Iran Agricultural Research
Volume:35 Issue: 1, Winter and Spring 2016

Growth retardants are natural or synthetic chemical substances which are directly applied to crops to alter some structural processes. It is expected that these alterations modify hormonal balance and growth leading to increased yield, improved crop quality or facilitated harvesting. Cycocel (CCC) or chlormequat chloride (2-chloro ethyl trimethyl ammonium chloride) as a synthetic growth retardant has been recommended for wheat since 1960s. Cycocel inhibits gibberellin biosynthesis via blocking ent-kaurene synthesis in the metabolic pathway of gibberellin production, resulting in reduced amounts of active gibberellins and consequent reduction in stem elongation. The stem shortening effect of cycocel in such cereals as wheat seems to be less important, due to release of many dwarf and semi dwarf wheat cultivars. However, using cycocel in cereal fields would be inevitable if its effect on grain yield is definite and this area needs further investigation. Importance of cycocel is greater under environmental stress conditions, and more research needs to be focused on cycocel-induced stress tolerance. In this paper, the current knowledge and possible applications of cycocel, which can be used to improve the growth and yield of cereals, have been reviewed and discussed. The role of cycocel to mitigate the harmful effects of drought and salt stresses in cereals is also examined. Furthermore, various biochemical and physiological processes leading to improved cereal crop production under the influence of cycocel are discussed.

To study the effect of tree roots on increasing water infiltration in soil and also to determine and assess the coefficients of different infiltration models, some infiltration tests were performed in three tree plantation areas in Badjgah, Fars province with different soil textures (clay loam for pear plantation, sandy loam for grape plantation, loamy sand for pine trees). In each plantation, four double rings were installed, whereas two double rings were placed under the tree in two sides of the tree truck with 50 cm distance and the other two double rings were placed on open space between the trees. Vertical infiltration of water into the soil was measured and the coefficients of five models of infiltration (i.e. Kostiakov, Kostiakov-Lewis, Philip, Soil Conservation Service (SCS) and Horton) were assessed. Furthermore, soil texture and initial soil water content were determined in these points. Results showed that all models accurately fitted to the measured values. The infiltration rate under the trees was higher than those between the trees due to the occurrence of roots and root channels that improved the rate of infiltration of water into the soil. The 180-minute infiltration under the trees increased 69% and 354% in loamy sand and clay loam, respectively compared with those on open space between the trees.

A detailed understanding of crop rooting systems will facilitate water use reduction, optimized nutrient uptake and irrigation scheduling more efficiently. A field experiment was conducted during 2005-2006 to investigate sugar beet rooting depth growth, irrigated with three irrigation methods (subsurface drip, surface drip and furrow) and two water qualities (recycled wastewater: EC= 1.52 dS m-1 and fresh water: EC=0.51 dS m-1) in order to improve irrigation water management. A local rooting depth model was developed and three empirical models describing the root growth were evaluated. A significant reduction in sugar beet root depth was observed in the plots irrigated with furrows compared to those irrigated with the pressure irrigation methods. However, no significant difference (p

Maize production, which is ranked after wheat and barely in Fars province, Iran, needs a considerable amount of irrigation water that is not available in scarce water conditions in drought situations. Therefore, proper planting method can improve irrigation water management. The objectives of the present study were to investigate the effects of two planting methods, on-bed and in furrow bottom, on maize growth and yield, and also on soil water content in root zone at different irrigation regimes in a semi-arid condition. The results can be used for improving or designing appropriate machinery maize cropping in-bottom of furrows. Experimental treatments were applied: water at amounts of 60, 80 and 100% of crop evapotranspiraton (ETc), and two planting methods on-bed and in-bottom of furrow were used. The experiment was conducted and analysed in a split-plot design with three replications. Results revealed that the irrigation regimes and planting methods had significant effects on grain yield and total dry matter of maize. The irrigation regime of 80% of ETc with planting in-bottom resulted in highest grain yield (8193 kg ha-1) and water use efficiency(1.05 kg m-3). Although the highest yield was obtained for in-bottom planting, the restricted root growth observed may be due to soil compaction resulting from furrower pressure on the soil. Hence, designing soil tillage tools for reducing the soil compaction beneath the seedbed is recommended for future studies.

