With the aggravation of climate change, the frequency and intensity of waterlogging disasters are increasing, which seriously restrict the sustainable crop production. It is an inherent and urgent demand for fully exploiting the potential of crops and improving their resistance to water stress and adaptability to climate change. With the in-depth study of physiological and biochemical mechanism of crop stress resistance, more attention has been paid to the important role of nitrogen application in stress resistance of crops. To further understand the regulatory effect and mechanism of nitrogen fertilizer on crop growth and yield under waterlogging conditions, the authors summarized the effects of waterlogging stress on photosynthesis of the aboveground part, antioxidant enzyme activity, membrane oxidation, endogenous hormone content, root growth and yield formation of crops, and the nitrogen regulation effects on these aspects, clarified the physiological mechanism of nitrogen fertilizer regulating crop growth and yield formation, and pointed out the problems in the study of nitrogen fertilizer regulating crop growth and yield under waterlogging stress. On this basis, we proposed some future research directions, such as applying new nitrogen fertilizer and modern high-tech technology, and breeding nitrogen efficient and stress resistant varieties to improve crop stress resistance.

This study aims at studying the effect of low temperature injury on grain filling of spring maize and determining the agro-meteorological indexes of low temperature injury in the grain filling period in northeast China. Pot planted spring maize was subjected to different levels of low temperature (mean 15℃, 17℃ and 19℃) in early grain filling period for 3, 5 and 7 days in the artificial climate chamber. The results showed that low temperature treatments decreased the number of kernels per ear, the kernel weight per ear, 100-kernel weight and the chlorophyll content, postponed the maturing period and increased the length of ear bald tip and the water content of kernels. As a result, the yield was decreased in various degrees. The lower the temperature and the longer the duration of low temperature, the higher the yield reduction of maize was. The yield of maize decreased the most under the treatment of 7 days at 15℃ among all the treatments, and compared with the control treatment, the kernel weight per ear was reduced by 32.4% and the 100-kernel weight was reduced by 9.2%. Therefore, low temperature in the early kernel filling period could result in the double reduction of kernel setting rate and kernel dry matter content, which is the most important factor affecting the yield components of spring maize.

To reduce the adverse effects of densification on maize plants by changing planting patterns, ‘Zhengdan 958'was used as the experimental material, three planting patterns were set up: equal row spacing planting, wide and narrow row planting and double row interlacing sparse planting. Three treatments were designed as 83300 plants/hm², 121000 plants/hm² and 151000 plants/hm², to study the reasonable planting pattern of high yield summer maize. By increasing the planting density of maize, the experiment increased the dry matter accumulation of root system and the total area of three ear leaves of maize, as well as the sunlight interception rate at the top of maize canopy, intercepted most of the light and achieved early maximum net photosynthetic rate (Pn). Taking a midday rest under strong light at noon could protect the photosynthetic system of leaves under strong light and increase the yield of maize significantly. The yield of double row interlacing sparse planting (SHJC) was 3402 kg/hm² higher than that of equal row spacing planting (DH), increased by 39.83%, and the yield of SHJC was 2774.7 kg/hm² higher than that of wide and narrow row planting (KZH), increased by 30.26%. Under the premise of ensuring the population quantity of maize, SHJC could reduce the competition of individual plant and ensure the development potential of individual plant. SHJC could significantly improve canopy light distribution, photosynthetic characteristics and maize yield, and 151000 plants/hm² had the best performance. The study provides a high-yield cultivation model for maize in Huang-Huai-Hai region.

In order to explore the effects of different fertilization treatments on the biomass and quality of barnyard grass, 4 fertilization treatments were set up (A: organic fertilizers, B: organic fertilizers + inorganic fertilizers, C: inorganic fertilizers, and D: no fertilization) with ‘Zhaomu No.1' as material. After collecting the samples, the biomass of barnyard grass was measured by drying constant weight method. The results showed that the biomass of treatment C was 871 g/m², which was 27.2%, 11.9% and 56.6% higher than that of treatment A, B and D. The crude protein content of treatment C was 10.38%, which was 19.8%, 2.9% and 13.2% higher than that of treatment A, B and D. The crude fat content of treatment B was 1.29%, which was 60.3% less than that of treatment D. The content of acid detergent fiber (ADF) and neutral detergent fiber (NDF) of treatment D were the lowest, 35.11% and 66.11% respectively. Among the 4 fertilization treatments, organic fertilizers + inorganic fertilizers had better comprehensive performance. The results of this study can lay a foundation for formulating proper cultivation techniques for high-yield and high-quality barnyard grass in the black soil area of northeast China.

