Effective Degree-days Research Articles

Climate change impact on Mediterranean viticultural regions and site-specific climate risk-reduction strategies

The global increase in extreme weather and climate events may dramatically impact agriculture, food safety, and socioeconomic dynamics. The Mediterranean basin is already exposed to extreme climatic events, severely challenging viticulture, a pivotal Mediterranean agro–industry. This study aims to understand better how climate is expected to evolve in six viticulturally important Mediterranean regions in Portugal, Italy, Turkey and Morocco, using a 4–member ensemble of climatic model projections under Representative Concentration Pathways (RCP) 4.5 and 8.5 for 2041–2070, and using the 1981–2010 period as a baseline. By comparing the main specific challenges these locations will face, we comparatively define the best strategies to reduce the impacts of climate change at the national and regional levels. Projections show increases in overall temperatures, up to + 3.6°C than the historical baseline, whilst precipitation projections indicate decreases that could reach 36% of the overall annual precipitation. Biological effective degree days, consecutive dry days, growing season length, tropical nights, or very heavy precipitation days, also show challenging prospects for viticulture in these countries. A screening of the adaptative strategies already undertaken in the studied countries suggests that growers are taking reactive rather than preventive strategies. Moreover, the discussion of the most suitable strategies in this study is region–specific, i.e., prioritised by the specific needs of each location. The conclusions drawn herein may support local growers, improving their decision–making based on the most adequate adaptive strategies to their conditions, thus optimising their sustainable production under changing climates.

Impacts of extreme agroclimatic indicators on the performance of coffee (Coffea arabica L.) aboveground biomass in Jimma Zone, Ethiopia

Estimating crop biomass is critical for countries whose primary source of income is agriculture. It is a valuable indicator for evaluating crop yields and provides information to growers and managers for developing climate change adaptation strategies. The objective of the study was to model the impacts of agroclimatic indicators on the performance of aboveground biomass (AGB) in Arabica coffee trees, a critical income source for millions of Ethiopians. One hundred thirty-five coffee tree stump diameters were measured at 40 cm above ground level. The historical (1998–2010) and future (2041–2070) agroclimatic data were downloaded from the European Copernicus climate change services website. All datasets were tested for missing data, outliers, and multicollinearity and were grouped into three clusters using the K-mean clustering method. The parameter estimates (coefficients of regression) were analyzed using a generalized regression model. The performance of coffee trees' AGB in each cluster was estimated using an artificial neural network model. The future expected change in AGB of coffee trees was compared using a paired t-test. The regression model’s results reveal that the sensitivity of C. arabica to agroclimatic variables significantly differs based on the kind of indicator, RCP scenario, and microclimate. Under the current climatic conditions, the rise of the coldest minimum (TNn) and warmest (TXx) temperatures raises the AGB of the coffee tree, but the rise of the warmest minimum (TNx) and coldest maximum (TXn) temperatures decreased it (P < 0.05). Under the RCP4.5, the rise of consecutively dry days (CDD) and TNx would increase the AGB of the coffee tree, while TNx and TXx would decrease it (P < 0.05). Except for TXx, all indicators would significantly reduce the AGB of coffee trees under RCP8.5 (P < 0.05). The average values of AGB under the current, RCP4.5, and RCP85 climate change scenarios, respectively, were 26.66, 28.79, and 24.41 kg/tree. The predicted values of AGB under RCP4.5 and RCP8.5 will be higher in the first and third clusters and lower in the second cluster in the 2060s compared to the current climatic conditions. As a result, early warning systems and adaptive strategies will be necessary to reduce the detrimental consequences of climate change. More research into the effects of other climatic conditions on crops, such as physiologically effective degree days, cold, hot, and rainy periods, is also required.

