Re-establishing a current rule on the grading of drought and flood in Nanjing from 1470 to 2012, based on historical drought and flood grades data in Nanjing from 1470 to 1950, monthly precipitation data from Nanjing National Basic Meteorological Station from 1951 to 2012 and the drought and flood grades standards for precipitation classification in "Chinese Map Collection of Drought and Flood Distribution in the Past Five Hundred Years". Morlet wavelet analysis and moving mean t-test were used as the research methodology to analyze the evolution characteristics of the drought and flooding grade series in Nanjing from 1470 to 2012. The result showed that between 1470 and 2012, it experienced 160 years of drought, 167 years of flooding and 216 years of normal conditions in Nanjing. Severe floods, severe droughts occur frequently and intensively. The occurrence of droughts and floods in Nanjing showed distinct phases. Drought dominated from 1470 to 1554, 1625 to 1652, and 1912 to 2012. From 1653 to 1805 and from 1849 to 1912, the normal dominated. Between 1806 and 1848 there was a significant alternating pattern of droughts and floods, and the region had experienced more droughts than floods over the past century. The drought and flood levels in Nanjing also exhibit multi−scale periodic oscillations, with the most significant oscillations occurring on time scales of 2−8y and 10−20y. Following these, there were long-period oscillations on the scales 64y, 32y, and 16y. At the present, the Nanjing region had entered a period of oscillation within the 2−8y period. In different time series, significant drought−flood mutations occurred around the years in 1554, 1615 and 1914, characterizing the climatic evolution of dry periods-pluvial periods-dry periods. Since the 20^th century, the duration of moderate flood in Nanjing had been shortened by a trend towards aridity. 

Based on the temperature and precipitation data from 50 meteorological stations on the Qinghai plateau from 1991 to 2022, the climate resources and climatic productive potential of the Qinghai plateau were evaluated by using the Miami and Thornthwaite Memorial models, mathematical statistics and R/S analysis under the background of the new climatic state. The results showed that: (1)the overall climate of the Qinghai plateau in the new climate state tended to be warm and humid, with an annual average temperature trend rate of 0.46℃·10 y⁻¹(P<0.01), with a significant warming in Tongde. The climate tendency rate of annual precipitation was 23.6mm·10y⁻¹(P<0.01), and there was a significant increase in humidity in Guinan. (2)The climate tendency rate of climatic productive potential on the Qinghai plateau was 27.7g·m⁻²·10y⁻¹(P<0.01), showing a significant upward trend. In addition, there were significant spatial differences in the climatic productive potential of the Qinghai plateau. (3)The increase in climatic productive potential was related to increase temperatures and precipitation. The climate warming and humidification were conducive to the increase in climatic productive potential. (4)The variation characteristics of the spatiotemporal distribution of climatic productive potential on the Qinghai plateau were closer to the trend of precipitation and precipitation was the most important factor affecting climatic productive potential. (5)The Hurst indices for average temperature, annual precipitation and climatic productive potential on the Qinghai plateau were 0.48, 0.28 and 0.36, respectively. The future trend was opposite to the past, and the climate may tend to be cold and dry, resulting in a continuous decline in climatic productive potential.

Based on soil gravimetric water content data at depths of 0−50cm collected during crop growth stages at the Wuwei Desert Ecological and Agricultural Meteorological Experiment Station over the past 12 years (March 2011-July 2022), contour plots were employed to analyze the spatial and temporal distribution in soil moisture derived from both automatic and manual observations in farmland of arid region, the differences and correlations between these methods were quantified using statistical indices such as root mean square error(RMSE) and absolute error(E), employing statistical indices such as RMSE, absolute error(E), and relative error(RE), comparative analysis of the differences and correlations between the methodologies was conducted, and this study identified the dynamic changes in soil moisture using different measurement methods, and corrected the automatically observed soil moisture data using regression equations. The results showed these were some differences in the spatial and temporal variation of soil moisture between automatic and manual observations. However, the overall change trend in soil moisture was roughly the same. The soil gravimetric water content of automatic observation was lower than manual observation, and the mean absolute error (E) was 2.4 percent points(PP). From the perspective of each soil layer, the average soil gravimetric water content observed for many years was the largest in 0−10cm soil layer. The frequency of absolute difference E<5 percent points of soil gravimetric water content in 10−40cm soil layer could reach more than 80%, and the frequency of absolute difference E<5 percent points of soil gravimetric water content observed in 40−50cm soil layer was 73.3%. In addition, the error value in the soil gravimetric water content in 20−30cm soil layer was the smallest under many years of observation. By correcting the soil moisture data of automatic observation, the frequency of absolute difference E<5 percent points of soil gravimetric water content in each soil layer reached more than 80%, which improved the accuracy of agricultural meteorological automatic monitoring data in arid areas, and further provided certain technical support and theoretical basis for farmland soil moisture drought warning and monitoring.