The aims of this study are to investigate the effects of low temperature stress on cell membrane peroxidation and antioxidant system in sugar beet, and provide reference for studying physiological mechanism of cold resistance in other plants. Sugar beet variety ‘KWS9147' was selected as the experimental material and cultivated in hydroponic culture. The low temperature (4℃) was used as stress treatment (L) and the room temperature (25℃) was used as control (CK). The changes of malondialdehyde (MDA) content and antioxidant system enzyme activity in sugar beet leaves before and after low temperature treatment were measured. The results showed that low temperature stress damaged the cell membrane and promoted the defense role of the antioxidant system. Compared with CK, the content of malondialdehyde (MDA) and the enzyme activity of the antioxidant system changed significantly 1 day after low temperature stress. The content of MDA increased by 31.32%, and the activities of total antioxidant capacity (T-AOC), superoxide dismutase (SOD), peroxidase (POD), ascorbic acid peroxidase (APX) and catalase (CAT) increased significantly by 10.74%, 4 times, 2.22 times, 32.85% and 2.56 times, respectively. In summary, the antioxidant capacity of sugar beet was improved for scavenging the accumulation of reactive oxygen free radicals (ROS) and alleviating membrane damage caused by membrane lipid peroxidation under low temperature stress.

The aims are to explore more sugar beet seed initiators to promote the germination, test the triggering effect of malic acid on seeds of sugar beet, and provide a theoretical basis for seed processing. We used TD701, TD703 and TD801 sugar beet seeds as the experimental materials and set five concentrations (1, 2, 5, 10 and 15 mmol/L), and a total of 15 experimental treatments. Then, we calculated the germination potential, the germination rate, the germination index and the vigour index. The test results showed that the 1 mmol/L malic acid improved the germination rate (67.67%), the germination potential (65%), the vigour index (199.84) for TD701 sugar beet seeds. 2 mmol/L malic acid improved the germination index (25.51) for TD701 sugar beet seeds. 1 mmol/L malic acid had the best triggering effect on TD801 sugar beet seeds, and the germination potential was 93.67%, the germination rate was 95.33%, the germination index was 39.53, and the vigour index was 316.88. However, different concentrations of malic acid had no effect on the germination of TD703 sugar beet seeds. As a result, different concentrations of malic acid have different effects on different kinds of sugar beet seeds, and the concentrations of proper triggering effect are also different.

In order to explore the best planting density and harvest time of Scutellaria baicalensis Georgi in central region of Gansu Province, in this study, the seedlings of S. baicalensis were used as experimental materials, the two-year-old and three-year-old medicinal materials of S. baicalensis were studied with planting densities of 450000 plants/hm², 600000 plants/hm², 750000 plants/hm², 900000 plants/hm², 1050000 plants/hm² and 1200000 plants/hm². The relative indexes of growth and yield were measured, and the planting benefit of S. baicalensis was estimated. The results showed that the seed yield of two-year-old and three-year-old of S. baicalensis was 50.46 kg/hm² and 62.77 kg/hm², respectively, when the planting density was 450000 plants/hm². The fresh medicine yield of two-year-old and three-year-old was 11167.23 kg/hm² and 16725.84 kg/hm², respectively, when the plant density was 1050000 plants/hm². When the planting density was 750000 plants/hm², the average single root was the longest and thickest, the yield of fresh medicine and seed were relatively high, and the net profit was the highest, reaching 41009.39 yuan/hm² and 85083.64 yuan/hm², respectively. Except the drying rate, the yield indexes of three-year-old S. baicalensis were significantly higher than those of two-year-old S. baicalensis, and the net benefit was increased by 35237.89yuan/hm² - 44074.25 yuan/hm². In conclusion, the optimal planting density of S. baicalensis in central Gansu is 750000 plants/hm², and the best harvest time is three years after planting.

