نشریه به زراعی نهال و بذر
سال سی‌ام شماره 1 (1393)

This research was carried out using a layout of randomized complete block design with four replications during 2004-2008 at Khair-Abad Research Station، Zanjan، Iran. The treatments were either removal or adding of grass pea and common vetch green manure and adding wheat green manure (originated from threshing grains as control) into the soil. In results obtained from two cycles of crop rotation، although there was no significant difference between grass pea and common vetch in terms of mean dry matter yield but total dry matter yield obtained from two rotation cycle in grass pea was 24. 2% more than of common vetch. In each of two rotation cycles، there was significant difference (p≥ 0. 01) among the treatments regarding dry matter of green manure and nitrogen accumulation in tissues of the above ground organs. In each of two cycle rotation، the least amount of dry matter (0. 29-0. 63 tha-1) and nitrogen accumulation (3. 98-9. 12 kgha-1) was obtained from control treatment. The treatments effect on onion yield، weight of soil particles diameter، soil organic carbon percent، biological and grain wheat yield were not significant. Highest values of these characters were obtained from adding green manure grass pea and common vetch treatments. Mean wheat biological yield (18. 5 tha-1)، wheat grain yield (7. 23 tha-1)، mean weight of soil particles diameter (1. 69) and soil organic carbon percent (0. 915) in grass pea green manure added treatment، was 12. 8، 14. 6، 13. 4 and 0. 2 percent higher than check treatment، respectively.

To investigate the effect of rotation on wheat yield and to determine the economic value of crop rotations، eight rotation treatments that had conducted in Jolge-e-Rokh Agricultural Research Station during 2006 - 2010، were evaluated economically، using partial budgeting and marginal analysis. Experimental design was، complete randomized block design with three replications. Treatments consisted of eight crop rotation T1: wheat continuous culture، T2: wheat، wheat، wheat، canola، wheat، T3: wheat، sugar beet، wheat، sugar beet، wheat، T4: wheat، potato، wheat، potato، wheat، T5: wheat، potato، wheat، canola، wheat، T6: wheat، sugar beet، wheat، potato، wheat، T7: wheat، forage corn، wheat، potato، wheat and T8: wheat، forage corn، wheat، sugar beet، wheat. Results indicated that pre plant and kind of crop rotation had significant effects on wheat yield in the final year. Comparing mean test indicated that wheat in rotation had significantly better yield than continuous planting (between 21 to 37 percent). In fixed price، T6 rotation (wheat، sugar beet، wheat، potato، wheat) with relative rate of return 90 % and net income 112. 99 million rails had the maximum rate of return and profit respectively، and T3 rotation (wheat، sugar beet، wheat، sugar beet، wheat) with 104 million rails net income followed it. Although change in prices led to change in selected treatment، but treatments in this study had the economical replacements and therefore، farm manager will be faced with flexible options.

Drought stress is the most important factor decreasing crop yield in dry and semi dry areas of the world، such as Iran. To investigate seed yield and drought stress tolerance indices of twenty soybean lines and cultivars، three experiments were conducted، each in a randomized complete block design with there replications، at Agricultural Research Station of Gorgan in 2010 and 2011. In the first experiment، all soybean genotypes were irrigated based on 50 mm and in the second and third experiments، the irrigation was based on 100 and 150 mm evaporation from evaporation pan، respectively. The mean seed yield of soybean genotypes in non-stress and stress conditions was 1989 and 1242 kgha-1، respectively lines. HT2 in non-stress conditions (2569 kgha-1)، PE10 in moderate stress conditions (2222 kgha-1) and WE6 in severe stress conditions (1688 kgha-1) had the highest seed yield، respectively. With regard to GMP، MP and STI indices، drought stress tolerance of PE10 and HT2 genotypes were more than those of other genotypes. Based on SSI index، genotypes L504 and M9 had the highest and the lowest tolerance to drought stress، respectively، while according to TOL index genotypes SG20 and L17 were the most and the least tolerant genotypes، respectively. The superior genotypes can be recommended for further breeding programs.

To study the effects of arbuscular mycorrhizal fungi (AMF) on photosynthesis، stomatal conductance، transpiration and leaf temperature of maize (Zea mays L.) under well-watered (I1)، moderate drought stress (I2) and severe drought stress (I3) conditions، two field experiments were conducted in agricultural research station in Khorramabad، Iran in 2011 and 2012. Each experiment was carried out as split-plot factorial based on randomized complete block design with three replications. Irrigation was imposed at three levels based on 70% (I1)، 50% (I2) and 30% (I3) field capacity، as the main plot. Mycorrhizal biofertilizer (Glomus intraradices) was applied at two levels of control or without application (M1) and application of 100 kgha-1 (M2) as the sub plot. Phosphorus fertilizer was also applied at three levels of control or without application (P1)، application of 75 kgha-1 (P2) and 150 kgha-1 triple superphosphate (P3)، as the sub plot. The results of combined analysis showed that، mycorrhizal biofertilizer application and different irrigation treatments significantly affected the measured traits. Mycorrhizal biofertilizer application led to improved photosynthesis، stomatal conductance، transpiration and leaf temperature، as much as 20، 3. 3، 9. 2 and 4. 2%، respectively. Photosynthesis، stomatal conductance and transpiration as affected by different irrigation regimes were decreased by increasing drought stress، but leaf temperature was increased by increasing drought stress. Different P fertilizer levels also significantly affected photosynthesis. Measured traits in AM plants had priority than non AM plants، as a consequence of enhancing nutrient uptake، extension of the root system and water status of the plants.

