Impact Of Temperature Regimes Research Articles

Effect of temperature on growth performance and immuno-biochemical changes in endangered golden mahseer, Tor putitora (Hamilton, 1923)

The present study to evaluated the effect of different thermal regimes on growth performance, oxidative stress, antioxidant enzymes, and immuno-biochemical responses of endangered golden mahseer, Tor putitora. A total of 144 healthy fingerlings were randomly distributed into four experimental groups (13 °C, 16 °C, 19 °C, 22 ± 0.5 °C) in triplicate rectangular fiberglass reinforced plastics tanks. The highest and lowest Growth rate, Specific growth rate, Daily growth index, Thermal growth coefficient, Viscera-somatic index, and Growth hormone were observed at 19 °C and 13 °C, respectively. The lowest SGR and VSI were observed at 22 °C. The feed conversion ratio was significantly higher in the control group (p < 0.05), whereas there was a significant decrease in all the treatment groups. The highest and lowest hepato-somatic index was observed at a temperature of 13 °C and 16 °C, respectively, while no significant (p > 0.05) impact of temperature regimes were observed on the length-weight relationship. Regarding hematological indices results, the hematocrit, hemoglobin, total erythrocyte count, and total leucocyte count were significantly higher at 13 °C, whereas the lowest was observed in all the treatment groups (p < 0.05). Higher myeloperoxidase activity and lysozyme activity were observed at 13 °C, whereas lowest at 22 °C. Anti-oxidant potential, SOD, and catalase (muscle) were significantly higher in the control group, whereas they gradually decreased with an increasing temperature. Catalase (liver) level was significantly higher at 22 °C. GST content was significantly higher at 22 °C compared to 13 °C, and GST content increased gradually with an increased temperature. The lipid peroxidation level in the liver and muscle was significantly higher at 22 °C and 13 °C, respectively. The present study concluded that the different phenotypic, antioxidative, and immuno-biochemical modulations of golden mahseer fingerlings in response to different temperature regimes could be used for better management and propagation.

Impact of Temperature Regimes on the Growth and Development of Cryptolaemus montrouzieri on Planococcus citri in Guava

Under laboratory condition the developmental periods of Cryptolaemus montrouzieri was reduced to an extent of 22.7 days at 35°C when fed with Planococcus citri while it was maximum (39.0 days) at 20°C. The adult longevity ranged from 47.4 to 51.2 days at 25°C and was less (37.6 days) at 35°C for both the sexes. The number of eggs laid per female (328.5) and feeding potential (182.6 nos) were maximum at 30°C than at 20°C and 35°C.

Projected distribution of the warm season droughts over the territory of Ukraine in 2021-2050

Introduction. Drought is a natural phenomenon that occurs in all climates, and is one of the most relevant natural hazards, which propagates through the full hydrological cycle and affects large areas, often with long-term economic and environmental impacts. A prolonged deficit in precipitation over a defined region cause a meteorological drought, while the other types of drought describe secondary effects on specific ecological and economic compartments. Recent trends in the drought distribution and intensity shows that Europe splits into two big areas, in which the southern and western regions have positive trends of drought frequency, duration, and severity, and the northern and eastern regions show a decrease in this parameters. Regarding the long events, territory of Ukraine belongs to the areas in which a prominent decrease in drought frequency, duration and severity are fixed. But positive trends in the drought characteristics are observed on the Black Sea coast, also in the Carpathian region, many droughts occurred in the past three decades. The purpose of this study to examine the results of analysis of the spatiotemporal distribution of warm season droughts (April-October) across the administrative areas of Ukraine in 2021-2050 under the climate scenarios RCP4.5 and RCP6.0 with them comparing. Data and methods. Drought estimation was performed using the SPEI index (the Standardized Precipitation Evapotranspiration index). The inclusion of temperature through the potential evapotranspiration (PET) along with precipitation data allows SPEI to account for the impact of temperature regime on a drought situation. A drought episode for given time scale is defined as a period, in which SPEI is continuously negative and reaches a value of –1.0 or less. In this study, the gridded fields of monthly air temperature and precipitation intensity from multimodel sets of global CMP5 models are taken for calculations of SPEI. Data access was made through the Climate Explorer. All data were averaged over the area of each of 25 administrative regions of Ukraine. Research results. Analysis of the time series of the calculated SPEI index for both scenarios showed that in all regions of Ukraine there will be a tendency to transition from moderately wet conditions in 2021-2035 to droughty conditions in 2037-2050. In the first half of the study period drought is expected near 2024, as well as in 2030-2033 almost in all provinces except southern areas. In the second half of the period prolonged seasonal drought is projected in 2044-2047 over all Ukraine and in some areas drought may reach an extreme intensity. Decade analysis of the SPEI7 time series showed that in both scenarios in all regions of Ukraine, the least number of dry seasons is expected from 2021 to 2030. The highest number of dry seasons in this period may reach up to 4-5 cases per 10 years in the western regions under RCP6.0 scenario. In other regions the number of dry warm seasons will be 2-3 cases per 10 years. In the period from 2031 to 2040, the number of dry seasons will increase substantially in all regions of Ukraine under RCP4.5 scenario, in which their number will be 5-6 cases per 10 years. Under RCP6.0 scenario, an increase in the number of droughts will be observed in all areas except the western regions, where will be from 2 to 4 dry seasons per 10 years. In the last decade from 2041 to 2050, in both scenarios, the number of dry seasons will increase throughout Ukraine compared to the previous decade. Under RCP6.0 scenario, the greatest increase is projected in the north of the country and in some other regions throughout Ukraine, where the maximum number of seasons with droughts will reached up 8-10 cases per 10 years. Conclusions. Comparison of the SPEI7 time series for both scenarios showed that under RCP6.0 scenario the transition from wet conditions to dry conditions is projected during long period from 2030 to the early 2040s. In this time, small interannual variations of the SPEI index across all regions are expected, and only in the last decade the dry seasons will prevail. In addition, in the RCP6.0 scenario, maxima of drought frequency are expected in few different regions of the country, compared with the RCP4.5 scenario, which indicates significant scenarios' differences in the predicted state of the regional atmospheric circulation determined the temperature and precipitation regimes in the future.

