Consistency of polyphenol oxidase (PPO) thermostability in ripening apricots (Prunus armeniaca L.): evidence for the presence of thermostable PPO forming and destabilizing mechanisms in apricots

Destabilization of thermostable polyphenol oxidase (TS-PPO) during the ripening of peaches has been previously shown (Yemenicio?lu, A.; Cemero?lu, B. Tr. J. Agric. For. 1998, 22, 261-265). This work studied the effect of ripening on thermal stability of apricot PPO for three different cultivars. Kabaa?i cultivar contained thermolabile PPO, whereas TS-PPO appeared in Hacihalilo?lu and Catalo?lu cultivars. The TS-PPO showed biphasic inactivation curves, and its D and z values between 60 and 90 degrees C varied in the ranges of 357-1.12 min and 11.9-12.7 degrees C, respectively. In Hacihalilo?lu cultivar the TS-PPO was very consistent and existed at all stages of ripening, whereas in Catalo?lu cultivar it appeared only at the half-ripe stage. The loss of consistent TS-PPO in Hacihalilo?lu apricots after partial purification by acetone precipitation and DEAE-cellulose chromatography suggested the non-covalent nature of its stabilization. The main purified fractions (F1 and F2) showed monophasic inactivation curves with similar thermal inactivation parameters (z(F1) = 10.4 degrees C, z(F2) = 10.1 degrees C). However, their kinetic properties against catechol (K(mF1) = 61 mM, K(mF2) = 122.7 mM) and substrate specificities were considerably different. The results of this study showed the presence of TS-PPO forming and destabilizing mechanisms in apricots. Further studies are needed for the solution of these mechanisms and to develop some new strategies that may be utilized by molecular techniques for a planned production of apricot cultivars provided with heat labile but normal PPO activity.     

Bioaccumulation, Detection and Analyses of Heavy Metal Pollution in Sultan Marsh and Its Environment

Sultan Marsh is one of the largest and most important wetlands in Turkey, Middle East and Europe, embodying saline and fresh water ecosystems, which provide a shelter for 426 bird species. The area has begun to contribute much to the tourism of Kayseri state and its environs. However, the sites in the vicinity of the sewerage – sludge and fertilizer plants are highly damaged due to pollution. As such, studies on the heavy metal status of water, sediment and plants were investigated. Phragmites australis, Ranunculus sphaerosphermus plants and samples of sediments were taken from 13 different stations of this Marsh. All sampling sites in the study area basin were generally more or less polluted when compared with the control sites. Cr concentrations in the roots of the plants were higher than in the sediment. The tissues of Phragmites australis accumulated heavy metals more than those of Ranunculus sphaerosphermus. The heavy metal accumulation in different parts of plants followed the sequence: root > stem > leaf. Both plants can be used as biological indicators while determining environmental pressures; however, Phragmites australis proved more appropriate for such studies.     

Sour Orange (Citrus Aurantium L.) Growth is Strongly Mycorrhizal Dependent in Terms of Phosphorus (P) Nutrition Rather than Zinc (Zn)

The partial sterilization of soil eliminates useful microorganisms, resulting in the reduced growth of mycorrhizae-dependent citrus plants, which are often unresponsive to the application of fertilizer. Research was conducted to test the hypothesis that indigenous mycorrhizae (IM) inoculation is as efficient as selected mycorrhizal inoculation under sterile and non-sterile soil conditions. Rhizophagus clarus and indigenous mycorrhiza spores, isolated from citrus orchards, were used as arbuscular mycorrhizae fungi under greenhouse conditions with sterile and non-sterile Çanakçi series (Typic xerofluvent) soils with low phosphorus (P) fertility. Different P (0 and 100 mg kg^?1) and zinc (Zn) (0, 5 and 10 mg kg^?1) concentrations were used at the start of the experiments. The shoot, root dry weight (RDW), root colonization, and P, Zn, iron (Fe), copper (Cu) and manganese (Mn) concentrations of the shoot were determined; mycorrhizae dependency (MD) was also calculated.

