Growing Degree Day Requirements Research Articles

Assessment of agricultural adaptations to climate change from a water-energy-food nexus perspective

Adapting agriculture to climate change without deteriorating natural resources (e.g., water and energy) is critical to sustainable development. In this paper, we first comprehensively evaluate six agricultural adaptations in response to climate change (2021–2050) through the lens of the water-energy-food (WEF) nexus in Saskatchewan, Canada, using a previously developed nexus model—WEF-Sask. The adaptations involve agronomic measures (early planting date, reducing soil evaporation, irrigation expansion), genetic improvement (cultivars with larger growing degree days (GDD) requirement), and combinations of individual adaptations. The results show that the selected adaptations compensate for crop yield losses (wheat, canola, pea), caused by climate change, to various extents. However, from a nexus perspective, there are mixed effects on water productivity (WP), total agricultural water (green and blue) use, energy consumption for irrigation, and hydropower generation. Individual adaptations such as early planting date and increased GDD requirement compensate for yield losses in both rainfed (0–60 %) and irrigated (18–100 %) conditions with extra use of green water (5–7 %), blue water (2–14 %), and energy for irrigation (2–14 %). Reducing soil water evaporation benefits the overall WEF nexus by compensating for rainfed yield losses (25–82 %) with less use of blue water and energy consumption for irrigation. The combination of the above three adaptations has the potential to sustain agricultural production in water-scarce regions. If irrigation expansion is also included, the combined adaptation almost fully offsets agricultural production losses from climate change but significantly increases blue water use (143–174 %) and energy consumption for irrigation while reducing hydropower production (3 %). This study provides an approach to comprehensively evaluating agricultural adaptation strategies, in response to climate change, and insights to inform decision-makers.

Variation across space, species and methods in models of spring phenology

Predicting spring phenology in temperate forests is critical for forecasting important processes such as carbon storage. One major forecasting method for phenology is the growing degree day (GDD) model, which tracks heat accumulation. Forecasts using GDD models typically assume that the GDD threshold for a species is constant across diverse landscapes, but increasing evidence suggests otherwise. Shifts in climate with anthropogenic warming may change the required GDD. Variation in climate across space may also lead to variation in GDD requirements, with recent studies suggesting that fine-scale spatial variation in climate may matter to phenology. Here, we combine simulations, observations from an urban and a rural site, and Bayesian hierarchical models to assess how consistent GDD models of budburst are across species and space. We built GDD models using two different methods to measure climate data: on-site weather stations and local dataloggers. We find that estimated GDD thresholds can vary up to 20% across sites and methods. Our results suggest our studied urban site requires fewer GDDs until budburst and may have stronger microclimate effects than the studied rural site, though these effects depend on the method used to measure climate. Further, we find that GDD models are less accurate for early-active species and may become less accurate with warming. Our results suggest that local-scale forecasts based on GDD models for spring phenology should incorporate these inherent accuracy issues of GDD models, alongside the variations we found across space, species and warming. Testing whether these issues persist at larger spatial scales could improve forecasts for temperate forests.

The Interactive Effects of Chilling, Photoperiod, and Forcing Temperature on Flowering Phenology of Temperate Woody Plants.

The effects of winter chilling, spring forcing temperature, and photoperiod on spring phenology are well known for many European and North American species, but the environmental cues that regulate the spring phenology of East Asian species have not yet been thoroughly investigated. Here, we conducted a growth chamber experiment to test the effects of chilling (controlled by different lengths of exposure to natural chilling conditions), forcing temperature (12, 15, or 18°C) and photoperiod (14 or 10 h) on first flowering date (FFD) of six woody species (three shrubs and three trees) native to East Asia. The three-way analysis of variance (ANOVA) separately for each species showed that the effects of chilling and forcing temperature were significant for almost all species (P < 0.05). Averaged over all chilling and photoperiod treatments, the number of days until FFD decreased by 2.3–36.1 days when the forcing temperature increased by 3°C. More chilling days reduced the time to FFD by 0.7–26 days, when averaged over forcing and photoperiod treatments. A longer photoperiod could advance the FFD by 1.0–5.6 days, on average, but its effect was only significant for two species (including one tree and one shrub). The effects of forcing temperature and photoperiod interacted with chilling for half of the studied species, being stronger in the low chilling than high chilling treatment. These results could be explained by the theory and model of growing degree-days (GDD). Increased exposure to chilling coupled to a longer photoperiod reduced the GDD requirement for FFD, especially when plants grew under low chilling conditions. However, shrubs (except Viburnum dilatatum) had lower chilling and heat requirements than trees, suggesting that, by leafing out sooner, they engage in a more opportunistic life strategy to maximize their growing season, especially before canopy closure from trees' foliage. Our results confirmed the varying effects of these three cues on the flowering phenology of woody species native to East Asia. In future climate change scenarios, spring warming is likely to advance the spring phenology of those woody species, although the reduced chilling and shorter photoperiod may partly offset this spring warming effect.