Management of nitrogen fertilization in crops is one of the most important components of integrated weed management. A two-year field experiment was conducted to determine the direct effects of wild mustard aboveground biomass and N content of wild mustard on oilseed rape yield. A set of factorial treatments was arranged in a randomized complete block design with four replications. Treatments were various wild mustard densities (0, 10, 20, 30, and 40 plant m-2) and nitrogen (N) rates (0, 50, 100, 150, and 200 kg N ha-1). Increased wild mustard densities from 10 wild mustard m-2 caused a decrease of 27 % in oilseed rape N content of shoot. Increase in nitrogen fertilizer caused an increase in N content of oilseed rape shoot up to 150 kg N ha-1, but no significant difference was found between 150 (0.88 %) and 200 (0.89%) kg N ha-1. Correlation analysis showed that there was a negative significant correlation between oilseed rape grain yield and weed biomass (r=-0.60, p≤0.05) and weed nitrogen content (r=-0.81, p≤0.01). Path analysis showed a highly negative significant direct effect (direct path: -0.88, p≤0.01) between weed biomass and oilseed rape grain yield. Correlation and path analyses indicated that the main factor which could cause oilseed rape yield loss was weed biomass and the second factor was N content in wild mustard.

In the past few decades, accumulation of heavy metals, such as lead (Pb), in soils has increased as a result of human activities.The environmental hazard associated with soil enrichment in heavy metals is related to their mobility and plant availability. Application of various materials such as humic may influence the amount of Pb taken up by plant. Four levels of each of liquid and solid commercial humic substances were applied in this study which were performed as two completely randomized factorial design experiments in a calcareous soil polluted with three levels of Pb. Results of a greenhouse study with corn (Zea mays L., cv Hido) showed that the two commercial humic substances with different chemical composition, affected dry mater yield differently. Influences of humic substances on dry mater yield were most likely dependent on their chemical composition. Maximum dry mater yield was observed at manufacturer's recommended levels of humic substances. But, the solid humic treatments had no significant effect on dry mater yield. Application of both liquid and solid commercial substances significantly increased uptake of Pb in corn shoots. Addition of humic substances significantly increased the enrichment factor in both experiments but affected the micronutrient uptake only slightly.

Today, the authenticity of meat products with less costly and desirable species has increased. Therefore and considering religious, economicalor public health concerns, proper actions should be taken to prevent such frauds. In this study, real time PCR assay was applied for rapid, sensitive and specific identification and quantification of chicken tissue in meat products. Specific primers were designed on the 16SrRNA chicken mitochondrial genes. The conventional PCR and SYBR Green RT-PCR were employed on DNA extracted from 150 samples, sausages and burgers. The results showed the presence of misused chicken meat in the sausages and burgers were 84% and 26%, respectively. Additionally, the Q-PCR assay was able to detect estimate rates of 10% to 50% of chicken meat in the products. The detection limit of the method could be quantitatively used by regulation authorities to control the quality of meat products.

Declining land productivity associated with decreasing soil organic carbon and nutrients is a significant issue in monoculture production. The field experiment with different rates of fertilizer systems (60 kg ha-1 N 100 kg ha-1 P, 300 kg ha-1 Bio-organic (organic fertilizer), 3 kg ha-1 Bioumik (biofertilizer), 30 kg ha-1 N 50 kg ha-1 P 150 kg ha-1 Bio-organic fertilizer and 30 kg ha-1 N 50 kg ha-1 P 1.5 kg ha-1 Bioumik) as main effects and five cropping systems (sole sesame, sole cowpea, 50:50 sesame-cowpea intercropping, 75:25 sesame-cowpea intercropping and 25:75 sesame-cowpea intercropping) as subplot effects were carried out to study the influence of fertilizer systems application on productivity in intercrops and monocultures. Intercropping of 50:50 sesame-cowpea compared to monoculture plots was highly productive in terms of land equivalent ratio (1.03), area time equivalent ratio (1.04) and land use efficiency (155%). Across fertilizer systems, the greater values of land equivalent ratio (1.24), area time equivalent ratio (1.25) and land use efficiency (186%) were obtained from 30 kg ha-1 N 50 kg ha-1 P 150 kg ha-1 Bio-organic. The results indicate that fertilizer application rate of 30 kg ha-1 N 50 kg ha-1 P 150 kg ha-1 Bio-organic and intercropping of 50:50 sesame-cowpea could be an effective pathway in raising of productivity toward sustainable agriculture through maximum exploitation of the biological potential for efficient acquisition of P, N and other resources.