Statistical data from Yunnan province between 2010 and 2019, including crop production sown area, yield and agricultural input materials during crop growth were selected to estimate the carbon emissions caused by agricultural inputs in the crop production process. The dynamic changes in carbon emissions, the proportion of each input in total carbon emissions, and the influencing factors of carbon emissions from agricultural inputs were analyzed. The results indicated that the carbon emissions and carbon emission intensity of agricultural inputs in crop production in Yunnan province from 2010 to 2019 showed an inverted “U” trend, with 2016 as the turning point, and a significant increase in carbon efficiency observed after 2016. Among the agricultural inputs, fertilizer contributed the most to carbon emissions, accounting for approximately 60.35% of the total emissions. Agricultural film, diesel, pesticides and irrigation accounted for approximately 17.55%, 12.77%, 8.25% and 1.08% of the total carbon emissions, respectively. National policies, crop planting structure, market demand, scientific planting techniques and agricultural production management systems had a significant impact on the changes in carbon emissions from agricultural inputs in crop production. It is recommended to strengthen national policy guidance, improve crop production technology levels, establish a mature agricultural management system, reasonably plan crop planting structures, reduce carbon emissions from agricultural production and promote green agricultural development.

 In this study, the two parameters (a and b) in the Ångström-Prescott (A-P) model for estimating solar radiation (R_s) were calibrated and validated at the seasonal and annual scales using the observations of R_s and sunshine hours from the three meteorological stations (Yan’an, Xi’an and Ankang) in Shaanxi province. Furthermore, the Penman-Monteith method was applied to calculate the reference crop evapotranspiration (ET₀) using the daily meteorological data from 92 stations in Shaanxi province from 1971 to 2021. The spatiotemporal variation characteristics of ET₀ were analyzed by linear regression analysis and Hurst index after Anusplin interpolation in Shaanxi province as a whole and in its three regions (northern Shaanxi, central Shaanxi, and southern Shaanxi). The results showed that: (1) the recommended values by FAO for the two parameters were not suitable for Shaanxi province. The ranges of calibrated parameters a and b at the three stations were 0.14−0.19 and 0.53−0.58 respectively. Annual scale with simpler calibration process was the relatively optimal choice. (2) Compared with the calibrated parameters at the annual scale, the ET₀ values estimated using FAO recommended values were overestimated by 8.6% in Shaanxi province overall. Specifically, the overestimations were 9.3%, 4.8% and 11.8% in northern Shaanxi, central Shaanxi, and southern Shaanxi, respectively. Regarding individual seasons, the overestimations were 7.5%, 9.5%, 8.1%, and 2.9% in spring, summer, autumn and winter, respectively. (3) From 1971 to 2021, the ET₀ values in Shaanxi province ranged from 764.54mm to 986.06mm, with higher value in central Shaanxi, followed by southern and northern Shaanxi. The temporal and future trends of ET₀ in the province and its three regions were not significant. The ET₀ in the spring, summer, autumn and winter seasons contributed to approximately 30.8%, 40.5%, 18.1% and 10.6% of the annual ET₀, respectively. In northern and southern Shaanxi, the seasonal ET₀ trends were not significant, whereas in central Shaanxi, the ET₀ showed significant increasing and decreasing trends in the spring and summer seasons, respectively. The future trends of seasonal ET₀ in the Shaanxi province and its three regions were not significant.