High-resolution Projection Dataset of Agroclimatic Indicators over Central Asia

To understand the potential impacts of projected climate change on the vulnerable agriculture in Central Asia (CA), six agroclimatic indicators are calculated based on the 9-km-resolution dynamical downscaled results of three different global climate models from Phase 5 of the Coupled Model Intercomparison Project (CMIP5), and their changes in the near-term future (2031–50) are assessed relative to the reference period (1986–2005). The quantile mapping (QM) method is applied to correct the model data before calculating the indicators. Results show the QM method largely reduces the biases in all the indicators. Growing season length (GSL, day), summer days (SU, day), warm spell duration index (WSDI, day), and tropical nights (TR, day) are projected to significantly increase over CA, and frost days (FD, day) are projected to decrease. However, changes in biologically effective degree days (BEDD, °C) are spatially heterogeneous. The high-resolution projection dataset of agroclimatic indicators over CA can serve as a scientific basis for assessing the future risks to local agriculture from climate change and will be beneficial in planning adaption and mitigation actions for food security in this region.

Assessment of agrometeorological indices over Southeast Europe in the context of climate change (1961-2018)

The regional response over Southeast (SE) Europe to the climate warming in global and continental scales has been confirmed to have essential impact on the agriculture and forestry since the middle of twentieth century. Normal variations in weather throughout a growing season cause variations in harvest and, generally, the impact could be large in terms of production amounts and economic returns. Agriculture is sensitive to the changes in weather and climate, and the occurrence of extreme events threaten the agricultural systems. Forests are particularly sensitive to climate change, because the long life-span of trees does not allow for rapid adaptation to environmental changes. This study provides an overview of the spatial patterns and the long-term temporal evolution of the following agrometeorological indices: growing season length, accumulated active temperatures and biologically effective degree days. Hence the focus is on the Growing season length, its start and end dates are analyzed separately. All indices are computed from the daily mean temperatures which, in turn, are derived from the output of the MESCAN-SURFEX system analysis of the collaborative initiative UERRA. The geographical domain of interest is Southeast Europe, and the assessment is performed at a very high spatial resolution on annual basis for the period 1961–2018. We find strong evidences of essential increase in the considered indices which dominates spatially over the low-elevated areas of the domain and is statistically significant at 5% level. Key message is also the revealed asymmetry of the increase in the most relevant index, the growing season length: its total lengthening is linked more to the shifting to earlier date of the start, rather than to its later cessation.

Long-term phenoclimatic averages of the Yuganskiy Nature Reserve territory and changes for 1961-2016

In light of the observed global climate changes in recent decades, we studied the local climate indicators and explored the possible links between the spring and autumn phenophases and climate data changes in the Yuganskiy nature reserve (N 600 17’; E74054’ – N590 23’; E74000’) in 1982-2016. The collected climate data include daily average, maximum and minimum temperatures, daily precipitation amount and intensity, and number of days with precipitation of 0.1mm or more, monthly average of snow depths, dates of first and last occurrence of daily mean temperatures 0, +5, +10°С through the year. Timing of sap movement and leaf fall start were used as the spring and autumn indicators of birch (Bétula péndula ) phenology. The mean value of weather averages in the 30-year period of 1961-1990 was used as reference. Trends were calculated using linear least squares regression. Statistical significance was determined by calculating the standard error of the trend estimate.&#x0D; We found that the annual mean temperature has increased from –1.9°С (1961-1990) to –0.8° С (1982-2016), with corroborating indicators including increased temperature of the coldest night of the year from –53°С (1961-1990) to –51.3° С (1982-2016) and increased frequency of significant positive temperature anomalies from 21% (1961-1990) to 37% (1982-2016). May, June, August and October nights have become successively warmer. The air temperature increase was not accompanied by a corresponding increase in precipitation.&#x0D; Statistically significant trends toward earlier onset of spring and summer from 1982 to 2016 were observed. The date of the last spring freeze has been advancing by 6.1 days per decade since 1982. A freeze-free season has lengthened by 7.7 days per decade. Linear trend of the snowmelt timing was –3.7 days per decade. Permanent snow cover period has been shortening by 7.7 days per decade. The date of the first occurrence of the daily mean temperatures of +10° С has been advancing by 5.1 days per decade. However, the 0 -+5° С lag has been lengthening significantly by 9.2 days per decade, and the number of biologically effective degree days (base +5C) has not statistically changed.&#x0D; Sap flux and leaf fall timing of B. pendula have been advancing almost simultaneously by 4.0 and 4.2 days per decade since 1985. Sap flux beginning and last spring freeze date have been found to be linearly correlated (r=0.904). The average lag of them was 5±1 days and has been lengthening by 3 days per decade (1985–2016).

