Effects of heat and drought stress on cereal crops across spatial scales

The production of cereal crops is increasingly influenced by heat and drought stress. Despite the typical small-scale sub-regional variability of these stresses, impacts on yields are also of concern at larger regional to global scales. Crop growth models are the most widely used tools for simulating the effects of heat and drought stress on crop yield. However, the development and application of crop models to simulate heat and drought is still a challenging issue, particularly their application at larger spatial scales. Previous research showed that there is a lack of information regarding the: 1. Response of cereal crops to heat stress, 2. Interactions between phenology and heat stress under climate change, 3. Improvement of crop models for reproducing heat stress effects on crop yield, 4. Upscaling of heat and drought stress effects with crop models, 5. Effects of climate and management interactions on crop yield in semi-arid environments. Five detailed studies were arranged to improve the understanding on the aforementioned gaps of knowledge: 1. A review study was set up to understand how crop growth processes responded to short episodes of high temperature. In addition, the possible ways for improvement of the heat stress simulation algorithms in crop models were investigated at a field scale. The reproductive phase of development in cereals was found to be the most sensitive phase to heat stress. Crop models aiming to model heat stress effects on crops under field conditions should consider the modelling of canopy temperature. This may also provide a mechanistic basis to link heat and drought stress in crop models. Generally, these two stresses occur simultaneously. 2. In a nationwide study, the interactions between the advancements of phenology and heat stress on winter wheat (Triticum aestivum L.) due to global warming, were evaluated between1951-2009 across Germany. The increase in temperature (~1.8°C) shifted crop phenology to cooler parts of the growing season (~14 days) and compensated for the effect of global warming on heat stress intensity in the period 1976-2009. The intensity of heat stress on winter wheat could have increased by up to 59% without any advancement in phenology. 3. A large-scale simulation study was conducted to investigate the effects of input (climate and soil) and output data aggregation on simulated heat and drought stress for winter wheat over the period of 1980-2011 across Germany. Aggregation levels were compared in several steps from 1 km × 1 km to 100 km × 100 km. Simulations were performed with SIMPLACE. Aggregation of weather and soil data showed a slight impact on the mean and median of simulated heat and drought stress at the national scale. No remarkable differences in simulated mean yields of winter wheat were evident for the different resolutions ranging from 1 km × 1 km to 100 km × 100 km across Germany. However, high resolution input data was essential to reproduce spatial variability of heat and drought stress for the more heterogeneous regions. 4. Two regional studies were arranged to evaluate the interactions between management and climate on crop production under climate change conditions. A crop model (DSSAT v4.5) was employed to assess the interactions between fertilization management of pearl millet (Pennisetum americanum L.), crop substitution [pearl millet instead of maize (Zea mays L)], and climate in semi-arid environments of Iran and the Republic of Niger, respectively. The pearl millet biomass production showed a strong response to different fertilization management in Niger. The highest dry matter production of pearl millet was obtained in combination with crop residues and mineral fertilizer treatment. The dry matter production of pearl millet was reduced by 11% to 62% under different climate change scenarios and future time periods (2011-2030 and 2080-2099). Results of this study showed that higher soil fertility could compensate for the negative effects of high temperature on biomass production. This was a result of the strong positive relationship between biomass production and the sum of precipitation under high soil fertility. Crop substitution as an adaptation strategy (new hybrids of pearl millet instead of maize) enhanced fodder production and water use efficiency in present and potential future climatic conditions in northeast Iran. However, the fodder production of both crops was reduced due to shortening of the period from floral initiation to the end of leaf growth under various climate change conditions. Benefits of crop substitution may decline under climate change resulting in higher temperature sensitivity of the new hybrids of pearl millet. Several conclusions were drawn from this study: It is necessary to consider canopy temperature instead of air temperature in crop models and use data from experiments under field conditions to improve and properly calibrate crop models for heat and drought stress responses. Crop models must also consider that effects of heat and drought stress on crops differ with phenological phases and can be compensated for by responses of other processes. An increase in the intensity of heat stress around anthesis can, for instance, be fully compensated for by the advancement in phenology in winter cereals under climate change. It is not necessary to use high resolution weather and soil input data for simulating the effects of heat and drought stress on crop yield at a national scale; but, high resolution input data are necessary to reproduce spatial patterns of heat and drought. Finally, implementation of management practices in cropping systems may change the response of crops to climate change. For this reason, management practices should be considered as an adaptation strategy

