Assessing Growth Dynamics and Exploitation of Alosa Immaculata (Bennet, 1835) in Relation to Thermal Conditions in the Lower Danube in 2025

This study aimed to evaluate the growth, mortality parameters, and exploitation rate of Pontic shad, Alosa immaculata Benett, 1835, in the Danube River, Romania (km 169–197). The sampling collection started with the first signs of Pontic shad migration, on 4 March 2023, and continued weekly until the beginning of June 2023, when the last specimens were caught in the nets. The estimation of the growth, mortality parameters, and exploitation rate was done in FiSAT (FAO-ICLARM Stock Assessment Tools). The von Bertalanffy growth equation was estimated at L∞ = 36.75 cm, the growth coefficient was k = 0.68 year−1, and the theoretical initial age was t0 = −0.67 year−1. The total mortality rate (Z) estimated was 2.76 year−1, with a natural mortality rate (M) and fishing mortality rate (F) of 0.89 year−1 and 1.87 year−1, respectively. The Z/k ratio was found to be 4.11 and the exploitation rate (E) was estimated at 0.68 year−1, indicating the overexploitation of Alosa immaculata stocks. In conclusion, this study provides valuable insights into the population dynamics of Pontic shad in the Danube River, Romania. The assessments of the growth parameters, mortality rates, and exploitation rates highlight a level of overexploitation of Alosa immaculata stocks. These findings underscore the importance of applying effective fishery management strategies to ensure the sustainability and conservation of this valuable fish species in the Danube River ecosystem.

Ozet : Bu calisma, 2000-2001 ve 2001-2002 yetisme sezonlarinda Harran Universitesi Ziraat Fakultesi deneme alaninda ilave sulanan kosullarda yurutulmustur. Calismada, farkli tarihlerde ekilen bugday cesitlerinin bazi gelisme donemleri icin gerekli GDD (Growing Degree Days) degerleri belirlenmistir. Denemede 5 ekim–18 ocak tarihleri arasinda 7’ser gun araliklarla, 16 farkli ekim tarihi kullanilmistir. Iki yillik sonuclarin ortalamasina gore; en yuksek sapa kalkma GDD degeri 19 ekim (824.2 0C), en dusuk GDD degeri ise 18 ocak (424.2 0C) ekim tarihinde belirlenmistir. En yuksek basaklanma GDD degerlerine 12 ekim (1651.1°C) ve 19 ekim (1649 °C), en dusuk degere ise 18 ocak (948.0 °C) tarihli ekimde ulasilmistir. Erken ekimden gec ekime dogru basaklanma GDD degeri azalmistir. Olgunlasma suresi GDD degeri 1814.8 °C ile (18 ocak ekim tarihi) 2988.5 °C (5 ekim ekim tarihi) arasinda degismistir. Ekim zamani geciktikce olgunlasma icin gereken GDD degeri azalmistir. Anahtar Kelimeler: bugday, ekim tarihi, GDD (Growing Degree Days) Determination of Some Growth Stages Growing Degree Days (GDD) Values of Wheat (Triticum ssp.) Genotypes at Different Sowing Times Abstract : This study aimed to determination of some growth stages Growing Degree Days (GDD) values in wheat on different sowing times. Sowing dates were between 5 October to 18 January with 7-days intervals. Field trials were carried out in the experimental area of Agriculture Faculty of Harran University in the growing seasons of 2000-2001 and 2001-2002 under the irrigated conditions. According to average of two years, the highest stem elongation stage GDD value was found at 19 October sowing date (824.2 0C), the lowest value was determined as a 424.2 0C at 18 January sowing date. The highest heading stage GDD value was found at 12 October (1651.1°C) and 19 October (1649 °C) sowing dates wheras the lowest value was 948.0 °C at 18 January sowing date. Heading stage GDD values decreased from erly to late sowing times. Maturation stage GDD values varied from 1814.8 °C (18 January sowing date) to 2988.5°C (5 October sowing date). When the sowing time delay, necessary maturation stage GDD values decreased. Key Words: wheat, sowing date, GDD (Growing Degree Days)

