Journal of Agricultural Science and Sustainable Production
Year:2011 | Volume:20/2 | Issue:4|Papers Count:11

Past researches have been showed that about 50% of whole needed energy for different stages of agricultural production is used for tillage operations. One of the most important stages of tillage operation is breaking hardpans created naturally or by trafficking. Great amount of energy needed for braking hardpan using traditional sub-soiler. The objective of this research was to find a method to loosen hardpan using less enery with optimum tillage conditions. Most of researches have been shown using oscillatory sub-soiler (oscillation can be in horizontal, vertical directions or combination of both of them) can decrease required draft and incerase sub-soiler performance and its efficiency. The most important factors affecting the sub-soiler's performance are: oscillating amplitude, frequency, oscillation angle of tine also tractor forward velocity. In this study an oscillating sub-soiler was simulated using ADAMS software. Increasing frequency reduced the engagement time of tine with uncut soil. Draft was reduced with increasing frequency 69% draft reduction was obtained at 8.85Hz, compared with rigid tillage. The required engine power shows there is an optimum frequency close to 3.5 Hz for minimum power to operated the sub-soiler.

The main purpose of this study is to investigate factors influencing attitude of managers towards integrating animal husbandry program (IAHP) in Tabriz district. The research design was descriptive – correlation and survey. The statistical population were, all animal husbandry managers of Tabriz district (N=331). Proportional stratified sampling method was used to select the 121 managers as samples of the study. The instrument for collecting data was a questionnaire which its validity was confirmed by panel of experts and its reliability calculated by Choronbach alpha coefficient (a=0.89). Results showed that 44% of managers have positive attitude towards the IAHP. Step-wise multi-variant regression analyses showed that 69% of variation of dependent variable (attitude of managers) could be explained by three factors: knowledge about the program, distance of new settlements with managers' house and the participation rate of their family members.

In order to investigate the effect of water limitation on morphological traits and water use efficiency in two soybean cultivars, a split-plot experiment was conducted in 2004 at the Research Farm of the Faculty of Agriculture, University of Tabriz, Iran. Irrigation treatments (I1, I2, I3 and I4: irrigation after 60±3, 80±3, 100±3 and 120±3 mm evaporation from class A pan, respectively) were assigned to main plots, and two soybean cultivars (Zane and Huck) were allocated to the sub plots. The results indicated that the Huck required less GDD (growing-degree days) to complete the growth and developmental stages, compared with Zane. Flowering and maturity for Huck occurred about 3 days earlier than those for Zane. The mean number of branches, plant height, biological and grain yields under well watering (I1) were higher than those under limited irrigations (I2, I3 and I4). All these traits were decreased with increasing water deficit. The highest harvest index was obtained from I1 treatment, however, this superiority was not significant statistically, when compared with other irrigation treatments. Therefore, it was concluded that water use efficiency (WUE) could be improved, with decreasing irrigation. However, the volume of water at each irrigation increased and grain yield decreased, as water deficit severed. Consequently, it seems that irrigation with low volume and short intervals might be more suitable for soybean production.

The yield of maize in Iran is very low as compared to other maize producing countries. One of the most important effective factors is non application of optimal plant population per hectare and maize hybrids differ in their response to plant density. In order to study the effect of different plant densities on yield, rate and effective grain filling period in maize hybrids, a factorial experiment based on randomized complete block design with three replications was conducted in 2007 at the Research Farm of the Faculty of Agriculture Mohaghegh Ardabili University. Experimental treatments were: maize hybrids in three levels (SC-404, DC-370, SC-504) with different plant densities (8, 10 and 12 plants.m-2). The results showed that yield and yield attributes characters (except of the number of grains rows) varied significantly due to the variation in population densities. The number of kernel per ear and number of grains per ear row increased with increasing plant density. The highest grain yield was obtained from 10 plant.m-2 density. Response of maize hybrids wasn’t the same for plant densities. The highest grain yield belonged to SC-504 hybrid and the least was in DC-370 hybrid. A two part linear model were used to quantifying the grain filling parameters. Cultivars and plant densities affected all grain filling parameters significantly.Maximum kernel weight, rate and effective grain filling period was obtained in low plant densities.Means of comparisons showed that maximum of kernel weight (0.35 mg) and effective grain filling period were obtained in SC-504 hybrid×8 plants.m2 and SC-404 hybrid×8 plants/m2. Minimum of it was obtained in DC-370 hybrid×12 plants/m2.

A survey of the natural resources situation in the Khorasan Razavi province reveals that this sector is faced with problems such as negative balance of water in the plains, soil salinity, and soil erosion.This study tries to estimate the technical efficiency of the states of the Khorasan Razavi province in agronomy and horticulture subsectors with attention to restriction of water resources. Required data is collected from yearbooks of Jihad Keshavarzi and Regional Water Organization of Khorasan Razavi province for years 1997, 2002 to 2004 and 2006. This study uses an integrated neural network and fuzzy clustering algorithm. Mean of technical efficiency in the case of considering water resource limitation is 77 percent while as in the case of not considering water recourse limitation is about 74 percent. Results indicate that considering water recourse limitation in agricultural production in each region can affect results of technical efficiency assessment for each state.

