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Long homogeneous meteorological data is important to study climate change. Evaluating the impact of data inhomogeneity on analyzing average temperature trends in Huai river basin is value for accurately understanding the response of agriculture, ecology and water resources to climate change. In this study, based on the homogeneous data and observation data of daily average air temperature from the National Meteorological Information Center, the trends of annual and seasonal air temperatures during 1961 to 2018 were calculated using simple linear regression at 172 meteorological stations over Huai river basin. Then the impacts of data inhomogeneity on analyzing mean air temperature trends during 1961 to 2018 were evaluated by using two terms Crop rhizosphere microorganisms is crucial for their growth, development and adaptability to stress. A field pot experiment was conducted using Yannong19(YN) with strong resistance to late spring coldness and which were inhomogeneity impacts and contribution rates. The results showed that the average air temperature series of 96 meteorological stations in Huai river basin were inhomogeneous, accounting for 55.8% of the 172 total stations. Before and after the homogenization, the regional annual average air temperature both increased significantly. But the increasing rate was underestimated due to the data heterogeneity, and the influence was -0.015°C•10y-1 with a contribution of -6.6%. For each station, 35 stations (20.3%) was positively affected and the warming rate was overestimated with an average contribution of 21.3%, while 61 stations (35.5%) were negatively affected and the warming rate was underestimated with an average contribution of -43.6%. The influences of inhomogeneity for four seasons showed little difference, which were -0.016°C•10y-1, -0.014°C•10y-1, -0.016°C•10y-1 and -0.015°C•10y-1, respectively. However, because of the slowest increasing rate, the absolute value of inhomogeneity contribution was largest in summer with a contribution of -40.0%. The contributions of spring, autumn and winter were -4.7%, -8.0% and -4.3%. Inhomogeneity mostly affected the temperature rising rate at each station in spring, autumn and winter, while led to a turning of temperature trend before and after homogenization at 20 stations (11.6%) in summer. [ABSTRACT FROM AUTHOR]

In order to elucidate the effects of low-temperature stress on the photosynthetic and stomatal properties of strawberry leaves during the flowering phase, the perennial strawberry cultivar 'Selva' was selected as the experimental material. The environmental control experiment was designed and conducted at Nanjing University of Information Science and Technology (NUIST) with Venlo greenhouse and artificial climate chamber in 2022. Two low temperature levels (15°C/5°C, 20°C /10°C) were set, and each of them represented day temperature with night temperature. Treatment T1 and T2 were used to distinguish them. The duration of low temperature was set at 3d, 6d, and 9d. The plants grown in the greenhouse with temperature set at 25°C/15°C were used as the control group (CK). Photosynthetic parameters and stomatal indices were determined for the leaves. The results showed that: (1) low temperature stress significantly inhibited the photosynthesis of strawberry, with the intensification of low temperature, the maximum net photosynthetic rate (Pnmax), light saturation point (LSP), stomatal conductivity (Gs), transpiration rate (Tr) gradually decreased, while light compensation point (LCP), dark respiration rate (Rd), intercellular CO2 concentration (Ci), stomatal limit (Ls) and water use efficiency (WUE) tended to increase. The main cause of the reduced photosynthetic rate was stomatal restriction. (2) Low temperature stress reduced the content of chlorophyll a, chlorophyll b, total chlorophyll content (a+b) and carotenoids in leaves. However, as the duration lengthened, the photosynthetic pigment content increased slightly, although it remained significantly lower than CK. (3) Low temperature stress had a particularly significant effect on leaf stomatal characteristics, i.e. the stomatal length, stomatal width, stomatal open degree, stomatal perimeter, stomatal area and stomatal opening ratio, which all decreased significantly with the decrease of temperature and the increase of the duration. Stomatal density tended to decrease but not significantly. This study showed that low temperatures reduced the stomatal size and the chlorophyll content, inhibiting the photosynthetic capacity of the leaves during the flowering stage. [ABSTRACT FROM AUTHOR]

