•We estimated regional wheat yields by assimilating satellite LAI datasets.•We generated a synthetic LAI time series using a Kalman filter (KF) algorithm.•We assimilated the synthetic LAI series into ...the WOFOST crop model.•Assimilating the synthetic KF LAI series reduced the estimation error.•Accurately assessing LAI is the key to successful data assimilation.
The scale mismatch between remote sensing observations and state variables simulated by crop growth models decreases the reliability of crop yield estimates. To overcome this problem, we implemented a two-step data-assimilation approach: first, we generated a time series of 30-m-resolution leaf area index (LAI) by combining Moderate Resolution Imaging Spectroradiometer (MODIS) data and three Landsat TM images with a Kalman filter algorithm (the synthetic KF LAI series); second, the time series were assimilated into the WOFOST crop growth model to generate an ensemble Kalman filter LAI time series (the EnKF-assimilated LAI series). The synthetic EnKF LAI series then drove the WOFOST model to simulate winter wheat yields at 1-km resolution for pixels with wheat fractions of at least 50%. The county-level aggregated yield estimates were compared with official statistical yields. The synthetic KF LAI time series produced a more realistic characterization of LAI phenological dynamics. Assimilation of the synthetic KF LAI series produced more accurate estimates of regional winter wheat yield (R2=0.43; root-mean-square error (RMSE)=439kgha−1) than three other approaches: WOFOST without assimilation (determination coefficient R2=0.14; RMSE=647kgha−1), assimilation of Landsat TM LAI (R2=0.37; RMSE=472kgha−1), and assimilation of S-G filtered MODIS LAI (R2=0.49; RMSE=1355kgha−1). Thus, assimilating the synthetic KF LAI series into the WOFOST model with the EnKF strategy provides a reliable and promising method for improving regional estimates of winter wheat yield.
The escalating issue of soil saline-alkalization poses a growing global challenge. Leymus chinensis is a perennial grass species commonly used in the establishment and renewal of artificial ...grasslands that is relatively tolerant of saline, alkaline, and drought conditions. Nonetheless, reduced seed setting rates limit its propagation, especially on alkali-degraded grassland. Inter-annual variations have an important effect on seed yield and germination under abiotic stress, and we therefore examined the effect of planting year on seed yield components of L. chinensis.
We grew transplanted L. chinensis seedlings in pots for two (Y
), three (Y
), or four (Y
) years and collected spikes for measurement of seed yield components, including spike length, seed setting rate, grain number per spike, and thousand seed weight. We then collected seeds produced by plants from different planting years and subjected them to alkaline stress (25 mM Na
CO
) for measurement of germination percentage and seedling growth.
The seed setting rate of L. chinensis decreased with an increasing number of years in pot cultivation, but seed weight increased. Y
plants had a higher seed setting rate and more grains per spike, whereas Y
plants had a higher thousand seed weight. The effects of alkaline stress (25 mM Na
CO
) on seed germination were less pronounced for the heavier seeds produced by Y
plants. Na
CO
caused a 9.2% reduction in shoot length for seedlings derived from Y
seeds but a 22.3% increase in shoot length for seedlings derived from Y
seeds.
Our findings demonstrate significant differences in seed yield components among three planting years of L. chinensis under pot cultivation in a finite space. Inter-annual variation in seed set may provide advantages to plants. Increased alkalinity tolerance of seed germination was observed for seeds produced in successive planting years.
