eng
Tarbiat Modares University
Journal of Agricultural Science and Technology
1680-7073
2345-3737
2000-10
2
4
231
241
article
Using a General Dynamic Econometric Framework to Specify
the Appropriate Model in Studying Agricultural Production
Structure: A Case Study of Crop Production in Iran
H. Salami
1
T. S. Veeman
2
Department of Agricultural Economics, Faculty of Agriculture. University of Tehran, Islamic Republic of
Iran.
Department of Rural Economics, University of Alberta, Edmonton, Canada.
This paper shows the role of the general dynamic model in empirical research of production
technology in agriculture. The model is a first order autoregressive multivariate
specification, first developed by Anderson and Blundell. This model is general enough to
nest several simpler dynamic as well as static models within it. Therefore, it provides a
framework for applying classical testing procedures and identifying the appropriate
specification in the empirical econometric model of production. The usefulness of the general
dynamic model is shown by estimating the production structure in the Iranian crop
sector. The results indicate that the Iranian crop production is best characterized by a
long-run static model derived from a non-homothetic translog specification which incorporates
non-neutral technological change and allows for structural change after the Islamic
Revolution of 1979.
http://jast.modares.ac.ir/article-23-8985-en.pdf
Crop sector
General dynamic
Model specification
Production structure
eng
Tarbiat Modares University
Journal of Agricultural Science and Technology
1680-7073
2345-3737
2000-10
2
4
243
256
article
Genesis and Morphological Changes of Soils under Irrigated
Date Palm in Southern Iran
M. Baghernejad
1
Department of Soil Science, Shiraz University, Shiraz, Islamic Republic of Iran.
Macro and micromorphological investigations were conducted on selected Xerepts soils
from southern Iran to identify changes in soil characteristics with time. Soil samples from
similar pedons of four irrigated orchards ranging in age from 20 to 100 years were studied
and compared with soil samples of a pedon of non-irrigated land. In addition to routine
analyses, undisturbed blocks of soils from each horizon of pedons were prepared and
used for micromorphological studies. Field data, micromorphological obsrevations and
laboratory data, permitted an overview of changes in soil characteristics and their role in
the pedogenesis. Changes observed include the type and distribution pattern of voids,
translocation and accumulatin of CaCO3, and the soil fabrics. Calcitic hypocoatings, and
compound dense complete calcite infillings in vughs, and large voids were attributed to
precipitation as induced by irrigation. There seems to be an increase in organic matter
content with time. This needs to be further studid to establish condition for carbon sequestration
and increased soil quality in arid regions.
http://jast.modares.ac.ir/article-23-11166-en.pdf
Micromorphology
Calcitic hypocoatings
Irrigated date palm
Xerepts
eng
Tarbiat Modares University
Journal of Agricultural Science and Technology
1680-7073
2345-3737
2000-10
2
4
257
262
article
Effects of Scarification and Temperature on Germination of
Licorice (Glycyrrhiza glabra L.) Seeds
H. Ghadiri
1
N. Bagherani Torshiz
2
Department of Crop Production and Plant Breeding, College of Agriculture, Shiraz University, Shiraz,
Islamic Republic of Iran.
Agricultural Research Center, Gorgan, Islamic Republic of Iran.
Laboratory experiments were performed to determine the effect of various scarification
treatments at four temperature regimes on germination of licorice seeds . A randomized
complete block design with four replications was used. Germination counts were made
every day for 2 weeks. At 50C, none of the chemically and mechanically scarified and non
scarified seeds germinated. At 15, 25, and 350C, mechanical scarification increased seed
germination to 94-98%. However, at these temperatures, velocity of germination of mechanically
scarified seeds were lowest among all treatments. Chemical scarification also
increased germination percentage significantly to 90-95% with 45 min soaking. At 15 and
250C, seed germination percentage and velocity of germination increased as the soaking
time in sulfuric acid increased from 5 to 30, 45, or 60 min. However, at 350C, there was no
difference in germination percentage between soaking times of 5 and 60 min. It appears
that soaking for 45 min provides full germination at 25 and 350C.
http://jast.modares.ac.ir/article-23-11099-en.pdf
Licorice dormancy
Weed biology
Weed seed germination
eng
Tarbiat Modares University
Journal of Agricultural Science and Technology
1680-7073
2345-3737
2000-10
2
4
263
270
article
Yield and Yield Components of Two Winter Wheat (Triticum
aestivum L.) Cultivars in Response to Rate and Time
of Foliar Urea Application
Y. Emam
1
A. R. Borjian
2
Department of Agronomy, College of Agriculture, Shiraz University, Islamic Republic of Iran.
Agricultural Research Center, Khanssar, Islamic Republic of Iran.
