جستجوی مقالات مرتبط با کلیدواژه « Direct seeding » در نشریات گروه « اکولوژی »

The main objective in agriculture production, so far, focused mostly on the increase of yield and production. Whereas today, economical and sustainable production is more important with regard to product quality, reduction of input consumption, conservation of natural resources and environment. Conservation tillage methods stabilize the soil productivity, reduce greenhouse gas emissions and protect the environment. The atmospheric concentration of greenhouse gases (GHGs) has been increased considerably in recent year's, as a result, human activities. Carbon dioxide (CO2) is the most important anthropogenic GHG; its annual emissions increased by about 80% between 1970 and 2004. Conservation tillage systems are increasingly considered as sustainable options to reduce the aftermaths of improper soil tillage. The objective of this study was to investigate energy flow and greenhouse gases emissions of sunflower production in three different tillage methods in northeastern part of Iran.

In order to evaluate the effect of three methods of sunflower production (conventional tillage and sowing, reduced tillage and direct seeding method) on energy consumption and global warming potential in rainfed conditions, this study was performed in the Kalpoosh of shahrood. Data were gathered from thirty representative fields by using a face-to-face questionnaire method and monitoring production practices and inputs used. After gathering of data, energy parameters and global warming potential were calculated based on CO2 balance. The energy amount of each input was calculated by multiplying the amount of consumed input on energy's equivalent. The output energy of sunflower was calculated by multiplying the crop yield on energy's equivalent. Other calculations of inputs and outputs in each method performed by energy coefficients.

The results indicated that total input energy in the conventional method, reduced tillage, direct seeding were 13169, 11814 and 10600 MJ.ha-1, respectively. Thus, conventional method had the highest rate of energy consumption (30 % higher than of direct seeding). Similar results reported by some researchers. The highest amount of total energy input related to nitrogen fertilizer and diesel fuel. Seedbed preparation had the highest rate of fuel and energy consumption (43.5 %) followed by nitrogen Fertilizer (37.6). Maximum of direct and indirect consumed energy, related to fuel and nitrogen, respectively. Similar results reported by some researchers. In three tillage methods, the share of irreproducible energy was the highest and small share of total energy consumption related to renewable energy. Rajabi et al. (2011) reported similar results. The energy efficiency of conventional method was less than other methods. This is due to the high share of machinery and fuel energy and greater use of workers and low yield per hectare. Reducing inputs consumption can be increased efficiency in agricultural systems. Feyzbakhsh and Soltani (2013) reported similar results. Maximum and minimum of energy productivity related to direct seeding (0.15 kg.MJ-1) and conventional method (0.11 kg.MJ-1), respectively. Maximum and minimum of global warming potential (GWP) was related to conventional method (1731 Kg.CO2 eq.ha-1) and direct seeding (1405 Kg.CO2 eq.ha-1), respectively. This issue is compatible with more fuel consumption in conventional method compared with direct seeding. In conventional method, the most rate of GWP was related to fuel consumption (44.8%) followed by nitrogen fertilizer (38.8%) and farm machinery (8.3%).

Based on this study results, through reducing of fuel consumption (replacing of obsolescent machinery and usage of modern implement, performing of farm operations in suitable soil moisture content and preventing of additional operations) and accurate consuming of nitrogen (according to soil testing), it is possible to reduce fuel consumption, greenhouse gas emission and environmental pollutions. 