In attention to the importance of forage plants and the necessity to use genetic resources and in order to overcome the environmental stresses such as salinity, uniform grass pea seeds (landrace of Maragheh) were selected and grown in hydroponic system. At 4-5 leaves stage, seedlings were subjected to 200 mM salt stress for a period of 10 days. Sampling was done from the leaves and roots of seedlings and it used to assess the antioxidant enzymes involving in defense mechanisms.Evaluation of antioxidant enzymes in grass pea leaves showed that despite a significant increase in catalase, total superoxide dismutase and guaiacol peroxidase, injury to the membranes has been increased. Likely, the increased damage to membranes would be caused by lack of significant increase in ascorbate peroxidase and isozyme of Cu/Zn-SOD. Because the low activity of this enzymes led to inefficient implementation of Mehler cycle following by reduce efficiency of xantophyll cycle and a change in Tylakoid status. Therefore, ROS production overcomes the plant defense mechanisms leading to increased lipid peroxidation under salinity. Interestingly in the root and under salt stress, the rate of damage to cell and organelle membranes was significantly reduced compared with the control. It seems unexpected behavior of root may be due to the changes in fatty acid compositions of the membranes structure.

To investigate the effects of different intercropping arrangements on barley and vetch forage yield and to find the land use advantage in the intercropping system, an experiment was carried out based on randomized complete block design with eight treatments and three replications at the Research Farm, Faculty of Agriculture, University of Tabriz in 2009. Treatments were barley and vetch monocrops, additive intercropping respectively barley: vetch in the ratio of 100:15, 100:30 and 100:45 and substitutive intercropping respectively, barley: vetch in the ratio of 2:1, 3:1 and 4:1. The results showed that, the highest amount of dry forage yield is obtained from 100:15 intercropping ratio. The highest intercropping advantage (4.41) was related to 100:15 additive intercropping ratio. Land Equivalent Ratio revealed that in 100:30 ratio, yield was %32 more than monocropping. The highest Relative Yield Total abtained from 100:30 additive intercropping was 1.14. Also, the greatest amount dry forage is 7030kg/ha in 100:15. Based on results of this experiment it can be stated that for the production of hay, additive intercropping method is superior on substitutive intercropping planting and monocroping sowing of barley and vetch.

The intensive use of pesticides has posed detrimental effects on the environment. Concerns over those environmental impacts have led to many efforts in pesticides usage reduction. As an example, economic instruments that can be used in explaining suitable policies. With Estimating the economic value associated with pesticide reduction and identifying the effective factors on administration and success of pesticide reduction policies can be assisted in designing pesticide regulations. The purpose of this study is to identify the economic benefits associated with pesticides reduction in Khuzestan province, Iran. The required data were collected from 180 farmers of Khuzestan province in 2009. The study uses Contingent Valuation survey to estimate farmers willingness to reduce three risk level (high, moderate and low) for five environmental categories (human health, birds, aquatic species, beneficial insects and livestock). A Tobit model with heckman two-stage procedure estimates is developed to determine the factors that affect farmers willingness to pay. With calculating the willingness to pay it was found that greater concern is evident for human health, birds and livestock, and relatively less for aquatic species and useful insects. The economic benefits for 15 environmental classes varied from 571623 Rials (human/high) to 56926 Rials (beneficial insects/low) per person per cropping season. The estimate of the Heckman two stage procedure results in determining the decisive factors in willingness to pesticides reduction strategies which consist of income, number of IPM strategies, farmer importance to decrease pesticides risk, farmer perception about environmental impacts, confronting with environmental impacts and own tenure, all with positive effect, while age and pest severity with negative effects. Farther results indicate that the variables of growing vegetables and percentage of IPM strategies have the most positive effect, while cropping corn and daily wage of hand weeding worker have the most negative effect on amount of willingness to pay.

In this study the optimal cropping pattern for Piranshahr- one of western Azarbaijan’s cities- was determined using Multi-objective Fuzzy Fractional Programming with the aim of moving toward sustainable agriculture. The cross section data of 2007-2008 were used for our analysis. Data were gathered through filling out 600 questionnaires from 60 villages of Piranshahr city by using twostage random sampling method. The results showed that the optimal cropping pattern using the Multi-objective Fuzzy Fractional Programming to achieve sustainability is different with the current cropping pattern. Moreover, the results of the stability indices (ratio of gross income to the use of chemical fertilizers and pesticides) showed the significance of this goal was built for sustainability.Sustainability indices determined for chemical pesticides fungicides, herbicides, insecticide, nitrogen, phosphate and fertilizer. Results indicate that elimination or minimization of chemical pesticides and fungicides is more important than other inputs.

In order to identify red kidney bean cultivars with high competitive ability a set of experiment was conducted at Research Farm of University College of Agriculture and Natural Recourses University of Tehran (Karaj) in 2006 and 2007, to evaluate the competition effect of red root pigweed on growth indexes, seed yield and yield components of red bean cultivars. In 2006 different densities of pigweed including 0, 4, 8, 16 and 32 plant/m2 and three cultivars of red bean (Akhtar, Sayyad and Line D81083) were used in a factorial experiment with complete randomized block design. In 2007, cultivars Gholi and mixed cropping of cultivar Gholi and Aktar were added to the first year treatments. Results indicated that the cv. Gholi and Sayyad had more leaf area index and crop growth rate than cv. Akhtar and Line D81083. The leaf area index and growth rate of pigweed in competition with the red bean cultivars of Gholi and Sayyad were lesser than that of cv. Akhtar and Line D81083 that indicate more competitive ability of cv. Gholi and Sayyad.The results indicated that in both years, the effect of pigweed density on bean seed yield and pod number per plant was significant. In 2007, the pigweed density of 32 plants/m2, reduced seed yield of cultivar Akhtar, Line D81083, Gholi, Sayyad and mixed cropping of Gholi and Akhtar, 72.5, 80.5, 49.8, 60.35 and 58.1 %, respectively. Based on the yield loss model coefficients (a & m) red kidney bean cultivars of Gholi and Sayyad had the most competitive ability and Line D81083 had the least competitive ability against the redroot pigweed. In 2007, redroot pigweed had more competitive ability against the all bean cultivars than 2006.