Growing degree days (GDD, base = 41 °F) may be useful for estimating alfalfa (Medicago sativa L.) morphological development (mean stage by weight, MSW) as a forage management tool. Our objective was to quantify the relationship between MSW and GDD of alfalfa in several environments and years. Data on MSW and GDD were collected from 22 growth cycles during five site-years. ‘Advantage’ alfalfa was sampled during spring and summer growth cycles during 1984 and 1985 at Ames, IA. ‘Cimarron’ alfalfa was sampled weekly during four growth cycles in 1989, seven cycles in 1990, and three cycles in 1992 at Stephenville, TX. Cimarron and ‘Florida-77’ were sampled during four growth cycles at Lubbock, TX, in 1992. Tests of homogeneity of intercepts and slopes resulted in equation groups for spring, summer, and fall for each location. Intercepts and slopes of the final spring, summer, and fall regression equations differed among locations, years, seasons, and cultivars. Morphological development rate was more rapid in summer than in spring or fall. Florida-77 developed more rapidly than Cimarron during the fall at Lubbock. Because the relationship between MSW and GDD differed among locations, years, season, and cultivars, GDD would not be a broadly applicable predictor of MSW. Research Question The concept of growing degree days (GDD) has been used in several crops to quantify crop development and as a management tool. Knowledge of the relationship between alfalfa morphological development and GDD may enable alfalfa producers to make better informed management decisions or schedule management practices more precisely. Before the concept can be applied to predicting alfalfa development, it must be determined if the relationship between GDD and alfalfa growth stage is stable across years and locations. Our objective was to determine if the relationship between mean stage by weight (MSW) and GDD was stable among years, locations, and cultivars. Literature Summary The Cornell mean stage system is a quantitative morphological index for describing alfalfa development and predicting forage quality. Northeastern and Midwestern studies have indicated the potential of the system as a tool for alfalfa management. Growing degree days (base temperature of 41 °F) are used in some alfalfa models to predict yield, morphological development, and forage quality. To enable robust equations for predicting alfalfa development (MSW), a constant relationship between GDD and MSW should exist. Previous reports indicate that this may not be so. Study Description This study used data collected during 22 growth cycles in five site-years. These were: Ames, IA. Spring and summer growth cycles during 1984 and 1985. The experiment was not irrigated. Alfalfa cultivar was ‘Advantage’. Four replicates were sampled in each cycle. Stephenville, TX. Spring, early summer, mid summer, and fall growth cycles in 1989; early spring, mid spring, late spring, early summer, mid summer, late summer, and fall growth cycles in 1990; spring, summer, and fall cycles in 1992. The experiment was irrigated. Alfalfa cultivar was ‘Cimarron’. Four replicates were sampled in each cycle. Lubbock, TX. Spring, early summer, mid summer, and fall growth cycles in 1992. The experiment was irrigated. Alfalfa cultivars were Cimarron and ‘Florida-77’. Two replicates were sampled in each cycle. At each harvest in each growth cycle MSW of alfalfa was determined according to the Cornell mean stage system. Linear regression was used to develop relationships between MSW and cumulative GDD. Applied Question What was the relationship between MSW and GDD and was this relationship the same in each year, growth cycle, location, and cultivar? In all instances, the relationship between MSW and GDD was linear; however, the equation parameters (intercept and slope) for each equation differed among seasons, locations, cultivars, and years (Fig. 1, 2, and 3). Regression analysis grouped equations into spring, summer, and fall cycles for each location. These data show that the relationship between GDD and MSW is not constant. Because this relationship is not stable among environments even for a single cultivar, a broadly applicable equation for predicting MSW from GDD may not be possible. Figure 1Open in figure viewerPowerPoint Relationship between mean stage by weight of alfalfa and cumulative growing degree days at Ames, IA; Stephenville (STPH), TX; and Lubbock (LBK; CM = Cimarron, FL 77 = Florida-77), TX, during the spring. Figure 2Open in figure viewerPowerPoint Relationship between mean stage by weight of alfalfa and cumulative growing degree days at Ames, IA; Stephenville (STPH), TX; and Lubbock (LBK; CM = Cimarron, FL 77 = Florida-77), TX, during the summer. Figure 3Open in figure viewerPowerPoint Relationship between mean stage by weight of alfalfa and cumulative growing degree days at Stephenville (STPH) and Lubbock (LBK; CM = Cimarron, FL 77 = Florida-77), TX, during the fall.

