Three new species of Gyrodactylus (Monogenoidea) from Varicorhinus capoeta gracilis (Keyserling) from the River Lenkoranka.

Three new species of Gyrodactylus Nordmann, 1832 are described from Varicorhinus capoeta gracilis (Keyserling) from the River Lenkoranka (Azebaijan SSR) as follows: G. varicorhini sp. n., G. capoetai sp.n. and G. mikailovi sp.n.     

Hydrolytic Enzyme Inhibitors and Necrotic Reactions in Potato Leaves Reduce Reproductive Success of Colorado Potato Beetle

In field and laboratory conditions the reproductive potential （survival at different stages of development） of the Colorado potato beetle has been measured, the dependence of the parameters of insects fertility on varietal features of the feed has been investigated, the food activity of the representatives of insects from four areas of the Southern Urals has been measured, the intensity and time of hypersensitivity reactions on potato leaves has been defined. In laboratory experiments, the level of activity of hydrolytic enzymes in insects and the level of activity of these enzymes inhibitors in the leaves of three potato varieties differing in their resistance to the Colorado potato beetle have been determined. The results show that the insects-representatives of different samples have different food activity in relation to different potato varieties. High mortality rates were revealed at feeding with leaves of potato of the Bashkir variety characterized by a high level of hydrolases inhibitors and relatively rapid development of necrotic reactions after the appearance of eggs laying on the leaves. We suppose that the neerogenetic barrier appearing in the form of necrosis is the major cause of the fetal mortality of insects. The level of the content of inhibitors inactivating larvae digestive enzymes affects the survival of insects at postembryonic stages. The speed of the necrosis emergence, the level of activity of digestive enzymes inhibitors in potato can be considered as criteria for the selection of breeding material for resistance to the Colorado potato beetle.     

Nitrous oxide emissions from fertilized,irrigated cotton (Gossypium hirsutum L.) in the Aral Sea Basin,Uzbekistan: Influence of nitrogen applications and irrigation practices

Nitrous oxide emissions were monitored at three sites over a 2-year period in irrigated cotton fields in Khorezm, Uzbekistan, a region located in the arid deserts of the Aral Sea Basin. The fields were managed using different fertilizer management strategies and irrigation water regimes. N₂O emissions varied widely between years, within 1 year throughout the vegetation season, and between the sites. The amount of irrigation water applied, the amount and type of N fertilizer used, and topsoil temperature had the greatest effect on these emissions.Very high N₂O emissions of up to 3000 μg N₂O-N m^?2 h^?1 were measured in periods following N-fertilizer application in combination with irrigation events. These “emission pulses” accounted for 80–95% of the total N₂O emissions between April and September and varied from 0.9 to 6.5 kg N₂O-N ha^?1.. Emission factors (EF), uncorrected for background emission, ranged from 0.4% to 2.6% of total N applied, corresponding to an average EF of 1.48% of applied N fertilizer lost as N₂O-N. This is in line with the default global average value of 1.25% of applied N used in calculations of N₂O emissions by the Intergovernmental Panel on Climate Change.During the emission pulses, which were triggered by high soil moisture and high availability of mineral N, a clear diurnal pattern of N₂O emissions was observed, driven by daily changes in topsoil temperature. For these periods, air sampling from 8:00 to 10:00 and from 18:00 to 20:00 was found to best represent the mean daily N₂O flux rates. The wet topsoil conditions caused by irrigation favored the production of N₂O from NO₃^? fertilizers, but not from NH₄⁺ fertilizers, thus indicating that denitrification was the main process causing N₂O emissions. It is therefore argued that there is scope for reducing N₂O emission from irrigated cotton production; i.e. through the exclusive use of NH₄⁺ fertilizers. Advanced application and irrigation techniques such as subsurface fertilizer application, drip irrigation and fertigation may also minimize N₂O emission from this regionally dominant agro-ecosystem.     