To explore the feasibility and supporting techniques of chemical defoliation technology in Liaohe Basin cotton area, the authors chose chemical defoliating agent Xinshaili, set up 2 planting densities, 2 treatment times and 5 treatment methods, and took water treatment as CK. Xinshaili could effectively promote the defoliation and boll opening of cotton. In terms of concentration, moderate concentration (2100 mL/hm²) was recommended for defoliation, while high concentration (2700 mL/hm²) for ripening. The defoliation effect of treating twice (1350 mL/hm²+1350 mL/hm²) was lower than that of once, but the ripening effect was significantly improved. In terms of planting density, the effect of defoliation and ripening of 8.25×10⁴ plants/hm² was better than that of 11.25×10⁴ plants/hm². In terms of treatment time, the effect of defoliation and ripening of treatment on September 5 was more obvious than that on September 15, but the yield was lower. Therefore, the treatment with planting density of 8.25×10⁴ plants/hm² and treatment time on September 15 is suggested for Liaohe Basin cotton area, and the defoliant concentration could be appropriately increased. 2 times treatment is also suggested for some areas with good conditions.

In order to scientifically apply the arbuscular mycorrhizal fungi (AMF) resources widely distributed in agroecosystems to herbs, AMF classification, the current status of Chinese herb resources and the application of AMF in herbs were summarized in the paper individually. AMF can not only improve the nutritional level and enhance the growth of herbs, but also promote the synthesis and accumulation of active substances in herbs such as terpenoids, steroids and flavonoids. Moreover, AMF show positive biocontrol effects on various soil borne diseases and pests caused by continuous cropping system of herbs. Therefore, AMF have great application potential in herbs' cultivation. Meanwhile, in view of the obligate symbiosis characteristics of mycorrhizae, some research issues still need to be explored, such as the expansion of the herb species associated with AMF, the mixed inoculation of AMF with other beneficial microorganisms, and the changes in soil ecological environment during the establishment of symbiosis. The study will provide reference for further research in the field.

The purpose is to provide theoretical reference and data support for optimizing the allocation of land resources and promoting the sustainable development of regional ecology, society and economy. Based on the construction of the evaluation index system of land use benefit, using the models of coupling coordination degree, relative development degree and obstacle degree, the spatial-temporal evolution characteristics and major influencing factors of the coupling coordination degree of land use ecology-society-economy system in 17 cities of the Shandong Province were explored. The results are as follows. Land use ecology-society-economy system of Shandong was in the primary coordination state of running-in stage and showed a continuous rising trend in 2008-2017. The coupling coordination degree increased steadily from 0.54 to 0.70, and its annual average was 0.63. The equilibrium level of coupling coordination degree among cities was gradually improved in 2008-2017. Its variation coefficient of coupling coordination degree decreased from 0.126 to 0.072, but the coupling coordination degree of land use ecology-society-economy system in different cities still showed an obvious gradient distribution difference from the east to the west of the province. There was a significant difference in the relative development degree among the ecological, social and economic subsystems of land use in different cities. The southern sides of central Shandong and its northern area, together with Weihai City, had constituted an obvious half-circle ecological lag region by 2017. Social and economic barriers affecting the coupling coordinated development of land use ecology, society and economy were dominant throughout, but the ecological impact increased since 2013. During the study period, the coupling coordination level of land use ecology-society-economy system in different cities in Shandong was continuously improved, but the differences among different regions were still obvious, and there was still more space for improvement. Therefore, it is suggested that different cities should consider the main obstacle factors of their own and implement differentiated development strategies according to local conditions.

To explore the coordinated relationship between crop planting structure and climate change in Sichuan Province, based on the climate data and crop planting area data of the province, this study analyzed the climate change, crop planting structure change and their coordination relationship from 2000 to 2018. The results showed that: from 2000 to 2018, the precipitation and accumulated temperature ≥10℃ in Sichuan showed a significantly upward trend, the climate tendency rate of precipitation was 53.5 mm/10 a, and the climate tendency rate of accumulated temperature≥10℃ was 123.7℃/10 a; the planting area of maize, oil crops, legumes and fruits increased significantly, the planting area of potato remained relatively stable, and the planting area of rice, wheat and other crops decreased significantly, and the proportion of planting structure of main crops changed significantly. The top three crops in Sichuan Province were rice, maize and potato, with an average proportion of 21%, 17% and 13%, respectively, and the proportion of rice was relatively stable among all kinds of crops; the proportion of wheat was decreasing year by year. The crop planting structure change and climate change in Sichuan Province from 2000 to 2018 were compatible with each other, and the coupling degree and coupling coordination degree were high.