Based on the monthly near−surface wind speed (sfcWind), surface downwelling short wave radiation (rsds) and precipitation (pr) from the 5 global climate models that participated in the phase 6 of the Coupled Model Intercomparison Project (CMIP6), the ERA−5 reanalysis data and the 83 observational stations over Guizhou, the characteristics of wind/solar/precipitation resources in Guizhou under three scenarios (SSP1−2.6, SSP2−4.5 and SSP5−8.5) were evaluated, using Quantile-Mapping to improve the simulation capabilities. The results showed that compared to the reference period (1995−2014), although there was little change in the relative anomalies of sfcWind under SSP2−4.5 and SSP5−8.5, the relative anomalies of sfcWind under SSP1−2.6 increased statistically significant at the level of 0.01 over Guizhou during 2025−2100, as well as rsds and pr under three scenarios, with growth of 1.22 percent points·10y⁻¹ (sfcWind, SSP1−2.6), 1.32/1.65/1.88 percent points·10y⁻¹ (rsds, SSP1−2.6/2−4.5/5−8.5) and 1.77/1.88/2.97 percent points·10y⁻¹（pr, SSP1−2.6/2−4.5/5−8.5）. Besides, the increases in rsds and pr were found generally in Guizhou during 21^st century with respect to 1995−2014, rising from west (near) to east (far) under three scenarios, while sfcWind had different change for different scenarios and areas. Taking the wind/solar/ precipitation resources at the 14 representative stations under SSP2−4.5 in Guizhou during the near−21^st century for example, the within and cross−regional complementarity was detected. Citing the case of Weining station from Jan to Dec, the seasonal complementarity was indicated due to making full use of solar/precipitation resources in summer and wind resource in winter/spring.

In order to explore the effect of sowing date on rice spikelets of main stem under different planting pattern (early−season rice, mid−season rice, ratoon rice and late−season rice planting pattern), an experiment with four sowing dates were conducted from 2018 to 2022 in Nanchang, Jiangxi province, in which the main varieties grown in Jiangxi were used. The results showed that the growth time required from sowing to heading stage for early−season rice and ratoon rice planting patterns showed a shortening trend with the sowing date were delayed, while the late−season rice planting pattern showed a longer trend with the sowing date were delayed. The sowing date had an extremely significantly (P<0.01) impact on the number of primary branches, secondary branches, and total spikelets on main stem under four planting patterns. Timely and early sowing of early-season rice and ratoon rice planting pattern were beneficial to increasing the number of primary branches, secondary branches, and total spikelets on main stem. Sowing early or late in middle−season rice and late−season rice planting pattern were not conducive to the increase of the number of primary branches, secondary branches, and total spikelets on main stem. There were an extremely significantly (P<0.01) correlation between the number of secondary branches and the total spikelets on main stems in four planting pattern. there were a significant correlation between the number of primary branches and the total spikelets on main stem in the middle−season rice, ratoon rice and late−season rice planting patterns (P<0.05), but the correlation with the total spikelets on main stem of early−season rice planting pattern was not significant. The correlation coefficient showed that the number of secondary branches > the number of primary branches. Path analysis showed that the contribution rate of the number of secondary branches to the total spikelets on main stem in each planting pattern were greater than the number of primary branches. In summary, the sowing date of four planting patterns in Jiangxi had a great impact on the number of primary branches, secondary branches, and total spikelets on main stem. It was necessary to reasonably arrange the sowing dates of four rice planting pattern. Among them, under the conditions of this experiment, the sowing dates of early−season rice and ratoon rice planting pattern were suitable to been advanced to March 11 and March 15 respectively, and the sowing dates of middle-season rice and late-season rice planting pattern were suitable to been arranged on May 15 and June 20−23 respectively, and it was beneficial to increase the number of primary and secondary branches, and then increased the total spikelets on main stem.

