Cultivar selection can increase yield potential and resource use efficiency of spring maize to adapt to climate change in Northeast China

Northeast China (NEC) is one of the major maize production areas in China.Agro-climatic resources have obviously changed,which will seriously affect crop growth and development in this region.It is important to investigate the contribution of climate change adaptation measures to the yield and resource use efficiency to improve our understanding of how we can effectively ensure high yield and high efficiency in the future.In this study,we divided the study area into five accumulated temperature zones (ATZs) based on growing degree days (GDD).Based on the meteorological data,maize data (from agrometeorological stations) and the validated APSIM-Maize Model,we first investigated the spatial distributions and temporal trends of maize potential yield of actual planted cultivars,and revealed the radiation use efficiency (RUE) and heat resource use efficiency (HUE) from 1981 to 2017.Then according to the potential growing seasons and actual growing seasons,we identified the utilization percentages of radiation (P_R) resource and heat resource (P_H) for each ATZ under potential production from 1981 to 2017.Finally,we quantified the contributions of cultivar changings to yield,P_R and P_H of maize.The results showed that during the past 37 years,the estimated mean potential yield of actual planted cultivars was 13 649 kg ha~(–1),ranged from 11 205 to 15 257 kg ha~(–1),and increased by 140 kg ha~(–1) per decade.For potential production,the mean values of RUE and HUE for the actual planted maize cultivars were 1.22 g MJ~(–1) and 8.58 kg (℃ d)~(–1) ha~(–1).RUE showed an increasing tendency,while HUE showed a decreasing tendency.The lengths of the potential growing season and actual growing season were 158 and 123 d,and increased by 2 and 1 d per decade.P_R and P_H under potential production were 82 and 86%,respectively and showed a decreasing tendency during the past 37 years.This indicates that actual planted cultivars failed to make full use of climate resources.However,results from the adaptation assessments indicate that,adoption of cultivars with growing season increased by 2–11 d among ATZs caused increase in yield,P_R and P_H of 0.6–1.7%,1.1–7.6% and 1.5–8.9%,respectively.Therefore,introduction of cultivars with longer growing season can effectively increase the radiation and heat utilization percentages and potential yield.     

APSIM玉米模型在东北地区的适应性

利用东北地区6个典型农业气象试验站的玉米田间试验数据和同期逐日气象数据对APSIM模型(农业生产系统模型)在东北玉米产区的适应性进行了初步研究。先依据各站第一组玉米试验数据对模型相关参数进行调试、确定,再利用另一组试验数据检验模型模拟玉米生育期、叶面积指数、地上部总生物量和产量的可靠性。结果表明,APSIM模型模拟的播种至出苗、开花和成熟各阶段天数与实测天数有较好的一致性,其误差分别为0~2.0、0.7~2.0和0.7~2.3 d;哈尔滨地区模拟的叶面积指数和地上部总生物量相对均方根差分别为33%和11%,模拟效果较好;黑龙江哈尔滨、海伦、泰来,吉林桦甸、通化和辽宁本溪的模拟产量与实际产量的NRMSE分别为18%、13%、4%、4%、5%和2%。说明APSIM模型对东北地区玉米生育期、叶面积指数动态变化过程、地上部总生物量动态变化过程和最终产量具有较好的模拟结果,验证后的APSIM模型在东北地区具有较好的适应性。以上结果为今后在东北地区深入开展玉米生产潜力以及解析产量形成的限制因素等研究提供了技术平台与支撑。     

Accounting for both parameter and model structure uncertainty in crop model predictions of phenology: A case study on rice

We consider predictions of the impact of climate warming on rice development times in Sri Lanka. The major emphasis is on the uncertainty of the predictions, and in particular on the estimation of mean squared error of prediction. Three contributions to mean squared error are considered. The first is parameter uncertainty that results from model calibration. To take proper account of the complex data structure, generalized least squares is used to estimate the parameters and the variance-covariance matrix of the parameter estimators. The second contribution is model structure uncertainty, which we estimate using two different models. An ANOVA analysis is used to separate the contributions of parameter and model uncertainty to mean squared error. The third contribution is model error, which is estimated using hindcasts. Mean squared error of prediction of time from emergence to maturity, for baseline +2 °C, is estimated as 108 days², with model error contributing 86 days², followed by model structure uncertainty which contributes 15 days² and parameter uncertainty which contributes 7 days². We also show how prediction uncertainty is reduced if prediction concerns development time averaged over years, or the difference in development time between baseline and warmer temperatures.     