Detecting flowering phenology in oil seed rape parcels with Sentinel-1 and -2 time series

A novel methodology is proposed to robustly map oil seed rape (OSR) flowering phenology from time series generated from the Copernicus Sentinel-1 (S1) and Sentinel-2 (S2) sensors. The time series are averaged at parcel level, initially for a set of 229 reference parcels for which multiple phenological observations on OSR flowering have been collected from April 21 to May 19, 2018. The set of OSR parcels is extended to a regional sample of 32,355 OSR parcels derived from a regional S2 classification. The study area comprises the northern Brandenburg and Mecklenburg-Vorpommern (N) and the southern Bavaria (S) regions in Germany. A method was developed to automatically compute peak flowering at parcel level from the S2 time signature of the Normalized Difference Yellow Index (NDYI) and from the local minimum in S1 VV polarized backscattering coefficients. Peak flowering was determined at a temporal accuracy of 1 to 4 days. A systematic flowering delay of 1 day was observed in the S1 detection compared to S2. Peak flowering differed by 12 days between the N and S. Considerable local variation was observed in the N-S parcel-level flowering gradient. Additional in-situ phenology observations at 70 Deutscher Wetterdienst (DWD) stations confirm the spatial and temporal consistency between S1 and S2 signatures and flowering phenology across both regions. Conditions during flowering strongly determine OSR yield, therefore, the capacity to continuously characterize spatially the timing of key flowering dates across large areas is key. To illustrate this, expected flowering dates were simulated assuming a single OSR variety with a 425 growing degree days (GDD) requirement to reach flowering. This GDD requirement was calculated based on parcel-level peak flowering dates and temperatures accumulated from 25-km gridded meteorological data. The correlation between simulated and S2 observed peak flowering dates still equaled 0.84 and 0.54 for the N and S respectively. These Sentinel-based parcel-level flowering parameters can be combined with weather data to support in-season predictions of OSR yield, area, and production. Our approach identified the unique temporal signatures of S1 and S2 associated with OSR flowering and can now be applied to monitor OSR phenology for parcels across the globe.

Thaumatococcus daniellii phenology and growing degree day requirements under different irradiance and fertiliser levels

AbstractThaumatococcus daniellii is a rhizomatous monocotyledonous, perennial herb species of the Marantaceae family. The fruit aril contains thaumatin, a sweet protein with sweetness intensity that is about 1,600–3,000 times that of sucrose and is extensively employed as a natural sweetener. The species has potential as an imperative economic crop if cultivated under proper agronomic practices. Phenological development and thermal time requirements are critical to ensuring a high yield. The aim of this study was to determine the phenological stages according to the BBCH scale and growing degree days (GDDs) under different irradiance and fertiliser levels. Seedlings were raised from rhizomes and grown on the field using a randomised complete block design with four treatments and three replications. The study was carried out at the Botanical Garden, Shah Alam, Malaysia, from July 2014 to February 2017. The treatments consisted of combinations of two irradiance and two fertiliser levels, which were designated as high irradiance with either low (T1) or high fertiliser (T2) and low irradiance with either low (T3) or high fertiliser (T4). A detailed phenological development using two‐ and three‐digit coding systems was conducted on 12 clumps (one clump/replicate/treatment). The species has eight principal stages, which include bud and leaf development, formation of side tillering, petiole elongation, emergence of synflorescence, flowering, fruit development and fruit maturity. Both irradiance and fertiliser levels affected certain phenological stages; with leaf, tiller, synflorescence and fruit strongly influenced by irradiance levels. Leaf growth was more vigorous under high irradiances compared with low irradiances and took about 36 to 42 days to attain full maturity. The clump growth or size is a function of tiller numbers. The tiller number increased with increase in clump age. The onset of certain phenological stages was associated with clump age. The clumps commenced production of synflorescence when tiller number was in the range of 30 to 40, and started fruit formation when tiller number reached 70. Both events occurred under a combination treatment of high irradiance with high fertiliser. The GDD requirement of any phenological stage or development of any plant part is contingent upon the duration of a particular stage or process, as measured in days after emergence or transplanting. The longer the duration, the higher the GDD and it varies with treatments. The total GDD required for the completion of the single leaf growth ranged from 852 to 1,022°C, while the emergence of synflorescence under high irradiance occurred with GDD of 5621 (T2) and low irradiance at 9387°C (T3). Fruit formation was observed only under high irradiance with GDD ranging from 9030 (T2) to 13,147°C (T1) during the study period. A description of phenological development according to BBCH scale and GDD requirements in response to differences in irradiance and fertiliser is imperative. It provides a detailed knowledge based on T. daniellii development vis‐à‐vis growth and environmental requirements. This will pave the way for attainment of an efficient crop agronomic practice.