Tomatoes are sensitive to low temperatures. The frequent occurrence of prolonged suboptimal temperature stress in recent years has posed significant threats to tomato production. To mitigate these effects, an experiment was conducted using the tomato variety ‘Yuanshuai No. 1’ in a controlled climate chamber. Seven treatments were set up: normal temperature (day/night 25/16±1℃), which was the normal temperature control (CK); suboptimal temperature (day/night 16/8±1℃), which was the suboptimal temperature control (CKL), foliar spraying of EBR which was EBR treatment, root application of 5mL·L⁻¹HIDS which was H1 treatment , root application of 15mL·L⁻¹HIDS which was H2 treatment, combined application of 5mL·L⁻¹HIDS and EBR which was E+H1 treatment, and combined application of 15mL·L⁻¹HIDS and EBR which was E+H2 treatment. The effects of root application of HIDS and foliar spraying of EBR (brassinolide) on tomato growth, photosynthesis, yield, and quality under suboptimal temperature during the seedling stage were studied. The results showed that suboptimal temperature inhibited tomato growth, leading to shorter plants, reduced photosynthetic capacity, and lower yield and quality. Under suboptimal temperature, the EBR treatment alone increased stem diameter, improved net photosynthetic rate (Pn), and significantly increased the number of fruits by 21.48% compared to CKL. With the addition of 5mL·L⁻¹ HIDS (H1) to the nutrient solution under suboptimal temperature, all growth indicators of tomato showed an upward trend compared to CKL, with increased photosynthetic pigment content and Pn, improved yield, and higher contents of soluble protein, soluble sugar, reduced Vc, and free amino acids. When foliar spraying of EBR was combined with H1 (E+H1), the leaf area of tomatoes increased significantly by 52.63%. With the addition of 15mL·L⁻¹ HIDS (H2) under suboptimal temperature, there were improvements in growth indicators, photosynthetic capacity, fruit yield, and quality. When EBR was also applied (E+H2), the stem diameter increased by 19.04% compared to that affected by CKL, chlorophyll and carotenoid contents also increased, and fruit yield significantly rose by 22.23%, along with higher contents of soluble protein, soluble sugar, and reduced Vc. Thus, under suboptimal temperature during the seedling stage, both individual and combined applications of HIDS and EBR led to upward trends in tomato growth indicators, increased stem diameter, shortened internode length, increased leaf area, enhanced Pn, and improved fruit yield and quality. The combination of root application of 15mL·L⁻¹HIDS and foliar spraying of EBR (E+H2) showed the best results.

 Yunnan province has a complex geographical environment, where altitude differences are larger from place to place and regional climate differences are significant. However, the province has the largest tobacco leaf production in China, and its flue-cured tobacco growing areas are spread over an altitude interval of 1000-2000m. In order to understand the internal relations between chemical quality of flue-cured tobacco and planting climate conditions, based on the field experiments and related climate data in 10 counties（districts） of Yunnan province from 2017 to 2020, the methods of principal component analysis and correlation analysis were used to analyze the effects of planting climates on the contents of nicotine（Nt for short）, total nitrogen（Tn） and protein （Pt） inside local tobacco leaves. The results showed that 35 samples with above−mentioned three tobacco chemical composition indices (constituted a dependent variable field) and 13 climate factors for each of 5 growth stages (constituted five climatic variable fields) were obtained through the tobacco field trial at 10 sites from 2017 to 2020. The cumulative degree for the first two or three principal components of any of the variable fields to account for the total variance of the temporal and spatial variability of the corresponding original variables was more than 82%. In the climate variable fields, the third principal component (F3 for short) of flue−cured tobacco field growth period （from mid−April to late August） and the F3 of mature period （from July to August）, which reflected the air humidity and amount of precipitation, were significantly positively correlated with the first principal component (F1) of tobacco chemical components variables field（P<0.05）, which expressed the contents of Tn and Pt inside tobacco leaves. The second principal component (F2 for short) of field growth period for flue−cured tobacco and the F2 of vigorous growth and mature period （mainly from June to August）, which reflected the advantages and defects of heat conditions, together with the F2 of vigorous growth period （from late May to late June）, which represented minimum temperature, were significantly negatively correlated with the F2 of tobacco composition variables field （P<0.05）, which expressed the Nt content of tobacco leaves. All of the above five principal components of the climate variable fields indicated that certain climatic factors had a synergistic effect on the accumulation of certain chemical components inside tobacco leaves. Above these results indicated that the relatively large air humidity and the amount of precipitation during tobacco field growth period and mature period were favorable for increasing the contents of Tn and Pt  inside Yunnan tobacco leaves. The relatively abundant heat in tobacco field growth period and during the vigorous growth and mature period, together with the higher minimum temperatures during the vigorous growth period, were detrimental to the formation and accumulation of Nt inside tobacco leaves. Bacause Yunnan is located in the low latitude plateau region and affected by southwest monsoon, the climatic conditions of most local tobacco planting areas for the whole vigorous growth and mature period of flue−cured tobacco were as follows: the average temperature was not higher than 22.0℃, the mean daily amount of precipitation was more than 5.5mm·d⁻¹, the average relative humidity was bigger than 80%, the mean daily sunshine duration was lesser than 5.0h·d⁻¹ and the average diurnal temperature range was greater than 8.0℃. Such climatic conditions resulted in a weakening of transpiration and photosynthesis, an increase in the temperature effectiveness of tobacco, and a prolonged period of growth and development of flue−cured tobacco, which were the main reasons for the relatively higher contents of the above three chemical compositions inside the tobacco leaves in Yunnan. The conclusion about the influences of climatic factors on the chemical quality of flue−cured tobacco leaves was verified by the relevant data from several provinces which annually produce large quantities of tobacco leaves in China. In view of Yunnan's significant interannual climatic fluctuations, distinctive climate conditions and regional climate differences, the results of the analysis can be applied to the development of characteristic tobacco leaves based on different local climate conditions. They would also help to predict/assess the changes in the chemical quality of tobacco leaves on the basis of the climatic fluctuations, which was intended to provide a scientific basis for the tobacco industry to rationally deploy raw tobacco leaves from different producing areas.