Relationship between viticultural climatic indices and grape maturity in Australia.

Historical temperature data and maturity records were analyzed for 45 vineyard blocks in 15 winegrowing regions across Australia in order to evaluate the suitability of common viticultural indices to estimate date of grape maturity. Five temperature-based viticultural indices (mean January temperature, mean growing season temperature, growing degree days, biologically effective degree days, Huglin Index) along with four springtime temperature indices (mean and maximum temperature summations for September, October, and November; growing degree days and biologically effective degree days modified to include September) were compared to maturity data in order to investigate index relationship to observed maturity timing. Daily heat summations for the months of September, October, and November showed the best correlation to day of year of maturity, suggesting that springtime temperatures are important relative to the timing of grape maturity. Mean January temperature, a commonly used index, had the poorest correlation with day of year of maturity of all the indices included in this study. Indices that included the month of April had poorer correlation than indices that shifted the months included in the growing season to be from September to March inclusive. Calculated index values for the past 30years for every region included in this study showed increasing temporal trends to various degrees, indicating that all regions studied are experiencing warming temperatures during the growing season. These results emphasize the need to reevaluate viticultural indices in the context of a changing climate.

Genotype by environment interactions in cowpea (Vigna unguiculata L. Walp.) grown in the Iberian Peninsula

The aim of this work was to determine the variance components and genetic and environmental stability of 12 cowpea genotypes at three locations (South-east of Spain: Cartagena, South and North of Portugal: Elvas and Vila Real, respectively) in the Iberian Peninsula in two consecutive years (2015 and 2016). The genotype, the environment and the genotype × environment interaction significantly influenced all the morphological and agronomical parameters evaluated. For both years, the highest yields were observed at Elvas, whereas Cartagena and Vila real were the most suitable places to obtain crop precocity. Cartagena was the place where the filling of the seed was the fastest, probably due to the higher temperatures and radiation. The thermal time model (effective degree-days) could be used to predict the period of cowpea development, therefore predict flowering and pod maturity date. Correlation analysis showed that days to flowering, days to maturity and the seed yield vs protein content exhibited negative correlations. The highest heritability was found for plant height and pod length at Cartagena and for 100-seed weight at Elvas and Vila Real. In conclusion, the variations that exist in the studied accessions could give rise to a breeding program to develop cowpea cultivars with interesting agronomic traits.

Spatial Analysis of Climate-Viticulture Indices for the Eastern United States

This study characterizes the climate structure in the Eastern United States for suitability of winegrape growth. For this study, the Eastern US is defined as the 44 contiguous Eastern most states. This excludes the premium wine growing states of California, Washington, Oregon and Idaho. For this characterization, a comparative study is performed on the four commonly used climate-viticulture indices (i.e., Average Growing Season Temperature, Growing Degree Days, Heliothermal Index and Biologically Effective Degree Days), and a new climate-viticulture index, the Modified-GSTavg (Mod-GSTavg). This is accomplished using the 1971 – 2000 PRISM 800-meter resolution dataset of climate temperature normal for the study area of 44 states and 62 American Viticultural Areas across the Eastern United States. The results revealed that all the climate indices have similar spatial patterns throughout the US with varying magnitudes and degrees of suitability.

