نشریه پژوهشهای زراعی ایران
سال هشتم شماره 6 (پیاپی 20، بهمن و اسفند 1389)

In many parts of the country farmers are faced with the problem of synchrony between sowing date of spring crops and the grain filling period of winter cereals. Competition for limited resources, mainly water results in delayed sowing in spring. In this research relay intercropping of winter/spring species was studied as an alternative practice for conventional double cropping system. Four intercrop treatments with ratios of 3:1, 3:2, 4:2 and 6:2 (wheat:corn) together with sole crop of each species was evaluated in a randomized complete block experiment with 3 replications. Corn seeds were sown in pre-established rows within wheat strips 32 days before harvesting wheat. During the growth period leaf area index, fraction of transmitted radiation and dry matter production was measured in two-weekly intervals and grain yield of species at harvest. Absorbed radiation during the season, radiation use efficiency of species, harvest index and land equivalent ratio were calculated based on the collected data. The results indicated that in all sowing ratios absorbed radiation by the intercrop canopy was significantly higher than sole crops. However, radiation use efficiency of species was not differed between treatments. As indicated by land equivalent ratio, relay intercropping treatments had yield advantage of 27 to 31% over sole crops which was mainly due to increased light absorption by the intercrop canopies. While the number of wheat rows had no drastic effects on the yield, the best results was obtained from 3:2 (wheat:corn) intercrop. It was concluded that relay intercropping of winter cereals with spring crops results in better utilization of resources and increased yield compared to double crop of the same species.

Freezing stress affected some vital processes of plant, and causing the disturbance on plant growth. In order to study the effect of freezing stress on electrolyte leakage (EL) of safflower (Carthamus tinctorius) a factorial experiment carried out using six safflower genotypes (k.w.16, k.w.6, k.w.3, line 295, zarghan 295 and IL-111) and six freezing temperatures (0,-4,-8,-12,-16,-20 0C) on the base of completely randomized design with three replications in Fall 2006. For acclimation, potted plants were grown in natural conditions till 5-7 leaf stage and then, the plants were frozen according to the freezing temperature (FT) regimes. Cell membrane integrity was evaluated through EL and also lethal temperature 50 (LT50) according to the EL percentage of samples were determined. The effects of FT and genotypes on EL and LT50 were significant (P

In order to evaluate the effects of shoot aqueous extracts of chickpea, black cumin and their mixed aqueous extracts on seed germination and seedling morphological characteristics of wild oat and mustard as two common weed, an experiment was conducted with a factorial arrangement based on completely randomized design with three replications. The experimental treatments were aqueous extracts in five levels (0, 10, 20, 40 and 60 percentage), Weed species in two levels (wild oat and mustard) and extract concentration in five levels (0, 10, 20. 40 and 60 percentage). Result indicated that the highest and the lowest percentage and seed germination rate, length of radicle and hypocotyle, dry weight of radicle and hypocotyle and radicle / hypocotyle ratio (R/H), were obtained in control treatment and 60% concentration, respectively. Aqueous extract of black cumin and mixed extracts had the highest and the lowest effect on percentage and seed germination rate, length of radicle and hypocotyle, dry weight of radicle and hypocotyle and radicle / hypocotyle ratio, respectively. Between two weed species, wild oat had the lowest percentage of seed germination and length of radicle compared with mustard. Mustard had the lowest seed germination rate, dry weight of radicle and hypocotyle and length of hypocotyle compare with wild oat. Generally, it was concluded that chickpea and black cumin aqueous extracts have highly inhibitory in terms of weed control that can be useful for sustainable agriculture.

This survey was conducted for base documentation of farm management with GIS and ArcView based on a 5-year data of the agricultural research station of faculty of Agriculture, Ferdowsi University of Mashhad, Iran as a case study. Soil properties and water quality were determined and the necessary data were recorded and analyzed by Excel, ArcView and ArcMap. Then, data (2003-08) available on farming practices were transformed to the appropriate maps. Maps for water resources and quality, soil suitability and farming practices and management (e.g. type of crops, rotation etc) were drawn. This is a prototype database and could be expended for and applied to large farming operations. Based on the result of soil and water analysis water quality of this farm is suitable to medium, texture of soil is medium to heavy with a relatively deep profile and permeability. Soil suitability classes were II and IIs.