Evidence for increasing global wheat yield potential

Wheat is the most widely grown food crop, with 761 Mt produced globally in 2020. To meet the expected grain demand by mid-century, wheat breeding strategies must continue to improve upon yield-advancing physiological traits, regardless of climate change impacts. Here, the best performing doubled haploid (DH) crosses with an increased canopy photosynthesis from wheat field experiments in the literature were extrapolated to the global scale with a multi-model ensemble of process-based wheat crop models to estimate global wheat production. The DH field experiments were also used to determine a quantitative relationship between wheat production and solar radiation to estimate genetic yield potential. The multi-model ensemble projected a global annual wheat production of 1050 ± 145 Mt due to the improved canopy photosynthesis, a 37% increase, without expanding cropping area. Achieving this genetic yield potential would meet the lower estimate of the projected grain demand in 2050, albeit with considerable challenges.Fil: Guarin, Jose Rafael. National Aeronautics and Space Administration; Estados Unidos. Columbia University; Estados Unidos. Florida State University; Estados UnidosFil: Martre, Pierre. Institut Agro Montpellier SupAgro; FranciaFil: Ewert, Frank. Universitat Bonn; Alemania. Leibniz Centre for Agricultural Landscape Research; AlemaniaFil: Webber, Heidi. Universitat Bonn; Alemania. Leibniz Centre for Agricultural Landscape Research; AlemaniaFil: Dueri, Sibylle. Institut Agro Montpellier SupAgro; FranciaFil: Calderini, Daniel Fernando. Universidad Austral de Chile; ChileFil: Reynolds, Matthew. International Maize and Wheat Improvement Center ; MéxicoFil: Molero, Gemma. KWS; FranciaFil: Miralles, Daniel Julio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Garcia, Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Slafer, Gustavo Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina. Universitat de Lleida; España. Institució Catalana de Recerca i Estudis Avancats; EspañaFil: Giunta, Francesco. Consiglio Nazionale Delle Ricerche. Istituto Di Scienze Dell Atmosfera E del Clima.; ItaliaFil: Pequeno, Diego N.L.. International Maize and Wheat Improvement Center; MéxicoFil: Stella, Tommaso. Universitat Bonn; Alemania. Leibniz Centre for Agricultural Landscape Research; AlemaniaFil: Ahmed, Mukhtar. University Of Pakistan; PakistánFil: Alderman, Phillip D.. Oklahoma State University; Estados UnidosFil: Basso, Bruno. Michigan State University; Estados UnidosFil: Berger, Andres G.. Instituto Nacional de Investigacion Agropecuaria;Fil: Bindi, Marco. Università degli Studi di Firenze; ItaliaFil: Bracho-Mujica, Gennady. Universität Göttingen; AlemaniaFil: Cammarano, Davide. Purdue University; Estados UnidosFil: Chen, Yi. Chinese Academy of Sciences; República de ChinaFil: Dumont, Benjamin. Université de Liège; BélgicaFil: Rezaei, Ehsan Eyshi. Leibniz Institute Of Plant Genetics And Crop Plant Research.; AlemaniaFil: Fereres, Elias. Universidad de Córdoba; EspañaFil: Ferrise, Roberto. Michigan State University; Estados UnidosFil: Gaiser, Thomas. Universitat Bonn; AlemaniaFil: Gao, Yujing. Florida State University; Estados UnidosFil: Garcia Vila, Margarita. Universidad de Córdoba; EspañaFil: Gayler, Sebastian. Universidad de Hohenheim; Alemani

Evidence for increasing global wheat yield potential

Wheat is the most widely grown food crop, with 761 Mt produced globally in 2020. To meet the expected grain demand by mid-century, wheat breeding strategies must continue to improve upon yield-advancing physiological traits, regardless of climate change impacts. Here, the best performing doubled haploid (DH) crosses with an increased canopy photosynthesis from wheat field experiments in the literature were extrapolated to the global scale with a multi-model ensemble of process-based wheat crop models to estimate global wheat production. The DH field experiments were also used to determine a quantitative relationship between wheat production and solar radiation to estimate genetic yield potential. The multi-model ensemble projected a global annual wheat production of 1050 +/- 145 Mt due to the improved canopy photosynthesis, a 37% increase, without expanding cropping area. Achieving this genetic yield potential would meet the lower estimate of the projected grain demand in 2050, albeit with considerable challenges

