Aiming to enhance disaster damage assessment and prevention capabilities in rice production, we established a rice high-temperature early warning and disaster risk assessment system. Four representative rice varieties underwent high-temperature control experiments during key stages susceptible to heat injury. Using a rice development period model to calculate high-temperature damage rates, a risk assessment and early warning system for high-temperature stress in rice were developed. Single point and regional dynamic warning simulations of heat damage in rice was conducted and verified. The risk assessment results for high-temperature damage indicated a low risk for early rice in the double-cropping rice area of southeastern Fujian, mainly occurring during the flowering. Early rice in the northwestern double-cropping rice area experienced relatively high to sub-high risks, with frequencies between 62% and 80%. The mountainous single-cropping rice area in northwestern Fujian showed widespread susceptibility to low-risk heat injury. In 2020, a simulation of single-point dynamic warning for high-temperature stress in Fujian Province involving 12 representative rice varieties showed a higher probability of severe heat injury for early rice in the southeastern double-cropping rice area (disaster damage rate: 51.1–55.4%), while mild heat injury was observed in the northwestern double-cropping rice area (disaster damage rate:12.1–26.8%). The mountainous single-cropping rice area in northwest showed a relatively high probability of moderate heat injury (disaster damage rate:18.2–29.4%). The regional warning simulation results showed that the areas with severe heat damage was mainly concentrated in the southeast of Fujian, while the mountainous single season rice areas in the northwest was experiencing moderate heat damage. Overall, the risk of heat injury to both early and single-cropping rice in the northwest was more severe than in the southeast. Comparison of simulated disaster damage rates with actual local rice production disaster damage rates and meteorological yield trends demonstrated consistent and warning outcomes across spatial and temporal variations.

Rice is a staple grain crop extensively cultivated in Fujian Province, China. This study examined the impact of high-temperature stress on rice yield and its components, focusing on four representative rice varieties, including early and middle rice grown in Fujian Province. Results indicate significant yield losses, with the most severe reduction of 60.8% observed during the flowering stage of early rice and over 40% during the meiosis and flowering stages of middle rice. High-temperature stress primarily affects early rice yield more at the flowering stage than at the grain-filling stage, whereas in middle rice, it is more severe at the meiosis stage than at the flowering stage. Leveraging historical climatic data spanning the past 20 years, a simulation model for high-temperature stress on rice yield was developed to assess disaster-induced yield loss rates, aiming to enhance prevention and disaster damage assessment for rice under high-temperature stress. Application of the model to four rice planting sites in Fujian Province revealed contrasting temporal changes between loss rates and meteorological yield, with middle rice experiencing more severe damage than early rice. The model’s effectiveness is validated by the strong correspondence between yield loss rate and meteorological yield across different regions, highlighting its robust simulation capabilities.

[目的]通过研究高温对水稻产量形成的影响,构建水稻高温热害模型,旨在提高水稻高温热害的防御和灾损评估水平.[方法]选用福建省种植的4个代表性品种,分别于早稻开花期和灌浆期、中稻减数分裂期和开花期,设置不同温度水平T1(35℃)、T2(41℃)和高温胁迫持续天数D1(3 d)、D2(7 d),以适宜环境条件为对照(CK),分析不同处理下水稻产量及其构成因素的变化,并据此构建高温热害对水稻产量影响的综合模型.根据近20年气象资料,利用模型对福建省四个水稻种植样点的产量进行灾损评估.[结果]早稻在开花期T2D2高温处理时,单株产量降幅最大,为60.8％;两个品种的结实率降幅在T2D2处理下可达60％.灌浆期高温对早稻单株产量影响较小,T2D2处理下为17.8％,两个品种结实率和千粒重降幅最大值分别为11.6％和9.0％.中稻两个品种受减数分裂期高温影响后,在T2D2处理下的单株产量降幅最大可达43.6％,每穗粒数下降为17.4％,结实率所受影响明显大于千粒重,降幅分别为30.8％和9.8％.中稻开花期T2D2高温处理对产量影响最大,单株产量降幅可达42.1％,结实率和千粒重受高温影响后降幅最大分别为37.0％和5.7％.根据项目组研发的水稻发育期模型和本研究结果确定了4个供试品种的遗传参数,构建了水稻关键发育期的高温累积度时和高温处理后灾损率之间的定量关系,进而分别构建了早稻和中稻的高温热害模型.对4个水稻种植样点进行灾损模拟,发现各地损失率和气象产量的时间变化规律正好相反,且中稻较早稻遭受高温危害更为严重.[结论]早稻开花期高温热害对水稻产量的影响大于灌浆期,中稻减数分裂期高温热害的影响比开花期严重.通过本研究确定的4个供试品种的遗传参数在代表性样点对生育期的模拟效果较好.构建的早稻和中稻高温热害模型对四个代表性样点的灾损模拟效果较理想.