Droughts are increasing in frequency and intensity as the global climate changes. Risk assessment for agricultural drought disasters is an important approach for disaster prevention and mitigation. Based on the formation mechanism of natural disaster risk, the index system model of agricultural drought risk assessment in North China was constructed, and the robustness of the established risk assessment model was tested by using the internal test method. Then based on the characteristics of agricultural drought risk formation in North China, the paper proposes corresponding risk prevention recommendations. The conclusions were as follows: when adjusting the indices and methods in the risk assessment model, the range of changes in the agricultural drought risk ranking for each city was mostly 1-2.5 places, and the model was relatively robust. With the exception of Beijing and Tianjin, which had the highest disaster prevention and mitigation capacity, central and northern China had the highest agricultural drought risk, which was previously linked to the high risk and vulnerability of these regions. The agricultural drought risk in northern Henan and southern Shandong is low, mainly due to the low risk. The 34 cities in North China can be divided into 6 agricultural drought risk clusters, which are not dispersed in space and cross-city distribution, and have good aggregation. Cluster 4, located in the northernmost mountainous areas, has the highest risk of drought, which is associated with high environmental vulnerability and low capacity for disaster prevention and mitigation, so agricultural areas should be reduced and agricultural input should be increased. Clusters 2, 5 and 6, located in the central and southern regions, have higher grain acreage and yields due to drought, so agricultural drought risk can be further reduced by increasing agricultural input and improving irrigation guarantee rate. [ABSTRACT FROM AUTHOR]

The artificial environment control experiment was conducted at Nanjing University of Information Science and Technology from November to December 2022 using strawberry "Selva" (Fragaria ananassa) as the test material, and the strawberry seedlings were selected and placed in the artificial climate chamber for low-temperature treatment in mid-November when they reached the flowering stage. Three levels of temperature were set: 5°C (daily minimum)/15°C (daily maximum), 10°C/20°C and 15°C/25°C (CK). The treatment duration was 3d, 6d and 9d. The kinetic parameters of photosystem fluorescence induction and protease activity of strawberry leaves were measured under different days of low-temperature to understand the effect of low-temperature on photosystem fluorescence and protease activity of strawberry leaves. The effects of low-temperature on the fluorescence properties of strawberry leaves and the activity of protease were measured. The results showed that (1) the light energy absorbed per reaction center (ABS/RC), the energy dissipated per reaction center (DIo/RC) and the energy captured per reaction center for QA reduction (TRo/RC) of strawberry leaves increased with decreasing temperature and increasing duration in the range of daily minimum temperature from 5°C to 15 °C, but the energy captured per reaction center for QA reduction (ETo/RC) increased with increasing duration. The energy captured per reaction center for electron transfer (ETo/RC) decreased. ABS/RC and DIo/RC were 1.367 and 1.718 times higher than those of CK for the treatment with daily minimum temperature of 5°C for 9d, respectively. TRo/RC increased by 7.42%, 14.66%, 25.27%, and 30.48% for daily minimum temperature of 10°C for 3d, 6d, 9d and daily minimum temperature of 5°C for 9d, respectively, compared to CK, while ETo/RC decreased by 1.71%, 20.39%, 26.65%, and 28.32%, respectively, compared to CK. The quantum ratio for thermal dissipation (φDo) increased significantly with the duration of low-temperature, 12.34% and 25.32% higher than CK at a daily minimum temperature of 5 C for 3d and 9d, respectively. However, the quantum yield for electron transfer (φEo) decreased with the prolongation of low-temperature, and decreased by 27.92% and 43.02% compared with CK for 3d and 9d, respectively. (2) The activities of superoxide dismutase (SOD),catalase (CAT), peroxidase (POD), and malondialdehyde (MDA) of strawberry leaves gradually increased with the decrease of temperature and the extension of the duration of low-temperature. The activities of SOD and POD reached the maximum at the daily minimum temperature of 5C for 6d, which were 1.39 and 2.03 times higher than those of CK, respectively, while CAT was less affected by low temperature. The MDA content was the highest at the minimum daily temperature of 5°C for 9d, which was 2.10 times higher than that of CK. The study showed that low temperatures will damage the structure and function of the photosystem of strawberry leaves, the photochemical efficiency decreases, the energy dissipated by heat increases, resulting in a decrease in the ability of PS II donor side to provide electrons, and the electron transfer efficiency decreases, strawberry leaves will stimulate the antioxidant system in the body, and produce a certain resistance to the environment, which shows that the activities of SOD, POD and CAT have different degrees of increase compared with CK. However, the cell membrane structure was still damaged and the membrane permeability increased. [ABSTRACT FROM AUTHOR]