Foliar urea application is one of the nitrogen (N) application methods in cereal grain
crops. Yield and yield components may be affected by foliar urea application. To investigate
the effect of rate and time of such treatment on yield and yield components of two
winter wheat cultivars, a field experiment was conducted at Badjgah, Agricultural Research
Farm (29° 36 N, 52° 32 E) of Shiraz University, Shiraz, Iran during 1998-99 growing
season. The experimental treatments were two winter wheat cultivars (‘Phalat’ and
‘Marvdasht’), five levels of foliar urea application (0, 8, 16, 24 and 32 kg N ha-1) at three
times of application (pre-anthesis, anthesis and post-anthesis). The experimental design
was a randomized complete block one with treatments arranged as split-plot factorial
with three replicates. The results showed that cultivars responded differently to the rate
of foliar N feeding so that, over the growth stages, Marvdasht cultivar produced significantly
greater grain yield (+19%) by application of 8 kg N ha-1, whereas, the Phalat cultivar
had greater grain yield (+27%) when it was supplied by 16 kg N ha-1. Increase in
grain yield was mainly due to an increase in number of grains ear-1. The fertile ears m-2
and mean grain weight were not significantly affected by foliar urea feeding, however, the
harvest index and biological yield were increased. The pre-anthesis foliar feeding with
urea resulted in higher yields as compared with later applications. Also the early foliar
urea feeding increased the harvest index from 42.4% to 46.9% at 32 kg N ha-1 in
Marvdasht cultivar. The results of the present investigation also suggest that late foliar
application could decrease nitrogen use efficiency.
http://jast.modares.ac.ir/article-23-12199-en.pdf
Grain yield
Foliar N application
Winter wheat
eng
Tarbiat Modares University
Journal of Agricultural Science and Technology
1680-7073
2345-3737
2000-10
2
4
271
279
article
Effects of Stocking Density and Grazing Period on Herbage
and Seed Production of Paraggio Medic
M. R. Chaichi
1
G. Tow
2
Agronomy Department, College of Agriculture, University of Tehran, Karaj, Islamic Republic of Iran.
Department of Agronomy and Farming Systems, College of Agriculture, University of Adelaide, Adelaide,
Australia.
Three stocking densities (20, 40, and 60 sheep/ha) were applied in four stocking periods
(0, 2, 4, and 6 weeks) on a Medicago truncatula cv. Paraggio pasture. Treatments were arranged
in a split plot system and compared through a completely randomised block design
with four replications.Grazing period had a significant effect (P<0.001) on availability
of both medic and other species separately. Total available forage (medic and other
species) was significantly affected by both stocking density (P<0.05) and grazing period
(P<0.001) and there was a significant interaction between stocking density and grazing
period (P<0.001). Grazing period was the only factor affecting the cumulative forage production
of medic and other species. Stocking density and grazing period both had significant
effects on total cumulative pasture production. Pod production significantly decreased
as grazing period increased. More seeds per pod were observed at low stocking
density as compared with other densities. There was a dramatic reduction in seed production
as grazing period increased (P<0.05).
http://jast.modares.ac.ir/article-23-1537-en.pdf
Forage production
Medic
Seed production
Grazing
sheep
stocking density
eng
Tarbiat Modares University
Journal of Agricultural Science and Technology
1680-7073
2345-3737
2000-10
2
4
281
290
article
Distribution of 32P between Roots and Tops of White Clover:
Effect of Mycorrhizal Fungi and Placement Distance
from the Roots
H. Mehravaran
1
A. Mozafar
2
E. Frossard
3
College of Agriculture, Urmia University, Urmia, 57135, Islamic Republic of Iran.
Institute of Plant Science, Swiss Federal Institute of Technology (ETH), Eschikon Experiment Station,
CH-8315 Lindau, Switzerland.
Institute of Plant Science, Swiss Federal Institute of Technology (ETH), Eschikon Experiment Station,
CH-8315 Lindau, Switzerland.
In a greenhouse experiment, the effects of Glomus intraradices and indigenous mycorrhizal
isolates from soils under plow and no-till treatments on the uptake of 32P placed
at 1, 2.5 and 4 cm from the roots of white clover (Trifolium repens) in 23, 37 or 46 days after
planting were compared.Spores of the indigenous fungi were mostly a mixture of
Glomus mossea, G. clarum, G. caledonium and G. claroideum . The colonization of the
roots with regard to hyphae, vesicle or arbuscules was significantly different among fungi.
