Control of irrigation amounts using velocity and position of wetting front

A new approach for the estimation and control of the quantity of water applied in an irrigation is presented in which irrigation is stopped when the wetting front reaches a critical depth, Z _L. An expression for calculating the critical depth Z _L was developed. A major parameter in this expression is the velocity of advance of the wetting front, V, which was shown to be directly related to the application rate, IR, and inversely related to the initial soil water content, _i. A depth probe (patent pending) was designed, constructed and tested for the purpose of monitoring the position of the wetting front during infiltration and redistribution and for computing the value of V. Equations developed for relating the velocity of advance of the wetting front to _i as well as for estimating the value of the critical depth Z _L were successfully tested under conditions of uniform distribution of the initial soil water content. An iterative learning process which utilizes the real time output from the depth probe during each irrigation and is therefore capable of handling realistic field conditions where nonuniformity is the rule is presented. The acquired information is used to estimate a critical depth of the wetting front, Z _L, for a planned final wetted depth, Z _F, during each irrigation. This process is incorporated in the depth probe and is used to stop irrigation and thus control the quantity of water applied.     

Incidence,risk factors,and outcomes for early postoperative seizures in dogs with rostrotentorial brain tumors after intracranial surgery

BackgroundSeizures in the early postoperative period after intracranial surgery may affect outcome in dogs.ObjectivesTo determine the incidence of early postoperative seizures (EPS) in dogs with brain tumors, identify specific risk factors for EPS, and determine if EPS affects outcome.AnimalsEighty‐eight dogs that underwent 125 intracranial surgeries for diagnosis and treatment of rostrotentorial brain tumors.MethodsRetrospective cohort study. All patients with a diagnosis of rostrotentorial brain tumor from 2006 to 2020 were included. Early postoperative seizures were diagnosed by observation of seizure activity within 14 days of neurosurgery. Previously diagnosed structural epilepsy, perioperative anticonvulsant drug (ACD) use, magnetic resonance imaging (MRI), and tumor characteristics were evaluated. Outcome measures included neurologic and nonneurologic complications, duration of hospitalization, and survival to discharge.ResultsDogs with rostrotentorial brain tumors had EPS after 16/125 (12.8%) neurosurgical procedures (95% confidence interval [CI], 7%‐19%). Presence of previous structural epilepsy was not associated with EPS risk (P = 1). Perioperative ACD use also was not associated with EPS (P = .06). Dogs with EPS had longer hospitalization (P < .001), were more likely to have neurologic complications postsurgery (P = .01), and were less likely to survive to discharge (P = .01).Conclusions and Clinical ImportanceIt is difficult to predict which dogs are at risk of EPS because the presence of previous structural epilepsy and the use of perioperative ACDs was not associated with EPS. However, seizures in the early postoperative period are clinically important because affected dogs had prolonged hospitalization, more neurologic complications, and decreased short‐term survival.     

Field estimates of scalar advection across a canopy edge

Measurements of the horizontal and vertical fluxes of energy and mass were taken at a crop canopy edge and downwind of it to examine the effects of inhomogeneity on surface-atmosphere exchange, for the ideal case of flat uniform terrain. Energy balance closure was also examined and the effects of the often-neglected advection terms on the energy budget were evaluated. The results show that neither vertical nor horizontal advection should be neglected for moderate distances downwind from heterogeneous boundaries, with the energy budget closure near the leading edge improved by more than 20% with the inclusion of the horizontal and vertical advection of latent and sensible heat. Significant mean advective horizontal and vertical flux divergences of water vapor and temperature were found even in typical daytime conditions. In stable conditions horizontal advection can be responsible for more than 15% of the scalar (water vapor) transport 136 canopy heights downwind of a change in water vapor source density and surface roughness.     

Soil phosphorus status and turnover in central-European beech forest ecosystems with differing tree species diversity

Problems in phosphorus (P) nutrition of forest trees raise questions concerning the soil P concentrations, pools and turnover in forests. In addition, it is not clear if, and to what extent, tree species diversity has an influence on the soil P status and turnover. The aim of this study was to investigate the P status and turnover in beech ( Fagus sylvatica L.) -dominated forest ecosystems on loess over limestone and to elucidate what role heterogeneities in tree species diversity would play. The soils of mixed species stands contained more organically bound P (710–772 kg ha⁻¹) than those of pure beech stands (378 kg ha⁻¹), whereas the inorganic P content differed little between the stand types. A large proportion (44–55%) of the total soil P was organically bound. This fraction was mainly dependent on the clay content of the soils and not on the tree diversity. The P input with leaf litter (1.4–2.1 kg ha⁻¹ year⁻¹) showed a tendency to increase with increasing diversity. The apparent P turnover times in the organic surface layers differed, with shorter turnover times in mixed species stands (2–3 years) than in pure beech stands (10 years). Possible explanations for the different turnover times were differences in the litter quality, interactions in mixed species litters and the soil pH and base saturation. Hence, the tree species mainly influence the apparent P turnover time in the organic surface layer, whereas the P concentrations and pools in the mineral soil are determined by the soil properties, particularly the clay content.     

