The DSSAT consists of a series of popular and widely used process-based crop growth simulation models. The models have been used worldwide to simulate crop biomass and yield, and soil nitrogen leaching under different management practices and various climatic conditions. The DSSAT has also proven to be a useful tool for selecting improved agricultural practices. Among all management agronomic factors, nitrogen fertilizer and crop species are major effective aspects impacting crops production. Although limited use of nitrogen fertilizer seems likely to reduce crop yield, high application rates of nitrogen causes serious adverse environmental effects. Thus, management of nitrogen fertilizer consumption decreases production costs and environmental pollution in agroecosystems. Therefore, the objectives of the present study were: (1) to determine the genetic coefficients and calibrate the CERES-Maize model (2) to evaluate the performances of the CERES-Maize model in simulating maize cultivars growth, development and grain yield for different fertilizer nitrogen application rates under Kermanshah climate condition.
This experiment was carried out in a split-plot design with 5 levels of nitrogen fertilizer application (0, 138, 238, 350 and 483 kg ha-1 urea) as main plots, 3 current maize cultivars SC-704, BC-678 and Simon as sub plots, and 4 replications in 2014. The required model inputs describe field management, daily weather condition, soil profile characteristics, and cultivar characteristics. The cultivar coefficients were obtained under optimum conditions (i.e., minimum stress in weather and nutrients). The genetic coefficients (P1, P2, P5, G2, G3 and PHINT) of the maize cultivars i.e. SC-704, BC-78 and Simon were determined using the GenCal software of DSSAT v 4.6 for 350 kg Urea ha-1 treatment (optimum nitrogen fertilizer amount based on the results of soil library). Model performance was evaluated by comparing simulated and measured values of maize cultivars phonological development stages (DVS), leaf area index, total dry weight and grain yield for independent nitrogen fertilizer treatment (0, 138, 238 and 483 kg Urea ha-1) by root mean square error (RMSE), normalized RMSE (nRMSE) and index of agreement (d).
The coefficients of P1, P2, P5, G2, G3 and PHINT ranged between 275 to 286 °C day, 0.576 to 1.80 days hr-1, 910 to 950 °C day, 940 to 990 number per plant, 7.0 to 7.9 mg day-1 and 51.70 to 51.97 °C day , respectively, for all cultivars. The CERES-Maize model was able to accurately simulate growth, development stages and yield for maize cultivars. For both simulated and measured conditions, leaf area index, total dry weight and grain yield were improved by increasing the application of nitrogen fertilizer. Simon cultivar had higher simulated (9925 kg.ha-1) and measured (10467 kg.ha-1) grain yield in respect to other cultivars. The validation results also indicated that the CERES-Maize model gave a reliable estimate of growth, development stages and grain yield for maize cultivars in the different fertilizer nitrogen application rates. The value of RMSE and nRMSE for leaf area index of SC-704, BC-78 and Simon cultivars were 0.56, 0.46 and 0.36 and 25.5%, 21.8% and 16.3%, respectively. The index of agreement (d) for leaf area index ranged from 0.94 to 0.98. The RMSE and nRMSE magnitudes for total dry weight of SC-704, BC-78 and Simon cultivars were 440.1, 569.6 and 419.7 and 6.2%, 8.2% and 5.8%, respectively. The index of agreement (d) for total dry weight ranged from 0.94 to 0.95. The RMSE and nRMSE values for SC-704, BC-78 and Simon grain yield were equal to 163.7, 345.2 and 314.4 and 4.3%, 11.4% and 8.1%, respectively. The index of agreement (d) for grain yield ranged from 0.93 to 0.98.
The results indicated that the CERES-Maize was parameterized reliably for three maize cultivars under Kermanshah climate conditions. The results of validation also showed that the CERES-Maize model was able to give an accurate simulation of all studied traits of maize cultivars except leaf area index in different fertilizer nitrogen application rates.

