eng
Tarbiat Modares University
Journal of Agricultural Science and Technology
1680-7073
2345-3737
2004-01
6
1
1
9
article
Effect of Row and Plant Spacings on Weed Competition with Pinto Beans (Phaseolus vulgaris L.)
Field experiment was conducted at the agricultural experiment station of Shiraz Uni-versity at Kushkak in 1996 to quantify the competitive ability of pinto beans (Phaselus vulgaris L. var. Daneshjou) with a naturally occurring population of weeds. An attempt was made to increase the competitive ability of the plants by altering row and plant spac-ings. An uncontrolled population of weeds reduced pinto bean yields by 75%. The ability of plants to reduce weed dry weight was further enhanced in medium and narrow rows compared to wide rows. Row and plant spacing combinations which maximized leaf area index when grown under weedy conditions also had significantly less weed dry weight. However, row and plant spacings did not reduce weed density. A significant negative cor-relation was observed between weed dry weight with leaf area index and final yield of pinto bean. For each kg ha-1 increase in weed dry weight, the corresponding pinto bean yield loss averaged 260 g ha-1. Season-long weed competition significantly reduced total number of pods per plant, number of seed per plant, and 100-seed weight.
http://jast.modares.ac.ir/article-23-10601-en.pdf
Weed competition
Pinto beans
Weed interference
eng
Tarbiat Modares University
Journal of Agricultural Science and Technology
1680-7073
2345-3737
2004-01
6
1
11
19
article
Behavior of Wheat Kernels under Quasi-static Loading
and its Relation to Grain Hardness
There are two reasons for measuring the mechanical properties of cereal grains. First, the possibility of grain classification based on texture and, second, to obtain information for modification in the design of post-harvest machinery. In both cases, the objectives will be the reduction of qualitative and/or quantitative losses of grain. In this research, eight different parameters obtainable from the force-deformation curves of wheat kernels un-der compression were determined. The most important of these included: the apparent modulus of elasticity, maximum compressive contact stress and maximum load at rup-ture. Other grain characteristics such as the dimensions of single wheat kernels and the particle size index of bulk samples for five varieties of wheat were measured. By per-forming 200 uniaxial compression tests on intact wheat kernels (from soft to very hard varieties), the values of modulus of elasticity ranging from 486 to 1631 MPa were deter-mined based on measurements according to the Hertz theory. Results indicated a simple linear relationship between grain hardness and mechanical properties, such as modulus of elasticity and deformation at the linear limit on the force-deformation curve, and physical attributes, such as grain mass and major diameter. Grain orientation had no significant effect on the dependent variables. Moisture content had a very significant effect on me-chanical properties. From the statistical analysis of the data (ANOVA and DMRT), it was found that it is possible to distinguish between soft and hard wheat kernels based on dif-ferent parameters obtainable from the force-deformation curve. Hence, any one of these parameters may be used as a suitable indicator for grain hardness determination.
http://jast.modares.ac.ir/article-23-12268-en.pdf
mechanical properties
Quasi-static loading
Single kernel
Wheat hardness
eng
Tarbiat Modares University
Journal of Agricultural Science and Technology
1680-7073
2345-3737
2004-01
6
1
21
30
article
Energy and Nitrogen Metabolism in Lambs During Feed
Restriction and Realimentation
Eighteen crossbred Swifter (Flemish ♀ X Texel ♂) male lambs, born in March 1997 and weaned at the age of approximately 3 months, were used to quantify effects of feed quality restriction and realimentation on changes in energy and nitrogen metabolism. The ration consisted of grass straw (17 MJ of GE and 46 g CP per kg DM) on an ad libitum basis and 35 g.kg-.75d-1 mixed concentrates (16.5 MJ of GE and 173 g CP per kg DM). At the age of approximately 3.5 months, the animals were randomly divided into six blocks, based on live weight, according to a randomized complete block design. Within each block, the animals were randomly assigned to two restricted treatments (R1 and R2) and a control treatment. Treatments R1 and R2 were subjected to feed quality restriction by withhold-ing concentrate for 3 and 4.5 months, respectively. A modified linear model was devel-oped to study the effects of restriction and realimentation. The comparison between treatments was made by analyzing the data of R1 and R2 animals as deviations from the control animal in each block. During the restriction period, restricted animals lost weight and showed a negative EB and NB, whereas their intake from low-quality roughage sig-nificantly (P < 0.001) increased. After realimentation, the R1 and R2 animals grew signifi-cantly (P < 0.001) faster than the C animals. The realimented animals persisted in ingest-ing more (P < 0.001) low-quality roughage and their EB and NB were greater (P < 0.001) than those of C animals. The R2 animals needed a longer period of realimentation be-cause of a longer period of restriction. The expression of compensatory growth was mainly related to a sustained higher (P < 0.001) grass straw (low-quality roughage) intake during realimentation periods, and greater (P < 0.001) efficiency of metabolizable energy intake. The maintenance requirement of realimented animals was lower (P < 0.001) only during the initial stages of realimentation compared with controls.
