JOURNAL OF AGRICULTURAL SCIENCE AND TECHNOLOGY (JAST)
Year:2004 | Volume:6 | Issue:3-4|Papers Count:8

The physiology of salt tolerance in chickpeas (Cicer arietinum) is low. Therefore, after screening of a large number of genotypes, two tolerant (SG-11 & DHG-84-11) and two susceptible (Pusa-256 & Phule G-5) chickpea genotypes were germinated in sterilized germination boxes under different levels of salt stress (NaCl : CaCl2 : Na2SO4) viz., 0.0 (control), 4.0 and 8.0dSm-1 in order to investigate the physiological basis of salt tolerance. The experiment was carried out in completely randomised design in three replications under simulated conditions. It was terminated after 8 days and the germinated seeds were subjected to various analyses. At maximum salinity stress, there was comparatively more accumulation of sugar, protein, proline and phenol in tolerant genotypes along with higher amylase, peroxidase, catalase and lower protease activities. All the characters were positively and significantly correlated. Some of these indices might be useful for improving chickpea genotypes against salinity stress.

A parasitological investigation on the blood of acipenseridae fish in the southern part of the Caspian Sea (Iran) from 2000-2002 was undertaken. Altogether, 60 specimens were examined. The fishes included to this study are considered as Acipenser persicus (Persian Sturgeon, 20 specimens), Acipenser guldenstadti (Russian Sturgeon, 20 specimens) and Acipenser stellatus (20 specimens). During this study two blood protozoa were revealed: Cryptobia acipenseris, and Haemogregarina acipenseris.The specimens were collected by gill net from a fishing station located at Anzali. The characteristics of the fishes were recorded and the collected materials were examined in fresh and stained preparation. The prevalence of infection was also studied. This is the first record of Cryptobia acipenseris and Heamogragarina acipenseris in Russian and Persian sturgeons (New host) in the southern part of the Caspian Sea (Iran). All fish specimens examined during this study were collected from their natural environment. Heamoflagellates were found in different sturgeon without any pathological effects, but in the intensive farming of Sturgeons, Haemogragarina acipenseris may lead to severe infections and may cause anemia which decreases the productivity of the farm.

Isabgol (Plantago ovata Forsk), is an annual herb cultivated as a medicinal plant in recent decades. Its seed contains mucilage, fatty oil, large quantities of albuminous matter, a pharmacologically inactive glucoside, namely Aucubin (C13 H19 O8 H2O), and a plantiose sugar. Medicinal plants are rich in secondary metabolites: their biosynthesis is controlled genetically and is affected strongly by environmental factors. In the present work, the influence of sowing dates (20th April, 5th and 20th May) and nitrogen-fertilizer levels (0, 50, 100 and 150 kg ha-1) was examined on the growth, seed yield and seed swelling factor (content of mucilages) of isabgol. The statistical design was a split-plot arrangement of a randomized complete block design with three replicates: the sowing dates and nitrogen fertilizer were considered as the main and sub-main plots, respectively. The plot experiment was installed in the experimental station of Zanjan region located in the northwest of Iran, under silty-clay soil conditions. According to the resulting data, the best time for sowing isabgol in such a region was 5th May and the suitable amount of nitrogen fertilizer was 100 kg ha-1. To discover any relationship, all measured independent variables were muliple regressed on the dependent variable (seed yield) followed by stepwise regression analysis. This verified that the seed yield among other independent characteristics tested appeared to show a significant positive effect on the seed swelling.

Salinity is the primary water quality concern in irrigated agriculture. An Electrical Conductivity (EC) meter and a hydrometer are two possible methods for measurement of irrigation water salinity. The conductivity meter method is based on measuring the amount of electrical current that a fluid will support. Although it is the most widely used method, the instrumentation is rather expensive and in some instances may require sample dilution. The hydrometer method is based on measuring the density of the fluid. The main objectives of this study were to compare these two methods and, based on hydrometer method, develop empirical models for prediction of EC, sodium adsorption ratio (SAR), and the principle ion concentrations in the irrigation waters of Yazd Province, Iran. The electrical conductivity, temperature, and density of 206 water samples from wells across Yazd Province were measured. Temperature correction factors for adjusting the hydrometer reading to 25o C were determined. The correlation between EC and hydrometer readings was high (R2 = 0.97). Although the empirical model developed for prediction of EC slightly underpredicted the measured values, it is still accurate enough for practical purposes. Hydrometer readings were also highly correlated with the principle ions and SAR. The salt type also affected the hydrometer readings. Magnesium sulfate solution had the highest density among the major salt types present in irrigation waters. Finally, a chart was developed for rough estimations of EC, sodium and chlorine concentrations in irrigation waters of Yazd Province, Iran.