Maize (Zea mays L.) cultivars grown in Egypt are not only numerous, but also show a wide diversity of exposure to stored grain pests causing damages that may threaten food security. Thus, the aim of this study was to assess the level of susceptibility of maize cultivars to infection by Sitophilus zeamais (Motschulsky), a voracious insect pest of stored maize. Likewise, to evaluate the efficacy of black pepper, Piper nigrum L. powder as an insecticide against this pest to protect stored maize. The susceptibility index values ​​showed that cultivars THW-310 and THY-352 were more susceptible to infection by S. zeamais, and the levels of some amino acids were higher than cultivars SHY-162 and SHW-10, which showed relatively low infection. In all maize cultivars, application of P. nigrum powder reduced the severity of S. zeamais infestation, significantly improved seedling growth, and % germination after six months of maize storage, compared to the untreated samples. The promising P. nigrum powder could be recommended for use as a part of an integrated pest management program in stored maize, particularly for a long storage periods.

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.

In order to investigate the effects of nitrogen levels on grain yield، phyllochron and leaf emergence rate of maize cultivars، a split plot experiment based on randomized complete block design with three replications was conducted at the Research Farm of Islamic Azad University of Ardabil during 2007 cropping. Factors were: nitrogen levels in main plots (0، 80، 160 and 240 Kg N ha-1) and maize cultivars in three levels (SC-301، DC-370 and SC-404) in sub plots. The results showed that phyllochron، time between the appearance of successive leaves on a shoot، was significantly affected by corn، nitrogen levels and interaction of nitrogen levels × maize cultivars. With increased nitrogen levels، the phyllochron was decreased but rate of leaf appearance was increased. Response of maize cultivars was different to these characteristics. Leaf appearance rate in SC-301 was more than SC-404 and DC-370. The highest leaf appearance rate and the least of time for phyllochron was obtained in treatment compounds of SC-301 with application of 240 kg N/ha. Grain yield was significantly as affected by nitrogen levels، cultivar and interaction of cultivar × nitrogen levels. Maximum grain yield was in SC-404 cultivar and minimum of it was in SC-301 cultivar. Means comparisons showed that maximum grain yield was obtained in SC-404 with application of 240 kg N/ ha. However، no significant different was between application of 160 and 240 kg n/ha. Minimum grain yield belonged to SC-301 without application of nitrogen fertilizer. If growth period was limited، it seems that SC-301 with 240 kg N/ha was applied in order to increasing leaf appearance rate and decreasing of phyllochron. However، if growth period wasn’t limited، it would be better to use of SC-404 with application of 240 kg N/ha.

The use of modern irrigation methods, deficit irrigation, the use of cultivars more resistant to drought stress, are ways to increase water use efficiency in agriculture. To study the effect irrigation level and type of maize cultivar on water use efficiency in forage and grain maize production, this research was conducted at the research farm of Agricultural and Natural Resources College of University of Tehran (Karaj) in 2017. The main treatments included two levels of irrigation (100 and 80% of maize water requirement) in subsurface drip irrigation system; sub-treatments included three maize cultivars KSC704, KSC600, KSC400. Experimental design was based on split plots based on randomized complete blocks. The studied traits were forage yield, biomass, grain, water use efficiency in forage, biomass and grain production, 1000-grain weight and harvest index. The results showed that the effect of irrigation level on the measured traits was insignificant and the effect of cultivar on them was significant at both irrigation levels. The highest amount of water use efficiency in biomass production was 4.37 kg / m3 in KSC600 cultivar and the highest water use efficiency in grain production was 2.43 kg / m3 in KSC704 cultivar (with KSC400 cultivar in a Statistical group) obtained at the irrigation level of 80%. Also, KSC400 cultivar, being in the common statistical group with KSC704 cultivar, had the highest 1000-grain weight of 537.3 grams. Deficit irrigation up to 80% of water requirement using subsurface irrigation system had not any significant effect on the yield of maize cultivars.

To investigate the effects of sowing date on yield and some physiological index of six forage maize cultivars in Rasht region, a field study was conducted in 2010. The experimental design was randomized complete blocks with factorial arrangement with three replications. Treatment consisted of four levels of sowing date (22 May, 3, 15 and 25 June), and six maize cultivars (SC 260, DC 370, SC 500, SC 647, SC 700 and SC 704). Results showed that sowing date and cultivar had significant effects on forage yield (dry and fresh) traits. The sowing date 3 June and cultivar SC 700 from a point forage yield (dry 28220.6 kg ha-1 and fresh weight 87017 kg ha-1) were better than other cultivars and sowing dates. The maximum LAI and CGR obtain from sowing date 3 June and cultivar SC 700. Based on the results obtained from this study sowing date 3 June and cultivar SC 700 with more suitable growth indexes is the reasons of increasing in leaf area development, plant photosynthesis activity, dry matter yield and finally more yield, was suggested in Rasht reign conditions.