The growth and development of crops is commonly regarded as a function of time alone. However, this approach can be inadequate due to temperatures which vary from year to year caused by global climate change. This prompted the development of the growing degree day concept, which incorporates information on both the passage of time and the temperature experienced by the crop plant during that time. Crop water requirements, which are estimated by multiplying reference evapotranspiration values by a crop-specific coefficient, play a crucial role in the management of hydrologic cycles on arable land. Consequently, it would be useful to identify the relationships between cumulative growing degree days and reference evapotranspiration, in order to develop new methods for predicting crop growth and development periods and calculating reference evapotranspiration. This paper describes annual trends in cumulative growing degree days values and their impact on grape growth. Three different methods for calculating cumulative growing degree days values were evaluated as well. Several key findings were achieved. First, for the period between 1952 and 1995, the cumulative growing degree days values for specific days of the year were normally distributed. Second, the relationship between the relative cumulative growing degree days value and the passage of time can be accurately described by using a cubic polynomial function. Third, the day-to-day change in the average relative cumulative reference evapotranspiration can be described using an exponential function of time, which can be used to calculate the relative cumulative reference evapotranspiration value for any given day of the year. Fourth, there was a significant correlation between the relative cumulative growing degree days and cumulative reference evapotranspiration values during the period between grape budding and maturity, which can be described using a cubic polynomial function. Finally, a new method for determining the ET0 value for any given day of the year was developed; this method requires only a knowledge of the CGDD-at-year-end and no sophisticated meteorological data.