Аналіз змін фітомаси деревостанів у лісових насадженнях міста Любліна з використанням моделі FORKOME

Дослідження фітомаси проведено на прикладі деревостанів, які знаходяться в актуальних межах міста Любліна (Польща). На дослідних площах розмірами 25 х 25 м, закладених у дубових (2 площі), соснових (3 площі) і по одній у грабовому, модриновому та березовому деревостанах, досліджено нагромадження загальної надземної фітомаси і фітомаси за фракціями. Прогнозовано можливі зміни фітомаси до 2035 р. за допомогою моделі FORKOME. Модель FORKOME дає змогу здійснювати щорічні імітації відновлення, росту і випадання дерев, а також враховує вплив екологічних чинників на деревостани. Модель також містить постійно покращуваний презентаційний рівень, який заповнює тривимірну візуалізацію елементів у деревостанах міста.

Effect of two temperatures on yield and increase in cranial skeletal abnormalities during early development of palm ruff,Seriolella violacea(Guichenot 1848)

The present study evaluates the effect of two temperatures, 14°C (T14) and 18°C (T18), on yield and the presence of cranial abnormalities during early development in north palm ruff (Seriolella violacea). Different time indices – days post-hatching (DPH), degree-days (D°) and effective degree-days (D°eff) – were used to analyse growth during cultivation. Several ontogenetic events were achieved in less time during cultivation at 18°C. Additionally, a larger total length and final weight, as well as a higher survival rate, were achieved after 80 days of culture at higher temperatures (T18 = 55.5 ± 1.5 mm; 2.87 ± 0.21 g; 1.80 ± 0.18% and T14 = 24.3 ± 2.2 mm; 0.26 ± 0.08 g; 1.33 ± 0.12%). D° and D°eff were valid as independent temperature indices for predicting the growth response of S. violacea against thermal variations. The frequencies of cranial skeletal abnormalities (mouth and opercular complex) were evaluated in the pre-flexion, flexion, post-flexion and juvenile stages. However, the frequency of cranial skeletal abnormalities at the end of this study was not significantly influenced (P > 0.05) by temperature, and values below 21% were recorded in both treatments. These results can be of practical use for optimizing culture conditions to maximize the yield and quality of S. violacea juveniles.

Influence of pre-harvest factors on quality of a winter cycle, high commercial value, tomato cultivar

The present study was conducted to study the effect of pre-harvest factors such as salinity and greenhouse air CO2 enrichment on the quality of a high commercial value, tomato cultivar. The experiment was carried out in two identical, adjacent multispan greenhouses, with polyethylene plastic covering. Hybrid Raf (cv. Delizia), tomato plants, were exposed to two treatments of salinity (5 and 7dSm−1) and two ambient CO2 concentrations (350 and 800μmolmol−1) in which CO2 enrichment was applied during the daytime according to a strategy linked to ventilation. The high salinity treatment (7dSm−1) increased firmness (N), total soluble solids content (SSC), titratable acidity (TA) and the percentage of dry matter of the fruit (% DM), however, the pH was reduced. In return, CO2 enrichment did not affect firmness, TA and pH, whereas SSC and % DM were increased. On the other hand, the climatic variations as temperature, radiation and CO2 concentration, during the period of fruit development (PFD) affected its duration. The effective degree days (EDDs) model that combines temperature and radiation was used to study the relationship with the PFD and quality parameters. A good correlation was found between PFD and EDDs (r2=0.95). Thus the thermal time model by incorporating radiation can be recommended for our region to predict the period of fruit development in a hybrid Raf tomato crop. With respect to quality parameters, an increasing trend was observed between fruit firmness in high salinity conditions and the EDDs though the correlation was weak (r2=0.50). We did not find a relationship on SSC, TA, pH and % DM. CO2 enrichment shortened two days of the PFD and salinity did not affect this parameter. According to the results, CO2 enrichment allows increasing the production of a high value commercial crop grown under saline conditions by reducing the time needed for complete fruit development without compromising organoleptic quality.

