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20 November 2022, Volume 43 Issue 11

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Hydrothermal Effects of the Conservation Tillage in Soybean Farmland in Northeast China: a Meta-analysis

GONG Xiao-ya, ZHAO Jin, YANG Xiao-guang

2022, 43(11):  867-880.  doi:10.3969/j.issn.1000-6362.2022.11.001

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Based on the soil temperature and humidity data of soybean farmland under conservation tillage in Northeast China in the published article, the impact of conservation tillage measures on the soil hydrothermal status of soybean farmland in Northeast China was quantitatively assessed by using conventional tillage (CT) as a control, no-tillage (NT), reduced tillage (RT), straw mulching (SM), and no-till straw mulching (NTSM) as treatments. The results showed: compared with CT, conservation tillage increased the soil volume water content of 0-170cm soil layer in soybean farmland in Northeast China by 9.2%, and reduced the temperature of the shallow soil layer (0-30cm) by 8.2%. Four conservation tillage could increase soil moisture under different climatic conditions; straw mulching could increase soil moisture content throughout the growth period of soybeans, and the effect on soil hydrothermal was greatest during the nutrition period of soybean, and soil temperature increased with the increase of straw mulching; the magnitude of soil temperature reduction by conservation tillage decreases with the decrease of soil clay particles, the magnitude of soil moisture increased by conservation tillage decreases with the increase of soil depth. Among them, NTSM at different soil depths was the most obvious effect of water storage and moisture retention, and the soil moisture in the soil layer of 0-20cm was increased by 32.9%. In summary, conservation tillage could increase soil moisture but reduce soil temperatures. Temperature, precipitation, growth period, straw mulching amount, soil type and soil depth all had an impact on soil hydro-thermality in soybean farmland under conservation tillage.

Driving Factors of Temporal and Spatial Variation of Reference Crop Evapotranspiration in Gansu Province

MA Ya-li, SUN Dong-yuan, ZHANG Rui, XU Jian, WANG Xing-fan

2022, 43(11):  881-892.  doi:10.3969/j.issn.1000-6362.2022.11.002

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Based on the daily meteorological data of 29 meteorological stations in Gansu province from 1984 to 2019, the temporal and spatial variation of ET₀ was analyzed. A variety of qualitative and quantitative analysis methods including principal component analysis, cluster analysis, grey relational analysis, path analysis, sensitivity analysis were organically combined to reveal the internal relationship between ET₀ and climatic factors, and to explore the sensitivity and contribution of ET₀ changes to the dominant factors in Gansu Province. The results showed that ET₀ increased significantly (α=0.05) in Gansu province in recent 36 years and the mutation occurred in 1998.The spatial distribution of ET₀ increased from southeast to northwest during the study period. The Gannan plateau was small, while the Hexi plain was large, and the high value of ET₀ varied from 1049.3mm to 1260.9mm. Principal component analysis showed that temperature, humidity and radiation had a greater impact on ET₀, while wind speed had a relatively small impact. Combined with the results of cluster analysis and grey relational analysis, daily maximum temperature T_max, relative humidity RH, wind speed u, precipitation P, and sunshine duration n were five key climatic factors. T_max was the most important factor, and P had the least effect. ET₀ had different sensitivity to climatic factors, and RH was the most sensitive. T_max, n and u had a positive effect, while RH had a negative effect, and the contribution rates of RH, T_max, n and u were 3.79%, 7.22%, −0.42% and 3.70%, respectively. ET₀ in Gansu province showed an increasing trend in recent 36 years, which was due to the combined effects of the decrease of RH and n, and the increase of T and u. The increase of T was the main reason for the increase of ET₀. The research results provide scientific basis for the scientific allocation of irrigation water, efficient development and utilization of water resources in this region, and revealing the response mechanism of hydrological cycle-evapotranspiration under climate change. Meanwhile, the exploratory combined application of multiple methods provides a new idea for the analysis of driving factors of ET₀ change.

Analysis on Safe Sowing Date of Double-cropping Early Rice with Different Seedling Raising Methods in Jiangxi under Climate Warming