Thermal time and precipitation dictate cereal rye shoot biomass production

Accurate characterization of corn ( Zea mays L.) hybrid maturity is important in the northeastern USA to maximize yield and avoid the risk of frost before maturity. Producers frequently grow hybrids that are rated by seed companies at more growing degree days (GDD) than are available in their area. This study was initiated to examine the relationship between the ratings and actual GDD accumulations to silking and black layer for corn hybrids at different locations and planting dates. Nine corn hybrids varying in GDD ratings to black layer from 2320 to 2900 were planted in replicated trials at three locations in Pennsylvania during 1992 and 1993. The locations consisted of short (2100 GDD), medium (2400 GDD), and long (2800 GDD) season environments. At the medium season environment, a second planting date approximately 18 d later was included in the experiment. Maturity was monitored every other day for silking and black layer development. Growing degree day accumulations between planting and silking averaged 91 GDD greater than the hybrid ratings, due primarily to drought stress, which delayed silking in two environments. Where drought stress was not severe most hybrids silked within 60 GDD of their rating. Growing degree day accumulations from planting to 50% black layer for the hybrids averaged 187 GDD less than their rating. Despite the discrepancy between the ratings and actual GDD accumulations, the ratings predicted the relative order of silking and black layer among hybrids reasonably well. When planting was delayed, the interval between silking and black layer was reduced in both years of the study for three hybrids by 89 GDD. This study shows that some hybrids frequently require fewer GDD to reach black layer than their rating in the Northeast and that, in some seasons, hybrids require fewer GDD to reach black layer when planting is delayed. Problem Description Growing degree day (GDD) accumulations for adapted hybrids to reach black layer in central Pennsylvania are often less than the rating supplied by commercial seed companies. In this study, we were interested in determining whether this phenomenon was influenced by hybrid, location, or planting date. Rationale for the study In several previous studies, GDD accumulations between planting and black layer for adapted hybrids were often less than the published GDD rating. In addition, many corn producers grow hybrids that appear to be too late when the GDD ratings were compared with actual GDD accumulations available. Extension literature from New York and Wisconsin that estimated GDD accumulations for hybrids also suggested that the GDD rating for some hybrids may be greater than the actual accumulation necessary to reach black layer. Inaccurate estimates of GDD requirements make accurate maturity recommendations for different regions and planting dates difficult. This is especially difficult in Pennsylvania, where considerable differences in season length can exist within a few miles. Study Description Nine Pioneer brand hybrids consisting of three early maturity hybrids (3861, 3751, and 3795) three medium maturity hybrids (3573, 3527, and 3479, and three late maturity hybrids (3394, 3241, and 3245) were evaluated for 2 yr in long (2800 GDD), medium (2400 GDD), and short season (2100 GDD) environments. At the medium season location, a second planting date, approximately 20 d later, was added to study the effect of delayed planting. At each site, the GDD accumulations between planting and 50% silk and planting and 50% black layer were determined. Applied Questions What was the relationship between the GDD ratings and the actual GDD required to reach silking and black layer? Where water stress was not a factor, all of the hybrids except 3861 and 3795 reached 50% silking within 60 GDD of their rating. At two of the sites, water stress delayed silking, so averaged across all sites, GDD accumulations to silking were higher than the ratings (Table ). In general, hybrids required fewer GDD to reach black layer than their ratings. Accumulations necessary to reach black layer ranged fiom 235 GDD more than the rating to over 500 GDD less than the rating, depending on the hybrid and the environment. At five of the six locations, all hybrids except one required fewer GDD to mature than their rating. Averaged over all hybrids, GDD accumulations to black layer were 187 GDD less than the ratings (Table ). Did the location (length of growing season) affect the relationship between the ratings of adapted hybrids and the actual number of GDD required to reach silking or black layer? No. We found that when adapted hybrids were grown in their maturity zone, they accumulated more than the rating to reach 50% silking in each region. The hybrids accumulated an average of 92 GDD more than the rating to reach 50% silking, but this was due mostly to drought stress that delayed silking in 1993. In 1992, ratings and actual GDD accumulated to silking were similar in all three regions. On the average we found that these corn hybrids required 235 GDD less than their rating to mature at the location where they were adapted. Even in the long season environment, the late hybrids matured in 222 GDD less than predicted by their ratings. This discrepancy is probably a conservative estimate since development was delayed in 1993 due to drought stress. These results indicate that in most areas in Pennsylvania we can expect that the actual GDD accumulation to black layer to be about 100 to 400 GDD less than the current ratings, or about 2100 GDD for the early (92–97 comparative relative maturity [CRM]) hybrids, 2400 for the medium (103–108 CRM) hybrids, and 2600 for the late (111–114 CRM) hybrids. How did planting date affect the relationship between the measured and rated GDD accumulations? Delaying the planting date by an average of 18.5 d increased the GDD accumulation between planting and black layer in 1992 and decreased the GDD accumulation in 1993. In 1992, the increased GDD accumulation to black layer with late planting was associated with a larger GDD accumulation to silking. In 1993, delaying planting reduced the GDD accumulation necessary to reach black layer by 8 GDD/d of planting delay. Averaged over both years, the interval between silking and black layer for three of the hybrids was reduced by an average of 89 GDD with delayed planting. This suggests that hybrids can reduce GDD requirements for the silking to black layer interval and under some conditions this will translate into a reduced GDD accumulation between planting and black layer. These results are consistent with those from previous studies conducted in Indiana and Ohio. Our results also demonstrate that factors other than GDD can affect corn development during both the vegetative and reproductive stages of growth. What are the practical applications of this study? The practical applications of this study are: (i) discrepancies may exist among seed company ratings and actual hybrid GDD accumulations to black layer in some areas, (ii) GDD accumulations to black layer are not fixed and can be affected by factors such as drought stress and planting date, (iii) much of the discrepancy between GDD ratings and actual accumulations to black layer occurs as a result of fewer GDD required between silking and black layer compared with the ratings, and (iv) when calibrated to local conditions, GDD can be used to predict hybrid physiological maturity reasonably well but expect a standard deviation in accumulated GDD across locations between planting and black layer for a given hybrid to be about 170 GDD. Accumulated growing degree days (GDD) between planting and 50% silking for nine hybrids observed at multiple locations in 1992 and 1993 compared with the seed company rating. Short Medium Long Company Hybrid 1992 1993 1992 1993 1992 1993 Mean rating ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ GDD ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ 3795 1181 1149 1161 1259 1192 1393 1222 1100 3861 1235 1191 1201 1315 1192 1508 1273 1110 3751 1254 1214 1198 1287 1215 1487 1276 1190 3573 1310 1251 1

