Comparison of steady- and unsteady-state drainage equations for determination of subsurface drain spacing in paddy fields: a case study in Northern Iran

In Northern Iran paddy fields, waterlogging is a serious problem. Provision of subsurface drainage seems to be a prerequisite for optimal crop production. Considering specific characteristics of the paddies, application of a suitable equation for planning of subsurface drainage systems is of great importance. In this study, five steady-state equations including Hooghoudt, Kirkham, Dagan, Ernst, and Ernst–Hooghoudt; and three unsteady-state equations including Glover–Dumm, Van-Shilfgard, and De-zeeuw–Hellinga were implemented to compute drain spacing. Required field data were obtained from 52 ha of paddy fields of “Haraz Human-Agriculture Resources Development Center,” located in Mazandaran province of Iran. The computed drain spacings were evaluated using dynamic equilibrium concept and DRAINMOD model. The minimum and maximum drain spacings were found to be 26 and 63 m corresponding to Glover–Dumm and Ernst equations, respectively. Based on the dynamic equilibrium concept, the averages of the computed water table depths for the drain spacings obtained by the unsteady-state equations were 0.5–0.63 m as compared with those obtained by the steady-state methods which were in the range of 0–0.43 m. According to the DRAINMOD model simulations, the maximum relative yield was 80.2 % which was obtained when the drain spacing was 26 m and it reduced to 73.5 % when the drain spacing was increased to 63 m. The computed drain spacings suggested by the unsteady-state equations were found to be more suitable than those obtained from the steady-state equations for the study area.     

Assessment of molecular genetic diversity of 384 chickpea genotypes and development of core set of 192 genotypes for chickpea improvement programs

Genetic Resources and Crop Evolution - Cicer arietinum L. (chickpea) is one of the most significant legume crops domesticated in the Fertile Crescent. This study was aimed to characterize a diverse...     

Comparison of genetic variation among accessions of <Emphasis Type="Italic">Aegilops tauschii</Emphasis> using AFLP and SSR markers

Genetic diversity of 54 accessions of Aegilops tauschii from five countries was assessed using sequence-tagged microsatellites (or simple sequence repeats, SSRs) and amplified fragment length polymorphisms (AFLPs). In the case of AFLP analysis, a total of 256 amplification products obtained, 234 of them were polymorphic across all the 54 accessions. A total of 224 fragments were obtained from the 24 SSR primers and 219 of fragments were polymorphic across all the genotypes screened. Based on both AFLP and SSR markers, the highest percentage of polymorphisms were obtained in Iranian and accessions of unknown origin. The highest polymorphic information content (PIC) value was observed for SSRs (0.82) while the highest marker index (MI) value was for AFLPs (8.5) reflecting the hyper-variability of the first and the distinctive nature of the second system. Principal co-ordinate analysis (PCO) revealed congruent patterns of genetic relationships for both data sets, but did not group accessions strictly according to their geographical origins. Poor correlation was found between AFLP and SSR marker loci. This low association may be due to low number of AFLP and SSR markers. These results show that molecular markers can help to organize the genetic variability and expose useful diversity for breeding purposes.     

Nutrient storage and turnover in organic layers under tropical montane rain forest in Ecuador

In tropical montane forests nutrients released from the organic layers of the soil can supply a large part of the vegetation's requirements. We have examined concentrations, storage, and turnover times of nutrients in the organic layer and the fluxes of nutrients by the fall of small litter (leaves, seeds, flowers, small twigs, and plant debris that passed an opening of 0.3 m × 0.3 m) in such a forest in Ecuador. The times taken for litter to turn over were estimated by relating nutrient storage in the organic layer to rate of litterfall and by incubating samples in the laboratory. The organic layer had a thickness of 2–43 cm, a mass of 30–713 t ha^?1, and a nutrient storage of 0.87–21 t N, 0.03–0.70 t P, 0.12–2.5 t K, 0.09–3.2 t Ca, and 0.07–1.0 t Mg ha^?1. The pH (in H₂O) ranged between 3.1 and 7.4 and was correlated with the concentrations of Ca and Mg (r= 0.83 and 0.84, respectively). The quantity of small litter (8.5–9.7 t year^?1) and mean concentrations of nutrients in litter (19–22 g N, 0.9–1.6 g P, 6.1–9.1 g K, 12–18 g Ca, and 3.5–5.8 g Mg kg^?1) were larger than in many other tropical montane forests. The mean turnover times of elements in the organic layer increased in the order, Mg (7.0 years) < Ca (7.9) < K (8.5) < P (11) < N (14) < S (15) when calculated as the quotient of storage in the organic layer to flux by litterfall; they were < 12 years for N, P, and S in the incubation experiment. Under optimum conditions in the laboratory, the mineralization of S was just as large as the S deposition by litterfall. In weakly acid soils Mn and Zn and in strongly acid soils Ca added in a nutrient solution were immobilized during incubation. Thus, lack of S, Mn, Zn, and Ca might limit plant growth on some soils.     