以宁麦13和扬麦23为供试材料,设置渍水(WG)、寡照(SG)和渍水+寡照(WS)3种胁迫处理方式,并在小麦拔节期、孕穗期及灌浆期进行不同持续时间(5、10、15 d)的盆栽试验处理,研究冬小麦不同生育期内渍水寡照胁迫对冬小麦干物质分配和产量的影响.结果表明:拔节期WG处理和WS处理导致茎分配指数增加,绿叶分配指数降低;孕穗期WG处理导致穗与绿叶分配指数下降,WS处理茎分配指数最高而绿叶分配指数最低;灌浆期WG处理导致茎分配指数增加,而使穗分配指数降低,WS处理茎、绿叶、穗分配指数所受影响均较小.拔节期SG处理绿叶分配指数降低,茎分配指数增加,孕穗期SG处理穗分配指数降低,灌浆期SG处理造成穗分配指数下降和茎分配指数增加.拔节期WG处理对产量影响最明显,宁麦13号和扬麦23号分别减产37.4％和28.5％;孕穗期和灌浆期均以WS处理减产幅度最大,孕穗期WS处理宁麦13号和扬麦23号产量分别下降47.9％和36.0％,灌浆期2个品种分别减产49.1％和37.3％.综合而言,拔节期不同处理导致的平均减产幅度最小(19.5％),而孕穗期不同处理导致的小麦平均减产幅度最大(28.7％).

长江中下游地区稻麦轮作的生产方式往往导致土壤排水不畅和养分流失.且该地区小麦生长季多阴雨,导致小麦渍害胁迫减产.探索合理的方法来缓解小麦渍害胁迫有重要意义.本研究开展盆栽试验,设置不同生物炭施用量和渍水处理,研究水稻秸秆生物炭对稻麦轮作土壤理化性质的影响.结果表明,随着生物炭施用量的增加,土壤容重呈下降趋势,有助于改善稻麦轮作土壤排水不畅的特点.同时,施用生物炭可显著增加土壤pH值、有机碳和有效磷的含量(P＜0.05).施用生物炭和渍水处理对土壤总氮含量没有显著影响,但生物炭施用量达到40 t/hm2时,渍水处理会导致土壤碱解氮含量显著下降(P＜0.05),表明生物炭有助于固定土壤氮.总体来看,施用水稻秸秆生物炭可改善稻麦轮作土壤的排水条件,维持土壤养分,有助于抵御渍害胁迫造成的小麦减产.

为明确稻田与邻近气象站的温湿度差异及其对水稻高温热害损失评估的影响,利用HOBO温湿度传感器,在江苏省南京市六合区柯郑村通过稻田小气候观测,分析了稻田与邻近气象站的温湿度差异,并利用水稻高温败育模型评估了该差异对水稻高温热害损失的可能影响.结果表明,从分蘖至成熟期,稻田的相对湿度比邻近气象站点高8百分点左右;分蘖至抽穗开花期稻田日最高温度比气象站点低1.1℃,灌浆期稻田与气象站日最高温度差异逐步减少,黄熟期后两者差异不大;而分蘖至抽穗开花期稻田日最低温度比邻近气象站低0.7℃左右.此后,随着低温过程的出现,稻田与邻近气象的日最低温度差异在增加,灌浆至成熟期差异达到2.0℃以上.当最高温度低于35℃时,考虑稻田和气象站点温度差异后,估算得到的败育率比直接利用气象台站数据低50％,随着高温指标的增加,该差异在减少.