Crop yield estimation at a regional scale over a long period of time is of great significance to food security. In past decades, the integration of remote sensing observations and crop growth models ...has been recognized as a promising approach for crop growth monitoring and yield estimation. Optical remote sensing data are susceptible to cloud and rain, while synthetic aperture radar (SAR) can penetrate through clouds and has all-weather capabilities. This allows for more reliable and consistent crop monitoring and yield estimation in terms of radar sensor data. The aim of this study is to improve the accuracy for winter wheat yield estimation by assimilating time series soil moisture images, which are retrieved by a water cloud model using SAR and optical data as input, into the crop model. In this study, SAR images were acquired by C-band SAR sensors boarded on Sentinel-1 satellites and optical images were obtained from a Sentinel-2 multi-spectral instrument (MSI) for Hengshui city of Hebei province in China. Remote sensing data and ground data were all collected during the main growing season of winter wheat. Both the normalized difference vegetation index (NDVI), derived from Sentinel-2, and backscattering coefficients and polarimetric indicators, computed from Sentinel-1, were used in the water cloud model to derive time series soil moisture (SM) images. To improve the prediction of crop yields at the field scale, we incorporated remotely sensed soil moisture into the World Food Studies (WOFOST) model using the Ensemble Kalman Filter (EnKF) algorithm. In general, the trend of soil moisture inversion was consistent with the ground measurements, with the coefficient of determination (R2) equal to 0.45, 0.53, and 0.49, respectively, and RMSE was 9.16%, 7.43%, and 8.53%, respectively, for three observation dates. The winter wheat yield estimation results showed that the assimilation of remotely sensed soil moisture improved the correlation of observed and simulated yields (R2 = 0.35; RMSE =934 kg/ha) compared to the situation without data assimilation (R2 = 0.21; RMSE = 1330 kg/ha). Consequently, the results of this study demonstrated the potential and usefulness of assimilating SM retrieved from both Sentinel-1 C-band SAR and Sentinel-2 MSI optical remote sensing data into WOFOST model for winter wheat yield estimation and could also provide a reference for crop yield estimation with data assimilation for other crop types.
The period between seed germination and seedling establishment is one of the most vulnerable stages in the life cycle of annuals in the saline environments. Although germination characteristics of
...seeds have been reported, the comparative germination patterns of dimorphic seeds and seedling growth to different abiotic stresses remain poorly understood. In this study, germination responses of dimorphic seeds to light and temperature were compared. Meanwhile, responses of dimorphic seeds and thereafter seedlings of
to different concentrations of NaCl and Na
SO
were also tested. The results showed that the light did not significantly affect germination percentage of brown seeds, but significantly promoted germination of black seeds. Brown seeds could reach high germination percentage over a wide temperature range, however, germination of black seeds gradually increased with the increase of temperature. Brown seeds had higher germination percentage and velocity than black seeds under the same salt conditions. However, black seeds had higher recovery germination than brown seeds when transferred to deionized water. Young seedlings had lower salt tolerance than germinating seeds. At the same concentrations, Na
SO
had stronger inhibitory effect on seed germination and seedling growth than NaCl. This study comprehensively compared germination traits of dimorphic seeds and seedling growth of
, and then developed a conceptual model to explain their adaptation to harsh saline environment.
Salinity is a pressing and widespread abiotic stress, adversely affecting agriculture productivity and plant growth worldwide. Seed germination is the most critical stage to seedling growth and ...establishing plant species in harsh environments, including saline stress. However, seed germination characteristics and stress tolerance may vary among geographical locations, such as various provenances. Suaeda salsa (Linn.) Pall. (S. salsa) is a halophytic plant that exhibits high salt tolerance and is often considered a pioneer species for the restoration of grasslands. Understanding the germination characteristics and stress tolerance of the species could be helpful in the vegetation restoration of saline–alkali land. In this study, we collected S. salsa seeds from seven different saline–alkali habitats (S1–S7) in the Songnen Plain region to assess the germination and seedling growth responses to NaCl, Na2CO3, and NaHCO3, and to observe the recovery of seed germination after relieving the salt stress. We observed significant differences in germination and seedling growth under three salt stresses and among seven provenances. Resistance to Na2CO3 and NaHCO3 stress was considerably higher during seedling growth than seed germination, while the opposite responses were observed for NaCl resistance. Seeds from S1 and S7 showed the highest tolerance to all three salt stress treatments, while S6 exhibited the lowest tolerance. Seeds from S2 exhibited low germination under control conditions, while low NaCl concentration and pretreatment improved germination. Ungerminated seeds under high salt concentrations germinated after relieving the salt stress. Germination of ungerminated seeds after the abatement of salt stress is an important adaptation strategy for black S. salsa seeds. While seeds from most provenances regerminated under NaCl, under Na2CO3 and NaHCO3, only seeds from S4 and S7 regerminated. These findings highlight the importance of soil salinity in the maternal environment for successful seed germination and seedling growth under various salinity-alkali stresses. Therefore, seed sources and provenance should be considered for vegetation restoration.