Fishery stock assessments and management provide valuable insights into various aspects, including fish growth patterns, recruitment, mortality rates, exploitation rates, and stock biomass. This study estimated the population dynamics parameters of Labeo senegalensis using FiSAT II software and analyzed length-frequency data collected from four sites in the Roseries Reservoir, Sudan. The von Bertalanffy growth model was applied to analyze growth patterns. Key parameters include asymptotic length L∞ and growth coefficient K derived from the von Bertalanffy growth function. The relative yield per recruit (Y/R) and relative biomass per recruit (B'/R) were calculated as exploitation functions to determine biological reference points. The exploitation rates at the maximum exploitation rate (Emax) were derived for 0.1 (E0.1) and 0.5 (E0.5) of the virgin biomass (E0) using the Knife-edge option. Structured virtual population analysis was conducted using FiSAT II software, incorporating parameters such as L∞, K, M, and F. The von Bertalanffy growth parameters were determined, with an asymptotic length (L∞) of 54.60 cm and a growth coefficient (K) of 0.260 yr.⁻¹. The recruitment patterns indicated a peak from April to August, coinciding with the rainy season. The annual rates of total mortality (Z), natural mortality (M), and fishing mortality (F) were calculated as 1.06 yr.⁻¹, 0.59 yr.⁻¹, and 0.47 yr.⁻¹, respectively, reflected an exploitation rate (E) of 0.45; while the maximum sustainable exploitation rate (Emax) was identified as 0.5. These findings indicate that Labeo senegalensis in the Roseries Reservoir exceeds the exploitation edge, highlighting the need for reduced fishing pressure to ensure sustainability. Early harvesting practices and gear selectivity pose risks to the long-term sustainability of the population. Implementing size limits, seasonal closures, and effort regulations may enhance yield while safeguarding the stock.

We evaluated 28 commercial corn (Zea mays L.) hybrids at 2 dates of planting and 24 check hybrids used as standards for establishing Minnesota Relative Maturity (Minnesota RM) at 1 date of planting to determine growing degree days (GDD) to black layer for each hybrid. The hybrids were grown at four locations in Minnesota in 1970 and 1971. Date of 50% black layer formation and percent grain moisture on this date were determined. Growing degree days from planting to black layer were calculated for each plot using the National Oceanic and Atmospheric Administration formula.Hybrids, locations, years, and dates of planting were highly significant sources of variation for GDD from planting to black layer. Hybrid ✕ location and hybrid ✕ year interactions were nonsignificant for growing degree days to black layer and the hybrid ✕ location ✕ year interaction was considered to be negligible in size even though it was statistically significant. The variance for GDD among hybrids within Minnesota RM groups of the check hybrids was highly significant but considerably less than the variance among the maturity groups.The correspondence between growing degree days to black layer and Minnesota RM rating was good on the average for both the commercial and check hybrids, but in a number of instances, hybrids that differed by 10 or more relative maturity units had similar growing degree day ratings. In our opinion, these data cast serious doubt on the usefulness of the GDD to black layer system of rating hybrids for maturity in Minnesota.At black layer, moisture percentage values ranged from 22.6 to 32.9%. The use of GDD from planting to 30% moisture content would tend to increase the range in GDD for the hybrids included in this study.