Simulating water use and N response of winter wheat in the irrigated floodplains of Northwest Uzbekistan

The crop-soil simulation model CropSyst was used to simulate growth, water- and N-uptakes of irrigated winter wheat (Triticum aestivum L. cv. Kupava) in Khorezm, in the dry lands of northwest Uzbekistan, Central Asia. CropSyst was calibrated using the findings of field experiments of 2005/06 and 2006/07 and validated for the 2007/08 season. A relative root mean squared error of 11% proved the accuracy between simulated and observed aboveground biomass and grain yield in 2007/08. Scenario analyses showed that N-leaching was high and ranged from 63 to 106 kg ha⁻¹ when irrigated between 749 and 869 mm during the first two cropping seasons. The simulated N-leaching was lowest and ranged from 7 to 15 kg ha⁻¹ when irrigation was only 148–395 mm during 2007/08. The considerable N losses during leaching and high N-uptakes by wheat together resulted in a negative N-balance even during applications of 180 and 240 kg ha⁻¹ of N-fertilizer. N scarcity in the N-balance was reduced with increasing N-fertilizer amounts and ranged from −29 to −153 kg N ha⁻¹ in 2005/06 and 2006/07. Despite a common shallow groundwater table in the region during some time of the year, scenario analysis revealed that only full irrigation water (580 mm) and N supply according to crop demand (180 kg ha⁻¹) guaranteed high grain yields, unless the water table is permanently shallow to overcome irrigation deficits. Limited irrigation and N application (40% and 55% of ‘optimal’, respectively) in combination with a groundwater table below 3 m resulted in a 55% yield decline. The CropSyst wheat model proved a robust tool for assessing the influence of water and N dynamics under conditions of varying irrigation and shallow groundwater tables. It thus has potential as a decision support not only in northwest Uzbekistan, but also in comparable regions of Central Asia.     

Induction of peroxidase as a disease resistance response in resistant (<Emphasis Type="Italic">Hibiscus trionum</Emphasis>) and susceptible (<Emphasis Type="Italic">Althea armeniaca</Emphasis>) species in the family malvaceae

The pathogen-induced biosynthesis of peroxidase (PO) in resistant and susceptible wild species of Malvaceae was studied. Specifically,Hibiscus trionum was found to be resistant to the wilt pathogenVerticillium dahliae, andAlthea armeniaca was susceptible. After inoculation withV. dahliae, PO activity increased more rapidly in the resistant plant: increased activity inH. trionum was noted within 1 h after inoculation, remained high for 5 h, and decreased after 18 h. After 5 days, the levels did not differ from the control. In the susceptibleA. armeniaca, PO activity did not differ statistically from the control even after 18 h, but was significantly higher after 5 days. Electrophoretic analysis of inoculated tissue extracts showed the occurrence of two new isoforms inh. trionum after inoculation; new isoforms did not occur inA. armeniaca. A chitin affinity chromatography column showed the presence of a chitin-binding peroxidase isozyme in healthyH. trionum that increased dramatically after inoculation. Two chitin-binding peroxidase isozymes were observed in healthyA. armeniaca: one (R _f 0.26) did not increase and the other (R _f 0.89) evinced only a small increase after inoculation.     

Response of <Emphasis Type="Italic">Sorghum bicolor</Emphasis> varieties to soil salinity for feed and food production in Karakalpakstan,Uzbekistan

Water and land salinization, caused by ill-practiced irrigation and drainage is acute and widespread in Karakalpakstan, Uzbekistan. A crop frequently grown in these marginal areas is sorghum because of its capability to adapt to saline conditions. However, the salt uptake potential of local varieties for salt-ameliorative purposes, as well as possible income-generation benefits, have not yet been studied. Therefore, field experiments on low, medium and highly saline soils were conducted using four sorghum cultivars (S. vulgare, S. cernuum, S. durra, and S. technicum). The effect of soil salinity on biomass, stover and grain yield, the baking and feed quality, and total water soluble salt (TDS) accumulation, was assessed according to varieties, plant fractions and growth phases. Results showed that S. cernuum had the highest grain yield on the low (5.13 t ha⁻¹), medium (6.05 t ha⁻¹) and highly (3.3 t ha⁻¹) saline soil. S. technicum showed the lowest growth potential under all salinity levels. TDS accumulation varied between 406 and 185 kg ha⁻¹ depending on variety, site, plant fractions and growth stage. Irrespective of the soil salinity levels and varieties, TDS was highest in stover and leaves, while highest TDS uptake, mainly chlorides and bicarbonates, occurred between booting and flowering. Baking quality of all varieties was extremely low, whereas the in-vitro feed was assessed as of medium quality. The findings indicate the scope of local sorghum varieties for phytomelioration of marginal lands in Karakalpakstan, while concurrently satisfying a wider range of rural livelihood needs.