农业气象灾害是制约作物高产优质的主要因素之一.长江中下游地区春季连阴雨天气导致的渍水寡照常常会对小麦生长发育过程造成严重影响.为定量研究其影响程度,本文选取了长江中下游地区的小麦主栽品种宁麦13和扬麦23作为试验材料,设置渍水、寡照以及渍水+寡照3种处理,在小麦拔节期和孕穗期进行不同持续时长(5、10及15 d)的胁迫试验以及灾后恢复试验,分析了渍水寡照对小麦发育进程、株高、叶片叶绿素含量及光合速率的影响.结果 表明:不同处理均导致2品种小麦的发育进程有所推迟,拔节期渍水和寡照的协同胁迫对小麦影响最大;小麦孕穗期受逆境胁迫后,将导致后期的籽粒灌浆以及成熟过程的延迟,且延迟时间与受胁迫的时长呈正相关;小麦的株高也会受到拔节期和孕穗期逆境胁迫的影响,孕穗期胁迫对株高的影响大于拔节期,其中渍水和渍水+寡照处理对株高影响显著,单一寡照胁迫影响较弱;不同生长阶段的渍水和渍水+寡照胁迫时,小麦的叶绿素含量出现不同程度下降;而寡照处理后叶绿素含量有两种不同的响应模式,拔节期单一寡照胁迫5d时,其叶绿素含量较对照更高,但随胁迫天数的增加而降低至对照水平之下;孕穗期寡照胁迫下,小麦的叶绿素含量均高于对照水平;各胁迫对小麦光合速率的影响表现为:受渍水或寡照的胁迫时间越长,光合速率下降幅度亦越大,其中拔节期光合速率对渍水+寡照的协同作用反应最敏感,孕穗期的光合速率变化在单一渍水胁迫时最明显.在拔节期受3种类型胁迫5d时,光合速率均能在短时间内恢复至对照水平,但随着逆境胁迫时间加长,其受抑程度加大,恢复所需时间亦越长,渍水+寡照胁迫时,对恢复过程影响最大;孕穗期渍水处理持续时长超过10 d或渍水+寡照胁迫处理15 d后,光合速率将无法恢复到对照水平,而寡照不同处理时长下,光合速率均可恢复.本研究结果可用于渍水寡照灾害损失评估,提升小麦生长模型在灾害下的适用性.

Waterlogging and sunlight shortage are important factors that significantly deteriorate the yield and quality of wheat. The objective of this study was to evaluate the effects of waterlogging and sunlight shortage on dry matter partition, yield and yield components in wheat. To quantify these effects, two wheat cultivars (i.e., Ningmai-13 and Yangmai-23) were selected, and three treatments of waterlogging (WG), sunlight shortage (SG) and waterlogging + sunlight shortage (WS) were set at jointing, booting and filling stages of wheat for different time durations (5, 10 and 15 days). The results showed that partition index of stem increased, while green leaf portioned index decreased significantly at jointing stage under WG treatment. At booting stage, WG treatment reduced green leaf and spike partition index. At the filling stage, the stem partition index was higher than CK, while spike partition index was lower than CK. Under the SG treatment, stem partition index was increased at jointing and filling stage, while decreased at booting stage. However, the influence of stresses increased as the treatment time duration extended at all stages. For yield, the WG treatment at jointing stage significantly decreased the yield by 37.4% and 28.5% for Ningmai-13 and Yangmai-23, respectively. At the booting and filling stage, WS treatment exhibited the most important influence. The yield of Ningmai-13 and Yangmai-23 decreased by 47.9% and 36.0% at booting stage, and 49.1% and 37.3% at filling stage, respectively. Overall, the yield declined was least at jointing stage, while significant at booting stage under different treatments. This study could provide synthesized novel insight for improving disasters effects on wheat and current wheat growth model.

