Maize potential yields and yield gaps in the changing climate of northeast China

Northeast China (NEC) is not only one of the major agricultural production areas in China, but it is also the most susceptible to climate variability. This led us to investigate the impact of climate change on maize potential yield and yield gaps in this region, where maize accounts for about 30% of the nation's production. The APSIM‐Maize model was calibrated and validated for maize phenology and yields. The validated model was then used to estimate potential yields, rain‐fed potential yields, and yield gaps for assessing the climate impacts on maize productivity in NEC. During maize growing seasons from 1981 to 2010, the analysis indicates a warming trend all across NEC, whereas the trends in solar radiation and total precipitation tended to decrease. When the same hybrid was specified in APSIM for all years, a simulated increase of maximum temperature resulted in a negative impact on both potential yield and rain‐fed potential yield. A simulated increase in minimum temperature produced no significant changes in potential or rain‐fed potential yield. However, the increase of minimum temperature was shown to result in a positive impact on the on‐farm yield, consistent with our finding that farmers adopted longer season hybrids for which the increase in minimum temperature provided better conditions for germination, emergence, and grain filling during night time. The gap between potential and rain‐fed potential yields was shown to be larger at locations with lower seasonal precipitation (<500 mm). Our results indicate that regions with the largest yield gaps between rain‐fed potential and on‐farm yields were located in the southeast of NEC. Within NEC, on‐farm maize yields were, on average, only 51% of the potential yields, indicating a large exploitable yield gap, which provides an opportunity to significantly increase production by effective irrigation, fertilization, herbicide, and planting density in NEC.     

Is Yield Increase Sufficient to Achieve Food Security in China?

Increasing demand for food, driven by unprecedented population growth and increasing consumption, will keep challenging food security in China. Although cereal yields have substantially improved during the last three decades, whether it will keep thriving to meet the increasing demand is not known yet. Thus, an integrated analysis on the trends of crop yield and cultivated area is essential to better understand current state of food security in China, especially on county scale. So far, yield stagnation has extensively dominated the main cereal-growing areas across China. Rice yield is facing the most severe stagnation that 53.9% counties tracked in the study have stagnated significantly, followed by maize (42.4%) and wheat (41.9%). As another important element for production sustainability, but often neglected is the planted area patterns. It has been further demonstrated that the loss in productive arable land for rice and wheat have dramatically increased the pressure on achieving food security. Not only a great deal of the planted areas have stagnated since 1980, but also collapsed. 48.4% and 54.4% of rice- and wheat-growing counties have lost their cropland areas to varying degrees. Besides, 27.6% and 35.8% of them have retrograded below the level of the 1980s. The combined influence (both loss in yield and area) has determined the crop sustainable production in China to be pessimistic for rice and wheat, and consequently no surprise to find that more than half of counties rank a lower level of production sustainability. Therefore, given the potential yield increase in wheat and maize, as well as substantial area loss of rice and wheat, the possible targeted adaptation measures for both yield and cropping area is required at county scale. Moreover, policies on food trade, alongside advocation of low calorie diets, reducing food loss and waste can help to enhance food security.     

Impacts of climate change on paddy rice yield in a temperate climate

The crop simulation model is a suitable tool for evaluating the potential impacts of climate change on crop production and on the environment. This study investigates the effects of climate change on paddy rice production in the temperate climate regions under the East Asian monsoon system using the CERES‐Rice 4.0 crop simulation model. This model was first calibrated and validated for crop production under elevated CO₂ and various temperature conditions. Data were obtained from experiments performed using a temperature gradient field chamber (TGFC) with a CO₂ enrichment system installed at Chonnam National University in Gwangju, Korea in 2009 and 2010. Based on the empirical calibration and validation, the model was applied to deliver a simulated forecast of paddy rice production for the region, as well as for the other Japonica rice growing regions in East Asia, projecting for years 2050 and 2100. In these climate change projection simulations in Gwangju, Korea, the yield increases (+12.6 and + 22.0%) due to CO₂ elevation were adjusted according to temperature increases showing variation dependent upon the cultivars, which resulted in significant yield decreases (?22.1% and ?35.0%). The projected yields were determined to increase as latitude increases due to reduced temperature effects, showing the highest increase for any of the study locations (+24%) in Harbin, China. It appears that the potential negative impact on crop production may be mediated by appropriate cultivar selection and cultivation changes such as alteration of the planting date. Results reported in this study using the CERES‐Rice 4.0 model demonstrate the promising potential for its further application in simulating the impacts of climate change on rice production from a local to a regional scale under the monsoon climate system.     

