To investigate the response of CORN to combined application of chemical fertilizers with rhizobacteria plant growth promoting, an experiment was conducted in 2017 at Research farm of Agricultural and Natural Resources Campus of Tehran University, Karaj, Iran, in a randomized complete block design with four replications. Four nutritional treatments including T1 (Control treatment without applying fertilizer), T2 (Just PGPRs), T3 (Use chemical fertilizers based on soil test) and T4 (T3 + PGPRs) were considered. According to the results, the highest total dry weight (3.9 kg/m2), crop growth rate (79.8 g.m-2.day-1), net assimilation rate (15.3 g.m-2.day-1) and GRAIN yield (18.2 ton.ha-1) were observed in T4 treatment and T2 treatment produced the highest  leaf area index (5.3), leaf area duration (205.2) and specific leaf weight (78.5 g.m-2) . Also, the lowest value of all traits was observed in in T1 (control) treatment. The results showed that the presence of rhizobacteria plant growth promotioninduction in the CORN nutrition program increased the growth and growth indices of the plant. Combined application of chemical fertilizers with rhizobacteria plant growth promoting resulted in the highest growth and final GRAIN yield of CORN.

One of the most important environmental factors affecting agricultural production, climate and small-scale man Spending it can control costs is costly.So the only way to tackle climatic limits the cognitive constraints in terms of coping with them and the crop is managed. The present study for CORN cultivation Zoning in Lorestan province, the climatic elements of temperature, relative humidity, and degree days of the ten synoptic stations in the Lorestan province additional environmental parameters were used for slope and soil PH. Among the important factors in temperature due to its more importance in degree of phonological form was investigated, then the zoning maps for the production of these crops GIS techniques were used. After the initial production of maps for definition matched layers and influential areas of fuzzy standard method were used. Finally, in order to integrate data based on the weight of the evaluation hierarchy (AHP) was used to map land prone Zoning CORN planted in Lorestan province, respectively. Zoning results using these methods showed that 2.34 percent province, an area prone to these crops, 8.55 percent semi-prone, poor and 13.08 percent in 76.03 percent in province with poor conditions where results indicate is most desirable places in the West region, central and northern parts of the province are scattered.

An experiment was carried out to evaluate the competitive effects of lambsquarters (Chenopodium album L.) on CORN (Zea mays L.) GRAIN yield, in Tabriz in 2008. Factorial experiment was established on randomized complete block design with three replications. Factors were five weed densities (1, 4, 8, 12 and 16 weeds m-1 of row) and four relative times of weed emergence (emerged with CORN; 10, 20 and 30 days after CORN emergence) including a weed free. Interaction of lambsquarters density and time of emergence on weed leaf area index at 75 days after CORN emergence was significant. Leaf area index in weed ranged from 2 in the highest to 0.19 at the lowest competitive condition. With increasing of weed density and delaying in emergence time its biomass reduced. Weed competition was caused a significant loss in GRAIN yield and time of weed emergence is more effective than weed density. Yield loss of CORN at different weed emergence times were 64%, 38%, 15%, 8%; and at different weed densities were zero, 23%, 35%, 46%, 53%, respectively, compared with control. Emergence of minimum four lambsquarters plants per meter of CORN row before 20 days after crop emergence and competition until late growth season was the economical threshold of this weed.