Two field experiments were carried out at El-Minia governorate (Middle Egypt) during 2018/2019 and 2019/2020 to evaluate the performance of 14 bread wheat cultivars namely; Gemmiza 9, Gemmiza 10, Gemmiza 11, Gemmiza 12, Sakha94, Sakha 95, Giza 168, Sids 12, Sids 14, Giza 171, Misr 1, Misr 2, Misr 3, and Shandaweel 1 under newly reclaimed lands. Randomized complete block design with four replications was used. The differences among bread wheat cultivars for all studied traits were significant in both seasons except days to heading in the second season and harvest index in both seasons. The results indicated that Gemmiza 12 recorded the lowest number of days to heading. Shandaweel 1 showed the earliest maturity than the other cultivars. Gemmiza 9 and 10 recorded the tallest plants in first season and Gemmiza 9 and Sakha 95 in the second season. Sids 12 produced the highest number of kernels spike-1 (59 kernels) in the first season, while it was (55 kernels) for Sids 12 and Misr 1 in the second season. Misr 3 recorded the highest number of spikes m-2. Giza 171 produced the highest values for 1000- kernel weight in both seasons (48.64 g and 39.01 g, respectively). The highest grain yield was obtained from Misr 3 in both seasons without significant differences among cultivars Gemmiza 10, Gemmiza 11, Sakha 94, Sakha 95, Sids 12, Misr 1, and Misr 2 in the first season and among Misr 2 and Giza 171 without significant differences in the second season. Meanwhile, Misr 3 recorded the highest biological yield in both seasons. Shandaweel 1 recorded the lowest number of grain filling duration (13.0 and 18.0), growing degree days (GDD) at grain filling stage (157.7 and 273.2), and growing degree days (GDD) at maturity stage (1317.8 and 1363.2) in both seasons. Significant and positive correlations were found between grain yield and biological yield, grain filling duration with growing degree days at filling stage and growing degree days at maturity stage, and growing degree days at filling stage with growing degree days at maturity stage. These results indicated the superiority and the suitability of Misr 3 and Misr 2 and high potentiality under the newly reclaimed lands at El-Minia Governorate.

Successful carrot seed production requires a delicately balanced climate. Yield and quality attributes are highly sensitive to temperature as well as moisture-related weather conditions that can serve as a conduit for establishment of diseases such as bacterial blight of carrot Daucus carota L. subsp. sativus. This study sought to improve understanding of the relationship of seasonal weather patterns and irrigation methods as they relate to carrot seed yield, economic outcomes, and potential for establishment of Xanthomonas hortorum pv. Carotae. Data was collected from 46 commercial scale carrot seed fields in Oregon and Washington from 2020 to 2023. Ordinary Least Squares regression was used for the estimation. Explanatory variables included the number of days from May to July where average relative humidity was 75% or greater, the number of days from May to July where maximum daily temperature was 35 °C or greater, irrigation methods, and the number of growing degree days from May to July. Despite the relatively small sample size and limited number of explanatory variables, basic relationships between weather and yield in commercial scale carrot seed production in semi-arid desert regions of the PNW were established. Results indicated every day of average relative humidity that was 75% or greater resulted in a yield loss of about 14.5 kg/ha. The estimated marginal cost of every day of high relative humidity was about $414/ha. Every day of heat that was 35 °C or greater resulted in a yield loss of about 11.13 kg/ha. The estimated marginal cost of every day of high temperature was about $318/ha. Every additional growing degree day resulted in a yield increase of about 0.40 kg/ha. The estimated marginal value of benefits from every additional growing degree day was about $11.34/ha. Irrigation methods were not found to have a significant impact on carrot seed yield.