The results indicate that R. clarus and indigenous mycorrhiza in sterile and non-sterile soil conditions considerably increased the growth of citrus plants. Owing to existing beneficial indigenous rhizosphere microorganisms, citrus plant growth without inoculation was better in non-sterile soils than in the sterile soils. In non-sterilized soil, the plant growth parameters of R. clarus-inoculated soils were higher than those of indigenous mycorrhiza-inoculated soils. Mycorrhizae infection increased certain citrus plant growth parameters, such as root infection, biomass and nutrient uptake (P, Zn, Fe, Mn and Cu). In sterile soil, the addition of up to 5 mg kg^?1 soil Zn and the inoculation of R. clarus significantly increased plant growth; inoculation with indigenous mycorrhiza produced more dry weight upon the addition of up to 100 mg kg^?1 phosphorus pentoxide (P₂O₅). Under sterile soil conditions, without considering fertilizer addition, MD was found to be higher than that of non-sterile soils. In general, the contribution of the indigenous soil spores is significant. However, indigenous soil mycorrhizae may need to be managed for better efficiency in increasing plant growth and nutrient uptake. The major finding was that the inoculation of citrus seedlings with mycorrhiza is necessary under both sterilized and non-sterilized soil conditions.     

Nutrient Removal in a Three-Step Sequencing Batch Reactor with Different Carbon Sources

A three-step sequencing batch reactor was used for nutrient (COD, NH₄-PO₄-P) removal from synthetic wastewater by using different carbon sources. The operation consisted of anaerobic, anoxic and oxic (An/Ax/Ox) phases with durations of 2/1/4.5 h. Different carbohydrates, glucose, lactose, sucrose, maltose and a mixture of glucose/maltose (50/50), were used as the sole carbon source in the first phase of experiments. Sludge age was kept constant at 10 days. Glucose was found to be the most suitable carbohydrate source with percent COD, NH₄-N and PO₄-P removals of 96%, 99% and 94%, respectively. Nutrient removals obtained with sucrose as the sole carbon source were close to those obtained with glucose. A mixture of glucose and organic acids (50/50) such as acetic, citric, propionic and butyric acid were used as carbon source in the second phase of the experiments. Maximum percent COD, NH₄-N and PO₄-P removals were 93%, 97% and 96%, respectively when a mixture of glucose and acetic acid (50/50) was used. Glucose-citric acid (50/50) combination also resulted in comparable nutrient removals.     

Effects of Various Parameters on Removal of NO2 Gases in Fixed Beds by Adsorption on Sepiolite

Removal of NO₂ gases in fixed beds was investigatedby using brownish, whitish and regenerated whitish sepioliteand perlite as adsorbents. For this purpose, NO₂ wasproduced by reaction of copper with nitric acid. The producedgas was mixed with air and the mixture was sent through a fixedbed. Studies were conducted using various gas flow rates,NO₂ concentrations, packing sizes and heights of bed.Remaining NO₂ within the gas mixture leaving the column,unadsorbed on packing, was further absorbed by passing itthrough a series of washing bottles, filled by a solution ofNaOH. At the end of the study, it was observed that theadsorption capacity of sepiolites, especially whitishsepiolite, was much higher than that of perlite. Additionally,it was seen that its adsorption capacity increased withincreasing bed height, particle size, NO₂ concentrationand decreasing gas flow rate.     

Management of femoral fractures in dogs with unilateral semicircular external skeletal fixators

Objective: To report use of semicircular external skeletal fixators (ESF) for management of femoral fractures in dogs. Study Design: Prospective clinical study. Animals: Dogs (n=16) with femoral fractures (n=18). Methods: A semicircular ESF system composed of 6‐hole 45° or 5‐hole 40° carbon‐fiber arches, 6 mm threaded rods, half pin fixation bolts, 6 mm nuts, and negative profile end‐threaded half pins were used for open repair of femoral fractures. ESF configuration, complications, limb use, fixator removal time, and functional outcomes were evaluated. Outcome was graded as excellent, good, fair, or poor. Results: Seventeen fractures with sufficient follow‐up healed. Eight dogs started using the limb immediately after waking up from anesthesia whereas initial limb use was 1–4 days after repair in the other dogs. Time to fixator removal ranged from 28 to 63 days (mean, 38 days). Functional outcome was excellent in 13 cases, good in 4, and poor in 1 nonunion. Conclusion: Semicircular ESF combined with open surgical reduction can be used to successfully repair metaphyseal and diaphyseal femoral fractures in young growing dogs.     