Modern maize hybrids in Northeast China exhibit increased yield potential and resource use efficiency despite adverse climate change

The impact of global changes on food security is of serious concern. Breeding novel crop cultivars adaptable to climate change is one potential solution, but this approach requires an understanding of complex adaptive traits for climate‐change conditions. In this study, plant growth, nitrogen (N) uptake, and yield in relation to climatic resource use efficiency of nine representative maize cultivars released between 1973 and 2000 in China were investigated in a 2‐year field experiment under three N applications. The Hybrid‐Maize model was used to simulate maize yield potential in the period from 1973 to 2011. During the past four decades, the total thermal time (growing degree days) increased whereas the total precipitation and sunshine hours decreased. This climate change led to a reduction of maize potential yield by an average of 12.9% across different hybrids. However, the potential yield of individual hybrids increased by 118.5 kg ha^?1 yr^?1 with increasing year of release. From 1973 to 2000, the use efficiency of sunshine hours, thermal time, and precipitation resources increased by 37%, 40%, and 41%, respectively. The late developed hybrids showed less reduction in yield potential in current climate conditions than old cultivars, indicating some adaptation to new conditions. Since the mid‐1990s, however, the yield impact of climate change exhibited little change, and even a slight worsening for new cultivars. Modern breeding increased ear fertility and grain‐filling rate, and delayed leaf senescence without modification in net photosynthetic rate. The trade‐off associated with delayed leaf senescence was decreased grain N concentration rather than increased plant N uptake, therefore N agronomic efficiency increased simultaneously. It is concluded that modern maize hybrids tolerate the climatic changes mainly by constitutively optimizing plant productivity. Maize breeding programs in the future should pay more attention to cope with the limiting climate factors specifically.     

施肥进步在粮食增产中的贡献及其地理分异

采用中长期田间试验对８种模拟施肥模型在温带的海伦试验站、暖温带的沈阳试验站和亚热带的桃源试验站进行了６～１０年试验,以比较、评价施肥在粮食生产中的贡献．结果发现,施肥在作物产量形成中的贡献随施肥制度和气候的热量因素所影响;在最佳施肥条件下,施肥在产量中的贡献率分别为海伦（温带）３０％、沈阳（暖温带）３８％、桃源（亚热带）４４％．按这一实验结果可以一般地估计：当其他技术条件不变时,施肥在产量形成中的贡献率最高可达３０～４５％,随所在地区气候的热量条件而不同．     

气候变化对黑龙江省水稻障碍型冷害的影响

明确气候变化对黑龙江省水稻孕穗期和抽穗期障碍型冷害的影响,可为水稻安全生产提供科学依据。基于黑龙江省70个台站1971—2012年的气象资料和10个台站1980—2011年水稻生育期数据,结合水稻障碍型冷害指标,分析了气候变化对黑龙江省水稻障碍型冷害的影响。结果表明:(1)水稻孕穗期障碍型冷害1990s发生频率最低,2000s发生频率最高;抽穗期障碍型冷害1970s和1980s发生频率高,1990s和2000s发生频率低。(2)抽穗期障碍型冷害发生程度大于孕穗期障碍型冷害。(3)不同熟型水稻品种可种植北界逐渐北移东扩,极早熟、早熟和中熟品种可种植范围分别缩小了5、21和11个县(市),中晚熟和晚熟品种可种植范围分别扩大了14和23个县(市)。(4)随着水稻种植格局的变化,不同熟型水稻障碍型冷害均在1990s发生频率最低,2000s发生频率最高。     

Closing the global ozone yield gap: Quantification and cobenefits for multistress tolerance

