نشریه پژوهش های کاربردی زراعی
پیاپی 102 (بهار 1393)

Rice (Oryza sativa), a salt-sensitive species, has considerable genetic variation for salt tolerance within cultivars. To evaluate salinity effects on growth, chlorophyll content and ion uptake of two rice genotypes (IR29 and IR651, sensitive and tolerant respectively) accompany with two semi-tolerant Iranian rice cultivars in a green house experiment were grown in normal condition till 6th leaf was fully expanded. Seedlings were exposed to salinity, EC12 dsm-1 and normal conditions (EC=1.65 dsm-1, Ushida solution base EC) for one week. Samples were taken 0, 4, 12, 24, 48, 96, 168 h after imposing the treatments. After imposing the treatment, we used the youngest & oldest leaves for measuring Na and K concentration and the youngest for chlorophyll. The scoring of leaves was from top to down (one for the young and four for old). Stomatal conductivity also measured on the youngest leaf in time interval as follow: 12, 24, 48, 72, 96 and 120 hours after stress treatment. In this experiment root and shoot dry matter reduced significantly under stress in all cultivars but this reduction was less in tolerant genotype (IR651) compare to others. There were no differences in K concentration in the young leaves between cultivars but there was more accumulation of K in old leaf of IR651 under salt stress. NaCl treatment caused to increasing significantly Na in the young and old leaves of all cultivars except the young leaf of tolerant cultivar. Chlorophyll concentration increased after 24 hrs of treatment but with long- time exposure a significant decline occurred in all cultivars.

The short arm of rye 1R chromosome (1RS) carries genes for resistance to diseases and pests. The presence of the 1RS arm also enhance adaptation, stress tolerance and yield potential of bread wheat. In the present study 17 bread wheat cultivars were screened to identify 1BL.1RS translocation (T1BL.1RS) by isoelectric focusing, C-banding and fluorescence in situ hybridization (FISH) methods. Isoelectric focusing of glucose phosphate isomerase (IEF-GPI) is a quick and economical method for identification of homozygous T1BL.1RS. The IEF-GPI results showed that cultivars Fallat and Sabalan don,t have cathodal band encoded by 1BS arm and therefore carry T1BL.1RS. In addition to confirmation of homozygous T1BL.1RS in Fallat and Sabalan by C- banding method, this method also showed that no heterogeneity was found for 1RS translocation in plant materials. FISH using rye DNA as a probe confirmed the IEF-GPI and C-banding results. Our results showed that cultivars Fallat and Sabalan contained the 1RS chromosome arm and therefore may be considered as a useful genetic diversity resources for wheat breeding.

In order to study of variation and relationships between yield and quality traits, 14 domestic populations of bitter vetch (Vicia ervilia) were collected from different parts of Lorestan province and sown in two separate experiments under irrigated and dry land farming system using randomized complete block design with three replications in khorramabad, Iran during 2005 and 2006. Data were collected and analyzed for dry matter (DM) yield, and quality traits. Results of combined analysis showed significant differences between two conditions for all of traits. In comparison between two conditions, the higher production and higher forage qualities were obtained for Irrigated and dry land farming system respectively. The effect of genotype was significant for DM yield and water soluble carbohydrates (WSC). Genotypes of Fahre (Aligudarz), Noorabad and Sarvand (Berojerd) with average values of 65.4, 22.8 and 19.6% had higher values for dry matter digestibility (DMD), WSC and crude protein (CP), respectively. DM yield was negatively correlated with WSC and positively correlated with crude fiber (CF). Correlation between DMD vs. acid detergent fiber (ADF) and CP vs. WSC were negatively significant. Using bi-plot diagram based on droughtresistance indices, the sensitive and tolerant genotypes were identified. Fahre (Aligudarz), Koehdasht, Malakhan (Noorabad) and Kahriz (Khorramabad) with average values of 2 to 2.25 ton/ha DM yield had higher production in both conditions and recommended for cultivaton in semiarid region of Lorstan province. Among them, Fahre (Aligudarz) and Kahriz (Khorramabad) had higher quality. Genotypes of Masoudabad (Azna), Zaghah (Khorramabad) and Aleshtar with average values 1.77 to 1.84 ton/ha DM yield, were identified as tolerant to dryness.