ZHANG Qi-ming, YI Yan-hong, LIAO Man-ting, GUO Shui-lian

2022, 43(11):  893-901.  doi:10.3969/j.issn.1000-6362.2022.11.003

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Ascertaining the safe sowing date of double-cropping early rice and the change rules of spring climate resources is an important basis for improving use efficiency of spring climate resources and agricultural production efficiency. Based on the daily average temperature data of 79 national meteorological stations in Jiangxi from February 1st to April 30th during the past 30 years (1992−2021), the distribution of safe sowing dates with 50% and 80% guarantee rates of double-cropping early rice with different seedling raising methods in Jiangxi under climate warming were systematically analyzed. The results showed that both average temperature and average pentad temperature increased significantly from 1992 to 2021, the climatic trend rates of average temperature was 0.055℃·y⁻¹, the most significant periods of climatic mean temperature increase were mainly concentrated in the 5th and 6th pentads in February, the 4th, 5th and 6th pentads in March and the 1st pentad in April, all above 1.5℃. The safe sowing dates of film-mulching dry seedlings, film-mulching wet seedlings, and direct seeding all shown a significant trend in advance, and the advance range from large to small is film-mulching dry seedlings> film-mulching wet seedling> direct seeding. Compared with the traditional sowing time, the safe sowing date of film-mulching dry seedlings in northern and central Jiangxi can be advanced to the end of early March, and which can be advanced to early March in the southern Jiangxi; the time of film-mulching wet seedlings in northern Jiangxi can maintain the traditional sowing date or be advanced to the early of late March, and in the central and southern Jiangxi this time can be advanced to the end of middle March; the time of direct seeding in northern and central Jiangxi can be advanced to 2-3 days before Qingming festival, and in the southern Jiangxi this time can be advanced to the end of late March.

Low Light during Reproductive Period of Tomato affects the Phenotypic Characteristics and Quality of Fruit

TAN Rong , JIA Tao, CHEN Xiao-li, GUO Wen-zhong

2022, 43(11):  902-911.  doi:10.3969/j.issn.1000-6362.2022.11.004

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"Harvest 74-560 RZ F1" tomato was cultivated in a plant factory with LEDs. One of the four reproductive stages (flowering stage, expanding stage, color turning stage and harvesting stage) was subjected to low light intensity of 160μmol·m⁻²·s⁻¹, while the other three stages maintained 1000 μmol·m⁻²·s⁻¹. The light intensity kept 1000μmol·m⁻²·s⁻¹ at all the reproductive stages in the control. The growth and fruit quality indices were measured to evaluate the effects of low light on tomato. The results showed that: (1) low light significantly affected the morphology of tomato plants at the flowering stage and expanding stage. Low light at flowering stage resulted in the most prominent overgrowth trend of tomato plants, as well as the least average number of leaves and nodes per plant which respectively decreased by 3.5 and 1.6 compared with the control. Low light at the expansion stage significantly reduced the content of carotenoid and the value of Chla/b compared with the control. The number of fruit set per plant after low light treatment at flowering stage was 53% lower than that of the control, while the number of fruit set per plant was not significantly affected by low light at other reproductive stages. The average yield of the first, second and third ear per plant after low light treatment at flowering or expansion stage was significantly lower than the other treatments. (2) Compared with the control, low light treatments decreased the soluble solid content of tomato fruit (first ear) in varying degrees, among which, the soluble solid content decreased by 25% after low light treatment at flowering stage. The soluble sugar content of tomato fruit decreased by 15% compared with the control, on the contrary, the total acid content increased by 26%, resulting in the lowest sugar/acid ratio of tomato fruit under this treatment. Compared with the control, low light treatments decreased the vitamin C content of tomato fruit in varying degrees, among which, the lowest vitamin C content was detected in tomato fruit subjected to low light treatment at the harvesting stage. This study showed that low light reduced the yield and quality of tomato, and the sensitivity of tomato to low light was different at varied reproductive stages. According to the growth characteristics and responses of tomato subjected to low light at different periods, it is of certain significance to supplement artificial light in order to stabilize the quality and yield of protected tomato.

Effects of High Temperature and High Humidity Conditions at Seedling Stage on the Chlorophyll Fluorescence Characteristics in the Center of Photosystem II of Cucumber Leaves

LI Yan-chen, YANG Zai-qiang, YANG Li, LUO Jing, ZHANG Feng-yin

2022, 43(11):  912-922.  doi:10.3969/j.issn.1000-6362.2022.11.005

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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℃(the highest daily temperature)/22℃(the lowest daily temperature), 35℃/25℃, 38℃/28℃ and 41℃/31℃.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℃/18℃, 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℃, with the increase of temperature, the normalized curve ΔV_t of fast fluorescence kinetics of cucumber leaves at seedling stage showed obvious convexity in J and K phases. The curve of ΔV_t at 41℃ was the most obvious (ΔV_J=0.24848, ΔV_K=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 (ΔV_J=0.00421, ΔV_K=-0.0031). With the increase of temperature, the energy dissipated per unit reaction center (DI_o/RC) and the quantum ratio used for heat dissipation (φD_o) both increased, reaching the highest at 41℃. Compared with CK, DI_o/RC and φD_o increased by 85.24% and 18.96% respectively at 41℃. The quantum yield for electron transfer (φE_o) and the energy for electron transfer captured by unit reaction center (ET_o/RC) were reduced, reaching the lowest at 41℃, which were 49.64% and 38.05% less than CK, respectively. Under the high temperature stress, ET_o/RC and φE_o were higher than 50% and 90% in the treatment of 70% relative air humidity. Compared with the 50% treatment, the ET_o/RC and φE_o 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.