Increasing both crop productivity and the tolerance of crops to abiotic and biotic stresses is a major challenge for global food security in our rapidly changing climate. For the first time, we show how the spatial variation and severity of tropospheric ozone effects on yield compare with effects of other stresses on a global scale, and discuss mitigating actions against the negative effects of ozone. We show that the sensitivity to ozone declines in the order soybean > wheat > maize > rice, with genotypic variation in response being most pronounced for soybean and rice. Based on stomatal uptake, we estimate that ozone (mean of 2010–2012) reduces global yield annually by 12.4%, 7.1%, 4.4% and 6.1% for soybean, wheat, rice and maize, respectively (the “ozone yield gaps”), adding up to 227 Tg of lost yield. Our modelling shows that the highest ozone‐induced production losses for soybean are in North and South America whilst for wheat they are in India and China, for rice in parts of India, Bangladesh, China and Indonesia, and for maize in China and the United States. Crucially, we also show that the same areas are often also at risk of high losses from pests and diseases, heat stress and to a lesser extent aridity and nutrient stress. In a solution‐focussed analysis of these results, we provide a crop ideotype with tolerance of multiple stresses (including ozone) and describe how ozone effects could be included in crop breeding programmes. We also discuss altered crop management approaches that could be applied to reduce ozone impacts in the shorter term. Given the severity of ozone effects on staple food crops in areas of the world that are also challenged by other stresses, we recommend increased attention to the benefits that could be gained from addressing the ozone yield gap.     

区域气候变化情景下气候变率对我国水稻产量影响的模拟研究

利用中国随机天气模型将中国区域气候模式ＲＣＭ与作物模式ＣＥＲＥＳ－Ｒｉｃｅ相连接,模拟了３种气候变率（０％,１０％,２０％）水平下未来气候（２０５０年,假定此时ＣＯ２浓度为５５０ｍｇ／Ｌ）对我国水稻主产区（广州,长沙,南京）灌溉水稻和雨养水稻在考虑ＣＯ２肥效与否条件下的产量,模拟结果表明;（１）气候变率对水稻产量的影响因经营方式和研究地区的不同而有差异,对灌溉水稻来说,气候变率对其产量有负面影响,     

Post‐heading heat stress and yield impact in winter wheat of China

Wheat is sensitive to high temperatures, but the spatial and temporal variability of high temperature and its impact on yield are often not known. An analysis of historical climate and yield data was undertaken to characterize the spatial and temporal variability of heat stress between heading and maturity and its impact on wheat grain yield in China. Several heat stress indices were developed to quantify heat intensity, frequency, and duration between heading and maturity based on measured maximum temperature records of the last 50 years from 166 stations in the main wheat‐growing region of China. Surprisingly, heat stress between heading and maturity was more severe in the generally cooler northern wheat‐growing regions than the generally warmer southern regions of China, because of the delayed time of heading with low temperatures during the earlier growing season and the exposure of the post‐heading phase into the warmer part of the year. Heat stress between heading and maturity has increased in the last decades in most of the main winter wheat production areas of China, but the rate was higher in the south than in the north. The correlation between measured grain yields and post‐heading heat stress and average temperature were statistically significant in the entire wheat‐producing region, and explained about 29% of the observed spatial and temporal yield variability. A heat stress index considering the duration and intensity of heat between heading and maturity was required to describe the correlation of heat stress and yield variability. Because heat stress is a major cause of yield loss and the number of heat events is projected to increase in the future, quantifying the future impact of heat stress on wheat production and developing appropriate adaptation and mitigation strategies are critical for developing food security policies in China and elsewhere.     

