Increase In Growing Degree Days Research Articles

Nitrogen rate and harvesting time based on growing degree days influenced winter cereal rye morphological traits, forage yield, quality, and farm profit in poorly drained Alfisols

AbstractWinter cereal rye (Secale cereale L.) (WCR) is often double cropped with maize for silage (Zea mays L.) to increase farm forage supply and profit. Spring nitrogen (N) fertilization to WCR could influence its production and quality at different harvesting times. Therefore, two on‐farm trials were conducted in the 2019–2020 and 2020–2021 growing seasons to evaluate the effect of harvesting time (late‐March to end‐of‐April considering the growth stage) and spring N fertilization (0, 23, 47, and 71 kg N ha−1) on WCR morphology, forage yield, nutrient removal, quality, and farm profit. Only two N treatments (0 and 47 kg N ha−1) were evaluated for each harvesting time in trial 1. A quadratic model best explained an increase in WCR dry matter (DM) yield in response to growing degree days (GDD) accumulation (R2 = 0.81). An increase in GDD linearly decreased WCR relative forage quality (RFQ). Benchmarking RFQ at 150 for dairy milk production indicates WCR should be harvested at a GDD of 543, at which WCR plant height was 31.8 cm and DM yield was 0.77 Mg ha−1. This resulted in loss of profit in both study years compared to later harvesting dates at higher GDDs. Benchmarking RFQ at 125 for heifer production indicated that harvest should occur at a GDD of 668, at which the WCR was 71 cm tall, and its DM yield was 2.25 Mg ha−1. Nitrogen balances were negative at the N0 treatment (0 kg N ha−1), indicating a need for some N to maximize WCR yield. We found that a rate between 21 and 47 kg N ha−1 maximizes yields reflecting slightly positive balances, in which the highest profits occur. Our results suggest that the harvesting time can be predicted by GDD and should be adjusted for RFQ. We conclude that less than 47 kg N ha−1 N fertilizer is required for WCR production in soils with manure history and high soil organic matter (>30 g kg−1).

Modelled changes in selected agroclimatic indices over the croplands of western Canada under the RCP8.5 scenario

AbstractTo assess the potential change in agroclimatic indices in western Canada, this study used a convection‐permitting Weather Research Forecasting (WRF) model to conduct simulations for the current climate (CTL, 2000–2015) and future climate under the RCP8.5 scenario based on a pseudo‐global‐warming (PGW) approach. Both CTL and PGW simulations were bias‐corrected to the GEM‐CaPA dataset using a multivariate quantile mapping method. An evaluation of the CTL simulation of daily maximum and minimum temperatures and precipitation during the growing season against the gridded observations has been performed, indicating good agreements in the spatial patterns of air temperature and precipitation in western Canada. The PGW − CTL differences in several selected agroclimatic indices were then examined. Due to rising temperatures, substantial increases in growing degree‐days (GDD) by 800–1,200° days and reductions in frost days by 10 to 20 days, favouring regional crop production, are found in southern Alberta and Saskatchewan. However, global warming also poses great risks to Canadian agriculture by modifying heat accumulations and water availability during the growing season. Plant heat stress will substantially increase by ∼50° days in southern Alberta and Saskatchewan, offsetting the positive effects caused by the reduction in frost days and increase in GDD. The southern Canadian Prairies will experience statistically significant increases in the number of dry days and precipitation deficit, suggesting an exacerbation of water stress on the Canadian Prairies by global warming.

Forewarning model development for mustard aphid (Lipaphis erysimi Kalt.) at Bharatpur and Hisar

The weekly aphid population on timely sown mustard crop and daily weather parameters recorded at ICAR-Directorate of Rapeseed–Mustard Research, Bharatpur and Hisar stations, during rabi seasons of 2003-04 to 2013-14 were used to develop forewarning model for aphid. In most of the cases, the appearance of population and its peak activity occurred during 51 standard meteorological week (SMW) and 8 SMW. The study revealed that the thermal time or growing degree days (GDD) consistently explained the aphid multiplication significantly in all seasons. The impact of other weather parameters on pest population was observed to be significant only in some seasons. The aphid population increased exponentially with increase in GDD. Further, the exponential coefficient varied among the varieties. The population build up was compared with the model predicted values in three common species (Brassicajuncea, B. rapa ssp. sarson and B. napus) grown at two stations. The results revealed that the predicted values derived using the model, were in close agreement with those of the observed.