Preference and performance of <Emphasis Type="Italic">Plutella xylostella</Emphasis> (L.) (Lepidoptera: Plutellidae) on canola cultivars

The diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), is an important insect pest of canola, Brassica napus L., in Ardabil, Iran. Host plant resistance is an essential component of integrated management of P. xylostella. We investigated the preferences and performance of P. xylostella on nine commercial cultivars of canola, namely Zarfam, RGS003, Adder, Okapi, Opera, Hyola401, Ebonite Option500 and Elite under greenhouse conditions at 23 ± 1°C, 50 ± 5% RH and 14L:10D. In free-choice situation, oviposition was lowest on Opera (23.5) and highest on Zarfam (44.7). In the life table study, fecundity of new generation female moths was lowest on Opera (95.4) and highest on Adder (145.7). Survival from egg to adult was significantly lower on Opera, Option500 and Hyola401 than on other tested cultivars. The intrinsic rate of natural increase (r _m) and population growth rate (λ) were lowest on Opera and highest on Zarfam. The generation time (T) was shortest on Zarfam (17.2 days) and longest on Hyola401 (19.9 days) whereas doubling time (DT) was longest on Opera (3.9 days) and shortest on Zarfam (3.0 days). Our results clearly suggest that Opera was the most resistant host among the tested cultivars and has the potential to be used in the integrated management of P. xylostella.     

Exogenously applied hexaconazole ameliorates salinity stress by inducing an antioxidant defense system in Brassica napus L. plants

The ability of hexaconazole (HEX) to ameliorate salinity stress was studied in canola plants (Brassica napus L.). Canola seedlings were subjected to sodium chloride (NaCl) treatment. A treatment with 200 mM NaCl reduced growth parameters, chlorophyll content and protein content as well as increased the proline (Pro) content in canola plants. In addition, NaCl stress increased the endogenous, nonenzymatic antioxidants and the activity of antioxidant enzymes, such as peroxidase (POX; EC 1.11.1.7), superoxide dismutase (SOD; EC 1.15.1.1) and catalase (CAT; EC 1.11.1.6). When these plants were treated with a combination of NaCl and 50 mg L⁻¹ HEX, the inhibitory effects of NaCl stress were decreased by increasing the root growth, shoot growth, dry weight (DW), chlorophyll content, protein content and antioxidant enzyme activity by ameliorating the salinity injury. These results suggested that HEX has an important role in the enhancement of plant antioxidant systems and resistance to salinity in canola plants.     

COMPARATIVE EVALUATION OF HYDROPIC DEGENERATION OF THE LIVER IN DAIRY CATTLE THROUGH BIOCHEMISTRY, ULTRASONOGRAPHY AND DIGITAL ANALYSIS

Ultrasonography of the liver of 181 Holstein-Friesian cows was performed and blood samples were collected for analysis. The hepatic ultrasonograms were evaluated and the echoes were analyzed digitally. After slaughter, liver specimens were taken and examined histopathologically. Of the 181 animals, 120 had a normal liver and 61 had hydropic degeneration of the liver, diagnosed through histopathologic examination. Diagnostic accuracy rates for hydropic degeneration were determined based on the following test positive conditions: a) for biochemical analysis—high levels of aspartate aminotransferase, alanine aminotransferase, total bilirubin and non-esterified fatty acids; b) for ultrasonography—presence of dark pattern and blurring of edges; and c) for digital analysis—low echo means at 1 cm and 3 cm from the hepatic surface. Digital analysis had the highest overall specificity, accuracy and positive predictive values for hydropic degeneration, followed by ultrasonography. The results suggest that ultrasonography and digital analysis of hepatic ultrasonograms can be used for diagnosis of hydropic degeneration of the liver in place of biochemical analysis.     

EVALUATION OF FATTY INFILTRATION OF THE LIVER IN DAIRY CATTLE THROUGH DIGITAL ANALYSIS OF HEPATIC ULTRASONOGRAMS

Ultrasonography of the liver of 49 Holstein-Friesian cows was performed, liver specimens were taken, examined microscopically and the fatty occupying rate (FOR) was calculated. Echoes from the hepatic B-mode ultrasonograms were quantified as histogram mean (Emean) and histogram mode (Emode) of echo amplitudes within various areas at a depth of 1–9 cm from the hepatic surface. Of the 49 animals, 26 had a normal liver and 23 had fatty infiltration of the liver, diagnosed through histopathological examination. Fatty occupying rate ranged from 1.7 to 64.5%, with 11 animals having 1–15% FOR (mild fatty infiltration), 6 having 15.1–30% FOR (moderate fatty infiltration) and 6 having > 30% FOR (severe fatty infiltration). At 1 cm, severe fatty infiltration had higher Emean and Emode than normal liver (p < 0.05). At 7 cm and 9 cm, moderate and severe fatty infiltration had lower Emeans and Emodes than normal liver (p < 0.001). The results suggest that digital analysis of hepatic ultrasonogram can be useful in the evaluation of the degree of fatty infiltration of the liver in dairy cattle.     

Effects of different temperatures and duration on germination of Lentil (Lens culinaris Medik.) seeds

The aim of this study was to seek optimum seed germination temperature of Lentil seeds. Germination tests were conducted for twenty-four genotypes with 3 replicates in a completely randomized design, were conducted to investigate germination behavior of lentil seeds subjected to six different heat temperatures (39, 46, 54, 61, 68 and 75°F) and duration on germination. The experiment results revealed that different temperature treatments were effective on mean germination percentage and suggested that there is relationship between the temperature treatment and germination rate. The mean germination was obtained for 39, 46, 54, 61, 68 and 75°F, 0.945, 1.590, 1.864, 2.305, 2.840 and 2.573 respectively. The experiment revealed that the different temperature treatments were effective on mean germination percentage and seeds germinated faster at higher constant temperatures and optimum germination occurred at 68°F.