Effect of Tuber Density and Trifloxysulfuron Application Timing on Purple Nutsedge (Cyperus rotundus) Control

Herbicides are the basis for conventional management of purple nutsedge, one of the world's most troublesome weeds. However, as concern rises over their environmental impact, farmers are being required to reduce herbicide usage. Herbicide efficacy is strongly affected by weed growth stage and density at application, and when herbicides are applied under optimal conditions, low rates can provide maximal control efficacy (CE). Therefore, this study aimed to determine the time window for control of purple nutsedge using a low rate of herbicide, based on an effective degree days (EDDs) model, at low (one tuber) and high (10 tubers) densities. Two experiments were performed under field conditions, in the summers of 2009 and 2010. Rate of 3.75 g a.i. ha−1trifloxysulfuron was applied once on each of five individual application dates. The growth of both treated and untreated plots was evaluated by means of leaf cover area (LCA) and biomass, which were then used to establish the time window for control. Results showed differences in both growth parameters between low and high tuber densities. The high-density patches reached LCA and fresh biomass values of 1,367 g and 1.12 m2, respectively, compared to 604 g and 0.69 m2, respectively, in the lower density patches. The favorable control periods based on biomass and LCA for the lower density patches were set to later dates than those for the higher density patches, 626 EDD compared to 483 EDD for biomass, and 786 EDD compared to 502 EDD for LCA, respectively. Although differences between the biomass- and LCA-based favorable control periods were observed at both tuber densities, the computed linear relations between the two growth parameters enabled adjusting them and setting the appropriate control period.

Effects of temperature on fertilized eggs and larvae of tawny puffer Takifugu flavidus

Tawny puffer Takifugu flavidus is a species found in China considered to have potential for aquaculture. Experiments were conducted to determine the optimal temperature for its incubation and larval culture. Fertilized eggs collected from cultured broodstocks that were induced to ovulate with a [d-Ala6-Pro9-Net]-luteinizing hormone-releasing hormone analogue were inseminated. The effect of temperature (19, 20, 23, 26 and 29 °C) on the hatch rate, incubation period, viability of 24 h post-hatch larvae and total mortality rate was assessed. The effect of temperature (20, 23, 26 and 29 °C) on the growth and survival of larvae from 3 to 19 days after hatching (dah) was also assessed. The results showed that the optimal temperature for successful development of fertilized eggs ranged from 23 to 26 °C, and the highest hatch rate, the optimal viability of 24 h post-hatch larvae and the lowest total mortality rate were all predicted using quadratic equations. The relationship between temperature and the incubation period of tawny puffer eggs was determined using the effective degree-day model. The temperature at developmental zero (t0) was 11.34 °C, and the sum of effective degree-days (k) was 52.356. The survival rate of tawny puffer larvae at 20 °C was significantly lower than among 23, 26 and 29 °C, whereas the survival rate was not significantly different from that at 23, 26 and 29 °C. The larval growth rate increased rapidly as the temperature increased, showing a linear relationship in the range of temperatures investigated. The optimal temperature for larval culture ranged from 23 to 29 °C.

Effect of potential atmospheric warming on temperature-based indices describing Australian winegrape growing conditions

Background and Aims: This paper describes the changes in temperature-based indices used to classify viticultural climates in Australia for three warming scenarios produced by the Commonwealth Scientific and Industrial Research Organisation: Mk3.0 global climate model for the years 2030, 2050 and 2070. Methods and Results: Temperature indices that describe grapevine growing season temperature (GST), ripening period temperature, accumulated biologically effective degree days and growing season length were calculated to produce maps of Australia for each warming scenario. Summary statistics of each index's median and range are presented for each Australian wine region under each warming scenario. The greatest change in GST (above the 1971–2000 mean) was modelled to occur for the Perth Hills region, increasing by 1.0°C by 2030, 1.9°C by 2050 and 2.7°C by 2070. The least change in GST was modelled to occur for the Kangaroo Island region, increasing by 0.5°C by 2030, 0.9°C by 2050 and 1.3°C by 2070. Conclusion: Of the 61 recognised wine regions, a median GST of over 21°C (an indicator of the limit of quality wine grape production conditions) was found for three regions for the period 1971–2000, for eight regions for the 2030 scenario, 12 regions for the 2050 scenario and 21 regions for the 2070 scenario. Significance of the Study: Without appropriate adaptations, some established viticultural regions of Australia may become less suitable for quality winegrape production, whereas regions that were once considered unsuitable for quality winegrape production may become more suitable.