Understanding the response of sorghum cultivars to nitrogen applications in the semi-arid Nigeria using the agricultural production systems simulator

Abstract

The Agricultural Production Systems simulator (APSIM) model was calibrated and evaluated using two improved sorghum varieties conducted in an experiment designed in a randomized complete block, 2014–2016 at two research stations in Nigeria. The results show that the model replicated the observed yield accounting for yield differences and variations in phenological development between the two sorghum cultivars. For early-maturing cultivar (ICSV-400), the model indicated by low accuracy with root means square error (RMSE) for biomass and grain yields of 20.3% and 23.7%. Meanwhile, Improved-Deko (medium-maturing) cultivar shows the model was calibrated with low RMSE (11.1% for biomass and 13.9% for grain). Also, the model captured yield response to varying Nitrogen (N) fertilizer applications in the three agroecological zones simulated. The N-fertilizer increased simulated grain yield by 26–52% for ICSV-400 and 19–50% for Improved-Deko compared to unfertilized treatment in Sudano-Sahelian zone. The insignificant yield differences between N-fertilizer rates of 60 and 100 kgha^?1 suggests 60 kgNha^?1 as the optimal rate for Sudano-Sahelian zone. Similarly, grain yield increased by 23–57% for ICSV-400 and 19–59% for Improved Deko compared to unfertilized N-treatment while the optimal mean grain yield was simulated at 80 kgNha^?1 in the Sudan savanna zone. In the northern Guinea savanna, mean simulated grain yield increased by 8–20% for ICSV-400 and 12–23% for Improved-Deko when N-fertilizer was applied compared to unfertilized treatment. Optimum grain yield was obtained at 40 kgha^?1. Our study suggests a review of blanket recommended fertilizer rates across semi-arid environments for sorghum to maximize productivity and eliminate fertilizer losses, means of adaptation strategies to climate variability.     

气候变化背景下播期对东北三省春玉米产量的影响

为探究气候变化背景下东北三省(黑龙江省、吉林省和辽宁省)春玉米适宜播期的变化程度,本文以东北三省春玉米潜在种植区为研究区域,基于1981—2015年气象资料,1981—2012年农业气象观测站玉米生育期、产量资料以及土壤资料,分气侯区对农业生产系统模型(APSIM)进行调参和验证,建立适用于东北三省10个不同气候区的模型相关参数,在各气候区利用调参验证后的APSIM-Maize模型设置不同播期,模拟各年代不同播期下春玉米潜在产量和气候生产潜力,综合高产和稳产性指标,明确了不同区域各年代不同条件下适宜播期范围。研究结果表明,APSIM模型对于东北三省7个春玉米品种开花和成熟两个关键生育期以及产量模拟结果与实测结果具有较好的一致性,表明APSIM模型能够较好地模拟研究区域春玉米生育期和产量。充分灌溉条件下,研究区域内适宜播期范围从4月16日至5月19日,空间上呈纬向分布南早北迟的特征; 20世纪90年代和21世纪00年代玉米适宜播期较20世纪80年代有提前趋势,其中20世纪90年代提前趋势更明显;第1、第3、第5、第7和第9气候区雨养条件下较充分灌溉条件下适宜播期有推迟趋势,推迟天数为3～6 d。雨养条件下各年代不同气候区理论上的适宜播期较目前生产中实际播期下的产量提高2.84%～9.96%。以上结果为进行未来气候变化对东北三省春玉米影响及其适宜播期等研究提供了技术支撑。     

Mitigating N2O emissions from cropping systems after conversion from pasture − a modelling approach

Converting pasture to cropping is common in many of the world’s agricultural systems. This conversion results in substantial net mineralisation of soil organic matter that builds up during a phase of pasture. A few studies have shown that this mineralisation leads to increased nitrous oxide (N₂O) emissions compared to long-term pasture or long-term cropping. Understanding of interactions leading to these significant emissions is still scarce but is needed to identify mitigation options for this situation. In this study, the Agricultural Production Systems sIMulator (APSIM) was used to investigate the optimal timing of pasture termination (relative to crop planting) and management of nitrogen (N) in crops after pasture termination to maximise crop yield and limit N₂O emissions. Beforehand, APSIM’s performance in simulating yields and N₂O emissions was tested against data from field experiments conducted in the temperate high-rainfall zone of southern Australia where N₂O emissions were monitored with automatic gas collection chambers during the first year of cropping wheat after terminating long-term pasture on two adjacent sites in two consecutive years. Field experiments and simulation scenarios showed very high N₂O emissions (up to 48 kg N₂O-N ha⁻¹ yr⁻¹) in the first year of wheat after pasture termination, even without N fertiliser application. Measured cumulative N₂O emissions, crop yields and soil mineral N and water content dynamics were simulated well with APSIM. Including a routine into APSIM to account for N₂O transport through the soil profile improved the simulation of daily N₂O emissions considerably, leading to up to 67% of the measured variability in daily N₂O emissions being explained by the model. We predicted that a short fallow between termination of pasture and sowing wheat, instead of a long fallow which is the common practice, reduces N₂O emissions by more than half in the first year of cropping without a noteworthy impact on crop yield. Reducing N fertiliser applications in the first few years after pasture termination by taking available soil mineral N into account, and applying the fertiliser six to twelve weeks after sowing instead of at sowing was predicted to further reduce N₂O emissions. Since the model was calibrated against experimental data during the first year after pasture termination only, experiments determining N₂O emissions in the first two or three years after terminating pasture are needed to confirm our predictions.     