Among crop plants, corn (Zea mays L.) need a great amount of nitrogen during its growth period. An increase in the efficiency of nitrogen application not only decrease environmental pollutions, but also it,s economical. This study was conducted to determine the effect of nitrogen fertilization management on the yield and nitrogen efficiency in corn during 2006-2009 at Safi-abad Dezful Agriculture Research Center. The experiment was arranged as factorial in a randomized complete block design with three replications. The first factor consisted of four nitrogen levels (0,100,150 and 200 kg N ha-1) and the second factor consisted of five time of application levels (as 1/3+1/3 at sowing and 6- 8 leaves, as 2/3 at 6- 8 leaves, as 1/2 +1/2 at sowing and 6-8 leaves, as 1/3 + 1/3 + 1/3at sowing, 6– 8 leaves and tassel appearance, and 1/4 +1/4+1/4+1/4 at sowing, 6-8 leaves, tassel appearance and flowering). The result showed that nitrogen levels and time of application on grain yield and 1000 grain weight were significant. Nitrogen levels on nitrogen efficiency indices and residual nitrate were significant. Time of nitrogen application on nitrogen utilization efficiency was only significant. Increasing in the amount of nitrogen application led to significant decrease the efficiency of nitrogen use, nitrogen uptake and nitrogen utilization, although, grain yield significantly increased. According to the result of this study, application of 150 kg N ha-1 with grain yield, 1000 grain weight and use efficiency of 7.96 t ha-1, 346 g and 44 kg kg-1 is recommended, respectively.

Scarcity of Irrigation water and decreasing of water resources with suitable quality are the most important limiting factors in the crop production in the most of countries such as Iran. Therefore research for optimum usage of water and economy in consume water is important policies for growing of production and the selection of cultivars with less necessity of water can help to matter.So, an experiment was carried out using a split plot design, in order to select the best irrigation and the best cultivar of oil rapeseed with a high yields of seeds and oil,.in the pattern of randomized completely block design in 3 replications. Irrigation system was the main factor at 2 levels, Tape and Furrow and cultivars as the second factor was Okapi, Slmo46, Opera and licord were evaluated in hamadan.The results showed that no significant differences in the yield of cultivars.The maximum of yield belongs to Opera cultivar with 3706 kg/ha.Irrigation and cultivars intraction were significant different at the level of 5% so that yield highest was optained from cultivar Opera with Tape irrigation system produced 3961 kg/ha and slm046 with furrow system produced 3710kg/ha as the minimum. The average of water use efficiency in Tape and Furrow irrigation was 1.34kg/m3 and 0.74 kg/m3 respectively.The average of water usage volume in Tape and Furrow irrigation was 2617 m3/ha and 4870 m3/ha respectively.

This experiment was carried out to evaluations the allopathic foliar application of safflower)Carthamus tintorius) aqueous extracts on growth and leaf cell membrane leakage of hairy vetech (Vicia villosa). The experimental arrangement was CRD in four replications. Results showed that by increasing the concentration of safflower extracts, shoot dry weight and peroxidase enzyme activity decreased in hairy vetch. Increasing the concentration of safflower extracts, increased malondialdehyde concentration and leaf electrical leakage in hairy vetech. The highest malondialdehyde concentration (0.202 nmol/FW) and the lowest shoot dry weight obtained from 15% safflower foliar extra application.

The objective of this study was to evaluate the effect of plant population and nitrogen rate on yield and yield components of corn (Zea mays L, hybrid 704) in 2008 at Mamasani region, Fars Province. The experiment was conducted as a factorial based on randomized complete block design with three replications. Experimental factors was four plant population (75000, 90000,105000, and 130000 plant ha-1) and three nitrogen rates (200, 300 and 400 kg ha-1). Results indicated that plant density, nitrogen and interaction between plant density and nitrogen had significant effects on 1000 grain weight. By increasing plant density, 1000 grain weight significantly decreased from 290 to 269 gr, and with increasing nitrogen rate from 200 to 400 kg ha-1, 1000 grain weight significantly increased from 269 to 287 gr. Associated with the interaction of plant density and nitrogen on grain weight, the highest 1000 grain weight was at density of 75000 plant ha-1 with consumption of 400 kg N ha-1 and the lowest was at density of 130000 plant ha-1 withconsumption of 200 kg N ha-1. By increasing plant density, number of seeds per ear significantly decreased from 584 to 491 and number of ear per m2 significantly increased from 7.4 to 12.9. Grain yield was significantly increased from 12910 to 16890 kg ha-1 by increasing plant population from 75000 to 130000 plant ha-1. Nitrogen rates and its interaction by plant population had no significant effect on number of seeds per ear, number of ear per m2 and grain yield. In summary, density of 130000 plants per hectare with consumption of 200 kg nitrogen per hectare will be introduced as the most appropriate treatment.

