Journal of Agricultural Science and Technology
Volume:3 Issue: 2, Apr 2001

To use remote sensing data effectively, one must understand the spectral characteristics of the particular features under investigations. To study the relationship between soil salinity and soil reflectance, four MultiSpectral Scanners (MSS) and seven Thematic Mappers (TM bands) over the Ardakan playa located on the Central Iranian Desert margins were selected. In this study soil map, soil salinity observations, an interpolated soil salinity map and 13 images in all, including 7 TM, 4 MSS and 2 Normalised Difference Vegetation Indices (NDVI) images were used. After smoothing the imagery using a 3× 3 kernel, and delineating the bare soil from vegetated areas, the correlation coefficients between soil salinity (Electrical Conductivity) and related Digital Number (DN) values from TM and MSS bands on different soil types, such as gypsiferons and saline soils, were calculated. The results obtained demonstrate the trend of the correlation coefficients between soil salinity and the related DN values of MSS and TM bands. Based on the results obtained, we may conclude that the presence of gypsum in soil plays a significant role in lowering the correlation coefficients between soil salinity and surface reflectance -further studies are required to draw more general conclusions. From the results obtained we may also conclude that the behavior of band 6 of TM on gypsiferous soil is completely different from that on saline soil and, therefore, we may generally conclude that Landsat TM imagery with six reflective bands, on the one hand, and the TM thermal band as complementary information to the TM reflective bands, on the other hand, contained some useful information that may play an important role in soil salinity studies and also the detection of gypsiferous soils in desert areas.
Keyw

ABSTRACT Projected global climate change may have a major influence on crop yield. The likely effects of climate change caused by increasing atmospheric carbon dioxide levels on rice yield in Iran were evaluated using a mechanistic growth model for rice, GSAC-rice, running under a climate change scenario predicted for a doubled-CO2 (2xCO2) atmosphere by the Geophysical Fluid Dynamics Laboratory (GFDL) General Circulation Model (GCM). Simulations were run for two locations with contrasting climates, one in the north (Rasht) and one in the south (Ahwaz) of Iran. GFDL predicted that as a result of doubling CO2, temperature increases by 4.5 and 4.6 0C during the rice growing season in Rasht and Ahwaz, respectively. Changes in solar radiation are minor, but rainfall during the rice growing season decreases by 38.8% (102 mm) for Rasht and 68.2% (5.8 mm) for Ahwaz. It was predicted that doubling [CO2] alone increased rice yield by 30%, but that yield decreases by 3.7 and 11.6% for each degree centigrade rise in temperature in Rasht and Ahwaz, respectively. As a result of the combined effect of both doubling [CO2] and the climate change accompanying it (predicted with GFDL), 8% greater rice could be produced in Rasht, but irrigation needs would be increased dramatically by 57%. In Ahwaz (the south of Iran), rice production could be halved and might not even remain a viable option unless plant breeders are able to produce more heat tolerant rice cultivars. It was concluded that rice production in the north and south of the country would change dramatically.

ABSTRACT In the first experiment, twelve species of the most plentiful and fresh seaweeds and one species of seagrass from the beach were collected at Kingston, South Australia. All species were then separately sun-and oven-dried and ground. The ground samples were analysed for dry matter, ash, organic matter, crude protein, crude fibers, ether extract and digestibility in vitro. The digestible and metabolisable energy of the samples were estimated by calculation. The results showed that all seaweeds and seagrasses contained a very high ash content, ranging from 19.5 - 40 per cent. The crude protein content of the samples was low and ranged from 4.4 - 7.3 per cent. The crude fiber in seagrass was considerably greater than in seaweed species (34.4 % vs 3.7 -10.1 %). The dry matter digestibility of samples ranged from 34.1 to 51.5, while the data also showed that the values for digestible and metabolisable energy of aquatic plants were very low as compared with lucerne (the control). From the first experiment it was concluded that, amongst marine plants available in South Australia, the seagrass Posidonia australis, because of its ready availability in great quantities and the environmental problems for residents, may be regarded as a potential alternative animal feedstuff. In the second experiment, samples of four different physical forms of seagrass, Posidonia australis green and fresh (from the water, and washed and un-washed from on the beach) were examined and compared for their chemical composition, including nonstarch-polysaccharides, uronic acids, neutral detergent fiber, acid detergent fiber and lignin, amino acids, crude protein, tannin, ether extract, soluble and insoluble ash. The results from this experiment showed that there were no significant differences between the four different physical forms of seagrass collected in terms of their most important chemical constituents.

ABSTRACT A single column cation exchanger resin was used to eliminate cations from renet cheese whey, with particular reference to the improvement of taste and flavor. Ten panelists were convened to assess the contribution of the mineral components to the salty taste of whey, judging on the basis of taste, flavor and color. The organoleptic characteristics of untreated whey were arbitrarily assigned a score of zero and the best treated whey in terms of quality, a score of 20. The use of a strong-acid cation exchange resin resulted in the removal of 28% of the calcium and 45% of the magnesium from treated whey with a concomitant increase in the concentration of sodium. The average score of treated whey increased from zero, for untreated whey, to 19.7 for the first element of whey passed through cation exchange resin.