To increase crop yield, farmers' income and utilization efficiency of newly-cultivated land, the authors carried out fertilization experiments in Hedong District of Linyi City in Shandong Province from 2018 to 2020 by integrating soil testing for formulated fertilization, organic fertilizer application, controlled-release fertilization and straw returning. The results showed that the soil nutrient content with different fertilization measures increased in varying degrees in 2020, and the largest increasing rate was found under organic fertilizer application and straw returning. And compared with conventional fertilization, soil testing for formulated fertilization, organic fertilizer application and straw returning all had higher yield and income. However, considering the cost of organic fertilizer application and straw returning, the combination of formulated fertilization with straw returning is the best for improving the nutrient content of newly-cultivated land and increasing farmers' income.

To provide a basis for the effective utilization of soil nutrients and agricultural management, the spatial variation rule of topsoil nutrients and its correlation with topographic factors were studied. The authors took Yanhe River Basin as the research object, the spatial distribution and variation of soil nutrients were studied by geostatistics and GIS. Based on DEM data, relevant topographic factors were extracted to analyze the influence of topographic factors on soil nutrient spatial distribution in watershed scale. The results show that the total nitrogen and organic matter in the topsoil of the study area are at a low level, the available potassium and available phosphorus are at medium level, and the pH is weakly alkaline. The spatial variation is in the following order: available potassium > available phosphorus > total nitrogen > organic matter >pH. The determination coefficients of the semi-variance function on soil nutrients are all more than 0.6, the spatial distribution of soil pH is the most fragmented, which are mainly influenced by structural factors. The nugget coefficient of soil available potassium and pH is less than 25%. With the influence of structural and random factors, soil total nitrogen, available phosphorus and organic matter have medium level of nugget effect. And the nugget coefficient of available phosphorus is the highest, indicating that human activities have greater influence on its spatial variation. The distribution of total nitrogen and organic matter increases first and then decreases from northwest to southeast. The distribution pattern of available potassium shows a wave of decreasing from northwest to southeast. The overall distribution trend of available phosphorus is reduced from middle to the upstream and downstream. The trend of pH change along a certain direction is not obvious. The correlation between soil nutrient spatial variation and topographic factors is consistent. In the region of low and flat terrain, the soil nutrients are more abundant, which is conducive to agricultural production. And the nutrient content is relatively low in the areas with large topographic relief at high altitude.

The aim is to promote the development and utilization of more bioactive peptides based on plants. The advance in extraction, preparation, isolation, identification and function verification of bioactive peptides were summarized, and the effects of different research methods and their application were compared and analyzed. Then, main problems in current research on bioactive peptides based on plants were summarized. At last, the study proposed that we should reduce the extraction cost and strengthen the standard system construction, which could lay a foundation for the future research of bioactive peptides based on plants.

The aim is to screen out SSR core primers suitable for sugar beet molecular biology experiments, and lay a foundation for subsequent construction of sugar beet fingerprint maps and genetic diversity analysis. In this paper, four different sugar beet germplasm resources and four different sugar beet varieties were used for the preliminary screening of 247 pairs of SSR primers designed based on the sequence of the whole genome coding region of sugar beet. The results showed that the majority of the 247 primer pairs had no polymorphism or poor polymorphism, while only 27 primer pairs had high polymorphism. These 27 primer pairs amplified a total of 103 bands, including 95 polymorphic bands, with a polymorphism ratio of 90.43%. The polymorphism information content (PIC) of these primers ranged from 0.549 to 0.983, with an average PIC value of 0.841 for each primer pair. The results of the experiment showed that despite the screening by e-PCR, it was still difficult to find suitable SSR primers for sugar beet, indicating that the genetic base of sugar beet was relatively narrow. These 27 pairs of SSR primers are suitable for sugar beet molecular marking, and could be a foundation for large-scale construction and application of the standardized identification system for sugar beet varieties.