This paper aims to develop a new design of a bentleg (BL) plow and to determine its performance as compared to the conventional one using finite element approach. The difference between the modified and conventional BL plows is the direction of angle between the projection of cutting blade on horizontal plane normal to plow shank and the line perpendicular to the plow shank in the same plane. The conventional (B1), and modified (B2) designs of BL plow were modeled at three rake angles R1= 7.5°, R2= 15° and R3= 22.5°. A three dimensional nonlinear finite element model was applied using ANSYS 8.1, 2004. The variation of calculated draft force by model indicated that minimum and maximum draft forces were obtained for B2R2 and B1R3 treatments, respectively. The minimum vertical force was measured for B1R1 treatment. Calculated draft and vertical forces were in good agreement with measured ones. An increasing positive x-y shear stress zone in the modified BL plow causes the soil lifting increase as compared to the conventional one. Similarities of the Von Mises stress contours to stress characteristic curves emphasize the validity of the analysis. The small size of the plastic Von Mises strain contours (plastic bubble) in the modified plow emphasizes the fact that the force requirement of the modified BL plow is less than that of the conventional one. Similarity of the stress distribution contours in soil block and the stress characteristic curves show the validity of the modeling.

Barley (Hordeumvulgare L.) is one of the most important cereals in the world which is used as human and cattle feed and for malt production. One of the most important steps in a hybrid and selection breeding program of barley is the selection of suitable parents with high general (GCA) and specific combining ability (SCA) for grain yield. In order to estimate the combining ability and heterosis in barley for a number of qualitative traits, seven genotypes were crossed in one-way diallel crosses using Griffing (Method II). Grain number per spike, grain weight per spike, spike weight, 1000-grain weight, number of spikelet, plant height, spike length, peduncle length, days to physiological maturity, and spikelet density were measured. Results of variance analysis showed that there were very significant differences between genotypes for all the measured traits. General combining ability (GCA) effect was significant for all traits, 166/352 genotype had the highest value of GCA for grain number per spike (4.757), grain weight per spike (0.245), spike weight (0.378) traits, whereas Specific combining ability (SCA) effect was significant for all traits except for plant height, days to physiologic maturity, and spikelet density. Three crosses 67/110×283/352, 95/110×216/352 and Sahra×216/352 showed the highest values of SCA for grain number per spike (7.704), grain weight per spike (0.371) and 1000-grain weight (8.619), respectively. Moreover, dominance variance was the most effective factor in genetic control of traits. Three crosses 216/352×283/352, 104/110×216/352 and Sahra×216/352 showed the highest values of heterosis for grain number per spike (4.95), grain weight per spike (44.13) and 1000-grain weight (31.6), respectively. Maximum and minimum broad sense heritability was obtained in the number of grains per spike (87/7%) and spike density (47/36%) respectively. Lowest and highest narrow sense heritability was obtained for peduncle length (15/72%) and weight of grains per spike (50/5%), respectively. Estimates of SCA showed that 95/110×216/352, such as 67/110×283/352 crosses could be used in breeding programs to release cultivar to increase yield-related traits.