In order to evaluate intercropping of summer savory (Satureja hortensis L.) and Persian clover (Trifolium resupinatum L.), an experiment was conducted in the Agricultural Research Station of Ferdowsi University of Mashhad in 2004 growing season. Treatments were sole cropping of Persian clover (eight rows), double-row intercropping of Persian clover and summer savory with 27, 40 and 80 plants.m-2 (eight rows) and sole cropping of summer savory with 27, 40 and 80 plants m-2 (eight rows). For this purpose a complete randomized block design with 4 replications was used. Shoot and stem percentage of summer savory in sole crop treatments were significantly higher than in intercrop. In sole crop treatments, these parameters decreased by increasing plant density, in contrast to the intercrop. Leaf percentage and leaf and flower to stem ratio of summer savory in sole crop treatments were significantly lower than in intercrop. In sole crop treatments, these parameters were increased by increasing plant density, in contrast to intercrop. Effect of different treatments on essential oil percentage of summer savory was not significant. In sole cropping of Persian clover treatment, dry weight of vegetative organs and stem percentage of Persian clover in the first harvest, was lower than other treatments. By decreasing plant density these parameters were decreased in intercropping. In the second and third harvests a reversed pattern was observed. The highest Area Time Equivalent Ratio was obtained in intercropping of persian clover and summer savory with 27 plants.m-2.

In order to compare three summer forage grasses including sorghum (Sorghum bicolor cv. Speedfeed), corn (Zea mayz S.C. 704) and pearl millet (Pennisetum americanum cv. Nutrifeed) for green chop forage production in double cropping system, a field experiment was conducted at research field of Tarbiat Modares University on 2006 growing season. Treatments were arranged in a split- plot design based on randomized complete blocks with four replications. In this research three forage crops as main factor and nitrogen rates (100, 200 and 300 kg N. ha-1 from the urea source) as the sub- plot were studied. Results showed the positive response of crops to nitrogen increment, in such a manner that millet with 300 kg N ha-1 produced 85.8 t ha-1 fresh forage (%20.3 more than sorghum and %30.9 more than corn). Regarding to the sustainable agriculture objects, millet and sorghum with 200 kg N ha-1could be suggested. Forage yield advantages of millet and sorghum to corn was %10 and %12 respectively. They produce 72.4 and 73.5 t ha-1 fresh forage under this treatment. Finally regarding to general advantages of sorghum and millet to corn, especially in unsuitable condition like as drought and poor soil fertility, it seems that changing the corn with sorghum or pearl millet could be an appropriate option. Also decision making for recommending one of sorghum and millet need to more information like qualitative attributes in details and determining animal feeding indices (voluntary intake) using in vivo methods.

Glycinebetaine (GB) as an osmoprotectant plays an important role in improving plant resistance to abiotic stresses. In order to assess the effect of GB spray on enhancing chilling tolerance in corn plants, an experiment with 7 concentration treatments (0, 2.5, 5, 10, 25, 50 and 100 mM) of glycinebetaine was carried out as randomized complete block design with three replications. Corn plants were sprayed by corresponding GB concentrations at 2 to 3- leaf stage and then were exposed to low temperature of 4ºC for 3 days. Following the chilling stress period, plants were located in the room temperature (25 ± 5ºC). Results showed that seedlings sprayed with GB concentrations of 10-100 mM were visually in a better status and more tolerant to chilling injuries. Moreover, chlorophyll content and root and shoot dry weight of seedlings sprayed with this range of GB were significantly higher than those sprayed with distilled water. In addition, electrolyte leakage was effectively declined by spraying the seedlings with GB in the range of 10-50 and further increase in GB concentration significantly enhanced electrolyte leakage. In total, the foliar application of GB resulted in relative improvement of chilling tolerance in corn seedlings.

In order to study the canopy, spike and flag leaf temperature in wheat genotypes under optimum and post-anthesis heat stress conditions and canopy relationships with some morphological and physiological characters, two separate field experiments were conducted in delayed and optimum sowing dates in Ahvaz, Iran in 2007-2008. The experimental site had a moderate winter and dry, hot summer. Plants with delayed sowing date experienced heat stress post-anthesis. Each split-polt experiment had a randomized complete block design with three replicates. The N application rates were (50, 100, and 150 KgNha-1) assigned in the main-plots. Sub-plots consisted of six bread and durum wheat genotypes. Temperature of canopy, spikes and flag leaf were measured in two growth stages (anthesis and milk stage) using a hand-held infrared thermometer. Results indicated that, organs temperature was affected by genotypeenvironment. Although, organs temperature increased as the N rate decreased, the effect of N treatments on organs temperature was not significant. In post-anthesis heat stress conditions, the genotypes that had higher flag leaf and canopy temperature due to higher growth stage duration (such as Star and D-84-5), lower ability in leaf rolling (such as Showa and D-84-5) and higher leaf width (such as Star and D-84-5), had higher chlorophyll reduction under post-anthesis heat stress conditions.