Arma chinensis Fallou has been regarded as one of the important natural enemy insects, and it has the characteristics of wide geographical distribution, various predation species, strong predation ability and good adaptability. Thus, A. chinensis is considered to have a bright development prospect. In order to summarize the advances of A. chinensis research in recent years, the aspects of its taxonomic position, geographical distribution and morphology, biological characteristics, artificial rearing technology, potential ability of pest control were reviewed. In addition, current problems of research on A. chinensis were analyzed, and the research direction and application prospect of A. chinensis were discussed.

The grain aphid Sitobion miscanthi (Takahashi), considered as S. avenae (Fab.) in China, is one of the most widely distributed aphid species which needs chemical control annually in northern China at wheat grain filling stage. The spatial-temporal population dynamics of the grain aphid is affected by geographical area, meteorological factors, natural enemies, agricultural practices, biodiversity, and resistance characteristics of wheat varieties to aphid at different growth stages in field. In general years, the dynamics of aphid population develop with the wheat growing and temperature rise in field. The aphid number has sporadic occurrence at the jointing stage of wheat seedling and cluster occurrence at booting stage, increases rapidly after head sprouting, and reaches the peak at mid-late stage of grain filling, and decreases sharply at milking stage. The aphid spatial distribution pattern follows random distribution - contagious distribution - aggregated distribution (mosaic distribution) - uniform distribution - aggregated distribution (mosaic distribution)- disappearance. The wheat grain number is affected weakly by aphids before wheat head sprouting because the population of aphids is very small in field. But the 1000-grain weight is significantly affected by the aphid as its population increases rapidly during grain filling stage in field. In this paper, an ecological control strategy is proposed for grain aphid. We suggest that the dynamic control index of this pest should be established according to the resistance/tolerance characteristics of wheat varieties to aphid during different growth stages. The priority should be given to the biological control before wheat head sprouting, and the dynamic control index should be strict; the chemical control should be carried out after head sprouting, and the dynamic control index could be loosened. The utilization of plant protection UAV combined with artificial intelligence is also suggested to automatically discover the occurrence center of aphid and other pests/diseases, and to spray pesticides precisely on the occurrence center in wheat field simultaneously.

In order to select effective and safe insecticides for controlling Spodoptera frugiperda, larvae of S. frugiperda were used as experimental materials in this study. The indoor toxicity of five insecticides was determined by impregnation method, and field control tests were conducted. The results of indoor toxicity test showed that the five insecticides had different indoor toxicities to the third instar larvae of S. frugiperda, and their LC₅₀ values from low to high were: 5% emamectin benzoate ME<60 g/L spinetoram SC<10% chlorfenapyr SC<40% phoxim EC<90% dipterex SP. The results of field control efficacy test showed that all the five insecticides had good control effects on the larvae of S. frugiperda. The control efficacies of 60 g/L spinetoram SC, 10% chlorfenapyr SC and 40% phoxim EC were 100% at 72 hours after the treatment, and the control efficacies of 5% emamectin benzoate ME and 90% dipterex SP were more than 90% at 72 hours after the treatment. Therefore, these five insecticides can be used as effective agents to control S. frugiperda.

In order to screen low-toxic and environment-friendly insecticides with high lethal effect on Spodoptera frugiperda, the larvae of S. frugiperda in maize were used as materials, field efficacy trials of six insecticides were carried out in 2020 and 2021. The results showed that the control efficiency of 18% tetraniliprole SC at 225 mL/hm², 8% methylamino abamectin·lufenruon SC at 450 g/hm² and 9% methylamino abamectin·indoxacarb SC at 450 g/hm² was 69.52%-81.01% one day after application, and the control efficiency reached the peak (90.22%-96.05%) 3 days after treatment, which was significantly better than that of the other three insecticides. The control efficiency of 14% chlorantraniliprole·lambda-cyhalothrin ZC at 450 mL/hm² and 6% abamectin·chlorantraniliprole SC at 750 mL/hm² reached the peak 7 days after application, which was 85.23%-92.74%, obviously better than that of the other insecticides. All the above five insecticides have good control efficiency and durability, and the control efficiency is better than that of emamectin benzoate, so they can be used in maize field to control S. frugiperda.