基于APSIM模型模拟水氮调控对旱地春小麦(Triticum aestivum)叶面积的影响

本研究针对水氮调控对旱地春小麦(‘定西42号’)叶面积的影响,采用大田试验数据与农业生产系统模型(agricultural production system simulator, APSIM)的结合,分别设定不同降水和施氮梯度对叶面积的变化趋势进行研究,试验获取2015-2017年定西田间试验不同水氮肥施入的试验数据,并对模型予以检验。APSIM模型对叶面积模拟精度较高,决定系数(R2=0.96)、归一化均方根误差(NRMSE=27.37%)、模型一致性指标(D=0.91)。结果表明:(1)随施氮量的增加,叶面积指数呈现先增后减的趋势;(2)随降水量的增加,叶面积整体呈现单一增长趋势;(3)水氮耦合作用中,降水量在自然降水基础上增加20%,施氮量为157.5 kg/hm2时,叶面积指数最高达2.766。本研究为田间试验水氮肥的施入量提供科学依据,为旱地春小麦增产提供了理论参考。     

干旱条件下APSIM模型修正及华北冬小麦产量模拟效果

干旱是影响华北地区冬小麦产量的主要农业气象灾害之一,作物生长模型是评估干旱对作物产量影响主要方法之一,但作物生长模型对极端天气气候条件下（如干旱）作物产量模拟效果仍存在不确定性。为提高作物模型在干旱条件下对作物产量模拟的精准性,该研究利用调参验证后的农业生产系统模型（agricultural production systems simulator,APSIM）,通过查阅与华北地区冬小麦相关的186篇大田试验文献获得1 876对观测数据,以作物水分亏缺指数为干旱指标,评估APSIM模型在冬小麦拔节-开花和开花-成熟阶段干旱对产量影响的模拟效果,提出APSIM在拔节-开花和开花-成熟阶段干旱对小麦产量影响的修正系数。基于历史气候条件、SSP245和SSP585未来气候情景资料,分析了冬小麦拔节-开花和开花-成熟阶段干旱时空分布特征,并采用修正系数校正后的APSIM模型评估华北地区冬小麦拔节-开花和开花-成熟阶段不同等级干旱对其产量的影响。结果表明,APSIM模型低估了拔节-开花阶段干旱对冬小麦产量影响程度,轻旱、中旱和重旱校正系数分别为0.85、0.91和0.85;APSIM模型可准确模...     

陕西关中冬油菜生长发育不同模型模拟精度研究

在陕西关中地区进行了连续6年(2009年9月—2015年5月)的冬油菜非充分灌溉试验,利用STICS、DSSAT和APSIM 3种不同模型对冬油菜物候期和产量等进行模拟,比较了3种不同模型的模拟精度。结果表明,3种模型中STICS模拟精度最高,平均RARE为3. 24%,APSIM模型次之,平均RARE为8. 79%,DSSAT模型最差,平均RARE为11. 38%。其中STICS模型对物候期和产量的模拟精度均为最高,DSSAT模型对物候期的模拟精度高于APSIM模型,而APSIM模型对产量相关指标的模拟精度高于DSSAT模型。由于2012—2013年生育期内降水量较低,3种模型的模拟精度均较低,说明3个模型对干旱胁迫条件下的作物生长模拟均存在一定不足。综合比较,STICS模型的模拟精度高于DSSAT和APSIM模型,因此推荐STICS模型为关中地区冬油菜生长发育和产量形成模拟的适宜模型。     

不同耕作措施下春小麦产量对温度变化的敏感性分析

为了研究温度变化对不同耕作条件下春小麦产量的影响,利用修正参数后的APSIM模型,自变量因子分别为最低温度、最高温度,在9种变化条件下对传统耕作+秸秆还田(TS)、免耕(NT)、免耕覆盖(NTS)3种耕作措施下的春小麦产量进行了模拟,并利用Surfer软件对产量变化率进行了敏感性分析。结果表明:在三种不同耕作措施下,春小麦产量变化率对最高温度的变化更为敏感,最高温度升高,产量变化率呈负敏感;在传统耕作+秸秆还田和免耕覆盖耕作措施下,春小麦平均产量分别是2 268.8 kg·hm-2和2 274.0 kg·hm-2,明显高于免耕耕作措施下的春小麦平均产量1 815.4 kg·hm-2;传统耕作+秸秆还田和免耕覆盖耕作措施下,小麦产量随温度变化相对稳定;当最低温度和最高温度在一定区域范围内变化时,传统耕作+秸秆还田和免耕覆盖产量表现更稳定。