نشریه یافته های نوین کشاورزی
سال دوم شماره 3 (پیاپی 7، بهار 1387)

In order to study the effect of nitrogen levels on yield, Physiological characteristicsand essential oil content of cumin seeds, an experiment was conducted in research farm of Qazvin agriculture instruction center in 2006. The experiment was laid out by adopting split plot design with four replications. Main plots were nitrogen (30, 60, 90 and 120 kg/ha) and subplots were local seed populations gathered from Sabsevar, Bojnord and Esfarayen. Results showed in using 120 kg Nitrogen/ha the highest seed yield (801kg/ha) essential oil yield (16.99 kg/ha), (19.59cm) and seed number /m2 (19400) were obtained. The highest harvest index as 45.08% belongs to 30 kg Nitrogen/ha. Esfarayen with 765.6 kg/ha, harvest index 45.25 and 2.52% essential oil content was the best treatment. Sabsevar had the highest plant high and Bojnord had the highest biologic. Seed yield and essential oil yield of Esfraen with using of 90 kg Nitrogen/ha was 828 and 20.3 kg/ha respectively.

In order to investigate of manure consumption on used efficiency in corn (SC704) an experiment was conducted in agricultural researches center of Hajiabad in Hormozgan. The experimental design was CRBD with four replications. Main plots were considered as four irrigation methods (irrigation of one side of hills to full growth, one side of hills Till steming and then from Two sides, one side of hills Till flowering then from Two sides irrigation) and four amounts of manure (0, 10, 20 and 30 ton/ha) were considered as subplots. Results showded that irrigation method and using manure have significant effects on water used efficiency, yield, 1000 cernel weight, biomass, number of grain per row and stem diameter (p<0.01). Maximum grain yield was related to Two side irrigation by 10070 kg/ha when 30 ton/ha manure. Also Maximum dry matter was related to notice trait.

In order to investigation of planting dates and irrigation regimes on physiological traits of two spring sufflower cultivars a field experiment was conducted in 2002.The experimental design was a split-split plot with four replications. Treatments were planting dates as main plots, irrigation regimes as sub-plots and safflower cultivars (Arak-2811, Esfahan Local) as sub-sub plots. The result showed that late planting and low irrigation decrease the physiological traits such as LAI, CGR, and LAR. NAR and LWR were not shown any significant differences between two considered cultivars, because those had similar growth period. Maximum LAI in first planting date and better irrigation was 4.75 and maximum LAI in third planting date and low irrigation was 3.89, which needed 1340 GDD. Highest CGR obtained between 1400-1500 GDD when LAI started to decline.Relative growth rate (RGR) showed net assimilation rate (NAR) also declining trend. NAR also decreased with time. LAR and LWR also showed a declining trend.

Trichoderma species have been used as biological control agent against soil-borne plant pathogenic fungi. Soil samples were collected from tobacco seedbeds of Mazandaran province. Common media including PDA, WA, CMA and Davet, s selective medium were used to isolate fungi from soil samples. Fungal obtaining isolated after prepare pure culture were identified at genus level by using Bissett key. Among 72 soil samples, 60 isolates were belonging to genus Trichoderma species. Because of the importance of genus Trichoderma as biocontrol agent, its species were recognized. Species were identified according to their macro morphological and micro morphological characters including feature and size of conidiophores, phialid and phialospere by using keys written to identification species of this genus. Dual culture of antagonistic fungi and pathogen on PDA plate revealed that the antagonists reduced and inhibited the mycelial growth of Sclerotinia sclerotiorum. Mycelial growth inhibition rate of Trichoderma species against. S. sclerotiorum were different and it ranges between 51/25%-94%. Identified Trichoderma spp. was including: T. harzianum, T. citrinoviride, T. longibrachiatum, T. koningii, T. virens, T. atroviride, T. ghanense. In greenhouse study, isolates Tr6a, Tr9b, Tr29-1 and Tr102 were effective in disease reduction percentage by 87.5, 81.25, 56.25 and 68.75 respectively. Also, these isolates caused in height, shoot and dry weight increase.