In order to study genetic diversity and detection relationship among agronomy traits, 169 barley recombinant inbred line (generation=RILs) and their parents “Igre” and “Arigashar”, were planted in a simple lattice design with two replications. Ten agronomic traits were scored on three randomly selected plants. The purpose of this study was detection of phenotype and genotype correlation between yield and yield components, estimation of direct and indirect effects of yield components on yield and its part in diversity justification. In analysis of variance differences between the lines for most of the traits was significant that showed enough diversity in population. Number of the rows and 1000- kernel weight had positive and negative correlation with yield, respectively. So number of the rows identified as an important traits (with 0/714) among all of the traits. In stepwise regression analysis, number of rows was the first trait that entered to the model and explained 51percent of the variation. In path analysis, number of rows showed the greatest direct effect on yield and the least amount belonged to spike length. In factor analysis, 5 independent factors explanied about 80/60 percent of the yield variation. The first factor that named plant high and the greatest coefficients related to spike length, number of node and plant height. In conclusion our results showed that the six rows barleys have greatest effect on yield, through own more seeds.

Rice is usually harvested at a high moisture content therefore it must be subjected to drying till the moisture below 14% and for longer storing till 12%. In this project a fixed laboratory dryer was selected for drying three varieties with three range of temperature 40, 50 and 60 C and two range of final moisture content 12% and 10% as completely randomized design. Correlation of crack kernel with drying temperature and final moisture was studied. There was no significant correlation between them. But all the varieties have lower broken rice at 10% moisture. The varieties response to temperature was different because they have different initial moisture content. Shafagh has initial moisture 17% and the others have initial moisture 15%, though shafagh showed higher broken rice at 60 C but shirody and fajr have no significant different between three temperatures.

An experiment was conducted to study the effect of sulfuric acid, temperature scales and the source of seed on to break hardness alfalfa seed (MedicagoscutellatacvRobinson). This study was carried out as a factorial experiment based on randomized complete design with four replications at the agricultural collage of Lorestan University in 2005. Acid treatment as the first factor (to rinse with acid and without rinsing) and temperature scales treatment as the second factor (5, 15, 30, 45 centigrade degree) and the source of seed as the third factor (Khoramabad and Karaj) were applied. The results showed that to rinse seed with sulfuric acid to break hardness alfalfa seed. Seed hardness was not significantly affected by exposing in fixed temperature, but germination percentage decreased in 45 centigrade degree treatment. Radicle length increased under temperatures around base temperature. Seed hardness was affected by soil texture type, so that the highest germination percentage was obtained from sandy soil.

In order to study the effect of fertilizing treatments and limited irrigation regimes on yield and yield components of Isabgol, a field experiment was conducted at Experimental Farm of College of Agronomy and Animal Sciences, University of Tehran. The experimental design was a split plot based on a randomized complete block design with three replications. In this research four irrigation regimes including full irrigation, light limited irrigation, moderate limited irrigation and severe limited irrigation, were assigned to the main plots and five fertilizing treatments including control (without fertilizer), chemical fertilizer, combined use of chemical fertilizer and Barvar Phosphate Biofertilizer, cattle manure and combined use of chemical fertilizer and cattle manure, were assigned to the sub plots. The results showed that irrigation regimes had significant effect (p≤ 0.05) on all measured traits. Grain yields decreased with decrement in irrigation frequency from full to severe limited irrigation; so the highest grain yields were obtained in full irrigation regime. The results also showed that fertilizing treatments had significant effect (p≤ 0.05) on all measured traits. The highest grain yield (1145 kg/ha) was obtained in combined use of chemical fertilizer and cattle manure treatment under full irrigation regime.