Salinity and drought affect yield response of bell pepper similarly

Abstract

There is a growing realization that an increasing number of countries are approaching full utilization of their conventional water resources and that the quantity of good-quality water supplies available to agriculture is diminishing. Effects of irrigation regime and irrigation water salinity on bell pepper including yield, fruit number and quality, vegetative and root growth, evapotranspiration and water use efficiency were investigated in this study by conducting two different experiments. Six different salinity levels of irrigation water and four different irrigation regimes were used as treatments. Considering the results from irrigation water salinity experiment, it can be concluded that as soil salinity increases, water consumption, water use efficiency, yield and other vegetative growth parameters of bell pepper were decreased. A polynomial relationship between soil salinity and water consumption was observed. It was found that bell pepper is moderately sensitive to salinity with a 1.2 dS m^?1 threshold and a 10.9% slope value. In the irrigation regime experiment, limited irrigation caused decreases in water consumption, yield and vegetative growth of bell pepper. Yield response factors were close in the cases of irrigation regime (1.50) and irrigation water salinity (1.40). Total soluble solids of bell pepper were increased due to both irrigation water salinity and water application rate but not dry matter ratio. Considerable water consumption decreases because of salinity were determined. Therefore, the effect of irrigation water salinity should be considered in irrigation management to prevent excess saline water application and to protect the environment.     

Effects of three biochar types on activity of β-glucosidase enzyme in two agricultural soils of different textures

ABSTRACT

Biochar has attracted significant attention due to the long-lasting nature, and prominent influence on soil characteristics. This study was conducted to evaluate changes in the activity of β-glucosidase enzyme (BG) in loamy and sandy loam texture soils following two winter wheat growing seasons. The experimental design was a randomized complete block with three replicates and four treatments. The treatments were two soils, three biochars (rice husk, corn cob and bean harvest residue), five biochar rates (BR) and five levels of mineral fertilizers (FR) or dairy effluent (DE). The fertilizers were applied at the beginning of each season, while biochars were applied only at the beginning of experiment. Soil samples were collected following the second season and analyzed for the BG activity. Addition of biochars reduced the BG activity and the decline was higher in sandy loam compared to loamy soils. Negative effect of biochar to BG activity was greater at the highest BR (3.0%) than the lower BR. Fertilizer additions along with DE biochar had significant effect on BG activity that increased with higher FR. Given the importance of BG activity in soil organic matter decomposition, biochar application can be considered a sustainable way of increase in carbon sequestration.     

Potential of Biosolids from Shrimp Aquaculture as a Fertilizer for Broccoli Production

Shrimp biosolids (SB) are composed of shrimp fecal matter and decomposed shrimp feed and remain as debris in the bottoms of drained ponds used to culture shrimp. These biosolids are considered waste and usually disposed of in landfills. SB is a valuable source of N, P, K and a variety of other useful plants nutrients; however, SB contains high levels of Na. Field research was conducted to evaluate the potential of SB as a fertilizer source used with and without an inorganic fertilizer source (Osmocote 14N - 6P - 12K) to grow broccoli (Brassica oleracea italica). Yield of marketable heads/ha varied with SB/Osmocote (OSM) ratios. OSM at 75 kg/ha in combination with 9.0 MT SB/ha increased heads/ha significantly compared to lesser rates of each fertilizer source. This SB/OSM fertilizer regime contained a total of 263N - 116P - 99K - 99Na/ha. The biological yield increased 13% with OSM at 150 kg/ha and SB at 9.0 MT/ha, but if OSM was increased to 300 kg/ha, yield decreased significantly by 21% probably due to excessive fertilizer salts from both sources restricting plant growth. Lettuce field bioassays after broccoli production did not indicate that either fertilizer source persisted in the soil. The sodium in SB needs to be considered carefully whenever this material is used and SB should be evaluated in experimental trials before commercial use on other crops.     

Biochemical composition of Mnemiopsis leidyi in the southern Caspian Sea

The biochemical composition of the invasive ctenophore, Mnemiopsis leidyi from the southern Caspian Sea was analysed in terms of total fractions of protein, lipid, ninhydrin-positive substances (NPS), polysaccharides (PS) and low molecular- weight carbohydrates (LMC). The sum of organic substances per gram dry weight was 84.2 mg g⁻¹. Protein was the major organic fraction followed by lipid and NPS. The NPS/ protein and LNC/PS ratio were 0.45 and 0.50 respectively. Starvation of M. leidyi for a 5-day period resulted in a 32.7% reduction of total organic content. These data will be important in evaluating the feeding condition of M. leidyi specimens from the field. This revised version was published online in July 2006 with corrections to the Cover Date.