Over three million hectares of salt-affected soils characterized with high salinity and sodicity caused serious land degradation in Songnen Plain, northeast China. Soil salinity–sodicity ...heterogeneous distribution under microtopography is usually influenced by several environmental factors. The side direction movement of soil water driven by water from depression is the key factor that aggravates the soil salinization under microtopography in dry condition. In this study, the differences in surface soil salinity–sodicity (0–10 cm) between dry year and wet year were compared, and the relationship between soil salinity–sodicity and environment factors such as ground elevation, surface ponding time, surface ponding depth, and soil moisture at four soil layers (0–10, 10–30, 30–60, and 60–100 cm) were analyzed using redundancy analysis (RDA) and simple correlation analysis (Pearson analysis) for two different hydrological years. Analyzed soil salinity–sodicity parameters include soluble ions (Na+, K+, Ca2+, Mg2+, CO32−, HCO3−, Cl− and SO42−), salt content (SC), electrical conductivity (EC), sodium adsorption ratio (SAR), and pH. Results showed that values of SAR, Cl−, and SO42− were significantly higher in dry year than in wet year, while Ca2+, Mg2+, K+, and HCO3− showed the opposite results. Values of Na+, CO32−, and EC were significantly higher at higher ground elevation gradient (20–40 cm) in dry year than wet year. Redundancy analysis indicated that spatial distributions and variations of salinity and sodicity in surface soil layer were related with environmental factors of ponding depth, ponding time and ground elevation in wet year, and they were related with ground elevation, ponding depth, ponding time, and soil moisture at 30–60 and 60–100 cm soil layer in dry year. Ponding depth and ground elevation rank first and second as the influential factors of the spatial distribution and variation of soil salinity–sodicity in wet year. However in dry year, primary and secondary influential factors are ground elevation and soil moisture at 60–100 cm soil layer.
Predicting crop maturity dates is important for improving crop harvest planning and grain quality. The prediction of crop maturity dates by assimilating remote sensing information into crop growth ...model has not been fully explored. In this study, a data assimilation framework incorporating the leaf area index (LAI) product from Moderate Resolution Imaging Spectroradiometer (MODIS) into a World Food Studies (WOFOST) model was proposed to predict the maturity dates of winter wheat in Henan province, China. Minimization of normalized cost function was used to obtain the input parameters of the WOFOST model. The WOFOST model was run with the re-initialized parameter to forecast the maturity dates of winter wheat grid by grid, and THORPEX Interactive Grand Global Ensemble (TIGGE) was used as forecasting period weather input in the future 15 days (d) for the WOFOST model. The results demonstrated a promising regional maturity date prediction with determination coefficient (R2) of 0.94 and the root mean square error (RMSE) of 1.86 d. The outcomes also showed that the optimal forecasting starting time for Henan was 30 April, corresponding to a stage from anthesis to grain filling. Our study indicated great potential of using data assimilation approaches in winter wheat maturity date prediction.
Soil salinity is a widespread and important abiotic factor impeding rice production by adversely affecting seed germination, seedling growth, and plant productivity. In this study, the rice cultivar ...TH899 was treated with 200 Gy of heavy-ion beam irradiation, and 89 mutant lines with stable phenotypes were selected using the pedigree method based on continuous assessment over six years. The seed germination performance of these mutants was tested under different saline-alkaline concentrations. Five highly tolerant lines were further evaluated in a series of experiments at the seedling stage and in the field. During the seedling stage, the reduction of seedling length, root length, fresh weight, and dry weight were dramatically lower in these five mutants than those in TH899 under saline-alkali stress. The K
/Na
ratio was higher in these five mutants than in TH899. In the field experiment, the grain yield of mutant lines was higher than that of TH899. In addition, the grain yield of mutant line M89 was higher than that of the local cultivar in actual production. These mutant lines are expected to increase grain yield in soda saline-alkaline regions in northeast China.