Biomass partitioning is a pivotal part of the function-structure feedback mechanism. To improve the simulation of aboveground biomass partitioning in growth models for rapeseed (Brassica napus L.), we developed an aboveground biomass partitioning coefficient model for main stem and primary branches, and the stems, leaves, and pods on them, by quantifying the relationships between the biomass partitioning coefficient of major organs aboveground and physiological day of development (DPD). To realize this goal, dry matter data of organs were derived from an outdoor experiment with rapeseed cultivars Ningyou18 and Ningza19 under different fertilizer and transplanting density treatments in the 2012-2015 growing seasons. The model was fitted by calculating the partitioning coefficients of different organs as the ratio of the biomass of organs and their superior organs and normalizing DPD into the [0, 1] interval. Various model variables were parameterized to explain the effects of cultivar and environmental conditions on biomass partitioning coefficients for different organs. Our descriptive models were validated with independent experimental data, the correlation (r) of simulation and observation values all had significant level at P < 0.001, the absolute values of the average absolute difference (d(a)) are all less than 0.062, except for the main-stem pods, primary branch, primary-branch leaves model, the ratio of d(a) to the average observation (d(ap)) are all less than 6.263%, and r are all greater than 0.9 except primary-branch leaves and primary-branch stems model. The results showed that most models have good performance and reliability for predicting biomass partitioning coefficient of the main stem, the primary branch, and the organs on them. This sets the stage for linking a growth model with the biomass-based morphological model, for the development of a functional-structural rapeseed model.

Continuous rain is the main meteorological constraint for winter wheat production in Jiangsu Province, accompanied by stresses of both waterlogging and shading. To evaluate the independent and combined effects on winter wheat at jointing stage, pot experiments were conducted using two cultivars, Ningmai 13 and Yangmai 13. Four treatments, CK (non-stressed), WA (waterlogging alone), SA (shading alone) and WS (both waterlogging and shading) were established with different durations. In the non-stressed environment, Yangmai 13 had higher production than Ningmai 13. However, Ningmai 13 had better production under stresses, indicating a better tolerance to waterlogging and shading. Comparing dry matter distribution and grain production showed that the negative effects of the stresses were in the order WA > WS > SA, demonstrating that shading had compensative effects on waterlogging at jointing stage. Results indicate that production loss of winter wheat due to continuous rain at jointing stage might be overestimated.

耕地地块破碎区水稻遥感提取是作物监测研究的热点问题之一.以苏州市高新区为例,通过挖掘关键物候期水稻与下垫面水体光谱特征组合差异,基于分蘖期与齐穗期两景16 m分辨率的GF-1 WFV数据,构建归一化差值植被指数(NDVI)差值法、归一化水体指数和比值植被指数(NDWI-RVI)差值法提取水稻分布,并深入探究了水稻面积提取精度及空间重合度影响因素.结果显示:与非监督分类和监督分类方法相比,植被指数差值法水稻识别精度贡献率可提升30％以上,NDVI差值法提取水稻种植面积的精度、空间重合度、制图总体精度和Kappa系数分别为86.2％、66.1％、92.2％和0.72;NDWI-RVI差值法上述指标分别高达95.5％、78.4％、93.5％和0.846,实现了利用少量中高分辨率遥感影像精确提取耕地地块破碎区水稻分布的目的,可实际服务于太湖地区农业生产及相关决策支持.

ABSTRACT The interannual variations of the East Asian subtropical westerly jet ( EASWJ ) and its related precipitation and atmospheric circulations during early summer and midsummer were investigated. The possible causes for the contrast between early summer and midsummer were also investigated. The results indicate that, in early summer, the EASWJ is influenced by a teleconnection pattern spanning the middle to high latitude region from the North Atlantic to the East Asian coast. Associated with the eastward pointing wave activity flux ( WAF ) along this zonal propagated wave train, the height anomaly in the middle to high latitude of East Asia exhibits alternating negative−positive−negative distributions in abnormal southward EASWJ years, resulting in anomalous convergence and increased precipitation in regions south of the Yangtze River ( SYR ). However, in midsummer, the EASWJ is more closely related to lower latitude circulations. A south‐to‐north propagated WAF , which originates from the South China Sea and tropical western Pacific, is responsible for the maintenance of the anomalous EASWJ and western Pacific subtropical high. Associated with the stronger and westward shifted western Pacific subtropical high and abnormal southward EASWJ , precipitation increases in the Yangtze‐Huaihe River Valley and decreases SYR , and vice versa . Contrast in the EASWJ‐related preceding sea surface temperature (SST) between early summer and midsummer were also investigated. In early summer, the meridional displacement of the EASWJ was significantly influenced by the North Atlantic SST in the preceding March–April period, whereas in midsummer the EASWJ displacement was strongly connected to the tropical Pacific SST in the preceding April–June period.

