Maryam Pourmorad; Mohammad Jafar Malakouti; Mohamad Tehrani
Abstract
Introduction: Optimum water consumption in agricultural production is of vital importance as one of the most important environmental factors affecting the growth and development of the plants, especially in arid and semi-arid regions such as Iran. On the other hand, drought stress, among other environmental ...
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Introduction: Optimum water consumption in agricultural production is of vital importance as one of the most important environmental factors affecting the growth and development of the plants, especially in arid and semi-arid regions such as Iran. On the other hand, drought stress, among other environmental stresses, is one of the most important factors that adversely affect the plant growth and yield. Due to the presence of hormonal compounds, organic acids (at low concentrations) can positively affect the production rate and the quality of agricultural products. Considering the water deficit and the necessity of saving water resources as well as the role of organic acids in reducing the negative effects of stress, in the present study attempts are made to investigate the effect of humic and fulvic acid on wheat yield (Triticum aestivum L.) under drought stress conditions.
Materials and Methods: The present study was carried out at the research farm of the national soil and water research institute located 15 km away from Karaj (with elevation of 1280 m) during the 1394-95 crop year. The experiment was a split-plot experiment based on randomized complete block design with three replications which included two main plots (full irrigation and stress) and 36 sub plots of Sivand cultivar. The treatments consisted of the main factor of irrigation regimes at full irrigation and stress levels (35% lower than water requirement) and a sub-factor including six control treatments (F0H0), no foliar application of fulvic acid, in-soil application of 20kg- ha of humic acid (F0H20), Foliar application of fulvic acid (F5H0), and no application of humic acid (F5H0), (F5H20), (F10H0) and treatment (F10H20). The wheat water requirement in the area was estimated by means of Netwat software and irrigation periods were determined based on weather forecast and soil moisture data. Irrigation was carried out using a system of drip irrigation with a specific pressure and discharge level. The stresses were applied from mid-April through consideration of different irrigation hours as compared to full irrigation time. After completion of the growth period, the plant water requirement was accurately estimated by Cropwat software and the percentage of applied stress was accurately calculated (approx. 35%). The Plant yield and some of its components were measured. Statistical analysis was performed through LSD method at 5% significance level using SAS software
Results: The mutual impact between irrigation and fulvic and humic acid applications on total and grain yield was not significant (P <0.05). The highest yield was related to the foliar application of fulvic acid (F10H0) with a total yield of 27331 kg/ha, which had no significant difference with treatment F5H20 (total yield of 25667 kg/ha). Under full irrigation conditions, treatments (F10H0, F5H20) led to 31.81% and 28.44% increase in grain yield (as compared to the treatment yield) respectively. Under low irrigation conditions, treatments (F10H0, F5H20) led to 46.66% and 34.33% increase in grain yield, respectively.
The Weight of 1000 Grains The application of humic acid and fulvic acid alone did not significantly increase the weight of 1000 grains. But the combined application of fulvic acid (F5H0) and humic acid (20 kg /ha) significantly increased the weight of 1000 grains (8.5%). Under low irrigation conditions, the combined application of humic acid and fulvic acid (F10H0) increased the weight of 1000 grains (as compared to the control group) by 14.75%.
Shoot Height The highest shoot height (126.86 cm) was obtained in foliar application of fulvic acid (F5H0) with the in-soil application of humic acid in full irrigation conditions, which increased the shoot height by 22.68% (as compared to the control group). The lowest average shoot height (99.66 cm) was obtained through no application of fulvic acid and humic acid in stress conditions.
Spike Length The application of fulvic acid (F5H0) had no significant effect on spike length. However, the combined application of humic acid (20 kg/ ha-) and fulvic acid (F5H0) increased the mean spike length. Regardless of irrigation conditions, the highest mean spike length was 9.188, 9.105 cm for treatments (F5H20, F10H0) and the lowest mean spike length was 8.258, 8.293 cm, for treatments (F5H0, F0H0).
A number of Grains per Spike The combined application of humic acid and fulvic acid (F5H0) and the application of fulvic acid (F10H0) led to 10% increase in the number of grains per spike as compared to the control group.