Thermal requirement of indian mustard (Brassica juncea) at different phonological stages under late sown condition.

Indian mustard [Brassica juncea (L.) Czern & Coss.] is a long day plant, which requires fairly cool climatic condition during growth and development for obtaining better seed yield. Various workers have correlated crop growth and development with energy requirement parameters, such as growing degree days (GDD), photo-thermal unit (PTU), helios thermal unit (HTU), photo-thermal index (PTI) and heat use efficiency (HUE). Therefore, GDD requirement for different phenological stages of 22 newly developed Indian mustard varieties was studies during winter (rabi) seasons of 2009–10 and 2010–11 at student instructional farm of C.S. Azad University of Agriculture and Technology, Kanpur, (Utter Pradesh). Study revealed that RH-8814, NRCDR-02 and BPR-549-9 recorded higher GDD (1703.0, 1662.9 and 1648.0), PTU (19129.8, 18694.2 and 18379.8), HTU (11397.7, 11072.2 and 10876.0), PTI (13.25, 13.14 and 13.08) and HUE (4.11, 3.84 and 3.71) at physiological maturity, while higher HUE was recorded (9.62, 8.99 and 8.91 kg ha−1 degrees-day) at days after sowing (DAS) to 50 % flowering. On the basis of study mustard genotypes RH-8814, NRCDR-02 and BPR-549-9 were identified as most heat-tolerant, as they maintained higher values for energy related parameters. Seed yield was highly positively correlated with GDD (r = 0.61, 0.65 and 0.75), PTU (r = 0.66, 0.64 and 0.74), HTU(r = 0.79, 0.68 and 0.73) at the above these three phenological stages, while negatively correlated with PTI at anthesis and at maturity. Hence, these parents could be used in crossing programme for achieving further improvement.

Unexpected role of winter precipitation in determining heat requirement for spring vegetation green-up at northern middle and high latitudes.

Heat requirement, expressed in growing degree days (GDD), is a widely used method to assess and predict the effect of temperature on plant development. Until recently, the analysis of spatial patterns of GDD requirement for spring vegetation green-up onset was limited to local and regional scales, mainly because of the sparse and aggregated spatial availability of ground phenology data. Taking advantage of the large temporal and spatial scales of remote sensing-based green-up onset data, we studied the spatial patterns of GDD requirement for vegetation green-up at northern middle and high latitudes. We further explored the correlations between GDD requirement for vegetation green-up and previous winter season chilling temperatures and precipitation, using spatial partial correlations. We showed that GDD requirement for vegetation green-up onset declines towards the north at a mean rate of 18.8°C-days per degree latitude between 35°N and 70°N, and vary significantly among different vegetation types. Our results confirmed that the GDD requirement for vegetation green-up is negatively correlated with previous winter chilling, which was defined as the number of chilling days from the day when the land surface froze in the previous autumn to the day of green-up onset. This negative correlation is a well-known phenomenon from local studies. Interestingly, irrespective of the vegetation type, we also found a positive correlation between the GDD requirement and previous winter season precipitation, which was defined as the sum of the precipitation of the month when green-up onset occur and the precipitation that occurred during the previous 2months. Our study suggests that GDD requirement, chilling and precipitation may have complex interactions in their effects on spring vegetation green-up phenology. These findings have important implications for improving phenology models and could therefore advance our understanding of the interplay between spring phenology and carbon fluxes.

Crop management and phenology trends in the U.S. Corn Belt: Impacts on yields, evapotranspiration and energy balance

Crop yields are affected by many factors, related to breeding, management and climate. Understanding these factors, and their relative contributions to historical yield increases, is important to help ensure that these yield increases can continue in the future. Two important factors that can affect yields are planting dates and the crop's growing degree day (GDD) requirements. We analyzed 25 years of data collected by the USDA in order to document trends in planting dates, lengths of the vegetative and reproductive growth periods, and the length of time between maturity and harvest for corn and soybeans across the United States. We then drove the Agro-IBIS agroecosystem model with these observations to investigate the effects of changing planting dates and crop GDD requirements on crop yields and fluxes of water and energy. Averaged across the U.S., corn planting dates advanced about 10 days from 1981 to 2005, and soybean planting dates about 12 days. For both crops, but especially for corn, this was accompanied by a lengthening of the growth period. The period from corn planting to maturity was about 12 days longer around 2005 than it was around 1981. A large driver of this change was a 14% increase in the number of GDD needed for corn to progress through the reproductive period, probably reflecting an adoption of longer season cultivars. If these changes in cultivars had not occurred, yields around 2005 would have been 12.6 bu ac −1 lower across the U.S. Corn Belt, erasing 26% of the yield increase from 1981 to 2005. These changes in crop phenology, together with a shortening of the time from maturity to harvest, have also modified the surface water and energy balance. Earlier planting has led to an increase in the latent heat flux and a decrease in the sensible heat flux in June, while a shorter time from maturity to harvest has meant an increase in net radiation in October.