Crop photosynthesis is sensitive to temperature variations, and the temperature dependence of photosynthesis is known to vary with growth environments and crop varieties. Crop models based on light use efficiency model, seldom correct parameter values related to the temperature dependence of photosynthesis for a specific crop, which unavoidably increases the simulation errors in dry biomass. In this paper, a scheme used to correct those parameter values was put forward with the rice crop model ORYZA2000 as an example to evaluate the scheme's performance. The temperature-controlled experiments were conducted to observe photosynthesis at heading stage of rice variety Liangyoupeijiu in 2012 and 2013. The data were first analyzed to retrieve photosynthetic characteristics from light response curves and CO2response curve. Based on their relationship with temperatures, temperature effect functions were established for all temperature sensitive photosynthetic parameters using Arrhenius and Peaked functions. A biochemical photosynthesis model was applied to simulate the changes of maximum leaf photosynthetic rate with temperatures, based on which temperature response curve for maximum leaf photosynthetic rate was produced and normalized to replace the default parameter values in ORYZA2000. The observations of above ground biomass (WAGT) of Liangyoupeijiu in two years were used to validate simulations before and after the correction. The normalized temperature response curve for maximum leaf photosynthetic rate of Liangyoupeijiu was different from the default response curve in ORYZA2000. From the corrected response curve, the optimal temperature for photosynthesis was between 38-40°C, higher than the default, and tem-perature effect coefficient was lower than the default between 10-20°C. Compared with the default parameter values, average relative error of the corrected parameter values was reduced by 3.3%. In conclusion, the method used in this paper can be an im-portant reference for improving biomass simulation accuracy and analyzing temperature dependence of photosynthesis for differ-ent crop varieties.

Waterlogging stress at different growth stages might have different effects on winter wheat yield,but the quantitative effects of waterlogging stress duration on wheat yield and its components are still unclear.To comprehensively evaluate the effects of waterlogging stress on winter wheat yield,Yangmai 13 was selected as the experimental cultivar,and pot experiment with different waterlogging stress duration (0,5,10 and 15 d) was conducted at jointing,booting and grain-filling stages,respectively,in the present study.Variations of winter wheat yield and its components under different treatments were investigated.Results of the two-year pot experiment showed that,waterlogging stress at different growth stages all caused yield losses of winter wheat,and the yield at different growth stages all showed a significant loss (P＜0.05) as the increase of waterlogging stress duration.The waterlogging induced yield losses showed a tendency that booting stage＞ jointing stage＞ grainfilling stage.The yield per plant was decreased by 0.79,0.59 and 0.48 g,respectively,for an extra day under stress,indicating that booting stage is the most sensitive growth stage of winter wheat to water logging stress,compared with jointing and grain-filling stages.Furthermore,waterlogging stress at different stages showed distinctly different effects on yield components.Waterlogging stress at jointing stage led to a reduction in spike number per plant,kernel number per spike and thousand-kernel weight simultaneously.And the yield loss at jointing stage was mainly resulted from the reduction of kernel number per spike.Waterlogging stress at grain-filling stage had a limited effect on spike number per plant and kernel number per spike,due to that the two yield components had been determined at early growth stage.The yield loss at grain-filling stage was mainly resulted from the reduction of thousand-kernel weight.Booting stage is the stage when vegetative growth converts to reproductive growth.Thus,waterlogging stress at this stage always induced more yield losses.By comparing the yield component,the reduction of spike number per plant and kernel number per spike were more severe under waterlogging stress at booting stage than that at grain-filling stage,while reduction of thousand-kernel weight was more severe under waterlogging stress at booting stage than that at jointing stage.The results could explain why waterlogging stress at booting stage,compared with the other two growth stages,was most sensitive to the winter wheat yield,and induced a more severe yield loss.To prevent the yield loss caused by waterlogging stress,meteorological conditions around booting stage should be paid close attention to,and ditching for drainage should be conducted simultaneously in the field for winter wheat production.Results of the present study showed that yield losses caused by waterlogging stress were closely related to the growth stage of winter wheat.