Heavy metal pollution in soil and environment can be reduced by their immobilization. The effects of chemical amendments as zeolite with three levels, 0 (Z1), 5% (Z2) and 10% (Z3) and triple super phosphate with three levels, 0 (P1), 0.25% (P2) and 0.5% (P3) on mine wastes collected and uptake of Pb and Zn by plant and wheat growth were determined. The mine waste was from Bama mine around Esfahan with very high total concentration of Pb (2300 mg kg-1) and Zn (16500 mg kg-1). Dry weight and concentrations of Pb and Zn by wheat in amended soils were studied under greenhouse conditions. Result showed that the application of amendments zeolite and phosphorous decreased Pb concentration in above ground plant biomass and Pb concentration was increased in wheat root. The interaction effect of zeolite and phosphorous on Pb concentration in above ground plant biomass and root was not significant. But in case of Zn element, only phosphorous amendment resulted in concentration reduction in above ground plant biomass and increased concentration in wheat root. The interaction effect of zeolite and phosphorous on Zn concentration reduction of above ground plant biomass and increase in Zn concentration of root were not significant. Moreover, wheat growth in the treated mine waste was superior to its growth in untreated mine waste. Zeolite did not show any effect on wheat growth. However, the interaction effects of zeolite and phosphorous on increasing of wheat above ground and root dry weight were significant.

Dodder is an annual parasitic plant that has not chlorophyll. This parasitic plant can attach to many field crops such as sugar beet. Also this parasite consumes some water, nutrients and assimilates from plants which result in decreasing of quality and quantity of crops yield. This study carried out in Chenaran county, Khorasan Razavi province, in order to evaluation of damage effects of dodder on qualitative and quantitative traits of sugar beet in 2006. Three fields which naturally formerly have infested by dodder, selected in three locations (Ghezlar, Masi Hazrati and Moghan). Sowing date was nearly in April in all fields. At the harvest time, in November, in each field 20 sample of sugar beet roots separately were harvested. Harvest area of each sample was 8m2. Each sample selected from spots which indicated nearly 80-100 percentage infestation. Observations were paired samples and then 20 samples of uninfested spots (with zero percentage infestation) at neighboring rows of infested spots with the same area (8m2) were harvested. Samples were analyzed with qualitative and quantitative standard methods. Obtained data were analyzed by SAS Software with t test and samples compaired in pairwise comparisons. Results indicated that dodder in all sugar beet fields reduced root yield (RY), sugar content(SC), sugar yield (SY), white sugar content (WSC), yield, white sugar yield (WSY), 15.07%, 1.06 Unit, 20.35 %, 7.40 %, 1.89 Unit and 17.73%, respectively. Root potassium content and harmful nitrogen content on field infested spots reduced (8.55% and 8.02 % respectively), but Na content increased 24.3% and molasses Sugar content (MS) increased 11.16 %. Conclusion from this experiment showed that dodder damage and its harmful effects were highly significant in all farms in Chenaran. Therefore consideration of field sanitation related to attachment of dodder to sugar beet is completely necessary. Also it had better consider methods of dodder control either before attachment or after attachment to sugar beet seedling.

In order to study the effects of different N sources in different salinity levels on photosynthesis٫ respiration and antioxidant enzymes activity of canola a factorial experiment was conducted in a completely randomized design in East Azarbaijan Agricultural and Natural Resources Research Center glasshouse in 2008. The first factor was different sources of nitrogen including NO3-/NH4+ ratios (0:100, 25:75, 50:50 and 75:25) and the second factor was salinity as 0 and 200 mM NaCl. The highest fresh and dry weight, leaf area, relative water content, photosynthesis, respiration and leaf P was obtained at 50:50 NO3-/NH4+ ratio in non-saline condition. Increasing salinity decreased significantly all above characteristics. But it seems that 50:50 NO3-/NH4+ ratio decreased negative impacts of salinity injury to plant. Antioxidant enzymes activity was significantly higher in saline condition than control. The lower ratio of NO3-/NH4+ led to higher activity of these enzymes. The enzymes highest activity obtained atNO3-/NH4+ ratios as 50:50 and 25:75. It was concluded that canola can tolerate better salinity stress in presence of proper ratios of N sources

