrekord climate, as a completely randomized design with five different nutrient solutions and three replicates, in Shahrekord University. The nutrient solutions were: 1) Research Station for Floriculture and Greenhouse Vegetables (the Netherlands), 2) Cornel University, 3) Savvas et al., 4) Yamazaki, and 5) Domingues et al. Results showed that maximum shoot fresh weight was obtained by application of Domingues et al. nutrient solution; of course, it had no significant difference with lettuce shoot fresh weight obtained by application of Cornel University and Savvas et al. nutrient solutions. Application of Savvas et al. nutrient solution led to significant increase in shoot Mn, Zn and Cu concentrations in comparison to other nutrient solutions. However, shoot P, K, Ca and Mg concentrations as well as shoot dry weight were not affected by nutrient solutions. Minimum nitrate accumulation in lettuce shoot was observed in plants nourished with Savvas et al. nutrient solution. Based on the maximum shoot fresh weight, minimum nitrate concentration and maximum elements’ concentration in lettuce shoot (Fe, Mn, Zn and Cu), application of Savvas et al. nutrient solution can be recommended for lettuce production in porous substrate hydroponic culture under the conditions of the present study.

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Abstract
Little information is available concerning ionic composition of the suitable nutrient solution for fodder maize production in soilless culture. Therefore, the aim of this study was to select a basic nutrient solution for production of fodder maize in soilless culture. A pot experiment was carried out as a factorial in a randomized complete block design with two factors of nutrient solutions and cultivar types and four replications in the research greenhouse of Shahrekord University. The nutrient solutions were: 1) full-strength Hoagland and Arnon, 2) half-strength Hoagland and Arnon, 3) Barry and Miller, 4) Alexander et al., and 5) Ruakura. Two maize cultivars of single cross hybrid 704 and single cross 410 were used. The results indicated that in both maize cultivars, the highest concentrations of nitrogen and phosphorus in leaf, stem and root were observed in the plants nourished with Ruakura nutrient solution. The application of Alexander et al. nutrient solution led to significant increase in potassium concentrations in leaf, stem, and root compared to other nutrient solutions. Optimum supply of nutrient requirements of maize with Ruakura nutrient solution resulted in significant increase in plant height, stem diameter, leaf area and leaf greenness index. In both maize cultivars, the highest shoot fresh and dry weights as well as water use efficiency were obtained in the plants nourished with Ruakura nutrient solution. Based on the results, application of Ruakura nutrient solution is suggested for the cultivation of both maize cultivars (i.e., single cross hybrid 704 and single cross 410) in soilless culture in order to produce fodder under the conditions similar to this study.

Background and Objective: Sustainable fodder production for feeding livestock is regarded as one of the challenges of agricultural sector in the recent years. One of the recently used methods for fodder production is hydroponic system (i.e., soilless culture). In soilless culture, all essential nutrients are supplied to the plant’s roots by nutrient solution. The factors such as plant species and cultivar type, the type of hydroponic system (open and closed), plant growth stage, edible part of the plant, growing season and weather conditions (temperature, light intensity and day length) are effective in choosing a suitable nutrient solution (1). Therefore, choosing the optimum nutrient solution is the fundamental key to success in this cultivation method. Considering the lack of sufficient information about ionic composition of the nutrient solution for production of fodder maize in soilless culture, the present study was carried out to select optimum nutrient solution for its production at the greenhouse conditions of Shahrekord University.

Methods: A factorial experiment using randomized complete block design was conducted with the two factors of nutrient solutions and maize cultivars (i.e., single cross hybrid 704 and single cross 410) and four replications in hydroponic culture at the research greenhouse of Shahrekord University. The nutrient solutions were: 1) full-strength Hoagland and Arnon, 2) half-strength Hoagland and Arnon, 3) Barry and Miller, 4) Alexander et al., and 5) Ruakura. Maize seedlings were transferred to 10 liter plastic pots containing perlite (with particle size of 0.5 to 5 mm) and were manually fertigated with nutrient solutions on a daily basis. At the end of tasseling stage, plant height, stem diameter, leaf greenness index and leaf area were measured. Then, plants were harvested and fresh weights of root, stem and leaf were determined. Plant biomasses were dried and dry weights of root, stem and leaf were measured. Plant samples were ground and the concentrations of N, P and K were measured in each part. In addition, water use efficiency was calculated by dividing shoot dry weight to the volume of the applied nutrient solution. Analysis of variance was performed using the SAS software. Means comparison was conducted using Duncan's multi-range test at p < 0.05.

Results: The results showed that the highest concentrations of nitrogen in leaf (31.5 g kg^-1) and stem (21.7 g kg^-1) were observed in the plants nourished with Ruakura nutrient solution in single cross hybrid 704. The root nitrogen concentration had a trend similar to the values in leaf and stem, and reached the highest level in the plants fed with Ruakura nutrient solution. In both maize cultivars, the highest concentration of phosphorus in leaf was observed in the plants fertigated with Ruakura nutrient solution. However, the highest concentrations of potassium in leaf, stem and root were recorded in the plants fed with Alexander et al., nutrient solution. Application of Ruakura nutrient solution led to an increase in the plant height, stem diameter, leaf area and leaf greenness index in both maize cultivars. The results revealed that the highest shoot fresh weights in single cross hybrid 704 (1102 g plant^-1) and single cross 410 (1076 g plant^-1) were obtained in the plants nourished with Ruakura nutrient solution. This nutrient solution resulted in the highest water use efficiency in both maize cultivars.

Conclusions: The results demonstrated that using Ruakura nutrient solution through optimal supply of the nutrients required for maize production in soilless culture, increased the plant height, stem diameter, leaf area and leaf greenness index in both maize cultivars. This increase led to the highest fresh and dry weights of shoot and root as well as greatest water use efficiency in maize plants. Consequently, in both maize cultivars (i.e., single cross hybrid 704 and single cross 410), application of Ruakura nutrient solution can be recommended for fodder production in the soilless culture under the conditions of the present study.

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