[Objective]Crop rotation of rice and winter wheat is a common farming practice in areas of the middle and lower reaches of the Yangtze River. However,the paddy soils under such a cropping system are always heavy in texture,and tend to bring about waterlogging stress to the crop of winter wheat during its growing season under monsoon climate of winter wheat,thus inducing severe yield losses or loss of the whole crop. It is,therefore,essential to seek for a low cost and environment friendly method to alleviate yield losses caused by waterlogging stress for the sake of local food security. Biochar is an effective soil amendment and can be used to reduce soil hardening and enhance soil organic carbon sequestration. Nowadays, researches have has been carried out on application of biochar in areas under the crop rotation system in the middle and lower reaches of the Yangtze River. However,little has been reported on quantitative evaluation of the effect of biochar alleviating waterlogging stress of winter wheat in South China.[Method]Therefore,in the present study,soil column and plot experiments were conducted to investigate effects of application of biochar derived from rice straw in paddy fields under the rotation system on growth of winter wheat at its early stage,in an attempt to obtain a preliminary evaluation of the prospects of biochar application to alleviate waterlogging stress. Effects of biochar application varying in rate on soil bulk density and soil water content at different depths were evaluated through the soil column experiment,and its effects on wheat germination and wheat growth at early stage were through the plot experiment.[Result]Results show that biochar application significantly reduced bulk density of the soil. When biochar was applied at a rate of 10 and 40 t hm-2,soil bulk density was lowered by 7.4% and 11.4%,respectively,compared with CK(the treatment with no biochar applied). Dynamics of the soil in water content varied with soil depth. biochar application facilitated soil water percolation,thus alleviating the risk of waterlogging. Specifically,in the soil applied with biochar,soil water content at 20 cm in depth dropped rapidly after a simulated rainfall event compared with that in CK. The changes in physical properties of the soil applied with biochar indicated that drainage conditions of the soil were improved,favoring growth of winter wheat. In addition,compared with CK,biochar application at a rate of 10 t hm-2(BC)accelerated seed germination and promoted wheat growth at its early stage. Samples of winter wheat were collected on D90 after sowing for analysis of plant height, taproot length and chlorophyll relative content(SPAD value)of the new fully expanded leaf. It was found that they were all significantly higher in the treatments applied with biochar than in CK(p<0.05). The findings fully demonstrate that biochar application is beneficial to wheat growth at its early stage. However, its effects on dry matter weight of root,stem and leaf were not significant. In terms of characteristics of the root system,the plants in the biochar treatments had longer taproot than those did in CK,but did not differ much in total root length and total root area,which may be explained by the heavy texture of the soil CK. In such soils,the plant can not have its taproot go deep and for compensation have more lateral roots developed for water and nutrient absorption.[Conclusion]On the whole,biochar application can significantly improve drainage of the soil under crop rotation and benefit growth of the wheat at its early stage. All the findings listed above demonstrate that biochar application has the potential to alleviate waterlogging stress. However,further efforts should be made to study effects of biochar application on physiology and yield of winter wheat subjected to waterlogging so as to validate the hypothesis.

SUMMARYClimate change has greatly affected agricultural production, and will lead to further changes in cropping system, varietal type and cultivation techniques for each region. The potential effects of climate change on rice production in Fujian Province, China, were explored in the current study with CERES-Rice model and climate-change scenarios, based on the self-adaptation of rice production. The results indicated that simulated yields of early rice in the double-rice region in south-eastern Fujian under scenarios A2, B2 and A1B increased by 15·9, 18·0 and 19·2%, respectively, and correspondingly those of late rice increased by 9·2, 7·4 and 7·4% when self-adaptation adjustment was considered, compared to scenarios without that consideration. In the double-rice region in north-western Fujian, simulated yields of early rice increased by 21·2, 20·5 and 18·9% and those of late rice by 14·7, 14·8 and 7·2% under scenarios A2, B2 and A1B, respectively, when self-adaptation was considered, compared to without consideration. Similar results were obtained for the single-rice region in the mountain areas of north-western Fujian, correspondingly increasing by 4·9, 5·0 and 2·9% when self-adaptation was considered compared to when it was not. In this single-rice region, double rice might be grown in the future at the Changting site under scenarios A1 and B2. When the self-adaptation adjustment was considered, the simulated overall output of rice crops in Fujian under scenarios A2, B2 and A1B increased by 5·9, 5·2 and 5·1%, respectively. Thus, more optimistic results were obtained when the self-adaptation ability of rice production was considered.