In order to determine the optimum sowing date for different spring wheat cultivars, a field experiment was conducted in Neishabour during 2003/04 and 2004/05 cropping seasons, using a split plot based on a randomized complete block design with three replications. Five sowing dates of Oct. 7(D1), Oct. 22(D2), Nov. 6(D3), Nov. 21(D4) and Dec. 6(D5) were assigned to main plots and sub-plots were consisted of eight spring wheat cultivars, Marvdasht, Cross Arvand, Mahdavi, Pishtaz, Falat, Shiraz, Chamran and BC Roshan. Results of combined analysis of variance indicated significant differences between many of traits and grain yield of planting dates and between cultivars. Due to temperature fell down below zero (-7  C) in April of the second year, and severe damage imposed to early sowing date, results between two years were completely different. Mean grain yield in first and second years, were 6600 and 6417 kg/ha, respectively that showed weather was desirable in first year. Stepwise regression showed No. of spike/m2, date of heading and No. of grain/spike determined 73% of grain yield in first year, and HI, plant height and No. of spike/m2 explained 70% of grain yield in second year. Partial coefficient of determination showed No. of spike/m2 in the first and the second years were 63 and 4% respectively, that indicated freezing at second year caused tillers were similar uniform with no difference between tillers. In general, results showed that for the best performance, date of sowing was Nov. 6 and Shiraz was the best cultivar, because the highest grain yield was obtained in this combination.

In order to study the sensitivity of 9 crops to atrazine soil residual, two separate experiments were conducted in field and greenhouse conditions. First experiment was conducted in a field with treated soil by atrazine based on split plot and the results evaluated in greenhouse conditions. Treatments in the field experiment included two organic manure application rates (0 and 50 t/ha) as main plots and 2 atrazine application rates (2 and 4 kg/ha atrazine a.i.) as sob plots. After corn harvesting soil was sampled at 0-15 cm surface layer in each plots in 15 points, after mixing the samples. Wheat, barley, sugar beet, pea, lens and colza planted in pots at greenhouse. Second experiment conducted in greenhouse conditions for evaluation of atrazine soil residual in completely randomized design. Treatments included atrazine soil residual concentrations (0, 0.2, 0.5, 1, 5, 10 and 15 mg/kg soil) and crops included wheat, barley, sugar beet, pea, lens, rape, bean and tomato. Results showed that atrazine residue had no effect on crops growth in field experiment treated with atrazine. It seems that atrazine residue in filed soil is lower that its damage threshold for crops or maybe for its fast removal in field than in control conditions. But in bioassay experiment (greenhouse experiment) crops response to atrazine residues were different. Results showed that onion and pea were most susceptible ant tolerant crops between studied species and based of ED50 parameter the other crops tolerance to total residue ranked as: pea< bean< lentil< sugar beet< tomato< barley< wheat< rape< onion.

In order to compare the growth indices and phenological stages of development of two local and commercial varieties of radish in response to different levels of population, an experiment was conducted as factorial on the basis of completely randomized block design in the greenhouse in Ferdowsi University of Mashhad, Iran during 2009-2010. Treatments were included two varieties of radish as first factor and three levels of population containing 85, 120 and 170 Pl m-2 as second factor. Phenological stages and growth indices including fresh and dry weight, leaf area, relative growth rate, special leaf area, leaf area ratio, net assimilation rate, edible part yield and dry matter allocation to leaves and roots in optimal conditions since the beginning of germination until final harvest were analyzed. The results showed that there is no significant difference between two varieties in relation to the germination time and 2 and 4 leaves stages in different planting densities. But two varieties responded differently to the different planting densities since the beginning of tubering. The local variety showed higher leaf area ratio and leaf area index, and higher intercepted radiation, but the allocation of photosynthate was more to leaves than edible root. Commercial cultivar showed significantly more economic yield than local cultivar. Increasing the population to170 pl m-2 significantly increased leaf area and leaf area index, radiation use efficiency, leaf weight and biomass, but it had no significant effect on the radish root weight.

Genetic relationships in 25 common bean genotypes were analyzed by using RAPD markers and agronomic traits. A field trial was carried out to evaluate 12 agronomic traits. Experimental design was randomized complete block design with three replications and 25 treatments. Results of field experiment showed large variability for yield and other traits among the tested genotypes. To study RAPD based DNA analysis, a total of 26 random primers generated 144 polymorphic bands, with an average of 5.54 polymorphic bands per primer. The average polymorphic information content (PIC) was 0.273 ranging from 0.077 (P17 primer) to 0.458 (P9 primer). The highest and the lowest marker index were recorded for P1 (3.55) and P17 (0.154) primers, respectively. The average of marker index was 1.59. According to the cluster analysis on RAPD markers, using UPGMA method and Jaccard's coefficients, Pinto, Kidney and Lima bean tested genotypes were segregated into three distinct groups except four genotypes. So efficiency of this method in this research was determined 21/25=%84.Whereas such case did not observe about agronomic traits. Finally, in this study the clustering results based on RAPDs did not match with those on agronomic traits using Mantel test (r=-0.062). Final result, RAPDs marker was determined as a suitable tool for separating bean genotypes in this research.