Organophosphorus pesticides (Ops) are commonly used in chemical control. Several problems caused by excessive application of Ops are increasingly serious, including environmental pollution and quality and safety of agricultural products. In the meanwhile, scientific researchers in various fields at home and abroad explored actively the methods of remediation aiming at OPs contamination. Based on the summary of the application status of OPs and microbial degradation mechanisms, this paper summarized the species of microorganisms degrading organophosphorus pesticides and the spectra of organophosphorus pesticides degraded by functional microorganisms in detail. Furthermore, future perspectives for microbial remediation technologies were discussed, hoping to provide a theoretical basis for the research in the field.

The study aims to explore secondary metabolite resources of endophytic fungus RP2 which is isolated from Glycyrrhiza uralensis and increase the accessing ways for volatile aroma components. Endophytic fungus RP2 was chosen as the object and identified by morphological observation and ITS sequence analysis, and its volatile components were analyzed by gas chromatography-mass spectrometry (GC-MS). The results showed that endophytic fungus RP2 was identified as Fusarium oxysporum. 11 volatile components were isolated and identified from the RP2 fermentation liquid, and 6 components were isolated and identified from RP2 mycelium. RP2 can produce a variety of volatile aroma components that can be widely used in current industrial production, such as 2-phenylethanol. This study is of great significance for the development and utilization of RP2.

To explore the flavor substances of different highland barley varieties, the volatile components of 8 highland barley varieties were analyzed and identified by gas chromatography-mass spectrometry (GC-MS). The results showed that a total of 40 compounds were detected in the flavor substances of the 8 highland barley varieties, including 10 aldehydes, 8 alcohols, 2 esters, 5 ketones, 3 acids, 4 aromatics, 4 hydrocarbons, 1 furans, 1 phenol and 2 other types. Aldehydes had the highest relative content in different highland barley varieties of 12.98%-58.09%, followed by acids of 3.99%-33.90%, alcohols of 6.88%-16.36% and ketones of 4.47%-12.78%. The classification analysis showed that the 8 highland barley varieties could be divided into two categories. ‘Goumang purple highland barley', ‘Longzi black highland barley', ‘1127', ‘Shanqing 9' and ‘Zangqing 320' had higher similarity and were classified as the same category, while ‘Zangqing 2000', ‘Zangqing 25' and ‘Xila 22' had higher similarity and were classified as the same category. When the Euclidian distance was 25, the two categories could be classified as the same one.

To achieve automatic recognition of apple leaf disease images, this paper studied the recognition model of apple leaf disease. According to the data set of plant disease collected through the network open-source, three kinds of leaf images were obtained with apple scab, apple cedar rust and apple gray disease respectively, and one healthy leaf image was used as the study object. 4433 images were selected randomly to build the data set for model training, and all of these samples were expanded and averaged. The data were preprocessed with offline and online augmentation. On the basis of five pre-training models (Resnet50, Mobilenet v2, Vgg16, Vgg19, Inception v3), the parameters were adjusted and optimized for the migration model. Comparing the training results of the five models, the optimized Resnet50 model could achieve 0.9770 of accuracy. Featured by rapid recognition and high accuracy, the optimized training model could identify the disease types accurately and rapidly, and provide support for the automatic diagnosis of plant diseases.

Sprouting vegetables are nutritious and environment-friendly, which possess broad prospects for development. However, the promotion of sprouting vegetables has been impeded by the large workload and limited specialized equipment for production. To satisfy the demand of automatic management in sprouting vegetable cultivation, a combined ultrasonic device was designed. The device is composed of base plate, pre-germination system, cultivation system, lighting system and control system. Using the device, experiments were carried out on pea and radish sprouts cultivation. The results show that without manual management, the automatic control system could realize the automatic water supply for the pre-germination and cultivation system, as well as the automatic light supplement for the lighting system. Additionally, using ultrasonic atomization in the pre-germination and cultivation system could not only satisfy the water requirement of sprouts, but also coordinate the contradiction of water and air supply of roots, thus accelerating the growth of sprouts while reducing the frequency of rotten roots. The combination mode of the device is flexible, which allows users to select one or more cultivation systems for the combined use according to their requirements. In short, the device could realize automation in sprouting vegetable cultivation, and is of certain significance for the promotion of sprouting vegetables.