In order to evaluate the effect of different levels of nitrogen fertilizer application on yield and yield components of some maize cultivars, a split plot experiment was done based on randomized complete blocks design with four replications in the campus of agricultural and natural recourses farm, Razi University, at 2014. Treatments were four levels of nitrogen fertilizer application (40%, 70%, 100% and 140% of the maize demand to nitrogen which based on the amount recommended by soil testis equivalent to 138, 238, 350 and 483 kg.ha-1 urea) as main plots and three common maize cultivars SC 704, BC 678 and Simon as sub plots. The results indicated that nitrogen fertilizer improved number of ear per square meter (12%), number of row per ear (9%), number of grain per row (32%), grain yield (63%) and total dry weight (58%). Simon cultivar had more need to nitrogen fertilizer to achieve maximum yield. Simon cultivar had the most grain yield (19%) than other cultivars. Harvest index was higher for Simon cultivar in fertilizer level of 140% while harvest index for other cultivars reduced by increasing of nitrogen fertilizer application from 40% to 140% of plant demand. Simon cultivar (10467 kg.ha-1) in 140% fertilizer level and SC-704 (8402 kg.ha-1) and BC-678 (8030 kg.ha-1) in 100% fertilizer level had maximum grain yield. In general, our results showed that in the studied region to achieve higher yield, it is better new maize cultivars be cultivated such as Simon.

To investigate the effects of sowing date on yield and quality of six forage maize cultivars in Rasht region، a field study was conducted in 2010. The experimental design was a randomized complete block using a factorial arrangement with three replications. Treatments consisted of four levels of sowing date (22 May، 3، 15 and 25 June)، and six maize cultivars (SC 260، DC 370، SC 500، SC 647، SC 700 and SC 704). Results showed that the sowing date had significant effects on forage yield and quality traits. Cultivars had also significant effects on forage yield، protein yield، water soluble carbohydrate percentage، and ash percentage. Results indicate that sowing date of June 15th and cultivar SC 700 for traits including forage yield (dry 28220. 6 kg ha-1 and fresh weight 87017 kg ha-1)، dry matter digestibility (72. 69%)، ADF (11. 98%)، water soluble carbohydrate percentage (32. 97%)، and total ash (6. 81%)، were better than other cultivars and sowing dates.

For investigation the effect of zeolite on vegetative characteristics and yield components of some maize cultivars under drought stress conditions (60% of field capacity), this experiment was performed in factorial based on randomized complete block design during 2017-2019. Factors studied in this experiment included 4 levels of zeolite (zero, 5, 10 and 15 tons per hectare) and four maize cultivars (Simon, hybrid BC678, KSC703 and KSC704). Based on the results, in drought stress condition, height and fresh and dry weight of plants was reduced. Application of zeolite moderated the effect of drought stress, so that application of 10 and 15 tons per hectare of zeolite improved morphological (plant height and fresh and dry weight of plant), physiological (water use efficiency and chlorophyll content), yield and yield components (Number of seed rows per ear, number of seeds per ear, 1000-seed weight and grain yield) and biochemical traits (soluble carbohydrates, proline, protein, total phenol and peroxidase activity characteristics). Based on the results, application of zeolite under drought stress conditions intensified the increase of soluble carbohydrates, proline, protein, total phenol and peroxidase activity in plant tissues and thus modulated the effect of drought stress on morphological and yield traits. In general, use of 10 and 15 tons per hectare of zeolite were the most suitable values to moderate the effect of drought stress in the studied maize cultivars. Also, among the studied cultivars of maize, Simon cultivar showed a better response to the application of zeolite under drought stress than other cultivars and was superior to other cultivars in terms of all studied traits.

