Effective Cumulative Temperature Research Articles

Spatiotemporal Dynamic Relationship of Meteorological Factors and Sugar Content of Sugarcane by Vector Autoregression Model

Sugarcane is a globally significant economic crop, and sugar content is a key determinant of its financial and industrial value. This study utilized sugar content information from spring-planted and ratoon sugarcane in six research regions across Guangxi, China from 2008 to 2023 along with concurrent meteorological data. By conducting statistical tests, the critical meteorological factors influencing the sugar content of sugarcane (effective cumulative temperature and rainfall) were identified. These factors were then used as independent variables to construct a vector autoregression (VAR) model, which was employed to analyze the spatiotemporal dynamic relationships between sugar content and meteorological variables across different planting periods. The empirical results demonstrated that the influence of effective cumulative temperature on sugar content across various regions and planting periods shifted from positive to negative in the short-term, eventually reverting to a positive effect after a period of alternating influences. The impact of rainfall mirrored effective cumulative temperature, though it was relatively less pronounced. The sugarcane in Nanning and Baise was less influenced by effective cumulative temperature and rainfall, with the short-term impact changing from positive to negative and diminishing over time. Our findings provide scientific insights for guiding the ecosystem management of sugarcane in China.

Optimization of sowing dates for enhanced rice yield: insights from field experiments in the middle and lower reaches of the Yangtze River, China

An efficacious strategy to adapt to climate change involves optimizing the planting season, a technique that has been extensively utilized to enhance the use of solar radiation and temperature resources in rice cultivation. Field experiments were executed in the middle and lower reaches of the Yangtze River, China, employing three distinct rice cultivars and seven disparate sowing periods spanning 2019 to 2021. The objective of assessing the impact of sowing date on apparent radiation use efficiency (RUEA), accumulated temperature use efficiencies (TUE), and overall rice yield. Subsequent to the delay of sowing dates, the duration of the comprehensive growth period initially exhibited a declining trajectory before subsequently escalating, with the reduction predominantly ascribed to a decrease in the number of days preceding heading. Furthermore, there was a tendency for both the mean daily and effective cumulative solar radiation to decline over the course of the growing period. The yield of the three rice varieties demonstrated an initial surge, which was then followed by a subsequent decline in reaction to the delay of sowing dates. A correlation analysis disclosed that solar radiation and effective cumulative temperature (EAT) were the predominant elements impacting grain yield. The outcomes of the path analysis indicate that EAT exerts the most substantial influence on yield, succeeded by cumulative total solar radiation (TSR), while photothermal quotient (PTQ) demonstrates the least impact on yield. There was a significant positive correlation between EAT and cumulative TSR with spikelets per panicle (0.237** and 0.218**), grain filling (0.753** and 0.576**), and grain weight (0.339** and 0.359**), respectively. The findings of this study indicate that an increase in yield is facilitated when the EAT after heading exceeds 594.9 ℃, the EAT surpasses 2016.7 ℃, the cumulative TSR before heading is above 1548.7 MJ m− 2, the cumulative TSR after heading is over 603.0 MJ m− 2, and the cumulative total radiation throughout the entire growth period is more than 2151.8 MJ m− 2. Furthermore, the most optimal sowing date, as identified by this study, is June 6. This study provides key insights into boosting rice productivity in the middle and lower reaches of the Yangtze River, China by analyzing the impact of temperature and solar radiation on yield and identifying optimal growth conditions.Clinical trial number Not applicable.

Study on biological zero and effective accumulated temperature of embryonic development and gonadal development of cuttlefish Sepia pharaonis

ABSTRACT Research on the aquaculture of cephalopods has emerged in the last 30 years. Compared to other animals, limited information exists on the fundamental biology of cephalopods, particularly regarding their gonadal and embryonic development. Detailed investigation into their reproduction and development could provide a solid practical basis for understanding their methods of reproduction and reproductive patterns for enhancing artificial-seeding cultivation techniques. Therefore, this study utilised the second generation (F2) of cultured cuttlefish, Sepia pharaonis Ehrenberg, 1831, controlling the hatching temperature of fertilised eggs and recording data at various stages of gonadal development. We calculated the biological zero, the effective cumulative temperature, the temperature coefficient for embryonic development and the effective cumulative temperature for gonadal development. The results indicated that the biological zero and effective cumulative temperature for embryonic development of S. pharaonis were 7.46 and 434.87 °C·d, respectively, with the optimal temperature range for embryonic development being 24–27 °C. The effective cumulative temperature for gonadal development was 853.04 ± 57.51 °C·d. This study provides essential information on the biological zeros and effective cumulative temperatures for both embryonic and gonadal development of S. pharaonis, offering significant practical information and a theoretical basis for future large-scale artificial cultivation of this species.