Water deficient and salinity are the important problems in arid and semi arid areas. Germination is the critical stage in plant development. In order to evaluation of sesame (Sesamum indicum) genotypes germination and emergence characteristic to salinity and drought stress, two separate experiments were conducted at Ferdowsi University of Mashhad, Collage of Agriculture at 2009. Experimental type was completely randomized design in factorial arrangement with 4 replications. Factors included salinity at 8 levels (0, -2, -3, -4, -6, -8, -10, -12 bar),drought at 7 levels (0, -1, -2, -3, -4, -6 and -8 bar) and three sesame cultivars (Sabzevar, Kalat, Oltan). Results showed germination and emergence parameters (germination percentage, germination rate, root length, shoot length, dry weight of roots and dry weight of shoots, ratio of root length to shoot) in all genotypes were significantly affected by salinity and drought stress. Increasing salinity and drought stress, reduced all above parameters in sesame genotypes. Most negative effect on sesame genotypes germination was obtained in drought stress. Germination of sesame genotypes was reduced in salinity stress in -6 bar, but these reduce in drought stress was observed in higher potential of -2 bar. Also shoot length of sesame genotypes had more decreased in drought stress than salinity stress. Among the studied genotypes, Sabzevar and Oltan genotypes had the highest and lowest indicators respectively at two stresses. According to these results, it seems in water deficient condition and salinity fluctuations, Sabzevar genotype is the appropriate sesame genotypes for optimal seedling establishment.

The erosion in dryland caused decrease in yield and soil quality, especially in slope land with conventional tillage. To investigate effect of tillage and planting methods in slope land on erosion and yield of dryland wheat, an experiment was conducted in 2007 at Kermanshah province. The statistical design for this research was strip split plots in RCB (Randomized Complete Blocks) with three replications. Two slope levels (6-8 and 10-12 percent) arranged in main plots, three tillage systems (conventional, reduced and no tillage) three levels of planting methods (hand spreading, seeding by a drill parallel and perpendicular to slope) arranged in sub-plots. The results revealed run off was shown 12031.98 L/hafor 6-8 percent slope while on 10 -12 percent was 13680.21 L/ha. The signification (P<0.01) grain yield was produced (2850 kg/ha) where chisel and sweep ploughs were applied. No tillage system produced 2750 kg/ha grain yield but was not significantly different with others. 79.33 kg/ha of potassium was lost at 6-8 percent slope compared to 103.20 kg/ha for 10-12 percent respectively.

The effects of drought stress and different chimical and organic fertilizers systems were studied on wheat yeild. This experiment was conducted as split plot based on completely randomized block design (CRBD) with four replications during 2009-2010. Irrigation treatment was in I1(irrigation disruption from anthesis stage) and I2 (spike formation to harvesting) and I3 (full irrigation, control treatment), and fertilizers treatment included chemical fertilizer (NPK), manure fertilizer(M), biological fertilizer(B), biological fertilizer + manure fertilizer(MB) at the beginning of plantation.The effect of disruption of irrigation & fertilizer was significant (%1) on plant height and grain yield. Interaction between irrigation and fertilizer on grain yield was significant at the 5% level. The highest yield of 5304 kg ha the I3 in the treatment and the lowest yield of 3413 kg per hectare in I1 was treated. The maximum yield was obtained 5081 kg/h from MB and minimum level was belong to B treatment with 3142 kg/h. Therefore, application of biological fertilizer plus manure fertilizer was recommended for producing high wheat yield (cv. Chamran) in Khuzestan province, even under drought stress.

In order to map the genomic regions affecting barley drought tolerance indices, an experiment was conducted at the Agricultural and Natural Resource Station of Sistan. Seventy tow double haploid lines of barley with their parents (Steptoe and Morex) were examined using two 9×9 simple Lattice (stress and non-stress), with two replications. Each plot consisted of six rows that were 3m in length and spaced 25cm apart. Based on the relative yield of genotypes in drought stress and non-stress conditions, drought tolerance indices Ys، Yp، TOL، MP، GMP، HM، DSI and STI were calculated. Positive transgressive segregation was observed for YP، YS، GMP، MP and TOL. Seventeen QTLs controlling different indices were identified that fifteen of them appear to be quite stable in different indices. Highest LOD score were obtained for HM on chromosome 2H. QTLs for drought tolerance indices were found on chromosomes 2H, 3H and 5H. QTLs overlapping show the relationship between indices. Therefore, gain through marker-assisted selection (MAS) in this population would be efficient.