With the decline in the most fisheries resources in the Yellow Sea, the yellow goosefish Lophius litulon has increased in commercial and ecological importance in recent years. We studied the length distribution, length-weight relationship, age composition, growth pattern, mortality, and exploitation rates of the yellow goosefish in the Yellow Sea. Total length (TL) of females and males ranged from 173 to 582 mm and 178 to 500 mm, respectively. The length-weight relationships were also estimated for females and males. Age classes from 2 to 4 years predominated in the samples. The von Bertalanffy growth function (VBGF), estimated based on non-linear least-squares methodology, showed significant differences between sexes. Females attained a greater estimated asymptotic total length (765 mm TL) compared to males (579 mm TL). The VBGF did not differ significantly between stocks of the northern Yellow Sea and the southern Yellow Sea. Estimated natural instantaneous mortality rate (M) ranged from 0.25/a to 0.33/a based on four age- and length-based methods. Total instantaneous mortality rate (Z) of total samples calculated by the age-based catch curve method was 0.591/a and the average fishing mortality (F) was 0.30/a. Estimated exploitation rate (E) was approximately 0.5, indicating that the population of L. litulon in the Yellow Sea may be sustainable. These results provide a reference for the present status of L. litulon and information for the management.

Standardization of weekly growing degree day accumulations based on differences in temperature observation time and method

최근 30년 동안 우리나라의 평균온도와 겨울철 온도가 각각 <TEX>$0.7^{\circ}C$</TEX>와 <TEX>$1.4^{\circ}C$</TEX>가 상승하였고 지속적으로 상승할 것으로 예측된다. 무는 매우 중요한 작물로 온난화에 따른 생육 모델 연구는 중요하다. 본 실험은 기상 이변에 따른 무의 생육량을 추정하기 위하여 정식시기와 질소 시비량을 다르게 처리하여 시험하였다. 파종시기는 4월 24일부터 5월 22일까지 14일 간격으로 3회에 걸쳐 실시하였고, 질소 시비량은 표준시비량의 0.5, 1.0, 2.0배 수준으로 3처리를 하였다. 그 결과, 무 파종 후 2개월째 생육은 4월 24일 처리구가 5월 8일과 22일 처리구보다 지상부 생체중이 높게 나왔다. 수확량 예측을 위한 생육 모델식은 질소 시비량별 GDD에 따른 지하부 건물중은 0.5N 처리구에서는 Y = 84.66 / (1+exp (-(GDD - 790.7) / 122.3)) (<TEX>$r^2$</TEX> = 0.92), 1.0N 처리는 Y = 100.6 / (1+exp (-(GDD - 824.8) / 112.8))(<TEX>$r^2$</TEX> = 0.92), 2.0N 처리는 Y = 117.7 / (1+exp (-(GDD - 877.7) / 148.5)) (<TEX>$r^2$</TEX> = 0.94) 로 나타낼 수 있었다. 구축된 모델식에 생육데이터를 사용하여 검정한 결과를 보면 기울기가 1.05-1.12로 다소 높게 추정하였지만 모델식으로 적용하는 것에는 무리가 없는 것으로 나타났다. 따라서 봄무 생산량 예측 시 GDD를 사용하여 수확량을 예측할 수 있을 것으로 사료되었다. The average annual and winter ambient air temperatures in Korea have risen by 0.7 and <TEX>$1.4^{\circ}C$</TEX>, respectively, during the last 30 years. Radish (Raphanus sativus), one of the most important cool season crops, may well be used as a model to study the influence of climatic change on plant growth, because it is more adversely affected by elevated temperatures than warm season crops. This study examined the influence of transplanting time, nitrogen fertilizer level, and climate parameters, including air temperature and growing degree days (GDD), on the performance of a radish cultivar 'Mansahyungtong' to estimate crop growth during the spring growing season. The radish seeds were sown from April 24 to May 22, 2012, at internals of 14 days and cultivated with 3 levels of nitrogen fertilization. The data from plants sown on April 24 and May 8, 2012 were used for the prediction of plant growth as affected by planting date and nitrogen fertilization for spring production. In our study, plant fresh weight was higher when the radish seeds were sown on <TEX>$24^{th}$</TEX> of April than on <TEX>$8^{th}$</TEX> and <TEX>$22^{nd}$</TEX> of May. The growth model was described as a logarithmic function using GDD according to the nitrogen fertilization levels: for 0.5N, root dry matter = 84.66/(1+exp (-(GDD - 790.7)/122.3)) (<TEX>$r^2$</TEX> = 0.92), for 1.0N, root dry matter = 100.6/(1 + exp (-(GDD - 824.8)/112.8)) (<TEX>$r^2$</TEX> = 0.92), and for 2.0N, root dry matter = 117.7/(1+exp (-(GDD - 877.7)/148.5)) (<TEX>$r^2$</TEX> = 0.94). Although the model slightly tended to overestimate the dry mass per plant, the estimated and observed root dry matter and top dry matter data showed a reasonable good fit with 1.12 (<TEX>$R^2$</TEX> = 0.979) and 1.05 (<TEX>$R^2$</TEX> = 0.991), respectively. Results of this study suggest that the GDD values can be used as a good indicator in predicting the root growth of radish.

