JOURNAL OF AGRICULTURAL SCIENCE AND TECHNOLOGY (JAST)
Year:2006 | Volume:8 | Issue:2|Papers Count:8

This paper examines the effects of agricultural land productivity improvement on the economy of Iran assuming that the domestic and international trade liberalizations will open up the opportunities to expand market access. A 25-sector computable general equilibrium model was developed to simulate the effects of this policy. The simulation results indicate that enhancing agricultural land productivity while implementing trade policy reform results in an expansion of agricultural sector which, in turn, leads to the expansion of food manufacturing and service sectors and mitigating the problem of unemployment. Furthermore, improving land productivity results in a decrease in the price of food products and an increase in real GDP. Consequently, food security enhances and Iranian welfare improves. As a result, this is an appropriate domestic policy for Iran. This policy results in an expansion of agricultural sector which in turn leads to expansion of food manufacturing and service sectors, mitigates the unemployment problem, improves the Iranian welfare as the real GDP increases, and improves the food security in Iran, as the price of food products decreases.

Since time immemorial, Iranian women have played a pivotal role in agriculture, the largest industry contributing to rural livelihoods. Hence, the present study was conducted in Tafresh area of Iran to examine factors influencing participation of rural women in mixed farming activities in 1999.This was a descriptive- correlation research project in which a total number of 300 rural women were selected through stratified random sampling technique and interviewed. A questionnaire was used as measurement tool for which the reliability coefficient was 0.90. According to the findings, sixteen characteristics of rural women had significant relationships with their overall participation in mixed farming. Nine variables, namely, women’s age, husband’s age, crop farming experience, animal husbandry experience, perceived role overload, total energy expenditure, energy expenditure in animal husbandry, time spent in animal husbandry and time spent in mixed farming  were positively and significantly correlated with overall participation of rural women in mixed farming. Whereas, energy expenditure in mixed farming activities, women’s education, husband’s education, animal ownership, extension contact, energy and time spent in household activities were negatively and significantly correlated with the overall participation of rural women in mixed farming. Stepwise regression analysis revealed that 48 per cent of variation in the overall participation of rural women in mixed farming was explained by three variables: marital status, woman’s education and time spent in animal husbandry. 

This research explores the possible benefits to be derived from interactions between wheels, for supporting a greater proportion of applied loads in the shallower soil layers. This creates possibilities for reducing the risk of deep soil compaction. Previous research indicated that different interaction modes occurred under simulated wheel arrangements, being mostly dependent upon the spacing between them. Hence, field experiments were arranged to investigate a range of spacings between dual wheels in practical situations. Two field conditions were prepared providing loose and firm surface layers. Dry bulk density, penetration resistance, wheel sinkage and contact area were measured under each arrangement. A clear link was identified between results previously obtained in soil bin tests and those in the field, confirming that spacing has a major effect on the potential benefits. As wheel spacing decreased the interaction increased, inducing a greater resistance in the soil surface layers to carry higher loads. The optimum range of appropriate spacings and interaction modes identified in the laboratory tests was found to be applicable in the field.

Thrips species injurious to grapes are known as pests in vineyards all over the world and belong to the main pests of grapes in West Azarbaijan, Iran. In this study, thrips species occurring in West Azarbaijan vineyards were identified and the predominant species documented according to their relative abundance at different growth stages. The seasonal abundance of predominant species was investigated by means of yellow sticky trap catches and weekly sampling from vegetative and reproductive organs of vines. Five species including: Rubiothrips vitis (Priesner), Thrips tabaci Lindeman, Tenothrips discolor (Karny), Tenothrips reichardti (Priesner), and Limothrips angulicornis Jablonowski, were collected and identified. R. vitis, constituting 92 and 66 percent of the thrips population on vegetative and reproductive organs, respectively, was found to be predominant. T. tabaci was not found on vegetative organs, but it was found to constitute 32 percent of the thrips found on reproductive organs (flowers). The two species R.vitis and T. reichardti are new records for the Iranian fauna. The number of adult thrips caught by sticky traps was positively correlated with the density of the adults on vegetative (buds and leaves) and reproductive (flower) organs in the first and second generations, respectively.