气候暖干化对甘肃省谷子产量的影响及对策

基于甘肃省甘州（河西温和干旱绿洲灌溉区）、安定（陇中温和半干旱旱作区）、西峰（陇东温和半湿润旱作区）气温、降水和谷子产量资料,计算出各区域谷子生育期内≥0 ℃、≥5 ℃、≥10 ℃、≥15 ℃、≥20 ℃活动积温以及生育关键期平均气温和降水量,用正交多项式拟合分离出谷子气候产量,并采用线性倾向、累积距平、Mann-Kendall法分析研究区气候和谷子气候产量的变化特征,以及气候变化对谷子产量的影响.结果表明：气候暖干化是甘肃各区域现代气候变化的主要特征,各地气温从20世纪90年代初开始呈显著上升趋势,降水从20世纪80年代后期开始显著减少;该区谷子产量与温度、降水量呈显著相关关系,旱作区谷子产量随生育关键期内气温增高、降水量增多而提高,河西走廊绿洲灌区谷子产量随气温增高而提高;气候暖干化严重影响谷子产量,西峰、安定、甘州谷子产量的气象波动指数分别占实际产量变异系数的73%、72%和54%,变暖后（1993-2008年）较变暖前（1985-1992年）所占百分率明显增大;气候变暖有利于谷子产量增加,与气候变暖前相比,气候变暖后西峰、安定、甘州谷子年均气候产量的增加量分别为30.6、43.1和121.1 kg·hm^-2.针对甘肃省未来气候继续暖干化的趋势,应进一步扩大谷子种植面积、调整谷子种植结构,同时,要根据不同气候类型区域、不同气候年型选种不同特性的品种,采取不同的种植措施.     

Attribution of climate change: a methodology to estimate the potential contribution to increases in potato yield in Scotland since 1960

Maincrop potato yields in Scotland have increased by 30–35 t ha^?1 since 1960 as a result of many changes, but has changing climate contributed anything to this? The purpose of this work was to answer this question. Daily weather data for the period 1960–2006 were analysed for five locations covering the zones of potato growing on the east coast of Scotland (between 55.213 and 57.646 N) to determine trends in temperature, rainfall and solar radiation. A physiologically based potato yield model was validated using data obtained from a long‐term field trial in eastern Scotland and then employed to simulate crop development and potential yield at each of the five sites. Over the 47 years, there were significant increases in annual air and 30 cm soil temperatures (0.27 and 0.30 K decade^?1, respectively), but no significant changes in annual precipitation or in the timing of the last frost in spring and the first frost of autumn. There was no evidence of any north to south gradient of warming. Simulated emergence and canopy closure became earlier at all five sites over the period with the advance being greater in the north (3.7 and 3.6 days decade^?1, respectively) than the south (0.5 and 0.8 days decade^?1, respectively). Potential yield increased with time, generally reflecting the increased duration of the green canopy, at average rates of 2.8 t ha^?1 decade^?1 for chitted seed (sprouted prior to planting) and 2.5 t ha^?1 decade^?1 for unchitted seed. The measured warming could contribute potential yield increases of up to 13.2 t ha^?1 for chitted potato (range 7.1–19.3 t ha^?1) and 11.5 t ha^?1 for unchitted potato (range 7.1–15.5 t ha^?1) equivalent to 34–39% of the increased potential yield over the period or 23–26% of the increase in actual measured yields.     

Mind the gap: how do climate and agricultural management explain the ‘yield gap’ of croplands around the world?

Aim As the demands for food, feed and fuel increase in coming decades, society will be pressed to increase agricultural production – whether by increasing yields on already cultivated lands or by cultivating currently natural areas – or to change current crop consumption patterns. In this analysis, we consider where yields might be increased on existing croplands, and how crop yields are constrained by biophysical (e.g. climate) versus management factors. Location This study was conducted at the global scale. Methods Using spatial datasets, we compare yield patterns for the 18 most dominant crops within regions of similar climate. We use this comparison to evaluate the potential yield obtainable for each crop in different climates around the world. We then compare the actual yields currently being achieved for each crop with their ‘climatic potential yield’ to estimate the ‘yield gap’. Results We present spatial datasets of both the climatic potential yields and yield gap patterns for 18 crops around the year 2000. These datasets depict the regions of the world that meet their climatic potential, and highlight places where yields might potentially be raised. Most often, low yield gaps are concentrated in developed countries or in regions with relatively high‐input agriculture. Main conclusions While biophysical factors like climate are key drivers of global crop yield patterns, controlling for them demonstrates that there are still considerable ranges in yields attributable to other factors, like land management practices. With conventional practices, bringing crop yields up to their climatic potential would probably require more chemical, nutrient and water inputs. These intensive land management practices can adversely affect ecosystem goods and services, and in turn human welfare. Until society develops more sustainable high‐yielding cropping practices, the trade‐offs between increased crop productivity and social and ecological factors need to be made explicit when future food scenarios are formulated.     

