Sunflower yield modeling with explainable artificial intelligence: Historical weather impacts across half a century of American production

Field studies were conducted in the northeastern part of the Republic of Croatia to determine the influence of the critical period of weed interference on sunflower (Helianthus annuus) yield, yield components, and oil content. For this purpose, different durations of competition were established, allowing weeds to infest the crop for increasing periods of time after planting or maintaining plots weed-free for increasing periods of time after planting. The beginning and the end of the critical period of weed control (CPWC), based on a 5% and 10% loss of sunflower yield, were determined by fitting the four-parameter log-logistic equations to the relative seed yield. The total weed biomass increased progressively in relation to the increase in the competition. The beginning of the CPWC period, based on a 5% acceptable yield loss, ranged from 141 to 234 growing degree days (GDD), which corresponded to the two-to-four true leaf development stage (the V2–V4 growth stages) across both sites and years. The crop had to be kept weed-free until a period when sunflower inflorescence began to open and flower (the R4–R5 growth stage) or from 1365 to 1932 GDD. The sunflower yield and yield components varied between the years and among locations. An increasing duration of weed interference negatively affected crop height, head diameter, and 1000-kernel weight, but not seed oil content.

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 tbat 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 bybrids 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 tbe 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.

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.

Developing a growing degree day model for North Dakota and Northern Minnesota soybean

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.

Sweet cherry (Prunus avium L.) is an important fruit tree for Slovenia, often threatened by spring frosts, especially the early flowering varieties. In recent decades, the occurrence of frost events has steadily increased, which has negatively affected cherry fruit production, especially in the Submediterranean part of Slovenia. Although fruit trees can tolerate severe cold during their dormant stage, the resistance of flower buds gradually decreases with phenological development in spring. Therefore, spring frost events that occur after the beginning of the growing season pose a major risk to fruit trees. An analysis of the probability of frost events in Slovenian cherry orchards was performed based on historical temperature data from the E- OBS database and climate model projections, in particular regionally downscaled EURO-CORDEX projections (ensemble of 6 models) for scenarios RCP4.5 and RCP8.5. The presented analysis is based on two phenological models for calculation of budburst - the growing degree days (GDD) model and the BRIN model. The projections showed an overall increase in frost risk for the majority of models and all selected sweet cherry varieties during the periods 2011–2040 and 2041–2071 compared to the reference period 1981–2010. For the end of the century (period 2071–2100), all of the ensemble projections showed a large increase in frost risk for the analyzed sweet cherry varieties. The projected increase in frost risk under the RCP4.5 scenario was calculated to be the highest for the Early Bigi variety, while under the RCP8.5 scenario the largest increase was calculated for the Germersdorf variety - a more than 40-fold increase in spring frost risk compared to the reference period.

Thermal time and precipitation dictate cereal rye shoot biomass production

SUMMARY Sunflower is an important oilseed crop because of its wide adaptability, suitability to mechanization, low labor needs and high protein and oil contents. The present study aimed to investigate the relationship between growing degree days and yield and yield components in different sunflower hybrids and to identify environmental factors and crop characteristics that affect grain yield in sunflower without irrigation in Berlin environmental conditions. The study was conducted in the experiment fields at the Crop Science Department of the Agriculture and Horticulture Faculty of Humboldt University during 2010. The experiment was laid out in a randomized block design, with four blocks of plots of eight Turkish cultivars (Sanbro, Tarsan, DKF-2525, TR-3080, EDR- 08-01, EDR-08-02, EDR-08-03, EDR-08-04) and two German cultivars (Pegasol, NK Delfi). It was determined that the differences among all the sunflower cultivars were statistically significant for plant height, stem diameter, head diameter, 1000 seed weight, dry matter, harvest index, seed yield per plant, seed yield, leaf number, GDD (Growing Degree Daysand sun radiation. The highest mean stem diameter, harvest index and 1000 seed weight were obtained from Pegasol. NK-Delfi had the highest mean head diameter and consequently the highest seed yield (3,876.6 kg ha-1), followed by DKF-2525 and Sanbro (3,498.7 and 3412.9 kg ha-1, respectively). The sunflower cultivars required between 127 and 137 days, 2,263.57°C GDD and 927.54 h sunshine radiation from planting to maturity, as the mean of all the cultivars. Generally, the seed yields of the Turkish candidate genotypes were lower than those of the other sunflower cultivars. The seed yield of these genotypes can be improved with another agriculture method. The rainfall and cold weather in May slowed the growth of sunflower and also the rainfall and cold weather in August delayed maturity. The dry and hot weather in June and July created stress on plants. In terms of seed yield, NK-Delfi, DKF-2525, Sanbro, and Pegasol proved to be suitable sunflower cultivars to be grown in Berlin.