In order to find the most appropriate planting patter and cultivar of grain corn, an experiment was conducted in Agriculture Research Station of Jiroft and Kahnooj, Iran for two years in 2007 and 2008 as a split-plot experiment based on a randomized complete blocks design with three replications. The main plot was planting patter at four levels of normal planting (single-row on one furrow), double-row on one furrow, in-furrow, or in-furrow planting and the conversion to normal. The sub-plot was the corn cultivars at four levels of hybrid single-cross 704, hybrid single-cross Karaj 700, hybrid single-cross 647 or hybrid single-cross 500. The results of two consecutive years showed that the effect of planting patter was significant on corn grain yield at 5% statistical level and the effect of cultivar was significant on corn grain yield at 1% statistical level. The highest grain yields were produced by the planting pattern of in-furrow and the conversion of normal and the pattern of double-row planting on one furrow (14.95 and 14.18 t/ha, respectively). In addition, the highest grain yield were produced by the cultivars hybrid single-cross 704 and hybrid single-cross Karaj 700 (15.81 and 14.60 t/ha, respectively). Therefore, given the availability of planting machines, the most appropriate planting patter of corn in Jiroft and Kahnooj is the in-furrow pattern and the conversion normal patter at 5-7-leaf stage as well as double-row planting on one furrow.

An experiment was conducted to determine the effect of five plants densities (100,200,300,400 and 500 grain m-2) on yield and its components in three rain fed barley cultivars (Ezeh, Mahor and Dopar). A factorial experiment based on randomized complete block design with three replications was conducted in agricultural research center of khorramabad city in the east of Iran (in 2006-2007). In this experiment the correlation between traits and the traits that had the greatest effect on grain yield was determined. Direct and indirect effects on yield traits were analyzed. The results showed that there was significant difference among cultivars in term of grain yield and interaction effect of cultivars and plant densities on grain yield was significant among different plant densities were not significant differences. Mahor cultivar in 100 grain m-2 treatment had the highest grain yield (6633 kg ha-1). The correlation coefficient between grain yield and biological yield, straw yield, Harvest index, hectoliter weight and numbers of spike per square was positive and significant but correlation coefficient between grain yield and flag leaf length and grain filling rate was negative and significant. The results of path analysis indicated that four characteristics including hectoliter weight, thousand kernel weight, numbers of grain per spike and numbers of spikes per square were main yield components for grain yield. Based on the results of path analysis among studied characteristics there was the most direct effect among the number of spikes m-2 (r=1.48**) and number of grain spike-1 (r=1.40**) with grain yield. The results showed that 300 grain m-2 treatment for barley cultivars can be recommended in rain fed condition.

In order to investigate the integration of phosphorus fertilizer different levels and phosphorus solubilizing bacteria P.fluorescens on quantitative and qualitative forage yield of two fall barley cultivars, an experiment carried out at research farm of college of Agriculture of University of Tehran during 2009-2010. The experiment design consisted of three randomized complete blocks in a factorial arrangement. Experimental factors consisted of phosphorus fertilizer different levels and phosphorus solubilizing bacteria included from 100% recommended phosphorus fertilizer and without seed inoculation, without phosphorus fertilizer and without seed inoculation (control), seed inoculation and with application of 100% phosphorus fertilizer recommended, seed inoculation and with application of 75% phosphorus fertilizer recommended, seed inoculation and with application of 50% phosphorus fertilizer recommended, and cultivars included of Fasih and Bahman. The highest of dry and fresh forage yield obtained in without inoculation with 100% fertilizer. Seed inoculation with 100% triple super phosphate fertilizer showed that maximum of number of leaf in plant, number of tiller, leaf dry weight and leaf/stem ratio, while the lowest of them observed in control. As regards forage quality, seed inoculation with 75% triple super phosphate fertilizer showed the highest percent of dry matter digestibility, water soluble carbohydrates and total ash, while the lowest of them observed in control. The highest percent of crude protein and fiber observed in seed inoculation with 100% triple super phosphate fertilizer and without triple super phosphate fertilizer and without seed inoculation (control), respectively. Between cultivars, Fasih had the highest of height, no. leaf in plant, spike height, leaf dried weight, stem dried weight, percent of dry matter digestibility, percent of water soluble carbohydrates percent of crude protein and total ash, and in the remain of investigated characteristics, Bahman had the highest of them. The present finding showed that seed inoculation with phosphorus solubilizing bacteria P.fluorescens in integrated with chemical fertilizers improved forage quantity and quality.

