SOIL AND PLANT INTERACTIONS (JOURNAL OF SCIENCE AND TECHNOLOGY OF GREENHOUSE CULTURE)
Year:2010 | Volume:1 | Issue:2|Papers Count:7

Aquaponics is one of the recirculating aquaculture systems in which plant grows without soil. Considering the lack of information about aquaponic culture for main crops like pepper and the absence of comparison of plant conditions in soilless culture, in this experiment eco-physiological characteristics of pepper in hydroponics and aquaponics were investigated. After starting the plants to flowering, eco-physiological parameters were measured using potable far-red gas analyzer LCA-4, ADC. The results showed that photosynthesis, stomatal conductance, transpiration, photosynthesis active radiation (PAR) and water use efficiency were higher in aquaponics compared to hydroponics, while, stomatal resistance and leaf surface temperature were higher in hydroponics. However, there was no significant difference in leaf surface temperature in hydroponics and aquaponics. It seems that due to better eco-physiological characteristics of pepper in aquaponics, its growth and development will be better in this system.

Reduction in rainfall and shortage of water resources has caused major damages to agricultural sector. Therefore, it is necessary to employ new methods in order to optimize use of water resources. In this research, the effect of irrigation method of PRD on tomato growth was compared with the conventional irrigation method. The results showed an increase in water use efficiency and total soluble solid of tomato fruits in the PRD treatment while color intensity, number and dry and fresh weight of fruit and severity of blossom-end rot remained unchanged. The PRD treatment reduced dry and fresh weight of shoot and fruit by 8 and 10 %, respectively. About 7.8 and 2.6% of fruits with blossom-end rot were in the PRD and control treatments, respectively. Despite significant reduction in dry and fresh weight of shoot and fruit, harvest index, potential water of leaves and fruit water content, due to 50% reduction in the used water, using PRD is a cost-effective method. Mechanization and scheduled harvest time in PRD method accounts for higher red fruit production and ripening rate.

A completely randomized factorial experiment was set up with 16 treatments and three replicates to study the effect of nitrogen and boron on yield, shoot and root dry weights and leaf concentration of nutrient elements in hydroponically grown tomato in greenhouse of Agricultural College of Zanjan University in 2008. In this experiment, tomato seed of Rio Grande Ug was selected and simple and interaction effect of four levels of N (100, 200, 300 and 400 mgL-1) and four levels of B (0.5, 1.0, 1.5 and 2.0 mg L-1) on tomato yield, shoot and root dry weights and leaf concentration of nutrient elements was investigated. The results indicated that the simple and interaction effect of nitrogen and boron on yield and tomato shoot and root dry weights were significant. Te highest yield and root dry weights were obtained in N200B1.0 treatment and the highest shoot dry weight was obtained in N300B1.0 treatment. By increasing the nitrogen level in the nutrient solution, leaf N and Mn concentration increased while B, Fe and Zn concentration of leaves decreased significantly. In contrast, by increasing the boron levels, leaf N, B and Zn concentration increased and Fe and Mn concentration of leaves decreased significantly. With respect to the results of this study, applications of 200 mg L-1N and 1.0 mgL-1 B of nutrient solution are recommended to obtain higher yield and better quality for tomato in hydroponic culture.

This experiment was conducted to determine the effect of salinity and nitrogen on growth and yield of tomato and concentration and total uptake of some nutrients in different parts of plant in hydroponics culture. Nitrogen (N) was used at 0, 1.5 and 3% levels as NH4Cl and NH4H2PO4 and salinity consisted of 0, 30 and 60 mM as NaCl and CaCl2 (2:1 w/w). A completely randomized design experiment was carried out under greenhouse conditions. Results showed that fruit fresh weight increased with N application but salinity treatment decreased fruit yield. Maximum fresh weight was observed in treatment with 3% N and without any salinity application, whereas minimum fresh weight was obtained with 30 mM salinity and without any N application. Application of 30 and 60 mM salinity increased fruit phosphorous concentration significantly (P<0.05), but it did not affect shoot and fruit concentration. Nitrogen application increased fruit, shoot and root phosphorous concentration significantly. Root, shoot and fruit N uptake increased with N application (without salinity) whereas at high salinity level, increase in N uptake was lower than at low salinity level. Salinity increase without N decreased fruit phosphorous and manganese uptake, root copper, zinc and manganese concentration and shoot manganese uptake. Furthermore, results showed that at low salinity level, N application can alleviate the negative effects of salinity on growth and yield of plant.