Analysis of Spatial-temporal Variation Characteristics of Meteorological Drought in the Hexi Corridor Based on SPEI Index

XUE Hua-zhu, LI Yang-yang, DONG Guo-tao

2022, 43(11):  923-934.  doi:10.3969/j.issn.1000-6362.2022.11.006

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Using the daily meteorological data of 21 meteorological stations in the Hexi corridor from 1965 to 2017, SPEI at different time scales was calculated based on the Penman-Monteith evapotranspiration model, and the temporal and spatial variation characteristics of meteorological drought in the Hexi corridor, such as the change trend, occurrence frequency and duration, were analyzed. The results showed that: (1) in the past 53 years, the SPEI of the Hexi corridor showed a significant upward trend on the monthly, seasonal and annual scales, which indicated that the drought had a significant weakening trend, but the drought lasted for a long time at individual stations, and the drought lasted for 11 months in 2013 in Wuwei. (2) The Hexi corridor had a trend of wetting in four seasons, and it was significantly wet in winter. Among them, the in spring, summer and autumn presented unstable drought changes, while the sudden change in winter around 1989 indicated the trend from drought to wet. (3) The spatial distribution of drought in the Hexi corridor had obviously regional characteristics. The arid area was mainly concentrated in the northwest, and the humid area was mainly concentrated in the south. (4) The frequency variety law of different grades drought occurance at different time scales was consistent .The frequency of mild to moderate droughts was much higher than that of severe and extreme droughts, and the spatial distribution characteristics of relatively high frequency areas of severe and extreme droughts on the annual and seasonal scales were opposite to those of mild to moderate droughts. Generally, the drought in the Hexi corridor had weakened in the past 53 years, which was beneficial to the local agricultural production and ecological environment. However, the climate change in this region is complex, and local drought needs to be paid attention to.

Development of Winter Wheat Leaf Morphology Measurement Software Based On Machine Vision

GONG Zhi-hong , DONG Chao-yang, YU Hong , LIU Bu-chun, LI Chun , LIU Tao, LI Jun-ling

2022, 43(11):  935-944.  doi:10.3969/j.issn.1000-6362.2022.11.007

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With the development of image processing and recognition technology, the technology of crop phenotype recognition is becoming more mature. In order to achieve accurate and rapid determination of leaf area and area coefficient of winter wheat with different varieties and different growth stages, VB.net and OpenCV software were used in the study. In the image processing and packaging library based on NET platform, a winter wheat leaf morphology measurement algorithm with machine vision was developed, and a software was designed and developed. The software can realize distortion calibration of digital images and simultaneously measure the length, width and area of multiple leaves. And then in order to verify the effect of software measurement, 100 green expanded leaves of winter wheat were selected, and the accuracy and stability of image recognition method were analyzed by comparing with the leaf length and width measured manually. The leaf area measured by WinDIAS leaf area analysis system. The results showed that the correlation coefficients of the winter wheat leaf length, width and area measured by image recognition method, manual and WinDIAS were more than 0.975 respectively, while the normalized root mean square errors were less than 0.10%. For the distortion calibration function of digital images, the maximum relative error between the measurement results and the original image is only 2% after the calibration of the image with the horizontal (vertical) scaling of 50% and the vertical (horizontal) beveling of 30°. It is suggested that the recognition method of winter wheat leaf morphology based on machine vision can accurately calibrate various distorted images, while it can be used as a new method to accurately measure the area, length and width of multiple leaves at the same time. It can be popularized and applied in agricultural scientific measurement, agricultural information service and agricultural meteorological observation service.

Influence Report of Weather on Agricultural Production in Summer 2022

ZHAO Xiao-feng, HAN Li-juan, LI Sen, HE Liang, LIU Wei

2022, 43(11):  945-948.  doi:10.3969/j.issn.1000-6362.2022.11.008

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In the summer of 2022 (June-August), the national average air temperature was 22.3℃, which was 1.1℃ higher than the same period of the normal year(1991−2020). There were sufficient thermal resources in major agricultural areas. The national average high temperature days reached 14.3d, which was 6.3d more than that in the same period of from 1991 to 2020, and had been the maximum value since 1961. The national average precipitation was only 290.6mm, being the second smallest in the same period since 1961. The national average sunshine duration was 677.4h, which was close to the same period in the normal year and 53.7h more than that in 2021. The weather in most summer-harvesting areas was fine, which was conducive to the full maturity and quality improvement in grain and oil crops. There were two obvious precipitation events in late June, which effectively alleviated the previous drought in the northern summer-sowing areas. However, the deviation of soil moisture was not conducive to timely summer planting in some areas in Shaanxi and Gansu. Most of the agricultural areas were exposed to sufficient light and heat, with no occurrence of obvious cloudy and rainy weather. There was abundant precipitation and suitable soil moisture in the northern agricultural areas, which was in favor of the growth, development and yield formation for local crops such as corn and soybeans. The continuous high temperature and lack of rain in the southern agricultural areas led to the development of agricultural drought and heat stress for crops such as rice and maize. The meteorological conditions limited the stable growth of crops, economic trees and fruits. Superimposed precipitation occurred in Liaoning and Shandong, resulting in waterlogging in some lowland areas. Moreover, periodical low temperature in early June and late August affected the growth, development and grain filling of -harvesting crops in the Northeast.