气候变化与水稻生长发育及产量形成关系的模拟研究

应用水稻生长日历模拟模型(RICAM1.3)模拟亚洲地区不同地点和不同气候条件下水稻的生育期和产量形成.其中3s-Beta模型被用于预测水稻开花期和描述水稻光温反应的3个连续阶段:基本营养生长期、光敏感期和光敏感后期.从时间与地理梯度的变化对水稻产量进行模拟,以中国、日本和菲律宾作为从北到南的地理梯度,以20世纪80年代气候变化作为时间梯度,应用RICAM1.3进行模拟.结果表明,模型具有广泛的适应性,能较好地模拟不同气候条件和不同水稻品种生育期的变化与产量的形成.     

Global evaluation of a semiempirical model for yield anomalies and application to within‐season yield forecasting

Quantifying the influence of weather on yield variability is decisive for agricultural management under current and future climate anomalies. We extended an existing semiempirical modeling scheme that allows for such quantification. Yield anomalies, measured as interannual differences, were modeled for maize, soybeans, and wheat in the United States and 32 other main producer countries. We used two yield data sets, one derived from reported yields and the other from a global yield data set deduced from remote sensing. We assessed the capacity of the model to forecast yields within the growing season. In the United States, our model can explain at least two‐thirds (63%–81%) of observed yield anomalies. Its out‐of‐sample performance (34%–55%) suggests a robust yield projection capacity when applied to unknown weather. Out‐of‐sample performance is lower when using remote sensing‐derived yield data. The share of weather‐driven yield fluctuation varies spatially, and estimated coefficients agree with expectations. Globally, the explained variance in yield anomalies based on the remote sensing data set is similar to the United States (71%–84%). But the out‐of‐sample performance is lower (15%–42%). The performance discrepancy is likely due to shortcomings of the remote sensing yield data as it diminishes when using reported yield anomalies instead. Our model allows for robust forecasting of yields up to 2 months before harvest for several main producer countries. An additional experiment suggests moderate yield losses under mean warming, assuming no major changes in temperature extremes. We conclude that our model can detect weather influences on yield anomalies and project yields with unknown weather. It requires only monthly input data and has a low computational demand. Its within‐season yield forecasting capacity provides a basis for practical applications like local adaptation planning. Our study underlines high‐quality yield monitoring and statistics as critical prerequisites to guide adaptation under climate change.     

长江中下游地区水稻孕穗开花期高温发生规律及其对产量的影响

以长江中下游平原7个省(市)的19个地区作为样点,统计分析了各样点近36年(1970—2005年)水稻始穗前15d至始穗后20d内日最高气温≥35℃的时空分布特点;并根据全球气候渐变模型GISS GCM Transient B Runs生成的研究区域2030、2050年的气候渐变情景,分析了该地区未来水稻孕穗开花期≥35℃高温逆境的时空演变趋势。结果表明:近36年来长江中下游的早稻孕穗开花期出现高温日数的上升趋势显著,未来气候情景下水稻逆境指标出现日数最多的是单季稻,其次依次为早稻、后季稻;双季稻种植区,在未来气候变化中,长江中游地区温度逆境出现日数将大于下游地区。研究区域水稻气候产量的增减与该地区水稻逆境指标的关系说明,高温导致的颖花败育是水稻减产的重要原因;未来气候变化的两种(2030、2050)情景下,长江中游地区的减产幅度大于长江下游地区,减产幅度最大的是长江中游地区的后季稻。     

1961-2010年潜在干旱对我国夏玉米产量影响的模拟分析

玉米是我国重要的粮食和饲料作物,旱灾是玉米生产中常见的气象灾害。采用CERES-Maize作物模拟模型,模拟了1961—2010年潜在干旱对我国夏玉米产量影响的时空变化趋势,并分析了其与大气环流因子间的关系,以期了解我国50年来夏玉米受旱的变化情况,并为干旱的研究方法提供一些参考。结果表明:(1)1961—2010年我国夏玉米的潜在产量损失呈略微下降的趋势,不同时期表现不同,其中20世纪60年代、90年代表现为上升趋势。(2)在过去50年里,我国夏玉米潜在旱灾损失中心有向东北移动的趋势,华北地区受旱程度的减轻和东北地区受旱程度的增强是造成损失中心移动的主要原因。(3)我国夏玉米潜在旱灾产量损失中心的经纬度和影响我国夏季降水的北极涡、副热带高压系统的部分指数具有显著的相关关系。当北极涡在生长季前期或同期偏小、偏弱时,我国夏玉米潜在旱灾产量损失中心将偏东、偏北,而副热带高压系统影响更为复杂。     