The seasonal temperature forecasting models in greenhouse based on multiple regression (MR), BP artificial neural networks (BPANN), random forest (RF) and support vector machine (SVM) were constructed using meteorological observations inside and outside the Venlo-type glass greenhouses from 27th February 2021 to 4th March 2023 at Nanjing University of Information Science & Technology, and then to validate all the models. The results showed that the fitting accuracy of the seasonal forecasting models for daily average and minimum air temperatures in the greenhouse was significantly higher than that of the seasonal forecasting models for daily maximum air temperature; the fitting accuracy of each model for air temperature inside the greenhouse in spring, summer and autumn was higher than that for winter. For the seasonal forecasting models of daily average air temperature and minimum air temperature, the fitting accuracy of the spring, summer and autumn forecasting models constructed by the four algorithms was higher, but the simulation effect of the RF model was more stable, and the coefficient of determination (R²) of the simulated values and the actual observed values were above 0.94, and the root mean square error (RMSE) and absolute error (MAE) were within 1.5 °C. For the seasonal forecast models of daily maximum temperature, the fitting accuracy of RF model for spring, summer and autumn was higher than other models in general, and its R² value was above 0.75. The MR model had higher accuracy for winter indoor air temperature and was more suitable for predicting winter greenhouse air temperature. The study concluded that it is feasible to choose the RF model to forecast the air temperature inside the glass greenhouse in spring, summer and autumn and the MR model to forecast the air temperature inside the glass greenhouse in winter, and this study can provide an important reference for the seasonal forecast of air temperature in Venlo-type glass greenhouse. [ABSTRACT FROM AUTHOR]

In order to study the effects of high temperature and high humidity on the chlorophyll fluorescence characteristics in the center of photosystem II of cucumber leaves at the seedling stage, a cucumber variety "Jinyou 101" was used as the test material to conduct an artificial environment control experiment. A three-factor orthogonal test was designed, and a high temperature conditions was designed with 4 levels: 32°C (the highest daily temperature)/22°C (the lowest daily temperature), 35°C/25°C, 38°C/28 °C and 41°C/31°C.The air relative humidity was designed with three gradient levels: 50%±5pp (percent point), 70%±5pp and 90%±5pp. The treatment duration was designed with 4 levels: 3d, 6d, 9d and 12d, and 28°C/18°C, 50%±5% was used as the control (CK). The kinetic parameters of chlorophyll fluorescence induction in cucumber leaves under different treatments were determined to understand the effect of high temperature and high humidity on the chlorophyll fluorescence characteristics of cucumber photosystem II center. The results showed that: In the daily maximum range of 32-41°C, with the increase of temperature, the normalized curve ΔVt of fast fluorescence kinetics of cucumber leaves at seedling stage showed obvious convexity in J and K phases. The curve of ΔVt at 41°C was the most obvious (ΔVJ=0.24848, ΔVK=0.09116), and both ΔK and ΔJ were >0. The normalized curve ΔWt exhibits a distinct K peak. However, the normalized curve ΔVt of 70% relative air humidity treatment had no obvious bulge (ΔVJ=0.00421, ΔVK=-0.0031). With the increase of temperature, the energy dissipated per unit reaction center (DIo/RC) and the quantum ratio used for heat dissipation (φDo) both increased, reaching the highest at 41°C. Compared with CK, DIo/RC and φDo increased by 85.24% and 18.96% respectively at 41°C. The quantum yield for electron transfer (φEo) and the energy for electron transfer captured by unit reaction center (ETo/RC) were reduced, reaching the lowest at 41°C, which were 49.64% and 38.05% less than CK, respectively. Under the high temperature stress, ETo/RC and φEo were higher than 50% and 90% in the treatment of 70% relative air humidity. Compared with the 50% treatment, the ETo/RC and φEo increased by 28.69% and 47.04% under the 70% relative air humidity treatment, and increased by 18.36% and 12.02% compared with the 90% treatment. Research suggests that high temperature destroys the structure and function of the photosystem of cucumber leaves, resulting in a decrease in photochemical efficiency. The relative air humidity of 70% can reduce the damage of high temperature on the donor side and acceptor side of photosystem II, and relieve the damage of high temperature on the photosynthetic mechanism of cucumber leaves. [ABSTRACT FROM AUTHOR]