Spring maize field trials were conducted in 2022 and 2023 in the Yinhuang Irrigation District of Ningxia, respectively, using a one-way randomized block design with a total of six potassium application levels of 0, 60, 120, 180, 240 and 300kg·ha⁻¹, which were recorded as K0, K1, K2, K3, K4 and K5, respectively. To analyze the change rule of photosynthetic parameters of spring maize leaves, the interrelationship between filling characteristics and yield under different potassium fertilizer treatments, to study the effects of different potassium application rates on the photosynthetic physiological characteristics, filling characteristics and yield of spring maize under drip irrigation and water−fertilizer integration, and to clarify the optimal potassium application rate for spring maize under drip irrigation and water−fertilizer integration technology. The results showed that the photosynthetic potential (LAD) of spring maize before flowering (V6-R1) accounted for about 20% of the whole reproductive LAD, and the post-flowering (R1−R6) LAD accounted for 80% of the whole reproductive LAD, and the accumulation of spring maize substances mainly occurred after flowering. The net photosynthetic rate (Pn) of spring maize leaves all reached the maximum peak in the R1 stage, and the K3 treatment significantly increased by 18.00% compared with the K0 treatment. Maximum grain growth (W_max) reached maximum in 2022 and 2023 in K3 treatment, which was 4.83% to 11.41% and 4.82% to 6.89% higher compared to other treatments, respectively. In addition, the number of days of grain filling duration (T) and the period of active filling were both maximized (P) in the K3 treatment. With the increase of potassium application, the maize yields all showed an increasing and then decreasing trend, and the K3 treatment had the largest yield, which was 14767kg·ha⁻¹ and 14964kg·ha⁻¹ in 2022 and 2023, respectively. Pearson's correlation analysis showed that there were highly significant positive correlations between photosynthetic potential, stomatal conductance and yield, and significant correlations between net photosynthetic Pn, intercellular carbon dioxide concentration(Ci), transpiration rate(Tr), W_max and P; Principal component analysis showed that the K3 treatment had the highest overall score for maize yield optimization. It indicates that reasonable application of potash fertilizer can effectively ensure photosynthesis of spring maize, prolong the duration of grouting and maximum grouting rate, increase the amount of maize growth at the maximum filling rate, increase the maximum filling rate, promote the transformation of substances, and thus improve the yield of spring maize.