A pot experiment was conducted in Isfahan University of Technology research greenhouse to investigate the effects of sewage sludge, compost and cow manure on growth and uptake of Fe, Zn, Mn and Ni in tagetes flower. A completely randomized research with three treatments (sewage sludge, compost and cow manure at 25 Mg ha-1) and three replicates was performed. Application of organic wastes significantly increased organic matter and CEC of the soil. Application of compost significantly increased DTPA-extractable Fe, Zn, Mn and Ni of the soil. The use of organic wastes increased tagetes flower growth. The growth of plant was highest in the compost treatment. Results indicated that Fe, Zn, Mn and Ni uptake by plant shoot, and the percentage of metals translocated to the shoot was greater in the compost treatment compared to other treatments. In general, the application of compost for tagetes flower had a positive impact on plant growth parameters and micronutrients uptake.

In order to determine the effects of cadmium on growth, physiological parameters, and nutritional elements’ concentration in tomato organs in a soilless system, an experiment was conducted in greenhouse of Isfahan Agricultural and Natural Resources Research Center in 2008 with a complete randomized block design with two treatments and 6 replications. The treatments were nutritional solutions of Hoagland with and without cadmium (20 mM). The measured indices included: RGR, NAR, RLGR, LAR, SLA, LWR, LWCA, length of the stem, fresh and dry weight of root and shoot, amount of sugar, photosynthetic pigments, and concentration of nitrogen, potassium, phosphorous, calcium, magnesium, iron, zinc, copper, manganese, and cadmium in root, stem, leaves and fruit. The results showed that cadmium (20 mM) had significant effects on some measured growth indices. Growth parameters such as RGR, NAR, RLGR, Ls, RDW, RFW, SFW and SDW decreased 13.3, 19.1, 13.3, 18.8, 59.5, 58.7, 53.9 and 65.3%, respectively, and SLA increased 12.2%. But physiological parameters were not significantly affected by cadmium. The Cd concentration in all organs increased except fruit, compared with control which was Cd free. High cadmium concentration had significant effects on concentration of Mn and Cu in the root, Mn and P in the stem and Mn in the leaves. Concentration of Mn increased 5.3 and 87.6% in the leaves and stem, respectively, while it decreased 58.4% in the root. Concentration of P increased 33.3% and Cu increased 2times more in the stem. However, Ca concentration decreased 76.7% in the fruit, compared with the control. In conclusion, it is not recommended to grow tomato in the soils with high Cd concentration (polluted soil) because of its negative effects on tomato growth.

Antimony (Sb) pollution has increased in recent years because of human activities and extensive usage of antimony compounds. To date, only a few researches have been conducted in this field in Iran. The purpose of this research is to determine fresh and dry weight, root permeability percentage and root concentration of Sb, Fe and Zn in the corn. This greenhouse research was performed in hydroponics. A factorial experiment (3 × 2 × 3) with three Sb concentrations (0, 6, 18 mgL-1), with and without P (0, 3 mgL-1), and three concentrations of NaCl (0, 60, 120 mM) in three replications was conducted. After 40 days, plants were harvested and the roots and shoots were separated. Increasing Sb concentrations, significantly reduced shoot weight. In the presence of Sb, shoot wet and dry matter increased with phosphorous addition because of the positive effect of phosphorous. Increasing Sb concentration with the same level of phosphorous produced plants with less fresh matter. Roots with lower phosphorous level had higher permeability, and increasing phosphorous concentration had a significant effect on root permeability. The highest and lowest root permeability was related to blank Sb level and 6 mg L-1 level of Sb, respectively. Increasing Sb concentration in nutrient solution first reduced and then significantly increased the root permeability. Root permeability also increased significantly by increasing salinity level in nutrient solution. Root Fe concentration of blank phosphorous level was about 13 percent higher than 3 mg L-1 of phosphorous but there was no significant difference in root Fe concentration between species in nutrient solutions with different levels of Sb and NaCl concentrations. The addition of Sb decreased root Zn concentration.