Current status and future strategy in breeding grasspea (Lathyrus sativus)

Efforts in grasspea (Lathyrus sativus) improvement have increased since the development of lines that are very low in the neurotoxin Beta-N-oxalyl-L-alpha-beta-diamino propionic acid (ODAP); also referred to as Beta-N oxalyl-amino-L-alanine (BOAA). Many programs now address several related aspects of improvement simultaneously. These include reduced ODAP concentrations, insect and disease resistance, nitrogen fixation, agronomic practices, fodder and forage production, and components for increased yielding ability. The coordinated, multidisciplinary approach now being applied to the genetic improvement of grasspea should allow the potential of this largely neglected grain legume to be fully realized.     

Field performance and molecular diversification of lemon selections

Lemon (Citrus limon (L.) Burm. f.) is one of the most important Citrus fruit for Turkey because of its great amount of production and export. It has been cultivated for a long time in Turkey, and therefore variations for agronomical traits are likely among cultivated lemons due to bud mutations and, hybridizations. The objectives of this study were to determine variations for some selected agronomical traits and genetic markers among 12 new lemons derived from selections. Tree growth, yield, fruit quality, and molecular diversification of these clones were determined. After four years of evaluation, ‘Kutdiken’ M-51 indicated the highest canopy volume. For yield per tree, the best clone was ‘Kutdiken’ M-51. After five years of evaluation, ‘Kibris’ M-54 had the highest fruit weight and acidity. ‘Italian Memeli’ M-56 contained the lowest seed number and the highest total soluble solids. Molecular analysis, as assessed with 22 random amplification of polymorphic DNA (RAPD) and 11 inter simple sequence repeats (ISSR) primers, indicated that seven of twelve clones were separated with RAPD markers, whereas four were distinguished with ISSR markers. Combined analysis of RAPD and ISSR data detected that similarity values among the lemons clones were between 0.97 and 1.00. It can be concluded that variations in orchards are abundant and mainly due to mutations.     

Family by environment interactions in shell size of 43-day old silver-lip pearl oyster (Pinctada maxima), five families reared under different nursery conditions

To understand the influence the environment and associated genotype by environment interactions will exert on future silver-lip pearl oyster (Pinctada maxima) selective breeding programs, this study assessed the relative performance in four shell growth traits of spat from five full-sib families, when spat were communally reared at different salinities (29, 34 and 40 ppt), food availability (high, medium and low), food quality (high, medium and low), and in a hatchery vs. ocean environment for 43 days.Rearing environment was found to influence growth expression, with significant differences evident when oysters were grown at different salinities in the ocean instead of hatchery, or when fed algae of differing nutritional quality. As indicated by MANOVA, family comparative growth performances were also altered when the environment changed, with significant environment by family interactions apparent in the food quality, food availability and hatchery vs. ocean rearing treatments. Changes in salinity, however, did not affect relevant family performances.These results indicate that growth and relative family performance in P. maxima may change dependent on local environmental conditions and that genotype by environment effects may need to be considered in breeding programs for this species.     

Penetration resistance and root growth of oats in tilled and untilled loess soil

Penetration resistance, bulk density, soil water content and root growth of oats were intensively studied in a tilled and an untilled grey brown podzolic loess soil. Bulk density and penetration resistance were higher in the top layer of the untilled soil compared with the tilled soil. In the latter, however, a traffic pan existed in the 25–30 cm soil layer which had higher bulk density and penetration resistance than any layer of the untilled soil. Above the traffic pan, rooting density (cm root length per cm³ of soil) was higher but below the pan it was lower than at the same depth in the untilled soil. Root growth was linearly related to penetration resistance. The limiting penetration resistance for root growth was 3.6 MPa in the tilled Ap-horizon but 4.6-5.1 MPa in the untilled Ap-horizon and in the subsoil of both tillage treatments. This difference in the soil strength-root growth relationship is explained by the build up of a continuous pore system in untilled soil, created by earthworms and the roots from preceding crops. These biopores, which occupy < 1% of the soil volume, can be utilized by roots of subsequent crops as passages of comparatively low soil strength. The channeling of bulk soil may counteract the possible root restricting effect of an increased soil strength which is frequently observed in the zero tillage system.     

Improved method for determination of pectin degree of esterification by diffuse reflectance Fourier transform infrared spectroscopy

An improved method for the determination of pectin degree of esterification (DE) by diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS) was developed. Pectin samples with a range of DE as determined by gas chromatography were used for developing a calibration curve by DRIFTS. A linear relationship between the DE of pectin standards and FTIR peak ratio for ester carboxyl peak area to total carboxyl peak area was found (R(2) = 0.97). Pectin DE of various samples was calculated from the linear fit equation developed by DRIFTS. Accuracy of the DRIFTS method was determined by comparing the DE values of four commercial pectins obtained by DRIFTS methods to the values obtained by the gas chromatography method. Greater precision was obtained for the FTIR measurement of test pectin samples when the ester peak ratio was used relative to the ester peak area.     

Effects of rhodium heterogeneous catalyst and isomerization conditions on linoleic acid conjugation of soybean oil

Rhodium heterogeneous catalyst was used to catalyze isomerization of linoleic acid in soybean oil to conjugated linoleic acid (CLA). A central composite rotatable design with five levels of three variables, namely, reaction temperature, stirring speed, and reaction time, was used to determine the maximum CLA yield. The formation of CLA during isomerization was greatly dependent on the reaction temperature and time. The CLA content of soybean oil increased from 0.63 to 202.42 mg/g oil when isomerization was done at 200 degrees C, with a stirring speed of 200 rpm for 49 min. Analysis of triacylglycerol positions showed that linoleic acid at any position in a triacylglyceride could possibly be isomerized to CLA.