The tomato variety "Fenguan" was used in a control experiment in a Nanjing University of Information Science and Technology experimental greenhouse from December 2019 to April 2020. Continuous light supplementation for 300min was used as the control treatment (CK). Treatment 1 (L1) was supplemented with light twice a day for 150min each time at an interval of 120min. Treatment 2 (L2) was supplemented with light 3 times a day for 100min each time and 2 times at 60min intervals. Treatment 3 (L3) was supplemented with light 4 times a day for 75min each time and 3 times at 40min intervals. Treatment 4 (L2) was supplemented with light 5 times a day for 60min each time and 4 times at 30min intervals. Photosynthetically active radiation was 600µmol⋅m-2⋅ s -1. The chlorophyll content, photo synthetic parameters, kinetic parameters of rapid fluorescence induction, and spectral characteristics of tomato seedling leaves were measured under supplementary light at different intervals. The results showed that (1) the increase in the frequency of light supplementation interval could promote the synthesis of some pigments in the leaves of tomato seedlings. At 36 days of treatment, chlorophyll-a content was 16.3% higher and carotenoid content was 19.6% more in the L4 treatment than in CK. (2) The three red-edge parameters λred, Sred, and Dred of tomato leaves under intermittent light supplementation showed a typical "redshift" phenomenon with increasing interval frequency, but the chlorophyll changes of leaves differed from the spectral pattern at the early stage of light supplementation. (3) The light saturation point (LSP), apparent quantum efficiency (AQE), and light compensation point (LCP) of tomato seedling leaves under prolonged intermittent light supplementation were higher than those of the continuous light treatment, and the higher interval frequency, the higher the net photosynthetic rate and the greater the photosynthetic capacity. However, tomato leaf stomata exert a delayed effect on light fluctuations, and stomatal delay alters the light capture process of leaf photosynthesis while limiting the transpiration and carbon exchange processes of stomatal movement. (4) The effect of intermittent light supplementation on the energy partitioning of PSII reaction centers showed a short-term reduction in the maximum photochemical efficiency of leaves, with an increase in the quantum yield captured by the reaction center (φPo) and for electron transfer (φEo) and a decrease in the quantum ratio for heat dissipation (φRo) when the number of treatment days increased, with a greater change at L4, where φPo decreased at L4 compared to CK at treatment day decreased by 3.8% at day 9 and increased by 11.6% at day 36, and φRo increased by 4.8% at L4 treatment and decreased by 6.9% at day 36 compared to CK at day 9 of the treatment. [ABSTRACT FROM AUTHOR]

It is important to quantitatively assess the climate suitability of tea and its response to climate change. Based on meteorological indices of tea growth and daily meteorological data from 1971 to 2010 in Zhejiang Province, three climate suitability models for single climate factors, including temperature, precipitation and sunshine, were established at a 10-day scale by using the fuzzy mathematics method, and a comprehensive climate suitability model was established with the geometric average method. The results indicated that the climate suitability was high in the tea growth season in Zhejiang Province, and the three kinds of climate suitability were all higher than 0. 6. As for the single factor climate suitability, temperature suitability was the highest and sunshine suitability was the lowest. There were obvious inter-annual variations of tea climate suitability, with a decline trend in the 1970s, less variation in the 1980s, and an obvious incline trend after the 1990s. The change tendency of climate suitability for spring tea was similar with that of annual climate suitability, lower in the 1980s, higher in the 1970s and after the 1990s. However, the variation amplitude of the climate suitability for spring tea was larger. The climate suitability for summer tea and autumn tea showed a decline trend from 1971 to 2010. [ABSTRACT FROM AUTHOR]