The US Fish and Wildlife Service (USFWS) uses the five-leaf developmental stage as a signal to the initiation of elongation in smooth brome (Bromus inermis Leyss.). In areas where certain plant community criteria are met, conducting a prescribed burn at elongation onset has reduced smooth brome populations. However, leaf stage identification presents USFWS managers with challenges due to the variability of smooth brome development in tallgrass prairies of the Northern Great Plains. The objective of this research was to develop an alternative method to determine when smooth brome populations reach the targeted 50% elongation by linking accumulated growing degree days and population-level plant phenological stages (mean stage count). We determined smooth brome phenological stages at sites in North Dakota, South Dakota, and Minnesota and calculated the corresponding number of growing degree days (using the base temperature of 0 °C). Linear regression models, correlating phenological stage and growing degree days, determined onset of elongation in the smooth brome population, regardless of leaf stage variation. The average accumulated growing degree days (1256 AGDD) and corresponding standard deviation (±155 AGDD) can be used to predict when 95% of smooth brome populations in northern tallgrass prairies reach 50% elongation. As part of USFWS Native Prairie Adaptive Management program, results will be used to assist management decisions regarding the timing of defoliation in an effort to enhance native plant communities where smooth brome is the dominant invader.

CR Climate Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials CR 34:233-240 (2007) - DOI: https://doi.org/10.3354/cr00690 Climatology of growing degree days in Greece Andreas Matzarakis1,*, Dafinka Ivanova2, Chris Balafoutis3, Timoleon Makrogiannis3 1Meteorological Institute, University of Freiburg, Werderring 10, 79085 Freiburg, Germany 2Agricultural University, Mendeleev St. 12, 4000 Plovdiv, Bulgaria 3Department of Meteorology and Climatology, Aristotle University, 54124 Thessaloniki, Greece *Email: andreas.matzarakis@meteo.uni-freiburg.de ABSTRACT: Growing degree days (GDD) were calculated for 40 meteorological stations distributed across Greece, on the basis of daily maximum and minimum air temperature (TMAX and TMIN, respectively) for the 10 year period from 1978 to 1987. Duration of growing periods (classified in 10 d intervals) differed among stations. The longest period was from April 1 to November 30, and the shortest from May 1 to September 30. Growing season varies across Greece from about 1600 GDD in the northern mountainous areas to >2900 GDD in the lowlands and the southernmost regions. Most spring-sown crops need no more than 1500 GDD to mature; consequently, there are no temperature limitations in Greece for crops such as corn, cotton and tobacco. Despite the sparse climatic network it was possible to create high resolution maps with statistically significant results (r = 0.83 to 0.89; p = 0.95), providing reliable information for agricultural planning. KEY WORDS: Growing degree days · Agriculture · Regional maps · Greece Full text in pdf format PreviousNextCite this article as: Matzarakis A, Ivanova D, Balafoutis C, Makrogiannis T (2007) Climatology of growing degree days in Greece. Clim Res 34:233-240. https://doi.org/10.3354/cr00690 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in CR Vol. 34, No. 3. Online publication date: September 18, 2007 Print ISSN: 0936-577X; Online ISSN: 1616-1572 Copyright © 2007 Inter-Research.