白背飞虱为害对水稻产量的影响及防治指标的研究进展

白背飞虱近年来已逐步上升为我国水稻上的最重要害虫之一。该文综述了白背飞虱以不同虫口密度、在水稻不同生育期、危害不同类型水稻品种和与其他病虫害复合危害对水稻产量的影响 ,以及允许产量损失率和各地制定的防治指标 ,并建议了进一步的研究内容。     

A framework for the identification of hotspots of climate change risk for mammals

As rates of global warming increase rapidly, identifying species at risk of decline due to climate impacts and the factors affecting this risk have become key challenges in ecology and conservation biology. Here, we present a framework for assessing three components of climate‐related risk for species: vulnerability, exposure and hazard. We used the relationship between the observed response of species to climate change and a set of intrinsic traits (e.g. weaning age) and extrinsic factors (e.g. precipitation seasonality within a species geographic range) to predict, respectively, the vulnerability and exposure of all data‐sufficient terrestrial non‐volant mammals (3,953 species). Combining this information with hazard (the magnitude of projected climate change within a species geographic range), we identified global hotspots of species at risk from climate change that includes the western Amazon basin, south‐western Kenya, north‐eastern Tanzania, north‐eastern South Africa, Yunnan province in China, and mountain chains in Papua‐New Guinea. Our framework identifies priority areas for monitoring climate change effects on species and directing climate mitigation actions for biodiversity.     

近20年气候变暖对东北水稻生育期和产量的影响

为探究近20年气候变暖对东北地区水稻生育期和产量的影响,利用东北三省近20年水稻生育期、产量数据和气候观测数据,采用数理统计等方法进行分析.结果表明: 1989-2009年东北三省水稻生长季日平均温度、最高温度和最低温度均呈上升趋势,降水量均呈下降趋势.与1990s相比,2000s黑龙江、吉林和辽宁三省水稻全生育期分别延长了14、4.5和5.1 d.东北地区5、6和9月温度升高可延长水稻全生育期,而7月温度升高则缩短生育期.除黑龙江省外,东北地区的审定品种和观测站点水稻生育期均呈相似的变化趋势,审定品种生育期的延长是导致观测站点水稻生育期延长的主要原因.东北地区日平均温度、最低温度和最高温度的变化均会影响水稻产量,温度上升对黑龙江省的增产效应较明显,尤其是三江平原以西地区.除辽宁省南部以外,其他地区升温均表现为增产.东北地区可以采取育种、栽培和耕作等措施充分挖掘水稻适应气候变暖的能力.
     

Climate trends account for stalled wheat yields in Australia since 1990

Global food security requires that grain yields continue to increase to 2050, yet yields have stalled in many developed countries. This disturbing trend has so far been only partially explained. Here, we show that wheat yields in Australia have stalled since 1990 and investigate the extent to which climate trends account for this observation. Based on simulation of 50 sites with quality weather data, that are representative of the agro‐ecological zones and of soil types in the grain zone, we show that water‐limited yield potential declined by 27% over a 26 year period from 1990 to 2015. We attribute this decline to reduced rainfall and to rising temperatures while the positive effect of elevated atmospheric CO₂ concentrations prevented a further 4% loss relative to 1990 yields. Closer investigation of three sites revealed the nature of the simulated response of water‐limited yield to water availability, water stress and maximum temperatures. At all three sites, maximum temperature hastened time from sowing to flowering and to maturity and reduced grain number per m² and average weight per grain. This 27% climate‐driven decline in water‐limited yield is not fully expressed in actual national yields. This is due to an unprecedented rate of technology‐driven gains closing the gap between actual and water‐limited potential yields by 25 kg ha^?1 yr^?1 enabling relative yields to increase from 39% in 1990 to 55% in 2015. It remains to be seen whether technology can continue to maintain current yields, let alone increase them to those required by 2050.