Water Use Efficiency The main effect of irrigation and the use of humic acid and fulvic acid on water efficiency was significant at 1% level. The mean comparison at 5% level showed that tension caused 68% increase in water use efficiency. The use of humic acid and fulvic acid increased water use efficiency significantly. The maximum water use efficiency (3.86 kg / m 3) was in spraying the fulvic acid at a concentration of 10 per thousand. Under full irrigation and low water use, the use of fulvic acid at a concentration of 10 per thousand increased water use efficiency as 43.34% and 62.25%
Conclusion: The results of this study showed that the combined application of fulvic acid (F5H0) and humic acid (F5H20) significantly increased all the traits under study. The application of humic acid in drought stress conditions led to 9.09 percent increase in grain yield as compared to the control groups in the full irrigation condition, and the application of humic acid and fulvic acid (F5H0), as well as foliar application of fulvic acid alone (F10H0) under stress conditions led to 23.86% and 24.9% improvement in grain yield respectively ( as compared to control treatments under full irrigation conditions) while foliar application of fulvic acid (F10H0) in drought stress conditions resulted in a 2.65% reduction in grain yield as compared to the same treatment under full irrigation conditions. The results showed that the application of fulvic and humic acid in low irrigation conditions can increase wheat yield and water use efficiency.
Mojtaba Fathi; َAhmad Landi; Mohamad Tehrani
Abstract
Introduction: Variety of soil reactions govern the distribution of metal micronutrients that includes complexation with organic and inorganic ligands, ion exchange, adsorption and desorption processes, precipitation and dissolution of solids and acid-based equilibria. The relative importance of these ...
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Introduction: Variety of soil reactions govern the distribution of metal micronutrients that includes complexation with organic and inorganic ligands, ion exchange, adsorption and desorption processes, precipitation and dissolution of solids and acid-based equilibria. The relative importance of these reactions depends on many factors such as soil physical, chemical, and mineralogical properties and the nature of metal ions. Environmental factors such as climate, physiographic position, and soil development may affect variability of some soil properties and thereby nutrient availability. The present research was conducted to find relationships between Iron, manganese, zinc, and copper availability and some major soil properties, physiographic condition and soil development.
Materials and Methods: Golpayegan region is located in northwest of Isfahan province in central Iran. The mean elevation of the studied area is 1790 above sea level. Annual precipitation was about 244mm and mean monthly temperature ranges from -6 in January to 34°C in August. The soils were developed on different physiographic conditions including piedmont plains, alluvial-fan, plateaus, and flood plains belonging to Entisols and Aridisols. Soil samples (0–60 cm) were collected from 98 grid points with 2000m distance in the agricultural area of Golpayegan. Particle size distribution, calcium carbonate, organic carbon, available potassium and phosphorus of the soils were measured by SWRI standard methods. Available Zn, Cu, Mn, and Fe were determined by addition of 10 g soil to 20mL 0.005M diethylentriaminepentacetic. The solutions were shaken for 2 h at 25°C, centrifuged, filtered, and Fe, Mn, Zn, and Cu concentrations were measured by an atomic absorption spectrophotometer.
Results Discussion: Studied soils were developed on calcareous material and about 60% of samples have more than 20% of calcium carbonate. Available Fe ranged from 1.4 to 6.5 mg kg-1 (mean 15.8 mg kg-1). Significant relationships were also found between DTPA-extractable Fe, organic matter (OM) and calcium carbonate. The results indicated that organic matter (OM) is the most influential soil characteristics that predict Fe availability. DTPA-extractable Mn in the soils ranged from 1.8 to 19.8 mg kg-1 (mean 7 mg kg-1). There were also no relationship between available Mn and soil properties. It has been reported that Mn availability in soils is mainly influenced by oxidation-reduction rather than other factors. Available Zn in the studied soils ranged from 0 to 2.4 mg kg-1 (mean 0.8 mg kg-1) and had significant correlations with particle size and OM contents. This result showed the importance of soil exchanger phase (clay and OM) in Zn availability in calcareous soils, and was in agreement with the findings of Wu et al. (2006) in soils of North Dakota. DTPA-extractable Cu ranged from 0.2 to 2.4 mg kg-1 (mean 0.9 mg kg-1). According to the report of Lindsay and Norvell (1978), 90% of soils had sufficient Cu. However, there were variations among soils in available Cu as a function of physiographic position. The highest values were found in the soils developed on piedmont plains. Significant relationships between available Cu and some major soils properties such as sand, clay, OM, and calcium carbonate were also found. This result was in agreement with findings of Wu et al. (2010) who concluded that soil properties influencing the spatial distribution of Cu availability.