Temperature plays an active role in growth and development of any plant. From sowing till maturity, the plant has to undergo different phenological phases called crop growth stages/plant growth stages. Measuring growing degree days (GDD) is employed to assess the growth and development of any plants provided all other factors required for the growth of the plants are conducive. The plant growth may cease if the plant experiences a certain low temperature specific to each plant species called base temperature. Keeping in view that each plant species and crop varieties has its own requirement of growing degree days from sowing to till harvest, a study was undertaken to assess the GDD requirement for rice crop varieties ADT 38 and CR 1009 during kharif and rabi, respectively, in South India The objective of this study is to (1) calculate GDD on daily basis (2) develop a mathematical model to forecast crop growth stage and maturity date based on AGDD (3) verify the model using field data and (4) provide farmers with a forecast tool to estimate crop growth and crop maturity date well in advance. The results revealed that the two cultivars attained physiological maturity at 134 and 154 days after sowing, respectively. Variation in the growing degree days was observed between cultivars. The growing degree days (GDD) of both the varieties of rice indicated that the variety CR 1009 availed more GDD (2481.3) as compared to variety ADT 38 (2207.9) due to longer duration of the variety.

Sunflower (Helianthus annus L.) having high degree of adaptability under wide range of climatic conditions, allow the crop to be productive in broad range of environments. Field experiments in autumn were laid out at Pir Mehr Ali Shah, Arid Agriculture University Rawalpindi, Pakistan for two years (2007 and 2008), to document the effect of growing degree days (GDD) on the performance of sunflower hybrids. Four sunflower hybrids, Alisson-RM, Parasio-24, MG-2 and S-278 were planted in randomized complete block design with four replications during autumn season. The data on growing degree days accumulation during autumn and their effect on achene, oil  yield and yield components of sunflower like number of achenes per head, hundred achenes weight, biological and achene yield was recorded. All these agronomic characters as well as oil characteristics were influenced by prevailing temperature. GDD collected during autumn season was thesame for both years of study. Amongst hybrids, the hybrid MG-2 showed the maximum values for all the agronomic as well as oil parameters during the autumn season. At the late planting of sunflower during autumn season, crop completes its life cycle in short duration and accumulates less heat units, thus, achene and oil yield along with yield attributes are affected accordingly.   Key words:  Growing degree days (GDD), yield and yield components, sunflower.

This research focused on examining the interrelationships between the natural conditions for growing grapes, as well as the quantitative and qualitative characteristics of the harvest. These are important criteria for the scientifically grounded selection of a territory for planting a vineyard, selecting varieties and determining the use of the resulting products. The characteristics of six model vineyards of the Aligote cultivar, located in various natural zones and viticultural regions of the Crimea, were analyzed. The values of climatic indicators were calculated, including the growing degree days above 10∘C (∑Т ∘С10), growing degree days above 20∘C (∑Т ∘С20), Huglin index, Winkler index, average growing season temperature, average September temperature, ratio ∑Т ∘С20/∑Т ∘С10,total precipitation during the year, total precipitation during the growing season, total precipitation in September, and Selyaninov hydrothermal coefficient. These were calculated usinggeoinformation and mathematical modeling for the locations of the analyzed vineyards. The content of the primary metabolites (total sugars, titrated acids and calculated indicators based on them) and secondary metabolites (phenolic components, oxidase activity) of grapes from the model vineyards were analyzed. The range of variation in the studied indicators within the analyzed territories was calculated, and the nature and magnitude of the relationships between the indicators were revealed. A cluster analysis of the analyzed vineyards was carried out and clusters were distinguished according to the degree of similarity in climatic parameters, as well as the content of the primary and secondary metabolites of the grapes. Keywords: grapes, agroecological factors, primary and secondary grape metabolites, ampeloecological zoning, terroir

The flowering process is adjusted to seasons through environmental signals, particularly photoperiod and temperature. Breaking dormancy, in trees, requires the completion of a period of chilling, which can be measured in hours below a certain temperature threshold. Budburst occurs once a heat requirement of accumulated degree days has been met. The studies of interactions between olive phenology and weather variables in a particular region can help us to predict the onset and length of flowering. The impact of air temperature on flowering phenology in five olive cultivars (‘Lastovka’, ‘Leccino’, ‘Levantinka’, ‘Oblica’ and ‘Pendolino’) was examined over a 5-year period (2005-2010) in an experimental orchard near Split (Croatia; central part of the Adriatic coast). The flowering periods were assessed by visual examination of trees. The flowering date (FD) was calculated as the number of days from January 1 until the start of the flowering period. The method proposed by Aron and Gat (1991) was used to estimate the number of chilling units (CU) using the daily maximal and minimal air temperatures. Number of CUs ranged from 282 to 1441. The heat accumulation dates started in the first days after the calculation of hours of chilling had been finished and continued until the start of flowering season. Heat units were expressed in growing degree days (GDD), and one GDD unit denoted 1°C above base temperature in 24 h. Three base temperatures were considered (9, 11, and 12.5°C). The flowering periods of most of the studied cultivars overlapped to some degree in each experimental year. The earliest start of flowering was recorded in 2007, while the latest start date was delayed for nine days in 2005. Duration of flowering period differed between cultivars and ranged from six to nine days. The temperatures during the months prior to anthesis influenced the onset of the flowering. A positive correlation was found between FD, CU and GDD, respectively. The highest correlation (R2=0.655) between FD and GDD was found when the threshold temperature was set to 9°C.

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.