Daily relationships between the maximum temperature in field conditions and rice seed setting rate were investigated by using the medium season late maturity hybrid rice variety regional trial data during 2004-2011 and daily maximum temperature data during 1984-2013 at 6 representative sta tions in the middle and lower Yangtze River Valley.It was pointed out that the high temperature sensitive period of the midseason rice in the middle and lower Yangtze River Valley mainly sustained from 4 to 36 days before the full heading stage.High temperature around 14 days before the full heading stage (near the meiotic phase) had the most important influence on the midseason rice seed rate in the middle and lower Yangtze River Valley.According to the daily maximum temperature during the meiotic phase,the high temperature-induced rice sterility simulation model which was developed by our project team was used to quantitatively forecast the high temperature-induced sterility of rice in the middle and lower Yangtze River Valley at the site scale.The RMSE of the simulated (year 2004) and forecasted (year 2007) relative seed setting rate was 4.74％ and 2.84％ respectively.The analysis showed that the high tempera ture damage of rice in the middle and lower Yangtze River Valley could be well forecasted by using the quantitative forecast method based on the high temperature-induced rice sterility simulation model.

选取扬麦13作为供试小麦品种,在拔节期、孕穗期和灌浆期设置4种不同遮阴持续时间(0、5、10、 15 d)的盆栽试验,模拟不同遮阴处理对小麦产量及其构成的影响.2年的盆栽试验结果表明,在不同生育期遮阴均导致小麦产量下降,且随遮阴时间延长,不同生育期小麦产量均显著下降.下降幅度呈现为拔节期>孕穗期>灌浆期,遮阴每增加1 d,产量分别下降1.53、1.30、1.16 g/株,表明拔节期是小麦阴害胁迫的敏感期.遮阴在不同生育期对小麦产量构成的影响存在显著差异.拔节期和孕穗期遮阴主要通过降低小麦穗粒数造成产量下降;灌浆期遮阴对小麦穗数和穗粒数的影响较小,主要通过降低千粒质量造成小麦产量下降.说明遮阴造成小麦减产与小麦所处生育阶段密切相关,在评估阴害对小麦产量的影响时,应考虑小麦所处生育期对产量及其构成影响的差异.

[Objective]Grain number per panicle is one of yield component factors for rice. In order to analyze the effect of high temperature on the grain number per panicle and develop the quantitative model to evaluate it, [Method]a pot experiment under different high temperatures and durations during meiosis stage was conducted with Liangyoupeijiu and Nanjing 45 as materials in 2014-2015. [Result]Grain number per panicle decreased with the rising temperature and prolonging duration exposed to high temperature. The relationship between grain number per panicle and temperature could be expressed with a quadratic equation. The terminal time of grain number per panicle sensitive to high temperature was five days before heading date. The validation result showed the model could better simulate the effect of high temperature during meiosis stage on the grain number per panicle with rRMSE 0.094 and 0.085 for Liangyoupeijiu and Nanjing 45, respectively. [Conclusion]This study would help improve the quantitative effect of high temperature on rice growth duration.

长江中下游稻区一季稻在抽穗开花期时常遭受低温冷害,因此确定一季稻安全齐穗期对于优化农事活动安排和降低灾害影响具有重要意义.在已有水稻安全齐穗期指标的研究基础上,拟结合水稻障碍型冷害损失评估模型,以长江中下游一季稻为例,通过模拟推算1981-2014年逐年水稻空壳率,并以多年80%保证率下超过生理空壳率的起始日期作为水稻安全齐穗期的确立依据,获得4种不同耐寒性水稻安全齐穗期的空间分布.结果显示,耐寒性最弱的籼稻安全齐穗期平均在8月30日,耐寒性较弱的粳稻为9月10日,耐寒性较强的粳稻为9月12日,耐寒性强的粳稻则为9月20日.模型推算的安全齐穗期普遍早于传统安全齐穗期指标的推算结果,平均约为14 d;相差最小的是耐寒性强的粳稻,模型推算约提前7 d,相差最大的是耐寒性最弱的籼稻,模型推算约提前23 d.由结果可见,从温度、空壳率2个方面约束水稻安全齐穗期,比仅从温度角度确定的安全齐穗期更有利于降低抽穗开花期遭遇障碍型冷害的风险,为研究区一季稻安全生产和农事活动安排提供了重要的参考.