In this experiment، seed rates in direct seeding methods of rice (cv. Hashemi) were compared and lodging related traits were evaluated in split plot lay out based on randomized complete block design with three replications and four seeding methods as main plots and three seeding rates (60، 80 and 100 kgha-1) as sub plots at Rice Research Institute of Iran، Rasht، Iran. Seeding methods consisted of drum direct seeding، hill wet seeding، broadcasting and pre-geminated seeding in puddle field. The maximum grain yield (2753 kgha-1)، internodes length، internodes fresh weight، third and fourth internode cross-section area (4. 43 and 7. 12 mm2، respectively)، third and fourth bending moment (493. 04 and 581. 93 gcm، respectively) and breaking resistance of third and fourth node (947. 24 and 1651. 89 gcm، respectively) were obtained in hill wet seeding method. The maximum grain yield (2486 kgha-1) was obtained in 100 kgha-1 seed rate. Increase in seeding rate resulted in decrease of internodes length، internodes fresh weight and bending moment of third and fourth internodes. Stepwise regression analysis showed that internode cross section area and internode flattening had highly significant effect on breaking resistance (verified 56% and 59% of breaking resistance، respectively). It seems it may possible to prevent the lodging problems in Hashemi rice production to a large extent by direct seeding of pre-germinated seeding in conditions of the intended region.

This experiment was conducted in 2007 and 2008 to evaluate the efficacy of metribuzin herbicide on weeds control and yield of maize، at research farm of the Agricultural Research Center of Safi Abad Dezful، Iran. The experimental design was a randomized complete block with 13 treatments in three replications. Treatments included preplant، preemergence and postemergence application of metribuzin at 3-4 leaf stage of maize and weeds each at 0. 35 and 0. 52 kg ai ha-1، preplant، preemergence and postemergence application of atrazine + metribuzin at 3-4 leaf stage of maize and weeds each at (0. 6 + 0. 175) kg ai ha-1، nicosulfuron at 0. 08 kg ai ha-1at 3-6 leaf stage of maize and preemergence application of atrazine + alachlor at (1. 2 + 1. 9) kg ai ha-1، together with weedy and weed free checks. The results indicated that compared to the weedy check، postemergence application of metribuzin at 0. 35 kg ai ha-1 and atrazine + metribuzin with 79 and 75% control، respectively، were the most effective treatments in reducing total number of weeds. Application of atrazine + alachlor، postemergence application of metribuzin at 0. 35 kg ai ha-1 and atrazine + metribuzin and nicosulfuron with 89، 87، 86 and 85% control، respectively، were the most effective treatments in reducing dry weight of weeds. Compared to the weedy check، postemergence application of metribuzin at 0. 52 and 0. 35 kg ai ha-1، atrazine + metribuzin and premergence application of atrazine + alachlor with 50، 44. 44 and 37% increase، respectively، were the most effective treatments in yield increase. According to these results، for weed control and yield increase of corn، postemergence application of metribuzin at 0. 52 or 0. 35 kg ai ha-1، atrazine + metribuzin or premergence application of atrazine + alachlor each at the abovementioned rates can be recommended.

The transplanting stage of seedling and planting depth، influence growth and yield of vegetable crops. An experiment was conducted to study the effects of these factors on yield of tomato cv. Petoearly CH in West Azarbaijan، Iran for two years. Seed was cultivated in nursery and then seedlings were transplanted to field at three growth stages of four leaves، six leaves and eight leaves. Three planting depths used for seedlings were the rootball، the cotyledon leaves and the first true leaf. The research was carried out as factorial experiment based on randomized complete block design with four replications. Results showed that with reduction in the number of leaves from eight to four، percentage of seedlings death after transplanting and vegetative growth decreased، and earliness، first harvest yield and total yield increased. Minimum number of days to flowering and fruit maturity، and maximum number of fruits، first harvest yield and total yield at first true leaf plantings depth were significantly different from other depths.

In the present study antioxidant compounds of oil of olive cultivar Roodbar and their changes during storage of fruits after harvesting were investigated with key sensory oil properties. Characteristics such as total polyphenols (TP)، total antocyanins (TA) and their antioxidant activities were assessed countinuously for a period of 12 days (every three days). The results showed that the quantity of total antocyanin and total polyphenolic compounds increased by time and the highest quantities were meansured at the third sampling time (9 days after storage). However، there was no significant difference between quantity of these compounds at the sixth and twelveth days after storage. Antioxidant activity of these compounds followed the same trend. Based on the results of this study، storage and expose of olive oil to air for a period of 12 days not only does not affect the antioxidants quantity and their activities، but they incresase during the first nine day after storage. However storage of olive oil for longer periods needs to be investigated.