Elm leaf beetle (ELB), Xanthoga leruca luteola (Muller), is considered as one of the most important and destructive phytophagous pests of Ulmus species in the north of Iran. In the current study, the effects of three host plants including Ulmus carpinifolia, U. carpinifolia var. umbraculifera, and Zelkova carpinifolia, on feeding indices and biochemical processes of ELB were examined under controlled conditions (25 ± 2 °C; 14:10 LD; 65% RH). The results showed that the highest efficiency of conversion of ingested food (ECI) (23.11±1.36 %) and efficiency of conversion of digested food (ECD) belonged to U. carpinifolia (79.9±4.12 %) and the lowest to Z. carpinifolia (p≤0.05). Relative growth rate (RGR) and approximate digestibility (AD) in U. carpinifolia var umbraculifera and U. carpinifolia were similar to each other. The highest consumption index (CI) belonged to U. carpinifolia var. um braculifera and the lowest to Z. carpinifolia (1.93±0.029, 1.47±0.054), respectively (p≤0.05). Significant differences were found among enzymatic activities of acid (ACP) and alkaline phosphatases (ALP), aspartate aminotransferases (AST and ALT) and lactate dehydrogenase (LDH) in the haemolymph of X. luteola larvae reared on three different host plants. The highest activities of LDH (33±0.58), AST (10074.7±25.25) and ALT (1053.75±5.6) were found in larvae fed on U. carpinifolia (p≤0.05). Also, the highest amount of protein and triglyceride (TAG: 126.5±0.866) was found in larvae fed on U. carpinifolia. The results show that all enzymatic activities significantly decreased on Z. carpinifolia compared with other host plants (p≤0.05). These results indicated that U. carpinifolia is the most appropriate host plant for larvae of X. luteolaas evidenced by the highest nutritional indices as well as activities of enzymatic component in intermediary metabolism.

The influence of foliar application of urea, humic acid (HA), Zinc (Zn), and Boron (B) on potato yield (CV. Cror) was studied in a field experiment during 2010-2012 at the research farm of Nuclear Institute for Food and Agriculture (NIFA). Treatments consisted of i) Control, ii) Nitrogen-Phosphorous-potassium (NPK) (250,150,250 kg ha-1) , iii) NPK (125,75,125 kg ha-1) with 0.03% HA, iv) NPK (125,75,125 kg ha-1) with 0.5% urea, v) NPK (125,75,125 kg ha-1) with 5 kg ha-1 Zn, vi) NPK (125,75,125 kg ha-1) with 1 kg ha-1 B, vii) NPK (125,75,125 kg ha-1) with 5 kg ha-1 Zn and 1 kg ha-1 B, viii) NPK (125,75,125 kg ha-1) with 5 kg ha-1 Zn, 1 kg ha-1 B and 0.03% HA . Urea, Zn, HA, and B were sprayed at vegetative, flowering, tuber formation and ripening growth stages. Among all the mentioned treatments, maximum tuber yield was obtained in the treatment receiving half NPK (soil applied) and H.A 0.03% (foliar applied). Maximum N and P content in potato tubers were also found in the same treatment. Results showed that half NPK (soil applied) foliar application of HA (0.03%) are economical and beneficial for the farmers of the area.

Almost all oyster mushroom producers in Iran produce this kind of mushroom without any kind of casing soil. Although different kinds of casing soils are available for Agaricus bisporus, limited information is available regarding Pleurotus ostreatus. Availability of peat in many regions around the world is a concern and some researcher's efforts have been devoted to a search for alternative materials which may be used as a substitute or as a combination with peat. This project was undertaken to determine whether vermicompost can be used as a casing soil for oyster mushroom cultivation when cultivated in bins. As a completely randomized experimental design with 3 replications, this study was accomplished with different casing materials including vermicompost peat (100:0, 75:25, 50:50, 25:75, 0:100 v/v) and leached vermicompost 㷦 (100:0, 75:25, 50:50, 25:75, 0:100 v/v) effects with control (without casing). Results showed when leached vermicompostwas added to the oyster casing material, the biological efficiency (BE) in the second flush and the percentage of mushroom dry mater (DM) were increased. The highest BE in the second flush (40%) was observed for cased substrate with 100% leached vermicompost, while the lowest BE (9%) showed the control. Percentage of DM was higher in control (3.44%) compared to cased treatments (1.65–3.29%). The BE was higher than 100% for treatment cased with leached vermicompost. Overall, total BE for treatments cased with leached vermicompost increased by 185% over non-cased treatment. Therefore, considering the fact that using casing for P. ostreatus production is a relatively easy and low-cost cultural practice yielding successful results, it can be used to enhance BE and maximize substrate utilization.