Soft robots have received a lot of attention because of their great human-robot interaction and environmental adaptability. Most soft robots are currently limited in their applications due to wired ...drives. Photoresponsive soft robotics is one of the most effective ways to promote wireless soft drives. Among the many soft robotics materials, photoresponsive hydrogels have received a lot of attention due to their good biocompatibility, ductility, and excellent photoresponse properties. This paper visualizes and analyzes the research hotspots in the field of hydrogels using the literature analysis tool Citespace, demonstrating that photoresponsive hydrogel technology is currently a key research direction. Therefore, this paper summarizes the current state of research on photoresponsive hydrogels in terms of photochemical and photothermal response mechanisms. The progress of the application of photoresponsive hydrogels in soft robots is highlighted based on bilayer, gradient, orientation, and patterned structures. Finally, the main factors influencing its application at this stage are discussed, including the development directions and insights. Advancement in photoresponsive hydrogel technology is crucial for its application in the field of soft robotics. The advantages and disadvantages of different preparation methods and structures should be considered in different application scenarios to select the best design scheme.
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•The response mechanism and structural form of photoresponsive hydrogels are reviewed.•The progress of the application of photoresponsive hydrogels in the field of soft robotics is presented.•Influencing factors limiting the application of soft robotics are discussed.•An overview of the application and future research trends are identified.
To elucidate the mechanisms contributing to fruit responses to senescence and stressful environmental stimuli under low temperature (LT) and controlled atmosphere (CA) storage, a label-free ...quantitative proteomic investigation was conducted in strawberry (Fragaria ananassa, Duch. cv. ‘Akihime’). Postharvest physiological quality traits including firmness, total soluble solids, total acidity, ascorbic acid and volatile production were characterized following storage under different conditions. The observed post-storage protein expression profiles may be associated with delayed senescence features in strawberry. A total of 454 proteins were identified in differentially treated strawberry fruits. Quantitative analysis, using normalized spectral counts, revealed 73 proteins common to all treatments, which formed three clusters in a hierarchical clustering analysis. The proteins spanned a range of functions in various metabolic pathways and networks involved in carbohydrate and energy metabolism, volatile biosynthesis, phenylpropanoid activity, stress response and protein synthesis, degradation and folding. After CA and LT storage, 16 (13) and 11 (17) proteins, respectively, were significantly increased (decreased) in abundance, while expression profile of 12 proteins was significantly changed by both CA and LT. To summarize, the differential variability of abundance in strawberry proteome, working in a cooperative manner, provided an overview of the biological processes that occurred during CA and LT storage.
Controlled atmosphere storage at an optimal temperature is regarded to be an effective postharvest technology to delay fruit senescence and maintain fruit quality during shelf life. Nonetheless, little information on fruit proteomic changes under controlled atmosphere and/or low temperature storage is available. The significance of this paper is that it is the first study employing a label-free approach in the investigation of strawberry fruit response to controlled atmosphere and cold storage. Changes in postharvest physiological quality traits including volatile production, firmness, ascorbic acid, soluble solids and total acidity were also characterized. Significant biological changes associated with senescence were revealed and differentially abundant proteins under various storage conditions were identified. Proteomic profiles were linked to physiological aspects of strawberry fruit senescence in order to provide new insights into possible regulation mechanisms. Findings from this study not only provide proteomic information on fruit regulation, but also pave the way for further quantitative studies at the transcriptomic and metabolomic levels.
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•The first comprehensive study employing a quantitative label-free approach on analysis of the strawberry fruit proteome.•Coordinated changes in physiological quality traits were characterized.•Six proteins were observed to be significantly increased in abundance by controlled atmosphere and low temperature.•Another six proteins were observed to be significantly decreased in abundance by controlled atmosphere and low temperature.•Candidate proteins representing important metabolic pathways which might contribute to storage tolerance were identified.
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