In order to study of different levels of zinc on yield, yield components and harvest index in maize plant mycorrhiza under drought stress, an experiment was carried out in research farm of Arak Islamic Azad University in 2006. The experiment was laied out in factorial based on RCBD with three replications. The treatments were consisted as three levels of irrigations(irrigation equal of crop water requirementcv as control, irrigation equal of 75% crop water requirement and irrigation equal of 50% crop water requirement), inoculation with mycorrhiza fungi (Glumus intraradices) at two levels (inoculation with and without mycorrhiza) and zinc sulphate at three levels (0, 25 and 45 kg/ha). The result showed that, drought stress reduced harvest index, yield and yield components significantly. Effects of mycorrhiza fungi on traits of number of grain per row, number of grain per ear, ear weight and grain yield was significant. Inoculation with mycorrhiza improved measured traits as compared to treatment of without mycorrhiza not only in condition of optimum irrigation but also drought stress. Using of mycorrhiza and zinc sulfate alone in condition irrigation control increased traits of measured. It was showded that with irrigation equal 75% water requirement, inoculation with mycorrhiza and 45 kg/hazinc sulfate obtain optimum yield.

Grain shattering of rapeseed in very sensitive by harvesting time. It increase dramatically by late harvest and early harvest couses to decreas index and yield performance. The goals of the present study were to identify the effect of harvesting date and time in day and night on rapeseed (cv. Okapi) yield, harvest index, some plant character, grain shattering rate and its percentage. The field experiment was conducted as split block design in complete randomized block with three replications in 2006-2007 at the Research Farms of Islamic Azad University, Arak, Iran. The harvesting date treatments consisted of three dates (10th and 26th of June, and 11th of July) and harvesting was taken four times per day and night (6.00am and 12.00pm, 6.00pm and 11.00pm). The results indicate that the grain harvested on 26th June was the most accurate date for rapeseed harvest time in Arak farm’s condition. Harvesting on 26th of June and at 6.00pm was the best term for beginning of harvesting. In this term the grain yield was the highest level up to 3600 kg/ha and the grain shattering percentage was the lowest one, by 14.0%. Any delay in harvesting from 26th June could result in the decrease of the yield and increase of the total grain loss. Harvesting at 11th of July was the critical date for the grain yield loss for two different reasons, first for increase of the shattering from 3.5% to 6.3% before harvesting and the second for grain shattering during the harvesting process in range from 14.8% to 16.3%.

In order to evaluation of the effect of redroot pigweed density and interference time on some physiological traits of sunflower two factorial experiments were performed with sunflower cultivars (Azarghol, Hysun and Allstar), redroot pigweed densities (8.3, 25 and 41.7 plants/m2) and relative times of weed emergence (emerged with sunflower, 15 and 30 days after sunflower emergence) during 2005-2006. Results revealed that in three sunflower cultivars, at high densities and early interference times of redroot pigweed leaf area index decreased, significantly. In Azarghol, reduction amount of leaf area per plant in emerging of 41.7 weeds/m2 was 12%, compared with control. In Allstar, weed density was more effective than interference time, while, in Azarghol and Hysun interference time was more effective than weed density with a view to effect on leaf area duration. Azarghol could tolerate 41.7 and 8.3 weeds/m2 from 30 and 15 days after sunflower emergence later, respectively, without reduction on yield. While intensity of inter-specific competition between redroot pigweed and sunflower in Allstar was higher than Azarghol and Hysun.

Effect of micronutrients and cycocel in drought tolerance of rapeseed was determined by using split factorial design on RCBD with 12 treatments and 4 replications. Experiment was done in research farm of Arak Islamic Azad University during 2007-2008. The treatments considened by irrigation as main factor in 2 levels (normal and drought), 3 levels of micronutrients (0, 1, 1.5 lit/ha) and 2 levels cycocel (0, 1.5lit/ha) as sub factors. 22 variables were determined which were included plant height, full and empty pod number per plant, pod weight per plant, pod number per stem and sub-branch, seed number per pod, stem diameter, seed weight per plant, 1000 seed weight, seed yield, total dry weight, harvest index, relative water content, ionic leakage, SOD, CAT, GPX, MDA, di-Tyro, 8-oh-dg. Result indicated high significant increase in antioxidant enzymes rate in drought condition which means the defensive mechanism of plant in drought condition. Micronutrients caused high significant difference in antioxidant enzymes rate between drought and normal condition so that caused drought tolerance in plant by decreasing the pressure of tension. In addition cycocel consuming resulted in high significant plant height decrease and stem diameter increase due to drought tolerance.