Performance of Six Wine Grapes Under Southwest Idaho Environmental Conditions

Abstract Adaptability, yield, quality attributes, and cumulative growing degree day (GDD) requirements of ‘Barbera 02’, ‘Cabernet Sauvignon 02’, ‘Cabernet Sauvignon 04’, ‘Chardonnay 29’, ‘Merlot 01’, and ‘Sangiovese 04’ wine grapes cultivar clones (Vitis spp.) under climatic conditions of southwest Idaho (Intermountain West region, USA) were evaluated during 2000 and 2001 seasons. ‘Sangiovese 04’ had significantly higher yield than ‘Cabernet Sauvignon 02’, ‘Cabernet Sauvignon 04’, ‘Chardonnay 29’, and ‘Merlot 01’ in both 2000 and 2001. ‘Barbera 02’ also had relatively higher yield than many other cultivar clones. ‘Cabernet Sauvignon 02’ had the lowest yield, although differences were not always significant. Other than cluster weight in 2000, no significant differences existed for yield, fruit quality attributes, or GDD requirements between the two ‘Cabernet Sauvignon’ clones (’Cabernet Sauvig non 02’ and ‘Cabernet Sauvignon 04). ‘Barbera 02’ and ‘Sangiovese 04’ had the largest, while ‘Cabernet Sauvignon 0...

Delayed Planting Effects on Flowering and Grain Maturation of Dent Corn

Delayed planting shortens the effective growing season for corn (Zea mays L.), increasing the risk of exposure to lethal cold temperatures late in the season before grain maturation. Consequently, growers often must decide whether to switch to early maturity hybrids to minimize this risk. The objective of this study was to determine whether delayed planting influenced the growing degree day (GDD) ratings of silking and kernel black‐layer (BL) development of corn. The effects of delayed planting on the phenological responses of three corn hybrid maturities common to the eastern U.S. Corn Belt were investigated at four locations in Indiana and Ohio over 4 yr. Thermal time from planting to silk emergence decreased an average of 34 GDDs for June vs. early May plantings while the grain‐fill period decreased an additional 110 GDDs with late plantings. The total decrease in GDDs from planting to BL was 144 GDDs for corn planted in early June compared with early May, equal to a linear response to delayed planting of 3.8 fewer GDDs per day of delayed planting. The three hybrids responded differently to delayed planting, with greater GDD decreases occurring with late‐maturity hybrid. Linear rates of GDD decrease with delayed planting ranged from 4.5 to 3.2 GDDs per day of delayed planting for late‐ and early maturity hybrids, respectively. Delayed planting decreases the GDD requirements of corn hybrids, resulting in less risk to grain maturation for adapted hybrid maturities from late‐season killing freezes than previously thought.

Delayed Planting Effects on Flowering and Grain Maturation of Dent Corn

Delayed planting shortens the effective growing season for corn (Zea mays L.), increasing the risk of exposure to lethal cold temperatures late in the season before grain maturation. Consequently, growers often must decide whether to switch to early maturity hybrids to minimize this risk. The objective of this study was to determine whether delayed planting influenced the growing degree day (GDD) ratings of silking and kernel black-layer (BL) development of corn. The effects of delayed planting on the phenological responses of three corn hybrid maturities common to the eastern U.S. Corn Belt were investigated at four locations in Indiana and Ohio over 4 yr. Thermal time from planting to silk emergence decreased an average of 34 GDDs for June vs. early May plantings while the grain-fill period decreased an additional 110 GDDs with late plantings. The total decrease in GDDs from planting to BL was 144 GDDs for corn planted in early June compared with early May, equal to a linear response to delayed planting of 3.8 fewer GDDs per day of delayed planting. The three hybrids responded differently to delayed planting, with greater GDD decreases occurring with late-maturity hybrid. Linear rates of GDD decrease with delayed planting ranged from 4.5 to 3.2 GDDs per day of delayed planting for late- and early maturity hybrids, respectively. Delayed planting decreases the GDD requirements of corn hybrids, resulting in less risk to grain maturation for adapted hybrid maturities from late-season killing freezes than previously thought.