Winter soil temperature dependence of alpine plant distribution: Implications for anticipating vegetation changes under a warming climate

The topographical heterogeneity of mountain landscapes and the associated species turnover over short distances should prompt us to examine the relationships between climate and mountain plant distribution at a much finer scale than is commonly done. Here, I focused on the root zone temperature experienced by low-stature perennial-dominated plant communities of temperate mountains, which are seasonally covered by snow. Based on the analysis of multi-annual recordings of ground temperatures across a broad spectrum of plant communities, I propose a habitat template using Growing Degree Days (GDD) and Freezing Degree Days (FDD). These two indices summarize soil thermal conditions experienced during the favorable and the unfavorable period for growth. This heuristic framework allows refining our working hypotheses on the range shifts of mountain plants in response to recent and future climate change. Regional trends in climate variables controlling GDD and FDD indicate that the combination of earlier snow melt-out and higher summer temperatures have led to an overall increase in GDD over the last decades. However the persistence of cold episodes in spring and in fall along with the shorter snow coverage suggest that the positive effect of an extended growing season might be counteracted by the detrimental effects of increasing FDD. I thus hypothesize (i) a local-scale, downward shift of plant species along mesotopographical gradients, with marked species infilling in sparsely vegetated, long-lasting snow patches that contain vacant niches and (ii) a watershed-scale upward shift of subalpine species inhabiting south-exposed grasslands and able to cope with moderate FDD. This perspective challenges the simplistic view of an overall range shift of mountain plants along elevational gradients and calls for the improvement of models of snow cover dynamics and root zone temperature to draw up realistic scenarios of mountain vegetation changes under a warmer climate.

Projecting Future Change in Growing Degree Days for Winter Wheat

Southwest Oklahoma is one of the most productive regions in the Great Plains (USA) where winter wheat is produced. To assess the effect of climate change on the growing degree days (GDD) available for winter wheat production, we selected from the CMIP5 archive, two of the best performing Global Climate Models (GCMs) for the region (MIROC5 and CCSM4) to project the future change in GDD under the Representative Concentration Pathways (RCP) 8.5 and 4.5 future trajectories for greenhouse gas concentrations. Two quantile mapping methods were applied to both GCMs to obtain local scale projections. The local scale outputs were applied to a GDD formula to show the GDD changes between the historical period (1961–2004) and the future period (2006–2098) in terms of mean differences. The results show that at the end of the 2098 growing season, the increase in GDD is expected to be between 440 °C and 1300 °C, for RCP 4.5, and between 700 °C and 1350 °C for RCP 8.5. This increase in GDD might cause a decrease in the number of days required to reach crop maturity, as all the GCM/statistical post-processing combinations showed a decreasing trend of those timings during the 21st century. Furthermore, we conclude, that when looking at the influence of the selected GCMs and the quantile mapping methods on the GDD calculation, the GCMs differences originated from the significant spatial and temporal variations of GDD over the region and not the statistical methods tested.

Geo-spatial analysis of temporal trends of temperature and its extremes over India using daily gridded (1°×1°) temperature data of 1969–2005

Daily gridded (1°×1°) temperature data (1969–2005) were used to detect spatial patterns of temporal trends of maximum and minimum temperature (monthly and seasonal), growing degree days (GDDs) over the crop-growing season (kharif, rabi, and zaid) and annual frequencies of temperature extremes over India. The direction and magnitude of trends, at each grid level, were estimated using the Mann–Kendall statistics (α = 0.05) and further assessed at the homogeneous temperature regions using a field significance test (α=0.05). General warming trends were observed over India with considerable variations in direction and magnitude over space and time. The spatial extent and the magnitude of the increasing trends of minimum temperature (0.02–0.04 °C year−1) were found to be higher than that of maximum temperature (0.01–0.02 °C year−1) during winter and pre-monsoon seasons. Significant negative trends of minimum temperature were found over eastern India during the monsoon months. Such trends were also observed for the maximum temperature over northern and eastern parts, particularly in the winter month of January. The general warming patterns also changed the thermal environment of the crop-growing season causing significant increase in GDDs during kharif and rabi seasons across India. The warming climate has also caused significant increase in occurrences of hot extremes such as hot days and hot nights, and significant decrease in cold extremes such as cold days and cold nights.