The use of green cover temperature for plant irrigation planning is one of the methods that has been considered by researchers. For this purpose, several indicators have been presented, among which we can mention the water stress index of the plant by Idso method. In order to plan summer CORN irrigation in climatic conditions of Ahvaz using green cover temperature, in 2018 research in the research farm of Shahid Chamran University of Ahvaz Faculty of Water Engineering under four types of irrigation regime including I0, I1, I2 and I3 respectively 120, 100, 80 and 60% of the plant's water requirement was done in a completely randomized design in three replications. Based on the results, the equation of the upper and lower base line for the CORN plant, treatment I1 (100% water requirement) for the development stage is 2. 89 and (Tc-Ta) ll = 1. 984-0. 0946VPD, for the middle stage is 3. 4 and (Tc-Ta) ll = 3. 217-0. 1669VPD and for the final stage of growth was equal to 1. 2 and (Tc-Ta) ll = 1. 147-0. 160VPD was obtained in degrees Celsius. The results also showed that the total water stress index for the growth period for the 120, 100, 80 and 60 treatments was 0. 17, 0. 22, 0. 35 and 0. 52, respectively. The relationship between plant water stress index and soil moisture level for different irrigation treatments was highly correlated and the equation of soil stress index with soil moisture for I1 treatment for the next day and before irrigation was equal to CWSI = 1. 8296-0. 0586ɵ, v and CWSI = 1. 038 0. 0281ɵ, v was obtained. The results showed that with decreasing water consumption, the plant's water stress index increased and with increasing water stress, the correlation between CWSI index and soil water depth decreased so that the highest R2 (0. 97) in I0 treatment and the lowest R2 (0. 88) was in I2 and I3 treatments. As the results of this study confirm, the plant's water stress index is a good tool for irrigation planning and optimal management in the field.

In order to investigate evaluate the relation of physiological to CORN GRAIN yield an experiment was conducted in Arsajan of Fars in 2009. The experiment was in factorial using randomized blocks design consisting of CORN hybrid in 6 levels (704, 504, 666, Maxima, Zola and Jeta) and 3 densities (4, 8 and 12 plants m-2).The results showed that there was significant difference between CORN hybrids.The highest GRAIN yield was observed in 504 followed by 704 and 666 and the lowest yield observed in Jeta. There was no significant difference between planting densities but different hybrids showed different responses to changing densities. The highest LAI was observed in 704 and 504 and highest CGR observed in 504. In addition 666 and 504 had high RGR values that imply positive roles of these physiological traits in GRAIN yield. Physiological traits responses in CORN hybrids were changes with different density, as high yielding hybrids in low to optimum densities showed better yield physiological performance.

In order to investigate genetic correlation and path analysis between GRAIN yield and yield components, fifteen early maturing hybrids of GRAIN CORN (Zea. mays) using a randomized complete block design with 4 replications were evaluated in Khoramabad agricultural research center, Iran. The data were collected and analyzed for ear emergence date, anthesis date, maturity date, plant height, ear height, plant stand, ear cover, GRAIN number per row, row number per ear, GRAIN depth, 1000- GRAIN weight, plant value, cob percent, GRAIN yield, stay green, stem and leaf resistant to disease. The results showed GRAIN yield was positively correlated with plant height, ear height, GRAIN depth, row number per ear, GRAIN number per row, but negatively with 1000-GRAIN weight, ear cover, cob percent and stay green. Between emergence date and maturity date and It was observed significant negative correlation stay green and leaf disease and  positive significant correlation with ear height, GRAIN depth and ear cover, suggested that late maturing hybrids with higher productivity were more resistant to diseases. The results of regression and path analysis showed that 1000-GRAIN weigh and cob percent were correlated with yield negatively, and GRAIN depth, plant height and plant stand were positively (R2=0.52) and had higher effects on GRAIN yield.

To evaluate the effect of nitrogen and water withholding in vegetative growth stage of CORN on efficacy of nicosulfuron and 2,4-D+ MCPA an experiment was conducted as a factorial arrangement in a randomized complete block design with three replications at Tarbiat Modares University in 2017. The first factor contained four treatments including application of nicosulfuron, 2,4-D+ MCPA, weed free and weed infested as control. The second factor consisted of normal irrigation and water withholding from 4 to 8 leaf stage. Third factor contained either urea application or no fertilizer application. Normal irrigation and nitrogen fertilizer application significantly increased nicosulfuron and 2,4-D+ MCPA efficacy in weed control and total weed dry weight decreased to 341 and 361 g.m-2 respectively compared 1370 g.m-2 as weed infested. Nicosulfuron and 2,4-D+ MCPA reduced weed total dry weight significantly under irrigation withholding. GRAIN yield increased with application of nitrogen and nicosulfuron. GRAIN yield was higher with application of 2,4-D+ MCPA than nicosulfuron without nitrogen application under irrigation withholding. Application of nicosulfuron with nitrogen application provided satisfactory weed control and increased GRAIN yield.