Journal of Soil and Plant Interactions

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Abstract In order to study the effects of different levels of nitrogen (N) and molybdenum (Mo) in nutrient solution on quantitative and qualitative traits and nitrate concentration of cucumber (Sultan cv.), a factorial hydroponic-experiment with completely randomized design and three replications was conducted in the greenhouse of Soil Science Department, Zanjan University, in 2009. The concentrations of N in nutrient solution were 238 and 310 mg/L, and Mo was used at the rates of 0.01, 0.1 and 1 mg/L. The results showed that the effects of N and Mo levels were significant (P≤0.01) on plant yield and growth indices such as average weight, length and diameter of fruit and chlorophyll content of leaf. The chlorophyll content of leaf increased but fruit yield and average weight, length and diameter of fruits decreased as the N concentration of the nutrient solution increased. Increasing the Mo level in the nutrient solution decreased the growth indices and yield of cucumber. The highest fruit yield was obtained when the concentration of Mo in the nutrient solution was 0.01 mg/L. But it didn’t have significant difference with 0.1 mg/L treatment. However, the yield decreased significantly as the Mo concentration increased to 1 mg/L. The effects of N and Mo levels of nutrient solution were significant (P ≤ 0.01) on nitrate concentration of the fruits. As the N level of nutrient solution increased, the nitrate concentration of cucumber fruit increased from 1356 to 2122 mg/kg (on dry weight basis), and exceeded the toxicity limit of 1500 mg/L. Increasing the concentration of Mo of the nutrient solution from 0.01 to 0.1 mg/L decreased nitrate concentration of fruits from 1961 to 1703 mg/kg, without decreasing the fruit yield. With an increase in N concentration of the nutrient solution, the fruit concentrations of N, potassium and calcium increased, but those of phosphorus, magnesium and Mo decreased significantly. Also, as the concentration of Mo in the nutrient solution increased, the concentrations of iron, manganese and in fruit increased and that of copper decreased.

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This research was conducted in order to investigate the possibility of using palm wastes compost as substrate for cultivation of Dieffebnbachia amoena at five levels (ratio of 0, 25, 50, 75 and 100% v/v as substitute for peat) and peat: perlite (4:1) treatment as control, as a randomized complete blocks design with three replications. Chemical and biological properties of palm wastes compost, physico-chemical characteristics of growth media and growth indices after 7 months were evaluated and measured. Results showed that carbon to nitrogen ratio (C/N=18) and germination test (71.25%) indicated that the palm wastes compost is mature and stable. Nutrients content, pH and electrical conductivity of compost was higher than peat. The physico-chemical characteristics of substrates showed that 75% compost ratio was in the ideal range. Evaluation of the growth indices such as plant height, stem diameter, fresh and dry weight of shoots, and fresh weight of roots shows that the highest and the least growth rate was obtained from 75% and 100% compost treatments, respectively. In general, palm wastes compost is a suitable substrate for growth of Dieffenbachia and could be replaced up to 75% with imported peat in peat-perlite mediums.

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Root knot nematode is one of the important plant pathogens that causes damage to many crops, including greenhouse crops. Pepper is an agricultural crop which its cultivation has increased in recent years, especially in greenhouses. Most of the adopted management methods for this nematode have not met the required efficiency. In this study, reaction of some pepper cultivars (Elmina, Tuvana, Chaliston, Sera Demre8, hybrid Aristotle, the California Wonder, Dymaz and Green chilli) to the presence or absence of two root-knot nematodes (M. javanica and M. incognita) was investigated. The nematode was isolated from infested root samples collected from Isfahan and Saveh greenhouses and was identified by the morphometric and morphological characteristics. Nematodes were reared on tomato. The seeds of pepper cultivars were sown in seedling trays and the seedlings with similar growth were transferred to the main pots (having diameter of 15 cm) containing 2 kg of sterilized soil (1:1:1 field soil, sand and manure). At the 4-leaf stage, they were inoculated with 2500 eggs and larvae per kg soil. The experiment was carried out as a factorial based on completely randomized design with four replications. Four months after nematode inoculation, results were evaluated using plants’ growth indices (fresh and dry weight of roots and shoots, length of roots and height of shoots) and growth and developmental factors of nematodes (number of moths per g of root, number of egg colonies per g of roots, number of eggs per colony of eggs, and population of second age larvae per 200 g soil). The Chaliston, California Wonder, hybrid Aristotle and Tuvana cultivars showed low sensitivity to M. javanica nematode, compared to other cultivars. The growth and developmental indices of nematodes in different cultivars showed significant difference. Therefore, based on the Canto-Saenz system, they were divided into two groups of sensitive and resistant cultivars. But all the cultivars were susceptible to M. incognita nematode, except California Wonder cultivar.

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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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