The stability of ten winter safflower cultivars and lines was evaluated in three different environmental conditions in Karaj, Isfahan and Darab in Iran, a randomized complete block design with 4 replications over three years (1995, 1996 and 1997). Simple analysis of variances of grain and oil yields from each experiment showed significant differences among the genotypes. After conducting a homogeneity test for error variances, combined analysis of variance was performed. An F. test of different sources of variation revealed that the effect of genotype × year × location interactions was significant (P<1%). Analysis of the grain and oil yields using the Eberhart and Russel method showed significant difference for the main effects of genotype and genotype × environment (linear) interactions and non-significant difference for deviation from regression. According to the classification of genotypes based on the mean of grain and oil yields, coefficient of regression and deviation from regression, the new line L.R.V.51.51 with its high grain and oil yields and stability was selected as a desirable genotype.

The choice of an efficient breeding procedure depends to a large extent on knowledge of the genetic system controlling the character to be selected. The objective of this study was to determine genetic parameters for yield and other traits including some of the yield components under three planting densities, using analysis of generation means (P1, P2, F1, F2, BC1 and BC2) derived from crosses of B73 with Mo17 and K74/1 inbred lines of corn. Analysis of variance reinforced the hypothesis that interaction of plant density on generation means depends on evaluating genotypes and the kind of trait. Generation mean analysis suggested that both additive and dominance effects were important for most of the traits evaluated in this study, but dominance had a more pronounced effect. Epistasis affected the expression of nine traits in both crosses at three planting densities. Expression of epistasis and genetic parameters differed in the two crosses and were influenced by plant density. Plant densities interacted more strongly with epistasis gene action than with additive or dominance gene action in both crosses. 

On-farm experiments were designed to investigate the response of maize establishment and grain yield to variation in tillage systems. The tillage treatments included arara ploughing followed by zig-zag harrowing and arara ridging (T1); emcot ploughing followed by zig-zag harrowing and emcot ridging (T2); mouldboard ploughing followed by disc harrowing and mouldboard ridging (T3); disc ploughing followed by disc harrowing and disc ridging (T4); manual ridging (T5). Generally, shallow (0-15.0 cm) tilled plots of T1 showed lower root lengths and root length densities than deep (0.28.0 cm) tilled plots of T4. However, there was higher soil penetration resistance (PR) in T1 than in T4. Increased PR in the range of 4.0 – 4.5 MPa decreased plant height (Hp), leaf area index (LAI), and maize grain yield (Yg). Reductions in Yg in the range of 35 – 50% can be expected for a reduction in soil moisture contents from 24.2 – 15.7%, w/w. Tillage treatment significantly (P<0.01) affected Yg. However, there were no significant differences at P<0.05 in the emergence rate index (ERI), LAI and Yg for the interactions of nitrogen levels × planting methods × tillage treatments. 

Use of saline water for irrigation has shown considerable promise. However, its effect on the solubility and bioavailability of native soil nutrients is not well understood. This study was conducted to evaluate the effects of salinity on the behavior of zinc(Zn) in calcareous soils. The soil samples with different physiochemical properties were collected from four locations in Khorasan province (Iran). The factorial experiment was carried out as a completely randomized design on soils with four levels of water salinity (0, 37.5, 75 and 150 mole m-3 prepared with the same equivalents of NaCl and CaCl2) and four reaction times (0, 10, 20, and 30 days) with three replications. DTPA-extractable Zn was measured in the incubated soil samples after the given reaction times. Different chemical forms of Zn were characterized after 30 days using the sequential extraction procedure. DTPA-extractable Zn increased by 1 to 6.3% with the increasing levels of salinity, and decreased from 8.7 to 3.9% by increasing the reaction time significantly (P<0.05). The determination of Zn compounds by the sequential extraction procedure revealed significantly different forms of Zn with the average amounts in the following order: (KNO3+H2O)-Zn(soluble+exchangeable forms) < NaOH-Zn(organic form) < EDTA-Zn (carbonate form) << HNO3 -Zn (residual). Salinity affected various forms of Zn i.e. soluble + exchangeable, organic and residual. Increasing soil salinity level increased the KNO3+H2O extractable Zn by 20 to 80% and the NaOH extractable form by 8.6 to 43%. DTPA-Zn was significantly correlated with the NaOH extractable form (r=0.98 P<0.05) and with the (KNO3+H2O)-Zn, (r=0.94 P<0.05). It was concluded that increasing salinity redistributed HNO3-extracted Zn (residual) to the KNO3+H2O extractable (soluble + exchangeable) and NaOH extractable (organic) forms of Zn.