Water stress is a serious environmental problem throughout the world. It is a consequence of both drought and salinity which may be relieved by breeding cultivars that can tolerate low soil water potentials. Alfalfa (Medicago sativa L.) is normally grown in arid and semi-arid zones. One approach to improving the ability of the crop tolerate drought is to make use of the variation provided by tissue culture derived from somaclonal variation. Seedlings of a moderately salt tolerant line CUF 101-1S derived from the commercial variety CUF 101 were used as a source of explants to initiate and regenerate tissue cultures. Regenerant plantlets were allowed to grow to maturity, selfed, and set seed. These seeds (R1) were germinated and grown in a nutrient medium containing 0, 200 and 250 g I-1 polyethylene glycol (PEG) 6000 and additional calcium as CaCl2 (4.0 mol m-3) for 14 days to assess their ability to withstand stress in the progeny generation. Tolerance to PEG was assessed using measurements of root and shoot lengths. Proline levels and activity of the antioxidant enzymes, catalase (EC 1.11.1.6) and glutathione reductase (GR) (EC 1.6.4.2) were also determined. Selected somaclones were more tolerant than the parent. A large increase in the level of proline was observed in the somaclones compared with the parent variety in response to PEG stress. The activity of catalase and glutathione reductase increased in the tolerant genotypes but remained unchanged in the parent when they were subjected to PEG stress.  

The sensory qualities of food such as aroma, taste, and texture are the most important criteria for distinguishing Basmati type rices from non-Basmati types. To map the gene(s) controlling aroma, bulked segregant analysis (BSA) using Random Amplified Polymorphic DNA (RAPD) markers was applied in an F2/F3 population of Basmati 370 (aromatic) and IR36 (non-aromatic). DNA samples from homozygous aromatic and homozygous non-aromatic plants identified on the basis of progeny tests were bulked and used for BSA. A total of 550 random primers were used and the primers, AG8 and AN1, produced polymorphism between aromatic and non-aromatic types. Association of AG8-AR, AN1-AR1, and AN1-AR2 with a gene for aroma was determined by surveying F2 individuals. The three RAPD markers AG8-AR, AN1-AR1, and AN1-AR2 were found to be linked to the gene for aroma with a distance of 6.9, 8.9 and 16.4 cM, respectively. Southern analysis with AG8-AR as a probe with 125 F2 individuals confirmed linkage between AG8-AR and the gene for aroma. AG8-AR was mapped on chromosome 8 flanked by two tightly linked markers, RZ617 and RG978, at 2.1 and 1.7 cM distances, respectively, indicating that this gene in Basmati 370 is located on chromosome 8.

In this investigation levels of calcium were measured on the flag leaves of the susceptible spring wheat cultivar Thatcher and its near-isogenic line that has Yr-18 gene-mediated durable adult-plant resistance (APR ). The results showed that crystals of various shapes were frequently present on the infected leaf areas in the spring wheat that has the APR to stripe rust. Crystals were characterized with an energy-dispersive X-ray microanalayser in conjunction with scanning electron microscopy (SEM). More calcium was mobilized into infected areas of the resistance line than into the susceptible genotype. The level of calcium in the non-infected areas of both resistant and susceptible hosts and on the infected areas of the susceptible genotype were nearly the same. The results indicated that calcium mobilization in the resistant near isogenic line upon infection with P. striiformis correlated with the elicitation of a defense response conditioned by the Yr-18 gene. This is the first report on the mobilization of calcium in a cereal-rust pathosystem as part of a resistance response.

The application of various models with different structures and applications for the assessment of hydrologic events such as floods and soil erosion is of much interest to both experts and decision-makers owing to a potential saving of time and money. The most recent version (1982) of the SEdimentology by DIstributed MOdel Treatment approach (henceforth SEDIMOT II) as a tool for flood and sediment estimation was selected to be evaluated for its applicability to the experimental Amameh watershed in Iran. The main watershed, with an area of 3712 ha, was divided into 12 sub-areas and required inputs were extracted for each of them. Afterwards, 12 storm events with a coincident hyetograph, hydrograph and sediment data were selected to run the model. A high degree of agreement of 92% was found between the computed peak discharge and the observed data whereas the applicability of the model in sediment yield estimation was found to be poor.