 Maize-alfalfa intercropping system is a new planting model to solve the problem of single cropping system in the cinnamon soil areas of Liaohe plain. To explore the interspecific competition relationship between maize and alfalfa and over yielding mechanism, and optimize maize-alfalfa intercropping configurations in cinnamon soil areas of Liaohe plain, a two-year (2021−2022) field experiment was conducted in Haifeng farm, Fuxin town, Liaoning province. The experiment was conducted in a completely randomized block design, consisting of five cultivation design, such as intercropping system of 2 rows maize and 2 rows alfalfa (2M2A), and intercropping system of 2 rows maize and 4 rows alfalfa (2M4A), and intercropping system of 4 rows maize and 4 rows alfalfa (4M4A), and sole maize (M), and sole alfalfa (A). Crop yield, dry matter accumulation and distribution of maize, and the competition relationship between maize and alfalfa under different row ratio configuration conditions were studied. The results showed that maize-alfalfa intercropping system had significant effects on maize dry matter accumulation and distribution, crop yields,interspecific competitiveness and productivity. The dry matter accumulation of maize in intercropping system at jointing stage was 2.2%−7.1% higher than that in monoculture, 17.8%−46.8% higher at silking stage and 21.8%−40.3% higher at milk ripening stage. Dry matter partitioning ratio to stem at jointing stage and silking stage and to ear at milk ripening stage increased in all intercropping systems, comparing with that of the sole maize system. The net yield of intercropping maize was significantly increased, with an average increase of 16.3%−26.4% in the two experimental years, but the net yield of intercropping alfalfa was significantly reduced, with an average decrease of 26.8%−48.0% in the two experimental years. The homogenized yield of intercropping maize and intercropping alfalfa was lower than that of monoculture due to the influence of crop area ratio. Maize was more competitive than alfalfa in maize−alfalfa intercropping system(C_MA＞0), and maize was the dominant crop, and alfalfa was the inferior crop. The order of C_MA was 2M2A>2M4A>4M4A. C_MA was significantly negatively correlated with the net yield of alfalfa. The interspecific competitiveness between maize and alfalfa significantly reduced the yield of alfalfa, resulting in changes in productivity of maize-alfalfa intercropping system. Interspecific competitiveness between maize and alfalfa could be regulated by adjusting row ratio configuration and strip width. The net yield of maize and alfalfa of 2M4A was the highest among three intercropping systems due to its C_MA was suitable. The land equivalent ratio of 2M4A was 1.01, which had certain intercropping advantage. It was concluded that 2M4A is suitable for popularization and application in the cinnamon soil areas of Liaohe plain.

Based on the daily air temperature and the water temperature monitoring data at 30cm depth from four crayfish-rice ecological meteorological stations in the primary production areas of crayfish in Hubei province during the period from March to May 2022−2024, a spring water temperature simulation model was established. Combined with daily meteorological data from 76 national basic meteorological stations in Hubei province from 1981 to 2022, using the moving average method to calculate the start seedling period for crayfish in Hubei province, analyzing spatiotemporal distribution characteristics of low-temperature cold damage during the spring seeding period of crayfish in Hubei province, a risk index model of low-temperature cold damage was constructed to evaluate the low-temperature cold damage risk of crayfish in different seedling periods in Hubei province, so as to provide scientific basis for the healthy and sustainable development of crayfish industry. The results indicated that the determination coefficient R² of the spring water temperature simulation model based on the average air temperatures of the current day, the previous day, and two days prior constructed in the study was 0.874. The root mean square error (RMSE) and relative error (RE) of the model validation were 1.14℃ and 5.14%, respectively. The model has high simulation accuracy and is able to predict the daily average water temperature in spring throughout the province. The main occurrence of low-temperature cold damage to crayfish during the seedling period in spring in Hubei province is in late March, with a frequency of 29.3%, 20.5%, and 0.2% for slight, moderate and severe damage respectively. There are differences in the occurrence time of low temperature cold damage in different regions: the occurrence time of low-temperature cold damage in southwestern Hubei was in mid March, while in northeastern Hubei, southeastern Hubei, Jianghan plain and other areas it occurred in late March; Northwest Hubei is slightly later, from late March to early April. Most of southeastern Hubei, eastern part of northeastern Hubei, southern Jianghan plain, and the Three Gorges river valley in southwestern Hubei, are high-risk areas for crayfish low-temperature cold damage, and it is appropriate to delay the start of seedling date to reduce the risk of low-temperature cold damage. The southern part of northwest Hubei, the central northern part of Jianghan plain, and the western part of southwest Hubei are areas with medium risk of crayfish low-temperature damage. The northern part of northwestern Hubei and the high mountains in southwestern Hubei are low−risk areas for crayfish low−temperature cold damage, and areas with sufficient water sources are suitable for expanding the scale of crayfish farming in spring. The risk index of low-temperature cold damage increased to 33.60%, 40.41%, 45.27%, and 53.00% respectively when the start of seedling date was advanced by 5 days, 10 days, 15 days, and 20 days; by contrast, the risk index of low−temperature cold damage reduced to 15.23% when the start of seedling date was delayed by 5 days, and the start of seedling date in the southeast will be from March 25-30, while in the northwest it will be from March 30th to April 15th; the risk index of low-temperature cold damage reduced to 7.80% when the start of seedling date was delayed by 10 days, and the start of seedling date in the southeast will be from March 30th to April 5th, while in the northwest it will be from April 5th to April 20th.