Strawberry variety 'Benihoppe' was used as the experimental material. The temperature treatments were set at 32 ℃/22 ℃, 35 ℃/25 ℃, 38 ℃/28 ℃ and 41 ℃/31 ℃ (daily maximum temperature/daily minimum temperature), and the stress days lasted for 2, 5, 8 and 11 d, with 28 ℃/18 ℃ as the control. We measured the photosynthetic characteristics, chlorophyll fluorescence characteristics, reactive oxygen species, protective enzyme activity and membrane lipid peroxidation of strawberry under different high temperature treatments. The key indices were extracted by principal component analysis. The high temperature stress index ( Z ) was defined to divide the high temperature stress grade. The results showed that 1) with the aggravation of high temperature stress and the extension of stress time, chlorophyll a (Chl a), chlorophyll b (Chl b), carotenoid (Car), light saturation point (LSP), maximum net photosynthetic rate ( P max ), apparent quantum efficiency (AQE) and maximum photochemical efficiency ( F v / F m ) decreased, while light compensation point (LCP) and dark respiration rate ( R d ) increased. 2) High temperature hindered the energy transfer of thylakoid in PSⅡ center (Δ W OK ＞0), and accelerated the reduction rate of PSⅠ terminal electron receptor pool. On the 11th day of the stress, except that under 32 ℃, all other oxygen evolution complexes (OEC) were inactivated. 3) The content of reactive oxygen species (H 2 O 2 Content and O 2 -· production rate) and malondialdehyde (MDA) increased with the stress days under different high temperature treatments. 4) The protective enzyme activities and soluble protein content increased first and then decreased with stress duration. 5) Based on principal component analysis (PCA) and combined with the difficulty of index acquisition, Chl a, P max , F v / F m and MDA were extracted as the key indices, and Z value was calculated. Five high temperature stress grades were divided which were normal (0< Z ≤1), mild (1< Z ≤2), moderate (2< Z ≤3), severe (3< Z ≤4) and extra severe (4< Z ). The results would be helpful for the prevention of strawberry high temperature disaster and the optimization of microclimate environment.

It is important to quantitatively assess the climate suitability of tea and its response to climate change. Based on meteorological indices of tea growth and daily meteorological data from 1971 to 2010 in Zhejiang Province, three climate suitability models for single climate factors, including temperature, precipitation and sunshine, were established at a 10-day scale by using the fuzzy mathematics method, and a comprehensive climate suitability model was established with the geometric average method. The results indicated that the climate suitability was high in the tea growth season in Zhejiang Province, and the three kinds of climate suitability were all higher than 0.6. As for the single factor climate suitability, temperature suitability was the highest and sunshine suitability was the lowest. There were obvious inter-annual variations of tea climate suitability, with a decline trend in the 1970s, less variation in the 1980s, and an obvious incline trend after the 1990s. The change tendency of climate suitability for spring tea was similar with that of annual climate suitability, lower in the 1980s, higher in the 1970s and after the 1990s. However, the variation amplitude of the climate suitability for spring tea was larger. The climate suitability for summer tea and autumn tea showed a decline trend from 1971 to 2010.

In order to understand the effects of stem numbers per ground area on the quality of standard cut Chrysanthemum morifolium, an experiment with different cultivars, different stem numbers per plant, different planting densities, and different planting dates was conducted in a greenhouse in Shanghai in 2005 and 2006. The effects of stem numbers per ground area on the canopy leaf area index and external quality of standard cut C. morifolium were quantified using the experimental data. Based on the physiological product of thermal effectiveness and PAR (PETP) the canopy absorbed, a model for predicting the effects of stem numbers per ground area on the quality of standard cut C. morifolium was developed, and validated with independent experimental data. The results showed that with the increase of stem numbers per ground area, the leaf area index increased, whereas plant height, stem diameter, leaf number, and flower diameter decreased. The model gave satisfactory predictions of the quality of standard cut C. morifolium cultivated with different stem numbers and planting density. The coefficient of determination (R2) and relative prediction error (RSE) based on the 1:1 line for fresh mass per stem, plant height, stem diameter, leaf number, flower diameter, and the number of qualified stem harvested per ground area were 0.95, 0.96, 0.94, 0.91, 0.81 and 0.97, and 16.1%, 10.1%, 12.8%, 13.4%, 15.9%, 16.1% , respectively. The model developed in this study could be used for the optimization of light and temperature management for standard cut C. morifolium cultivated with different stem numbers and planting densities in greenhouse.

Based on the effects of light and temperature on chrysanthemum quality and the experiments with different chrysanthemum varieties and planting dates, a quality prediction model of greenhouse standard cut chrysanthemum with the physiological product of thermal effectiveness and PAR (PTEP) as the measurement scale was developed and validated. The results showed that the predicted results, including the number of unfolding leaves, leaf area, plant height, stem diameter, internode length and flower diameter, accorded well with the observed ones, and the determination coefficient (R2) and relative prediction error (RSE) based on 1 : 1 line were 0.99, 0.98, 0.98, 0.92, 0.87 and 0.88, and 5.5%, 6.5%, 5.9%, 4.1%, 11.2%, 12.4%, respectively. This model was of high precision and practicable, which could be used in optimizing the light and temperature management for greenhouse standard cut chrysanthemum production.