Effect of temperature on incubation period and hatching success of obscure puffer Takifugu obscurus (Abe) eggs

Artificially fertilized eggs of obscure puffer Takifugu obscurus were obtained by induced spawning of cultured broodstock and incubated at temperatures of 15, 19, 23, and 27 °C. The results showed that the optimal temperature for obscure puffer embryonic development ranged from 19 to 23 °C, based on total hatch rate, viability of newly hatched larvae 24 h post-hatch, and total mortality rate of eggs. At the given temperature range, the times taken for 50% embryos to hatch were 11.3, 6.6, 5.0, and 4.2 days, respectively. There was significant difference in time to 50% hatch among the temperatures used in this experiment. The power law model, quadratic equation, exponential equation, and effective degree-day model all provided good fits for the relationship between incubation temperature and time to 50% hatch, with r 2 values greater than 0.90. The formulae for these were y=1031.7T −1.6885, y=44.721−3.1574 T+0.0615 T 2, y=34.663e −0.0813 T and y=78.905/( T−7.6033), respectively, where y is time to 50% hatch in days, and T is incubation temperature in degrees Celsius. The effective degree-day model was determined to be the best model because of efficient computation, good fit to the experimental data, and most importantly, the derived parameters, k (the sum of effective degree-days) and t 0 (the temperature of biological zero), have important biological meaning. Based on the effective degree-day model, the t 0 and k values were calculated as 7.6033 °C and 78.905 degree-days, respectively.

Models to estimate phytomass accumulation of hydroponic lettuce

The protected and hydroponics cultivation are increasing in Brazil, demanding a better knowledge of crop performance in this environment. Plant dry matter accumulation as a function of solar radiation, temperature, relative humidity and other weather parameters in greenhouse is different when compared with field cultivation. With the purpose of proposing models to characterize the temporal variation of leaf and total dry matter production of hydroponics-grown lettuce (Lactuca sativa L.) and to determine the flowering period and the maximum dry matter accumulation rate as a function of plant relative development (relative degree-days), solar radiation and effective thermal index, two experiments (Spring and Autumn) were carried out in the greenhouse, at Santa Maria, Rio Grande do Sul State, Brazil. Growth and development models are useful in obtaining basic information on the plant &lt;FONT FACE=Symbol&gt;´&lt;/FONT&gt; environment interactions, maximizing the use of resources in greenhouse, as well as, to define the best form of crop management. The cultivar Vera was chosen as function of its earliness. Models were proposed to estimate the temporal variation of dry matter accumulation, where the best results for relative development were obtained using effective degree-days, characterizing the importance of the air temperature for the vegetative phase and the solar radiation for the reproductive. The yield and quality of the lettuce seeds evidenced a high potential of hydroponics technique.

Effect of Temperature on the Egg Hatching of Potamanthus formosus (Ephemeroptera: Potamanthidae).

Eggs of Potamanthus formosus were kept at constant temperature (range 4.8-30°C) in the laboratory. The percentage of eggs hatched was 34-53% over a mean temperature range of 15-30°C, peaking at ca. 20°C, but dropping abruptly below 15°C to almost zero at ca. 13°C. The developmental time (Y) was inversely related to the water temperature, and the relationship was well described by a hyperbolic equation. The threshold temperature for egg development was calculated to be 10.5°C for 50% hatch based on the relationship between the rate of development (1/Y) and temperature. This suggests that the threshold temperature for egg development may differ from that for egg hatching. The calculated values of the summation of effective degree-days were 222.2 above 10.5°C for 50% hatch. Extrapolating the results to a natural stream, eggs must be laid until late in September to hatch by the time water temperature decreases to 15°C. The above estimation suggests that eggs laid late in the emergence period from June to October would not hatch before winter. These eggs may overwinter and hatch in spring. This conjecture is supported by the fact that the number of tiny nymphs evidently increased in April and May.