Crop loss assessment is critical for decision making in flooding management. From the perspective of disaster chain, flooding damage is a complex interaction of hazard factors (e.g., extreme precipitation), local topographic attributes and vulnerability of affected bodies, and thus characterized by large temporal and spatial variations. Developing a physically based modelling chain that can capture the dynamic evolution and spatial heterogeneity of the disaster process is critical for timely and efficient emergency response to flooding prevention. This study presented a modelling framework for estimating crop loss due to flooding, by coupling the flooding vulnerability curves with the Rainfall−Runoff−Inundation (RRI) model developed by the International Center for Water Hazard and Risk Management. The flooding vulnerability curve was shown as a function of inundation depth, duration and crop stage. A quantitative assessment of crop loss at gridded scale was established by integrating the inundation maps, crop distribution, and flooding vulnerability curves. The framework was applied to two representative flooding events on the Jianghan plain to demonstrate its capability to estimate crop losses due to rainstorm−induced flooding. The results showed that the RRI model could reasonably simulate the formation and retreat of the flooding peak as well as the surface inundation dynamics in accordance with the rainstorm, with the simulation error ranging from −14.8% to 11.5% for the runoff, the simulation accuracy exceeding 80% for the inundation area, the matching rate ranging from 84.2% to 87.1% for the inundation depth, and the estimated deviation of crop loss rate were −33.8% to 6.4%, −10.8% to −9.5%, and −6.0% to 1.8% for areas covered, areas affected and areas of total crop failure, respectively. The method proposed in this study provides a fundamental support for the rapid assessment and risk early warning for flooding mitigation and post−disaster reconstruction.

 In the autumn of 2024 (September−November), the national average temperature was 11.5°C, which was higher than the average of the same period from 1991 to 2020, and consecutively increased in the sixth year as well as created a new high record since 1961. The national average precipitation was 134.4mm, and 14.4% more than the same period from 1991 to 2020. The national average sunshine hours were 536.5h, and 6.0% less than the same period from 1991 to 2020. In most agricultural areas across the country, the light and heat conditions in autumn were relatively good to the crops. The first frost date in the northeast China was later than usual, and the cold dew wind had little impact on the late rice in the south part of China. The meteorological conditions were conducive to the filling and ripening, harvesting, drying of autumn-harvest crops and sowing of autumn-planted crops. Overall, the harvest and planting activates progressed smoothly in autumn of 2024, excluding the periodic droughts in the eastern part of the Sichuan basin and the middle and lower reaches of the Yangtze river, which affected the quality improvement of economic forest fruits and the sowing and emergence of autumn rapeseed. Nearing to the end of this period, a cold snap weather caused heavy snowfall mainly in the northeastern part of Inner Mongolia and northeast China, which is unfavorable for agricultural and pastoral production.