In order to study the effects of nitrogen and drought stress on yield, yield components and seed quality of corn (hybrid single cross 704) a field experiment was conducted at agricultural research station in Islamabad Gharb in 2009. Experiment design was split plots based on randomized complete block design with three replications. Main plots included full irrigation requirement, 80 percent and 60 percent of full irrigation requirement and nitrogen (as urea) included: recommended amount based on soil test (170 kg of pure nitrogen per hectare), 30 percent more than this amount (221 kg of pure nitrogen per hectare) and 30 percent less than this amount (119 kg of pure nitrogen per hectare) inserted as sub-plots. The results showed that depending on stress severity drought caused reducing of leaf area index, plant height, biological yield, grain's starch content, yield and yield components. So that severe drought stress decreased the grain yield to 45.62 percent as compared to full irrigation. Application of nitrogen fertilizer equal to 170 kg/ha increased leaf area index, plant height, biological yield and yield components, that finally caused increasing the grain yield, but nitrogen application more than plant demand (In drought conditions) didnt have a positive effect on the yield. In the present study increasing the soil moisture and nitrogen simultaneously increased the grain yield, but using more nitrogen fertilizer under the condition of water stress decreased the grain yield. The maximum amount of grain yield (19.23 t/ha) was achieved from full irrigation and 221 kg/ha nitrogen and the lowest amount (9.17 t/ha) was obtained by treatment of severe drought stress and same amount of fertilizer.

Present limitations on available water resources especially for use in agriculture sector, shows that more attention to irrigation water management is inevitable. Deficit irrigation is a practice to improve use of unit volume of water. In this research, efficacy of CROPWAT 8.0 model was evaluated against field data under deficit irrigation management on soybean in Karaj. In 2008 and 2009 agronomical years, this experiment was conducted in the form of complete randomized blocks design. Furrow surface irrigation treatments consisted of conventional deficit irrigation treatments at 75% and 50% soil moisture deficit compensation (DI75% and DI50%), partial root drying treatment at 50% soil moisture deficit compensation (PRD50%) and full irrigation treatment (FI). The actual amounts of crop coefficient which we got in our research studies were substituted in the model. The results showed that the model evaluation indices RMSE, CRM and SD were equal to 3.47, -0.14 and 15.2 respectively in agronomical year 2008 and were equal to 4.22, -0.11 and 3.77 in agronomical year 2009. Also, the estimated yield reduction by the model was very close to actual results. These conclusions were achieved by replacing some management parameters in the model such as crop coefficients for the recommended values of the model. Positive amounts were obtained for EF index (0.87 and 0.91) which indicates the high efficacy of model in predicting crop yield. This study showed that application of CROPWAT 8.0 model by adjusting crop coefficients in the different growth stages, length of plant growth period during planting, and soil and plant characteristics can lead to acceptable results.

Different methods of cultivation are now being used for preparation of sugar beet seedbed in different regions of the country. Full or part of the primary and secondary tillage operations are conducted in the fall and spring or a combination of those, are common that executed, using different tillage implements. Tillage implements affects on crop yield, soil structure, fuel consumption (energy), and operation time. Therefore, we can increase the farmer's incomes by reducing the operation costs and time, if different tillage methods were used and found a way to maintain the crop yields at optimal. This experiment was conducted during three years, with five treatments (five tillage methods) and four replications in a randomized complete block design. Treatments were: one treatment, preparing seedbed in early fall, three treatments, preparing seedbed in both fall and spring and another treatment preparing seedbed in spring. The results showed that the lowest tractor fuel consumption due to the treatment of preparing seedbed in early fall was 70.21 L.ha-1, and the minimum operation time due to the treatment of preparing the seedbed in spring with the moldboard plow + disk and leveler was 8.18 hr.ha-1. Results also showed that the operation of preparing seedbed in the fall and spring had the greatest effects on improving the soil physical properties, however, none of the tillage methods had no significant advantages to the other methods to increase crop yield. Some of the tillage methods can be used in the cultivation of sugar beet due to lower time and fuel consumption.