http://jast.modares.ac.ir/article-23-6240-en.pdf
Energy metabolism
Feed restriction
Metabolizability
Nitrogen metabolism
Realimentation
eng
Tarbiat Modares University
Journal of Agricultural Science and Technology
1680-7073
2345-3737
2004-01
6
1
31
40
article
Behavior of Landsat Thematic Mapper Wavebands on Lut
Desert (Iran)
To study the capabilities of remotely sensed data in discriminating land cover types and geomorphologic features of desert, the southeast of Lut Desert was selected. In this study, seven bands of Landsat Thematic Mapper (TM), data and other sources of information such as topographic maps (1:50,000), aerial photos (1:20,000) and field data were used. The visual image interpretation was performed based on photomorphic unit analysis and interpretation keys. To classify the images, 10 training classes were used for maximum likelihood classification algorithm. Then the classified images were assessed with the test areas and the overall accuracy was about 92 percent. Based on the obtained results it may be concluded that Landsat TM thermal and reflective bands could be useful for studying Lut Desert conditions especially in the Yardang and sand dune regions. From the results obtained we may also conclude that such a hyper arid climatic and bare land are suitable conditions for a better understanding of the behavior of TM wavebands on different sur-faces and soil conditions.
http://jast.modares.ac.ir/article-23-11050-en.pdf
Desert
Image classification
Lut Desert
Sand dune
TM wavebands
Yardang
eng
Tarbiat Modares University
Journal of Agricultural Science and Technology
1680-7073
2345-3737
2004-01
6
1
43
55
article
Effects of Paclobutrazol on Vegetative and Reproductive Growth and Leaf Mineral Content of Mature Apricot
(Prunus armeniaca L.) Trees
In the absence of dwarfing rootstocks for apricot (Prunus armeniaca L.), techniques that reduce vegetative growth while enhancing fruit quality and yield are important in the orchard management system. Four year old mature apricot trees cultivars Nasiri, 35Shahroodi, Jahangiri, Shahroodi and Noori on apricot seedling rootstocks, planted at a density of 1250 trees ha-1 and grown at Tarbiat Modarres University (TMU) orchard were used. The effect of soil applied paclobutrazol (0.5 and 2 g tree-1 a.i.) on apricot trees was studied over three years period during 1998-2000 seasons. Treatment effects on vegetative and reproductive growth characteristics and the leaf nutrient status of the apricot trees were determined. Results indicated that paclobutrazol (PBZ) significantly reduced vege-tative growth during the experiment. The total pruning dry weight, shoot growth and trunk cross sectional area (TCSA) of treated trees were lower than those of the controls. Although, results showed that fruit load, crop density and total soluble solids (TSS) of fruits were not affected by applied treatments compared with the control. In addition, PBZ decreased nitrogen (N) concentration, but, phosphorus (P), potassium (K) and cal-cium (Ca) concentrations were not affected by the treatments. Chemical name of PBZ is: (2RS, 3RS)-1- (4-chlorophenyl)-4,4-dimethyl-2-(1H-1,2,4-triazol-1-yl)pentan-3-ol.