Global wheat production with 1.5 and 2.0°C above pre‐industrial warming

Efforts to limit global warming to below 2°C in relation to the pre‐industrial level are under way, in accordance with the 2015 Paris Agreement. However, most impact research on agriculture to date has focused on impacts of warming >2°C on mean crop yields, and many previous studies did not focus sufficiently on extreme events and yield interannual variability. Here, with the latest climate scenarios from the Half a degree Additional warming, Prognosis and Projected Impacts (HAPPI) project, we evaluated the impacts of the 2015 Paris Agreement range of global warming (1.5 and 2.0°C warming above the pre‐industrial period) on global wheat production and local yield variability. A multi‐crop and multi‐climate model ensemble over a global network of sites developed by the Agricultural Model Intercomparison and Improvement Project (AgMIP) for Wheat was used to represent major rainfed and irrigated wheat cropping systems. Results show that projected global wheat production will change by −2.3% to 7.0% under the 1.5°C scenario and −2.4% to 10.5% under the 2.0°C scenario, compared to a baseline of 1980–2010, when considering changes in local temperature, rainfall, and global atmospheric CO2 concentration, but no changes in management or wheat cultivars. The projected impact on wheat production varies spatially; a larger increase is projected for temperate high rainfall regions than for moderate hot low rainfall and irrigated regions. Grain yields in warmer regions are more likely to be reduced than in cooler regions. Despite mostly positive impacts on global average grain yields, the frequency of extremely low yields (bottom 5 percentile of baseline distribution) and yield inter‐annual variability will increase under both warming scenarios for some of the hot growing locations, including locations from the second largest global wheat producer—India, which supplies more than 14% of global wheat. The projected global impact of warming <2°C on wheat production is therefore not evenly distributed and will affect regional food security across the globe as well as food prices and trade

Yield effects of selected agronomic innovation packages in maize cropping systems of six countries in Sub-Saharan Africa

Implementation of suitable innovation packages into cropping systems is required to address the issues of food security and improvement of the crop yield in Sub-Saharan Africa. However, quantification of the effects of innovation packages such as increase in fertilizer application rates, introduction of high yielding cultivars or change in farming practices such as sowing date and irrigation, generally requires substantial investments, in particular the quantification at large scales. Crop models are widely employed to estimate the impacts of agronomic decisions on cropping systems and to detect the most suitable areas for their implementation. The main goal of the study is to quantify the effects of a) change in nitrogen fertilization rate, b) adjustment of sowing date, c) implementation of new cultivars, and d) supplementary irrigation on maize cropping systems across six African countries including Ghana, Nigeria, Kenya, Malawi, Ethiopia and Burkina Faso. For this purpose, 30 years (1980-2010) of climate data are used as well as soil and management information obtained from global datasets at 0.5° x 0.5° spatial resolution. The nitrogen and cultivar packages were tested for all six countries whereas the changes in sowing dates (Ghana and Malawi) and the irrigation (Ethiopia) package were used in specific countries only. The crop modelling framework SIMPLACE was used to test the effects of innovation packages at the country level. The model results indicated that the agronomic innovation packages could improve maize yield by 1 t ha-1 to 2.3 t ha-1 in the studied countries. The magnitude of the yield improvement is country and package specific. The largest maize yield improvements across the packages were obtained by increase in nitrogen application rate, assuming that other nutrients like phosphorus and potassium are not limiting crop growth and yield. However, in some cases a combination of the agronomic innovation packages showed the highest maize yield. We conclude that it is vital to combine the agronomic packages to fill the gap between potential and current yields of maize in Africa. This will require appropriate incentives and investments in extension services, fertilizer distribution networks, and farmer capacity building

Change in crop management strategies could double the maize yield in Africa

Change in cropping practices is required to address the food security issues in Africa. Yet, testing of the performance of such changes, in particular at large scales, often needs significant investments. Crop models are widely used tools to quantify the effects of agronomic decisions on cropping systems and to identify the most promising areas for their advancement and implementation. Here in this study we quantify the impacts of individual and combined change in management scenarios including changes in (i) rates of nitrogen application, (ii) supplementary irrigation and (iii) new cultivar (with higher radiation use efficiency) on maize cropping systems over Africa based on 30 years (1980-2010) of climate, soil and management information obtained from global datasets at 0.5° x 0.5° spatial resolution. The crop model SIMPLACE was used in this study and it was tested against FAO statistics to evaluate the model performance under the current management conditions with traditional cultivars and average nitrogen application rates of <10 kg N ha-1. The model results showed that the combined changes in crop management could improve the range of maize yield from 1.2 t ha-1 to 2.9 t ha-1 over the study period in Africa. The magnitude of the yield improvement is country and scenario specific. The largest maize yield improvements were obtained in the combined innovations rather than individual practices in particular for the supplementary irrigation. We conclude that it is essential to implement combined technology packages to fill the gap between attainable and current yield in Africa and that will require appropriate incentives, and investment in extension services, fertilizer distribution networks and farmer capacity strengthening. We also need to combine the results with a robust economic model to evaluate the benefits and risks of the required investments for such changes in crop management

Climatic Suitability of Growing Summer Squash (Cucurbita pepo L.) as a Medicinal Plant in Iran