Uptake of 32P from different distances from the roots was strongly dependent on the mycorrhizal
isolate used and the plant-symbiont age. Indigenous fungi were more effective in
translocating 32P from short distances compared with G. intraradices as measured in the
plants. At the age of 46 days, for example, fungi from no-till and plowed plots transported
8-10 times more 32P to the plants as compared with G. intraradices, when32P was placed at
1-cm distance from the roots. These differences, however, disappeared when 32P was
placed at 2.5 or 4 cm from the roots. As the plant-symbiont grew older, relatively more
32P was translocated to the tops and the differences between fungi in this respect became
more pronounced. In 21-, 37- and 46-day-old plants, for example, and when 32P was
placed 1 cm from the root surface, 18, 21 and 56%, respectively, of the absorbed 32P was
translocated to the tops in plants inoculated with fungi from plowed fields. Progressively
lesser amounts of total absorbed 32P were translocated to the tops as 32P was placed farther
away from the roots. For example in 46 days after planting 51, 30 and 11% of total
absorbed 32P was translocated to the tops when 32P was placed at 1, 2.5 and 4 cm from the
roots, respectively, white clovers being inoculated with fungi from no-till soil. It is concluded
that the native mycorrhizal fungi , after a long period of different tillage practices,
may have different effects on the partitioning of absorbed phosphorus within white clover.
http://jast.modares.ac.ir/article-23-1409-en.pdf
Glomus spp
32P transport
VAM
Trifolium repens (white clover)
eng
Tarbiat Modares University
Journal of Agricultural Science and Technology
1680-7073
2345-3737
2000-10
2
4
291
298
article
Relationship between Nuclear Polyhedrosis Virus Susceptibility
and Larval Weight in Heliothis armigera
A. A. Pourmirza
1
Department of Plant Protection, Urmia Universiy, Urmia, Islamic Republic of Iran.
The population response of Heliothis armigera larvae to nuclear polyhedrosis virus
(NPV) was investigated. The virus was introduced by permitting the larvae to feed on lettuce
leaves. Median lethal doses (LD50) were determined. The estimated LD50 values for
the first, second, third, early, and late fourth larval instars were 5, 141, 1226, 5168 and
24553 polyhedra per larva respectively. In the fifth larval instar a degree of maturation
resistance against virus infection was observed. An inverse relationship between mortality
and larval weight was detected. Expressing the results in terms of LD50 / mg of the larval
weight eliminated the observed variation in the susceptibility of larvae. The estimated
LD50 values for each of the larval instar groups were used to predict the response of the
larval population to virus infection. This procedure provided a sound determination of
the response pattern, from which 96% of the variation in the larval susceptibility could be
described in terms of the log larval weight.
http://jast.modares.ac.ir/article-23-1552-en.pdf
bioassay
Heliothis armigera
Viral infection
eng
Tarbiat Modares University
Journal of Agricultural Science and Technology
1680-7073
2345-3737
2000-10
2
4
299
305
article
Modeling of Orange Mass Based on Dimensions
A. Tabatabaeefar
1
A. Vefagh-Nematolahee
2
A. Rajabipour
3
Department of Agricultural Machinery Engineering, College of Agriculture, University of Tehran, Islamic
Republic of Iran.
Department of Agricultural Machinery Engineering, College of Agriculture, University of Tehran, Islamic
Republic of Iran.
Department of Agricultural Machinery Engineering, College of Agriculture, University of Tehran, Islamic
Republic of Iran.
There are instances in which it is desirable to determine relationships among fruit
physical attributes. For example, fruits are often graded on the basis of size and projected
area, but it may be more suitable and/or economical to develop a machine which grades
by mass. Therefore, a relationship between mass and dimensions or projected areas and/
or volume of fruits is needed. Various grading systems, size fruits on the basis of specific
parameters. Sizing parameter depends on fruit and machine characteristics.Models for
predicting mass of orange from its dimensions and projected areas were identified. Models
were divided into three classifications: 1- Single and multiple variable regression of
orange dimensions (1st classification). 2- Single and multiple variable regression of projected
areas (2nd classification). 3- Estimation of orange shape; ellipsoid or spheroid based
on volume (3rd classification). Ten Iranian varieties of oranges were selected for the study.
3rd classification models had the highest performance followed by 2nd and 1st classifications
respectively, with R2close to unity. The 2nd classification models need electronic systems
with cameras for projection whereas, 1st classification models are used in the simple
mechanical systems, except multiple variable ones, of and 3rd classification models need
more complex mechanical systems. Among the systems that sorted oranges based on one
dimension (Model 2), system that applies intermediate diameter suited better with nonlinear
relationship as: M = 0.07b2 – 2.95 b + 39.15 with R2= 0.97.
http://jast.modares.ac.ir/article-23-3459-en.pdf
Dimensions
Mass models
Orange
Sorting
Sizing