Mining and smelting activities have contributed to increasing levels of copper (Cu) and zinc (Zn) in soils around of Sarcheshmeh copper mine (Kerman, Iran). Soil chemical analysis showed that the available of Cu and Zn (extracted with DTPA-TEA) were 260.1 and 9.2 mg kg-1 soil, respectively. Phytoextraction is one of the most popular and useful phytoremediation techniques for removal of heavy metals from polluted soils. For chemically-assisted phytoextraction, different chelating agents such as EDTA and citric acid are applied to soil to increase the availability of heavy metals in soil for uptake by plants. A pot experiment was conducted to elucidate the performance of chelating agents addition in improving phytoextraction of Cu and zinc Zn from a naturally contaminated soil by maize (Zea mays L.) cultivars.
A factorial experiment in a completely randomized design was carried out bythree factors of chelate type, chelate concentrations and maize cultivars with three replications in 2012 at ShahreKord University. Chelating agents were Ethylene Diamine Tetra Acetic Acid (EDTA) and citric acid (CA). They were applied in concentration levels of 0, 0.75 and 1.5 mmole kg-1 soil with irrigation water. The three maize cultivars used were single cross 704 (SC-704), three v cross 647 (TVC-647), and single cross 677 (SC-677). The pots were 23 cm in diameter and 23 cm deep, and were filled with 4 kg of a silty loam, calcareous soil taken from the surface layer of Sarcheshmeh copper mine area. Maize plant s was grown under greenhouse conditions over 90 days. After the harvest, soil available Cu and Zn contents (extracted with DTPA-TEA) were determined by atomic absorption spectrophotometry (AAS). Plant samples (shoot and root) were dried for 48 h at 70ºC to determine their dry matter content (yield). Total Cu and Zn concentrations in root and shoot of maize were measured after digestion plant samples by AAS method. The shoot and root uptakes were calculated by multiplying Cu and Zn concentrations by dry mass. The effects of chelating agents and maize cultivars over the measured properties were evaluated using the two-ways ANOVA. The least significant difference (LSD) was used to compare means of treatments using SAS 8.02.
The results revealed that applying both chelates caused an increase of soil available Cu and Zn contents. The maximum of soil Cu (401.9 mg kg-1 soil) and Zn (17.1 mg kg-1 soil) were obtained by using EDTA with 1.5 mmole kg-1 soil in TVC-647 and SC-704 cultivars, respectively. This was due to formation of water-soluble complexes between EDTA with Cu and Zn in soil and help in their desorption from soil particles. EDTA was more effective than CA at increasing Cu and Zn available in the soil. The results indicated that EDTA-addition in 1.5 mmole kg-1 soil significantly reduced root and shoot fresh weight in all maize cultivars compared with the control (except root fresh weight in SC-677). This reduction was due to increasing soil available Cu and Zn contents and their toxic effects on plant growth as well as toxic impacts of EDTA on soil microorganisms and growth of plant.on the other hand0.75 mmole kg-1 soil CA addition induced significant increases in root fresh weight as compared to the control (except root fresh weight in TVC-647). Application of CA in concentration level of 0.75 mmole kg-1 soil led to the greatest quantity of shoot (12.85 g pot-1) and root (21.38 g pot-1) fresh weight in TVC-647 and SC-704 cultivars, respectively. Citric acid has a natural origin and is easily biodegraded in soil. It is not toxic to plants; therefore plant growth is not limited. The highest Cu concentration in root and shoot of maize (2506.1 and 335.6 mg kg-1 dry weight, respectively) were obtained in TVC-647 cultivar using 1.5 mmole kg-1 soil of EDTA – 62.2% and 422.9% greater than those obtained with control. The highest shoot Cu (871.1 μg pot-1) and Zn (76.7 μg pot-1) accumulations were recorded in TVC-647 cultivar using 1.5 mmole kg-1 soil of EDTA and CA, respectively.
Due to importance of Cu contamination in studying soil, it is suggested that EDTA-addition at 1.5 mmole kg-1 soil can be an appropriate chelator candidate for TVC-647 maize cultivar for environmentally safe phytoextraction of Cu in soil. It is noticed that application of EDTA in soil for long time has not recommended for phytoextraction of heavy metals. Because EDTA is non biodegradable substance and can leach into ground-water and causes other environmental hazardous risks.