Diversification of production by including a broader range of plant species, can significantly contribute to improve health and nutrition, livelihoods, household food security and ecological sustainability. Exploring the climate impact on any given crop is one of the first priorities to find new suitable areas for production and management of new crops. Summer squash (Cucurbita pepo L.) is an economically valuable plant with various medicinal potentials. In order to investigate summer squash cultivation feasibility under Iran�s climate, three main agricultural regions (Azerbaijan, Khorasan and central part of Iran (Fars and Isfahan)) were selected. These regions suitability for summer squash cultivation were evaluated by considering three vital climate variables encompass temperature, precipitation, and sunshine hours. These regions show distinct and representative climatic conditions of Iran. Annual and growing season average of maximum, minimum, mean temperature, precipitation, and sunshine hours were calculated (May-September) for all locations with 44 years historical weather data (1961-2005) for 8 locations (Oroomieh, Tabriz, Khoy, Mashhad, Sabzevar, Birjand, Shiraz and Isfahan), 39 years (1966-2005) for 2 locations (Kashan and Fassa), 28 years (1977-2005) for 4 locations (Ardebil, Abadeh, Bojnurd and Shargh Isfahan) and 20 years (1985-2005) for 9 locations (Mahabad, Sarab, Maragheh, Parsabad, Khalkhal, Ferdous, Ghaen, Kashmar and Sarakhs). Climatic demands of summer squash were determined by four years field studies at four different locations in Iran. Our results showed Azerbaijan region has a suitable condition for this crop cultivation especially from precipitation and temperature perspectives. Central part of Iran and Khorasan were also found as partly suitable locations however as they are near to deserts with hotter and drier climate, there might be some other crops considered as priorities in these areas

Climatic Suitability of Growing Summer Squash (Cucurbita pepo L.) as a Medicinal Plant in Iran

Diversification of production by including a broader range of plant species, can significantly contribute to improve health and nutrition, livelihoods, household food security and ecological sustainability. Exploring the climate impact on any given crop is one of the first priorities to find new suitable areas for production and management of new crops. Summer squash (Cucurbita pepo L.) is an economically valuable plant with various medicinal potentials. In order to investigate summer squash cultivation feasibility under Irans climate, three main agricultural regions (Azerbaijan, Khorasan and central part of Iran (Fars and Isfahan)) were selected. These regions suitability for summer squash cultivation were evaluated by considering three vital climate variables encompass temperature, precipitation, and sunshine hours. These regions show distinct and representative climatic conditions of Iran. Annual and growing season average of maximum, minimum, mean temperature, precipitation, and sunshine hours were calculated (May-September) for all locations with 44 years historical weather data (1961-2005) for 8 locations (Oroomieh, Tabriz, Khoy, Mashhad, Sabzevar, Birjand, Shiraz and Isfahan), 39 years (1966-2005) for 2 locations (Kashan and Fassa), 28 years (1977-2005) for 4 locations (Ardebil, Abadeh, Bojnurd and Shargh Isfahan) and 20 years (1985-2005) for 9 locations (Mahabad, Sarab, Maragheh, Parsabad, Khalkhal, Ferdous, Ghaen, Kashmar and Sarakhs). Climatic demands of summer squash were determined by four years field studies at four different locations in Iran. Our results showed Azerbaijan region has a suitable condition for this crop cultivation especially from precipitation and temperature perspectives. Central part of Iran and Khorasan were also found as partly suitable locations however as they are near to deserts with hotter and drier climate, there might be some other crops considered as priorities in these areas

Crop production in Türkiye: trends and driving variables

Climate change and a rapidly increasing population boost the pressure on Türkiye’s cropping systems to increase crop production in order to meet rising food demand. It is unknown whether and in which direction trends and variability in harvested area and yield separately affect crop production in Türkiye. The objective of this study was to (1) quantify the long-term (2004–2020) trends of planting/harvested areas, yield and crop production for the 16 vital annual crops in Türkiye, (2) quantify the separate contribution of harvested area and yield on crop-specific production variability and (3) the potential of water and temperature-based remote sensing variables on capturing the variability of harvested areas and yield. The harvested area of the most grown crops (10 out of 16) such as wheat and barley showed a declining trend. However, the yield trend was increased for all of the study crops, which in some cases overcompensated for the decline in the harvested area on crop production. The harvested area showed a more robust explanatory power for production variability than yield except for the crops with higher breeding investments and subsidized by authorities such as wheat and sugar beet. The water-related remote sensing variables and combination of water and temperature variables largely explained the variability of the harvested area in Türkiye. In order to stabilize crop production in Türkiye, better and more efficient water management plans are crucial