In order to find the superior genotypes and high yielding potato varieties, the experiment was carried out on 33 introduced potato genotypes and varieties based on a complete randomized block design with four replications, in which a number of morphological characteristics were investigated. Results of analysis of variance on the recorded traits revealed that the studied genotypes were significantly different based on the studied characteristics. Regarding the importance of big size potato tubers and its effects on the potato total yield, the yield correlated characteristics were studied by path analysis on phenotypic and genotypic correlations, for their positive and negative direct and indirect effects. Among the studied characters, thirteen characters showed high correlations either to the big size tuber or to the other yield components, which were used in the path analysis. The most phenotypic direct effects on the big size tuber yield were imposed by total tuber weight per plant, number of main stems per plant and plant dry weight. Several traits such as fresh total plant weight and date of maturity showed high negative direct effects on big size potato tuber weight. The majority of the studied characters affected the increment of big size tuber yield through their indirect effects. The most genotypic positive and negative direct effects were imposed on big size tuber yield by total tuber weight per plant, tuber length, maturity date, fresh plant weight, number of medium and small tubers, respectively. Indirect effects of the studied characteristics showed more effective influence on big tuber yield rather than direct effects.

In order to study drought stress, Zn and, Fe foliar application on grain yield and yield components of sorghum (sorghum bicolar L. Moench)in Sistan region, an split plot experiment was carried out base on randomized complete block design with 3 replications during summer2010. Three irrigation levels (normal irrigation, pre-anthesis drought stress and post-anthesis drought sress) ialocated in main plots. Four foliar application levels(Zinc, Iron, Zinc + Iron and control) were also ialocated on sub plots. Development stages were evaluated under different irrigation and foliar application levels,Characteristics such as seed yield, harvest index, biological production and protein percent were estimated after harvesting. Results showed that the effect of drought stress was significant on grain yield and harvest index and the effect of foliar application was significant on all of the studied characters. Interactions between foliar application and drought stress on all of the treats were not significant. Therefore, the treatment of Fe and Zn foliar application along with normal irrigation was suggested as the best treatment for obtaining the heighest yield.

Nitrogen is one of the most limiting nutrients for cereal production in many parts of Iran. The effects of crop residue incorporation [0 (control), 25 and 50% of wheat (Triticum aestivum L.)] and nitrogen (N) levels (0, 150, and 300 kg ha-1) on corn (Zea mays L.) grain yield and nitrogen use efficiency were investigated at Agricultural Research Station, Shiraz University, Shiraz, Iran for two years (2009-2010). The experiments were carried out as a split plot based on randomized complete blocks design with three replications. The results showed that with increasing nitrogen fertilizer (from 150 to 300 kg ha-1) and crop residues (from 25 to 50%), RNE (Recovery N Efficiency) and ANE (Agronomic N Efficiency) were reduced. Application of nitrogen more than 150 kg ha-1 increased the amount of nitrogen loss from 69 to 121 kg ha-1. There was a liner relationship between the amounts of nitrogen higher than 150 kg ha-1, and the NHI (Nitrogen Harvest Index), but adding more than 50 percent of crop residues caused no significant difference in the NHI. The maximum grain yield was obtained in plants treated with 300 kg N ha-1 and 25 percent of crop residues incorporation. According to results, the use of 25% of crop residue and 150 kg N ha-1 due to acceptable yield, reduce nitrogen loss and increase the efficiency of nitrogen better than other treatments.

This research was carried out at Agricultural and Natural Resources Research Center, Isfahan, Islamic Republic of Iran (Kabootar abad) for two years (2006-2007). The experiment was conducted as a split plot arranged in randomized block design with four replications. Treatments were four levels of N fertilizer [110, (160 = Soil and Water Research Institute recommendation), 210 and 260 kg ha-1] as main plots, and four rates of P fertilizer [23, (46= Soil and Water Research Institute recommendation), 70 and 92 kg ha-1) as subplots. Results showed that consuming 110 kg N fertilizer, production would be similar to other levels of​​ N treatments. So this treatment is both economically and environmentally, is recommended. But, the nitrogen concentration in leaves was significantly reduced in this treatment. Unlike the results of nitrogen fertilizer, reduced of phosphate fertilizer consumption (compared to the recommended amount of Soil and Water Research Institute) caused a significant reduction in yield. This lower performance was associated with a reduced number of capitula per plant and weight of capitula. In this treatment, the phosphorus concentration in leaves remained constant but the amount of phosphorus in the 0-30 cm soil depth was reduced significantly. In this study the interaction of nitrogen and phosphorus on yield was not statistically significant.