ECOSYSTEM OF KULUNDINSKOE LAKE IN THE PERIOD OF DEMINERALIZATION

Research on hyperhaline lakes began in 1977. Commercial interest to Artemia (at the stage of cysts) as a starting feed for hydrobionts served as the basis for monitoring of hyper haline lakes in the Altai Territory. Kulundinskoe lake is recognized as one of the largest basins in the Kulundinskaya plain of Ob-Irtyshskoye interfluve with population of fairy shrimp Artemia Leach, 1819. Comprehensive hydrobiological surveys in the growing season (April-October) 2018 show the dynamics of phytoplankton, zooplankton and stages of Artemia salina development in Kulundinskoe Lake . The researchers analyzed the impact of temperature regime and water salinity in the vegetation period of 2018 on Artemia salina status and productivity of the basin. Water mineralization varied within 83.4 - 93.0 g/l, which indicates lower salts concentration in the leach compared to the average many-year value which is explained by the change of water regressive stage to transgressive one. Monitoring of hyperhaline basin in the vegetation period of 2018 showed a depressive status of Artemia salina development due to demineralization of the basin. At the beginning of vegetation period, the temperature regime was unfavorable for Artemia salina development in the lake. That resulted in low numbers of copepods. Due to depressive development of Artemia salina in Kulundinskoye Lake in the vegetation period of 2018, the basin is seen to have lost its economic relevance.

Effect of seeding date on development of clubroot in short-season Brassica crops

Recent studies on the effect of temperature on clubroot of Brassica spp., caused by Plasmodiophora brassicae, have demonstrated that temperature has an important impact on each component of the disease cycle under controlled conditions. The current study was conducted to assess the impact of temperature regime on clubroot incidence and severity on two short-season Asian vegetable crops, Shanghai pak choy (B. rapa subsp. chinensis var. communis) and Chinese flowering cabbage (B. rapa subsp. chinensis var. utilis) under field conditions. Each crop was seeded at about monthly intervals from May to September on a naturally infested site near Bradford, Ontario in 2008 and 2009. A soil-drench treatment with cyazofamid fungicide (trade name Ranman® 400 SC) was included at each seeding date to assess the interaction of fungicide and temperature. Clubroot severity was assessed at weekly intervals from 2–3 wk after planting until about 6 wk after planting using a 0–3 scale. Clubroot incidence and severity were consistently higher on Shanghai pak choy than Chinese flowering cabbage, but both host crops exhibited a similar pattern of symptom development. Clubroot severity was highest in the July seeding (warmest mean temperature), slightly lower in June and August, and lowest in the May and September seeding dates (lowest temperatures). Clubroot levels were also positively correlated with rainfall. Cyazofamid fungicide consistently reduced clubroot levels. We conclude that producers of short-season crops can select seeding dates to avoid losses from clubroot, even in heavily infested fields. Both moderate soil temperatures (17–26 °C) and adequate soil moisture must be present for the development of severe clubroot.

The impact of temperature regimes on development, dormancy breaking and germination of dwarf shrub seeds from arctic, alpine and boreal sites

It has been suggested that the infrequent sexual reproduction of arctic dwarf shrubs might be related to the harsh environmental conditions in which they live. If this is the case, then increases in temperature resulting from global climate change might drastically affect regeneration of arctic species. We examined whether recruitment of Empetrum nigrum ssp. hermaphroditum and Vaccinium uliginosum (hereafter E. nigrum and V. uliginosum) was affected by temperature during three reproductive stages: seed development, dormancy breakage and germination. Seeds were collected from an arctic, an alpine (only E. nigrum) and a boreal site with different climates; stored at different winter temperatures and incubated for germination at different temperatures. Seeds of V. uliginosum developed in the boreal region had a higher percentage germination than did seeds developed in the Arctic. In contrast, seeds of E. nigrum from the arctic site had a higher or similar percentage germination than did seeds from the alpine and boreal sites. Increased winter temperatures had no significant effect on resulting germination percentage of E. nigrum. However, V. uliginosum seeds from the arctic site suffered increased fungal attack (and thus decreased germination) when they were stratified under high winter temperatures. Seeds of both species increased germination with increased incubation temperatures. Our results suggest that both species would increase their germination in response to warmer summers. Longer summers might also favour the slow-germinating E. nigrum. However, increased winter temperatures might increase mortality due to fungal attack in V. uliginosum ecotypes that are not adapted to mild winters.