Variations in the potential climatic suitability distribution patterns and grain yields for spring maize in Northeast China under climate change

As climate changes, suitability zones for the cultivation of some crops may shift. In Northeast China (NEC), it is critically important for the agricultural community (e.g. farmers, advisors) to understand the potential shift in suitable cropping zones for spring maize in order to adapt to climate change. The potential climatic suitability can be defined as how actual temperature and solar radiation conditions match the requirements of crop growth under non-limited situations. Here, we used yield potential to reflect the potential climatic suitability, which is determined by the characteristics of crop, solar radiation, temperature, and photoperiod, given the assumption that water, nutrients, pests, and diseases are not limiting the crop growth. We assessed the annual yield potential of spring maize during 1961–2010 in NEC with APSIM-Maize. And then we analyzed the variations in potential climatic suitability zones and the possible effects of these variations on maize production potential. The results show that growing degree-days (GDD) during the growing season for spring maize universally increased in all the locations of this study during the period of 1981–2010 (period II) as compared to the period of 1961–1980 (period I). A total of 66 % of the locations show a decrease in accumulated sunshine duration (ASD) during the growing season during period II as compared to period I. Both coefficient of variation (CV) of GDD and CV of ASD showed an increase during period II as compared to period I. Under the background of climate change, the potential climatic suitability for spring maize was worsened during the most recent five decades: the yield potential declined and the yield stability decreased. In particular, most of the very suitable zone in Jilin and Liaoning during period I turned into suitable or moderately suitable zone during period II. Meanwhile, the total area of marginally suitable zone and no suitable zone increased by 16 % during period II as compared to period I. We detected a close correlation between the decrease in ASD and the decrease in potential climatic suitability, R = 0.56, p < 0.01. We also found a close correlation between the increase in GDD and the decrease in potential climatic suitability, R = −0.25, p < 0.05. Given the same crop varieties and farming management, the total production potential for spring maize in the entire NEC reduced by 4.3 % during period II as compared to period I.

Effect of climate change and use of improved varieties on barley and canola yield in Manitoba

An, H. and Carew, R. 2015. Effect of climate change and use of improved varieties on barley and canola yield in Manitoba. Can. J. Plant Sci. 95: 127-139. A stochastic production function was estimated to investigate the effect of fertilizer inputs, changes in weather conditions and the use of improved varieties on barley and canola yields and its variability in Manitoba. Adoption of improved barley varieties did not have a significant effect on yield, while the adoption of herbicide-tolerant hybrid canola varieties was positively correlated with yield. An increasingly warmer climate in Manitoba is expected to have a slightly negative effect on mean barley yield and yield variance. In contrast, a warmer climate is expected to have a negligible effect on mean canola yield, but a positive effect on yield variability. Our results showed that a projected 50% increase in growing degree days would lead to a decrease of less than 1% in barley and canola yields.

Long-Term Summary of Ryegrass Varieties and Ploidy Types in Mississippi

Annual ryegrass (Lolium multiflourum) is the most important cool-season forage crop in Mississippi. It is seeded on more than 500,000 acres every year in the state and consequently seed companies intensely market the area with claims of superior genetic performance. Marketing literature observed in Mississippi focuses on the performance of tetraploid (4×) versus diploid (2×) with claims that 4× varieties provide better yield, disease resistance, and seedling vigor. These claims have rarely been substantiated on long-term performance variety trials. Archived Mississippi State forage variety test data from 1987 to 2012 were compiled for 10 diploid and tetraploid varieties grown at four physiographic locations (Starkville, Raymond, Newton, and Poplarville). Differences in the mean yields between 2× and 4× were only detected in Newton and Poplarville, where 2× varieties had a 4% yield advantage and 4× averaged 10% greater yields, respectively. Across the state, ryegrass yields for both ploidy levels increased over time (4×, R = 0.19931, P = 0.0105 & 2×, R = 0.18816, P = 0.0003), but correlations were variable by location. Biomass yields for both ploidy levels decreased over time in Starkville despite an increase in GDD (Growing Degree Days). With the exception of Raymond, year was the only factor influencing yield. The data suggest that ploidy level of ryegrass in Mississippi has minimal impact on seasonal yield production. However, genetic improvement other than polyploidy induction has increased yield over time.