Soil science
Maryam Ghorbani; shahram kiani; Ali Moharrery; Sina Fallah
Abstract
IntroductionThe gradual decrease in the fertile soils surface due to environmental pollution and urbanization phenomena has reduced the possibility of sufficient fodder production. In addition, the strict dependency of the agricultural sector on water resources in an age of drastic climate change ...
Read More
IntroductionThe gradual decrease in the fertile soils surface due to environmental pollution and urbanization phenomena has reduced the possibility of sufficient fodder production. In addition, the strict dependency of the agricultural sector on water resources in an age of drastic climate change necessitates providing novel solutions for agricultural production. One of the methods that has gained attention for providing fodder is its production through soilless culture techniques. Maize can be a suitable option for fodder production in soilless culture due to high starch and sugar content, low seed cost, high biomass production, and rapid growth. Proper nutritional management of maize in soilless culture is highly important for increasing the quantity and quality of forage greenery. Little information is available regarding the impact of nitrogen form on the growth, yield and chemical composition of forage plants including maize in soilless culture. This experiment was conducted to investigate the effect of nitrogen form on the chemical composition, leaf photosynthetic pigments concentration and yield of two fodder maize (Zea mays L.) cultivars in soilless culture. Materials and MethodsA factorial experiment based on randomized complete block design was conducted with the two factors of ammonium to nitrate ratio in the nutrient solution (0:100, 12.5:87.5, 25:75, 37.5:62.5 and 50:50) and maize cultivars (i.e., single cross hybrid 704 and single cross 410) and four replications in hydroponic culture at the greenhouse of Shahrekord University. After seed germination and emergence of the first two leaves, the maize seedlings were transferred to 10-liter plastic pots containing perlite (0.5-5 mm) and were manually fertigated with different ammonium to nitrate ratios on a daily basis. Before harvesting, chlorophyll a, b and (a+b), and carotenoids were quantified in leaves of plants. At the end of the tasseling stage, the plants were harvested. After harvesting, the root, stem, and leaf parts were separated, and the fresh weights of the samples were measured. Plant samples were dried in an oven at 60 °C. Then, dry weights of samples were measured and samples (root and leaf + stem) were ground for nutrient analysis including of N, P and K. Analysis of variance was performed using SAS software version 9.4. Means comparison was conducted using Duncan's multi-range test at p <0.05. Results and DiscussionThe results showed that in single-cross hybrid 704 and single-cross 410 cultivars, respectively, increasing the applied ammonium to 37.5% and 50% in the nutrient solution caused a significant increase in the shoot nitrogen concentration. Application of ammonium in the nutrient solution led to an increase in shoot and root phosphorus concentration in both maize cultivars compared to the nutrient solution without ammonium. The highest concentration of phosphorus in shoot (18.02 g.kg-1) was observed in the single-cross hybrid 704 cultivar when maize plants fed with a nutrient solution containing 50 percent ammonium, which was 3.2 times higher than the shoot phosphorus concentration in plants fed with nutrient solution without ammonium. Furthermore, at the 50:50 ammonium to nitrate ratio in the nutrient solution, the lowest root potassium concentration was recorded in both maize cultivars. In single-cross hybrid 704 cultivar, application of nutrient solution with ammonium to nitrate ratio of 50:50 resulted in a significant 31% decrease in leaf chlorophyll a concentration compared to plants fed with a nutrient solution containing 25% ammonium (with the highest chlorophyll content). The leaf chlorophyll a concentration in single-cross 410 cultivar showed an increasing trend with increasing ammonium in the nutrient solution up to 25 percent, and then a decreasing trend with further increase in the ammonium proportion. Moreover, a 31.4% significant decrease in chlorophyll b concentration was observed in plants fed with a 50:50 ammonium to nitrate ratio compared to plants fed with a 37.5: 62.5 ammonium to nitrate ratio. The highest leaf carotenoid concentration was recorded in single-cross hybrid 704 cultivar and at 25:75 ammonium to nitrate ratio, which was 1.4 times higher than the leaf carotenoid concentration compared to plants fed with nutrient solution without ammonium. The highest relative leaf moisture content was observed in the plants nourished with ammonium to nitrate ratio of 25:75, which showed a significant 20% increase compared to the ammonium-free nutrient solution. The results also indicated that the application of 50% of nitrogen in the form of ammonium in the nutrient solution led to a significant decrease in the leaf surface area of maize. The highest shoot and root fresh weights were obtained in the plants nourished with 25:75 ammonium to nitrate ratio and in the single-cross hybrid 704 cultivar. The results showed that the highest water (solution) use efficiency based on fresh weight was recorded in plants fed with 25:75 ammonium to nitrate ratio and in the single-cross hybrid 704 cultivar. ConclusionBased on the results of the present study, the highest shoot and root fresh weights of both maize cultivars were obtained in plants fed with 25:75 ammonium to nitrate ratio. Given the limitations of water resources and rainfall, optimal use of minimum water to produce maximum agricultural crops must be cnsidered. According to the results of this research, application of nutrient solution with ammonium to nitrate ratio of 50:50 led to ammonium toxicity and a reduction in forage yield in both maize cultivars. Therefore, replacing 25% nitrate in the nutrient solution with ammonium and selecting the single-cross hybrid 704 cultivar (due to higher yield compared to single cross 410 cultivar) is recommended to achieve maximum fodder yield in soilless culture under conditions similar to this study.