Conclusions: Nutrient availability is one of the most critical concerns of plant production in calcareous soils of Golpayegan . Different pedogenic processes, variable deposition and transport, and different weathering regimes affect micronutrient content, distribution, and availability. Results indicated that Fe deficiencies followed by Mn and Zn in the studied soils are more critical than Cu deficiencies. In fact, 90% of soils had sufficient Cu. Mainly micronutrient availability in the studied soils was related to soil texture and organic matter, although Mn availability showed no relationships with major soil properties. It was concluded that the availability of Fe, Zn, and Cu may be predicted to some extent using some factors such as soil properties and physiographic condition. Availability of Fe, Zn, and Cu in Torrifluvents developed on piedmont plain was higher than in other soils and this may be due to the high amounts of OM and clay, whereas Haplocalcids developed on plateaus had the lowest content. Generally, it was concluded that the mentioned factors affect metal distribution and cycling in the soils and thereby metal availability for plants. On the other hand, prediction of micronutrient availability using these factors can be taken into consideration for better management.
F. Moshiri; M. Ardalan; M. Tehrani; Gh. Savaghebi
Abstract
Abstract
Due to calcareous soil conditions, zinc deficiency is a yield limiting factor for wheat production in Iran. One solution for this problem is the cultivation of Zn-efficient wheat varieties. Ten wheat cultivars (nine bread wheat and one durum wheat) with different tolerance to Zn deficiency ...
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Abstract
Due to calcareous soil conditions, zinc deficiency is a yield limiting factor for wheat production in Iran. One solution for this problem is the cultivation of Zn-efficient wheat varieties. Ten wheat cultivars (nine bread wheat and one durum wheat) with different tolerance to Zn deficiency were studied in a greenhouse experiment. Plants were treated with Zn (10 mg Zn Kg-1 soil as ZnSO4.7H2O) and without it. Based on the results of pot experiment, two wheat cultivars with different Zn efficiency were selected to assess the ability of phytosiderophore release from their roots. Visual Zn deficiency symptoms, such as light colored necrotic patches and reduction in plant height appeared more severe in Alvand, Mahdavi (bread wheat) and Yavares (durum wheat) cultivars. Under Zn deficiency, shoot dry matter decreased in most cultivars. Zn efficiency of wheat cultivars ranged from 80.4% to 106.2%. Based on shoot dry weight, Pishtaz and Darab were the most Zn-efficient and Alvand and Mahdavi were the most Zn-inefficient wheat cultivars. Zn supply markedly increased the Zn concentration and content of shoots of all cultivars. Cultivars differed in Zn uptake under Zn-deficient and Zn-sufficient conditions. On average, Zn-efficient cultivars had more Zn uptake efficiency compared to Zn-inefficient cultivars. Our results strongly suggested that sensitivity to Zn deficiency varied widely among wheat cultivars. Different susceptibility of cultivars did not correspond well with the Zn concentration of the shoot. In contrast, the total amount of Zn of shoot was better related to the sensitivity of wheat cultivars to Zn deficiency. Under Zn deficiency, different ability of genotypes to release phytosiderophore from roots was observed. Pishtaz exuded more phytosiderophore than Alvand. Higher Zn uptake in Zn-efficient wheat genotypes may be attributed to higher release rates of Zn-mobilizing phytosiderophores from roots.
Keywords: Wheat cultivars, Zinc efficiency, Zinc concentration, Zinc uptake