ABSTRACT Foliar analysis of natural deciduous tree species of basswood (Tilia americana L.) (BA), American beech (Acer grandifolia Enrh) (BE), and white ash (Fraxinus americana L.) (WA) was carried out in 1994 in southern Quebec. The Diagnosis and Recommendation Integrated System (DRIS) was developed from the traditional method to find the preliminary norm and indices of N, P, K, Ca, and Mg for the above species. The growth decade 1983-1994 in a high yielding sub-population was used to develop DRIS norms for the identification of DRIS functions and indices in relatively depleted levels of those elements in the declined growth of three species. Foliar nutrient deficiencies were found with K (-3.72) and N (-2.96) for basswood, Ca (-10.43) and Mg (-4.93) for beech, and N (-6.16), Ca (-2.56) and K (-2.05) for white ash. The DRIS analysis indicated that basswood and white ash were relatively depleted of K and N, while beech had a deficiency of Ca and Mg, and white ash had a limitation of N. These results suggest the usefulness of DRIS for foliar tissue analysis as an indicator of nutritional status and elemental stresses in natural forests. The DRIS indices were also discussed from the traditional approach.

A field study was conducted to evaluate the agronomic response of eight isolines of cv. Clark on a clay loam soil (at Karaj-Iran, 35048´) to four plant population densities of 11.3, 18.5, 68.5, and 103.4 plants per square metre. Significant yield increase was obtained as a result of higher plant density. Differences among the cv. Clark isolines were significant (p<0.05). Yield components such as numbers of branches, pods, and seeds per plant decreased linearly as population density increased. Adjustments in pods and seeds per plant resulted from altered branches per plant. The isolines which exhibit profuse branching (e.g. E1E2E3, E1e2E3, E1E2 e3) were capable of optimising yield when planted at low densities. The second dynamic factor that aided yield compensation by plant population density was greater total dry matter partitioning, which resulted in a significantly greater harvest index at the lower compared with the higher plant density. The results indicated that total biomass and crop growth rate were the major elements explaining the reduced yield compensation factors at higher plant population density. Plotting the fitted seed yield values against the number of dominant alleles showed the effect of the maturity genes on the response of seed yield to plant density.

ABSTRACT To measure soil water content (or soil matric suction) in thin layers of about 30mm, conventional gypsum blocks are not suitable. To carry out the task, mini-gypsum blocks were constructed using plaster of Paris in an innovative fashion. A power relationship was found between the soil water content and the mini-gypsum blocks’ readings in kΩ. The calibration results showed that readings of mini-gypsum blocks were sensitive to temperature. A normalized resistance deviation method was adopted to compensate for the effect of temperature on the sensor readings. After calibration, the high coefficient of determination obtained ensured the use of the mini-gypsum blocks for further experiments.

ABSTRACT Cotton (Gossypium hirsutum L. cv. Varamin) an important industrial crop of Iran, is grown in 300,000 ha, with an average seed -cotton yield of 1750 Kg.ha-1. The main obstacle in the way of increasing average cotton yield is imbalanced fertilizer use. Along with urea and triple super phosphate, cotton growers also need K, Mg, Zn, Fe, Mn, Cu, and B, so these elements’ critical levels should be determined in cotton fields. Field experiments were conducted in 12 different fields in 1997 to determine critical levels of Fe, Zn, and B in soil, and to study the effects of these micronutrients on the yield and quality of cotton in Varamin region. The experiment design was a randomized complete block one (RCB) with four treatments and three replications. Treatments were; NPK, NPK+Fe, NPK+Zn, and NPK+B. Iron was applied as FeEDDHA (20 kg.ha-1), Zn as zinc sulfate (40 Kg.ha-1), and B as boric acid (20 Kg. ha-1) prior to planting. Average seed cotton yield, lint yield, seed index, and boll weight increased significantly by adding Fe, Zn, and B. In a cotton field with higher soil B concentrations, cotton yield decreased with B fertilizer. Critical levels of Fe, Zn, and B were determined based on Cate-Nelson graphical and analysis of variance methods. In graphical method critical levels of Fe, Zn, and B were 4.8, 1.1, and 1.0 mg.Kg-1 soil, respectively, while on the basis of analysis of variance method, these levels were 5.5, 1.1, and 1.3 mg.kg-1 soil, respectively. In one field, boll shedding decreased by Zn and Fe treatments but was not affected by B addition. Iron to Zn ratio in cotton leaves increased at Fe treatment and decreased in Zn treatments. Boron treatment increased B content of leaves. Furthermore, zinc sulfate decreased B toxicity in the cotton leaves. In short, applying micronutrients increased quality and yield of cotton in Varamin region.

ABSTRACT Leaf and root explants from 10 to 20 day– old seedlings of Plantago lanceolata, were cultured on MS, MSH, NT and B5 basal media with various concentrations of different plant growth regulators. The best callus induction was obtained with 0.4 mgl-1 2,4-D in MSH I with 400 callus index. Callus growth was significantly stimulated (P=0.05)with 0.8 mgl-1 2,4-D and 0.1 mgl-1 Kin in MSH II, with 799 mg fresh weight and 79 mg dry weight. A higher production of mucilage was obtained in MSH II. The mucilage content of different media varied from 10.40 to 14.73% dry weight. Perusal of the data reveals significant differences with regard to the total mucilage content. Callus has nearly 3 times and 1.5 times more mucilage than seeds and leaf and root parts respectively.