Sabireh Golshahi; Ahmad Gholamalizadeh Ahangar; Noshin Mir; Maryam Ghorbani
Abstract
Introduction: First and the most important requirement of human being is food and food supply, which is directly, or indirectly associated with agriculture. Iron is a critical element for the growth, expansion and survival of the plant, since multiple metabolic and a physiological process is essential ...
Read More
Introduction: First and the most important requirement of human being is food and food supply, which is directly, or indirectly associated with agriculture. Iron is a critical element for the growth, expansion and survival of the plant, since multiple metabolic and a physiological process is essential for the proper functioning. Agricultural areas in the world have a high pH in soil, which in turn decreases iron absorption by plants. Iron deficiency depending on many soil and environmental factors as well as plant genetic that in turns can decrease the yield and product quality. One method of overcome iron deficiency in plants is foliar application. A foliar application of iron fertilizer in agriculture is the common practice, especially in soils that accompanied with iron deficiency. The proper use of various types of fertilizers is the main solution to improve and maintaining soil fertility and increase crop production. The objective of this study is to evaluate the effect of foliar application of iron sources on growth parameters, concentration and absorption of iron in shoot and root and enzymes activity of catalase (CAT), ascorbate peroxidase (APX) and guaiacol peroxidase (GPOX) on forage sorghum plant to determine the best combination of iron fertilizer.
Materials and Methods: An experiment was conducted in a completely randomized design with factorial arrangement and three replications in greenhouse condition on forage sorghum (Sorghum Bicolor (L.) Moench) varieties of speed feed. The treatments included two levels of iron (0.25 and 0.5 g Fe.L-1 with Control (C)) from nine iron sources (Iron chelate (F1), Iron sulfate (F2), Iron oxide nanoparticles (F3), Monodisperse iron oxide nanoparticles (F4), Green nano iron (F5), Polymeric iron chelate (F6), Polymeric iron sulfate (F7), Polymeric iron oxide nanoparticles (F8) and Polymeric monodisperse iron oxide nanoparticles (F9)). The soil was obtained from educational and research greenhouses of Zabol university and after air drying and sieving passing 2 mm, some physical and chemical characteristics of soil such as texture, pH, electrical conductivity, cations exchange capacity, calcium carbonate equivalent, organic matter, total nitrogen contents, available P contents, available K contents and available Fe contents was measurement. Spraying of iron resources performed in two stages (4 leaf and the two weeks after first spraying). After two months of planting, the shoot cut from the surface of the soil and roots of the plants collected. Some parameters such as shoot and root dry weight, chlorophyll a, b and carotenoids, iron concentration in shoot and root, iron absorption in shoot and root, and activity of the enzyme (catalase, ascorbate peroxidase, guaiacol peroxidase) was measured. The experimental data examined using Excel and SAS 9.4 statistical software and the averages were compared using Duncan’s Multiple Range Tests at 0.01 and 0.05 significance level.
Results: Results analysis of variance indicated that the interaction effects between iron resources and iron level on the dry weight of shoots and roots, chlorophyll a and b, iron absorption in shoots and roots, enzymes guaiacol peroxidase. Ascorbate peroxidase and catalase were significant at the level of 5 percent and iron concentrations in shoots and roots were significant at the level of 1 percent. The carotenoid content in leaves in the simple effects of iron resources was significant at the level of 5 percent. According to the results, foliar application of treatments on dry weight of shoots and roots, Fe concentration and Fe absorption by shoots and roots, chlorophyll a, b and the enzyme activity of APX, GPOX in addition CAT were significantly increased compared to Control. Foliar application at 0.25 g Fe.L-1, chlorophyll b in the treatment of monodisperse iron oxide nanoparticles, Fe concentration and Fe absorption in the shoots in treatments of polymeric iron sulfate and polymeric iron chelate, respectively. Fe concentration and Fe absorption in the roots in treatment of polymeric monodisperse iron oxide nanoparticles and APX activity in iron chelate treatment increased significantly compared to control. At level of 0.5 g Fe.L-1, dry weight of shoots in the treatment of iron chelate, dry weight of roots and CAT enzyme in the treatment of green nano iron, chlorophyll a in the treatment of polymeric iron chelate and GPOX enzyme in the treatment of monodisperse iron oxide nanoparticles were compared with the control increased significantly. The simple effects of iron sources indicated that the highest level of carotenoids observed in the foliar application of polymeric iron chelate.