Sunflower (Helianthus annuus L.) is one of the plants cultivated for oil or seed. Sunflower oil contains many useful fatty acids. One of methods to increase plant yield and decrease input consumption is transplanting. Transplanting can increase seed yield components such as head number per plant, seed number per head, 1000-seed weight. Transplanting increased seed yield and quality compared to direct seeding due to no frost at the beginning of growth season and increasing flowering length. By delaying transplanting, seed germination or transplant establishment is reduced. Time interval from seeding till beginning and terminating flowering length can be reduced by delaying at seeding, but by transplanting flowering duration length increases. Drought losses crop productions especially at plant critical growth periods such as seed filling stage. In arid and semi-arid areas like Iran, water shortage leads farmers to plant low- water crops. By transplanting of sunflower, water can be saved, because seedling can be grown by a little water in controlled condition. In addition, some plant growth stages coincide with cool and rainy weather in spring. Many farmers use transplanting for warm season crops, but transplanting of sunflower has not been well studied. This research was aimed to assess sunflower transplanting under common sowing date and early sowing in Kermanshah climate condition. An experiment was conducted at greenhouse and research field, campus of agriculture and natural resources, Razi University in 2015 and 2016. In the first year, factors included three planting methods (direct seeding, 4-week transplanting and 6-week transplanting) and sowing date (early sowing, common date sowing). In the second year, treatments included 4- week transplanting at early sowing (superior treatment in the first year) and direct seeding (control). At harvesting stage, four plants per plot were selected and traits such as plant height, stem height, stem diameter, leaf number, internode length, leaf width, leaf length, leaf fresh weight, stem fresh weight, seedling fresh weight, leaf dry weight, stem dry weight and biomass were measured. Leaf greenness was measured by SPAD device and stomatal conductance was measured by porometer device. Leaf area was determined by digimizer software. Leaf relative water content, chlorophyll a and b, seed yield and yield components also were measured. Data were analyzed by SAS software. Mean were compared using LSD test. Analysis of variance of 2015 data, showed that planting method and planting date had significant effect on plant height, leaf relative water content, dry matter and leaf area. 4-week transplant at early planting date had the highest dry matter production and leaf area selected for the second year. It seems that by delaying in transplanting, sunflower plant become more sensitive to cold air and low temperature damages plants, so lower dry matter production was produced. Results of the second year showed that transplanting increased green leaf number, leaf area, chlorophyll a, plant fresh weight, plant dry weight, leaf to stem ratio, stem length, plant height, seed number per head, dehulled seed weight, hull weight, seed yield and 100-seed weight. It seems in transplanting, maximum stem length, plant height, green leaf number and leaf area was occurred when sunlight was maximum, so plant had higher radiation use efficiency and dry matter production. In addition, transplanting had higher seed yield than seeding probably due to weed suppression, rapid establishment, shorter growth duration and faster flowering. Transplanting increased seed yield and weight due to lack of coincidence of plant critical stages to adverse environmental conditions, suitable plant cover, prolonging the grain filling period and store assimilates in grain. In conclusion, it is suggested to plant 4-week sunflower transplant at early date in Kermanshah climate condition.

To investigating the density of weeds in direct seeding wheat in the corn straws (no tillage wheat), a split factorial experiment was carried out in randomized complete block design with four replications and three factors including cultivar at 2 levels, (Chamran and Behrang), seed density at 5 levels (50, 100, 150, 200 and 250 Kg/ha) and nitrogen fertilizer from urea source at 6 levels (0, 50, 100, 150, 200 and 250) in fall of 2011 – 2012 in an agricultural farm located 30 km south of Dezful. The result of analysis of variance revealed that the effects of cultivar, seeding and nitrogen fertilizer on weed density and dry weight of weeds and yield and grain yield components were significantly different at 1% level. The least weed density was observed at 250 Kg/ha, with one weed per square meter. Results showed that greater consumption of nitrogen fertilizer will increase the dry weight of weeds per area unit, so that the fertilizer level of 250 kg nitrogen per hectare with an average of 9.9 grams in the square meter had the highest dry weight of weeds per area unit. The no tillage seeding caused increasing the grassy weeds. Using seeds over 100 Kg/ha which decreases yield grain and increases nitrogen consumption to the level 150 (Kg/ha) resulted in significant increase in grain yield. Chamran cultivar, with grain yield average of 413.70 (kg/ha) was preferd to Behrang cultivar.