http://jast.modares.ac.ir/article-23-6412-en.pdf
Growth
Apricot
Fruit
Nutrient
Paclobutrazol
Prunus armeniaca L
eng
Tarbiat Modares University
Journal of Agricultural Science and Technology
1680-7073
2345-3737
2004-01
6
1
57
62
article
Extraction and separation of Antioxidative Compounds
from Salvia leriifolia Leaves
In this research, methanolic extraction of Salvia leriifolia leaves produced a higher yield and antioxidative activity than other organic solvents (ethanol, acetone, chloroform, n-hexane). The methanolic extract was reserved about 24 hours in the refrigerator and its precipitates were then separated. The extract was separated into 12 fractions by thin-layer chromatography (TLC). The highest yields were found in fractions with Rf values of 0.29, 0.54, 0.11 and 0.38 at 16.24%, 12.48%, 8.81% and 7.60%, respectively. All fractions and also whole methanolic extract and precipitates of methanolic extract had more anti-oxidative activity than the control based on the thiocyanate method. Whole methanolic ex-tract, precipitates of methanolic extract and most separated fractions showed more anti-oxidative activity than –tocopherol. The fraction with Rf value of 0.29 at 16.24% yield and 85.61% antioxidative activity of synthetic antioxidant BHT based on thiocyanat method was chosen as the fraction with the highest yield and the highest antioxidative ac-tivity.
http://jast.modares.ac.ir/article-23-1485-en.pdf
Antioxidant activity
Salvia
eng
Tarbiat Modares University
Journal of Agricultural Science and Technology
1680-7073
2345-3737
2004-01
6
1
63
72
article
Expression Analysis of Two Senescence Involved Genes in Brassica napus and Arabidopsis thaliana
Expression analysis was carried out to characterise the level and time of expression of two senescence related cDNAs, LSC650 and LSC54, in Brassica napus and Arabidopsis thaliana. The extent of DNA sequence similarity showed that the LSC650 gene may en-code the catalase homologous to Cat3 in Arabidopsis thaliana the role of which is to scav-enge H2O2. Also, LSC54 gene encodes a metallothionein protein that may detoxify metal ions in plant cells. Plant leaves were characterised at different developmental stages by biochemical analysis, including chlorophyll and protein assays. Northern analysis re-vealed strong levels of LSC650 and LSC54 expression in senescent leaves and lower levels in mature green leaves, but very weak or no expression in young leaves in B. napus. The transcription of genes, LSC650 and LSC54, was almost at the same level with few changes between maturity and senescence in leaves of Arabidopsis at different plant growth phases, being due to a possible unknown stress. The results indicate that both genes stud-ied may act as antioxidants, and have a role in scavenging active oxygen species (AOS) caused by catabolism of macromolecules during senescence.
http://jast.modares.ac.ir/article-23-7036-en.pdf
Brassica napus
Active oxygen species (AOS)
Arabidopsis thaliana
Catalase
Metallothionein-like protein
Senescence
eng
Tarbiat Modares University
Journal of Agricultural Science and Technology
1680-7073
2345-3737
2004-01
6
1
73
83
article
Summer Forage Sorghum Yield, Protein and Prussic Acid Contents as Affected by Plant Density and Nitrogen
Topdressing
Two similar field experiments were carried out at Kushkak and Fars Agricultural Ex-perimental Staties to determine the effects of plant densities and nitrogen topdressing (NT) rates on forage yield, some agronomic traits, protein and prussic acid contents of forage sorghum (Sorghum bicolor L. Moench var. Sudenense). Both experiments were conducted as spilt plots arranged in randomized complete block design with four replica-tions. Plant density consisted of 25, 33 and 50 plants m-2 in the main plots and nitrogen topdressing rates were 0, 100, 200 and 300 kg N ha-1 as urea in the sub-plots. Increasing plant density increased main stem height (MSH), leaf area index (LAI), total tiller num-ber m-2 (TTN), total fresh forage (TFF), total dry matter (TDM), leaf dry matter (LDM), and stem dry matter (SDM) yields. However, it decreased crude protein percentages (CPP) and had no effects on leaf-stem ratio at both locations. Increasing nitrogen rates in-creased MSH, LAI, TTN, TFF, TDM, CPP, forage prussic acid percentage (FPAP) and decreased leaf-stem ratio. Optimum plant densities and NT rates for these experiments were 50 plants m-2 and 200 kg N ha-1, respectively at both locations. Nitrogen applications had more effects on the second than the first out. The reaction of forage yields and most agronomic traits to the treatments were extremely similar at both locations.
http://jast.modares.ac.ir/article-23-7245-en.pdf
Plant density
Crude protein
Dry forage
Fresh forage
Prussic acid
Total tillers number