Effect of water temperature on the development of Portunus trituberculatus larvae in the off-season breeding mode (Decapoda, Portunidae)

Abstract To clarify the influence of different water temperatures on the development of Portunus trituberculatus (swimming crab) larvae during off-season (early autumn) breeding, a gradient of four rearing temperatures of 27, 29, 31 and 33°C was set up, and the effects of water temperature on larval development were systematically compared. The results showed that the moulting cycle (MC) from the zoea 1 (Z1)-zoea 2 (Z2) stage was not significantly affected by water temperature (), remaining at approximately 3 days. However, in the Z2-megalopa (M) stage, the MC in the 31°C group was consistently the shortest. The total developmental duration and total effective cumulative temperature during Z1-M in the 31°C group were the lowest at 9.97 days and 250 days · °C, respectively. According to the equation of water temperature and larval development rate, the development rate was the fastest when the water temperature was 31°C. As the water temperature increased, the survival rate (SR) of larvae at various stages gradually decreased. The SR of the 27°C group was consistently significantly higher than that of the 33°C group (), especially in the M stage, where the SR of the 33°C group was only 2%, which was significantly lower than that of the 27°C and 29°C groups (). Among the antioxidant indexes, both superoxide dismutase (SOD) and total antioxidant capacity (T-AOC) were the lowest in the 29°C group at 315.75 U/mg protein and 0.36 mmol/g protein, respectively, and both were significantly lower than those in the 33°C group (). Catalase (CAT) and glutathione peroxidase (GSH-PX) were both the lowest in the 31°C group, and in this group the CAT was significantly lower than in the 33°C group, and GSH-PX was significantly lower than in the 27°C group (). For malondialdehyde (MDA) content, the four groups were basically maintained at about 2.5 nmol/mg protein, and there was no significant difference (). In terms of digestive enzyme activity, the activity of lipase (LPS) was basically maintained at 1.93 U/g protein. The other four digestive enzyme activity differences were mainly reflected in that the 31 and 33°C groups maintained relatively higher levels than the 27 and 29°C groups, especially the activities of α-amylase (AMS), and cellulase (CL) in the 33°C group, which were significantly higher than those in the 27 and 29°C groups (). Comprehensive indicators indicate that a water temperature between 29 and 31°C is the appropriate temperature for the development of the larvae of off-season breeding swimming crabs.

Research and development of a predictive system for fall armyworm early warning on maize crop

The rapid increase in fall armyworms (FAW, Spodoptera frugiperda) in recent years has posed major challenges to maize growers around the globe. To keep larval density below the economic threshold, we need interdisciplinary agricultural solutions like plant protection epidemiology, the Internet of Things, and scientific data techniques for early detection, monitoring, forecasting, and making informed decisions. Pest control should be planned ahead of time to prevent indiscriminate pesticide spraying, waste, and a negative effect on the environment. In this study, the authors plan to create a comprehensive iFAWcast software system that will automatically predict, alert, and gather research data on fall armyworms on maize crops in Vietnam. The system is comprised of three major components: (i) An automatic forecasting and alerting tool for fall armyworm outbreaks on the web platform; (ii) An agriculture reporting, forecasting, alerting, and user management tool on the web platform; and (iii) A mobile app that provides forecasting and alerting services on fall armyworms to farmers based on their geographical location. The iFAWcast system includes a central computation that dynamically updates weather forecasts from the Visual Crossing API and the OpenWeatherMap API, as well as a formula for the effective cumulative temperature based on the characteristics of fall armyworms on maize crops in Vietnam. The developed system was tested using data collected straight from the field, yielding extremely accurate and dependable results.

Effect of sowing date on radiation and temperature use efficiencies of rice in the low-light region of China

Sowing date optimization is an effective measure for adapting to climatic change and has been widely used to optimize the use of solar radiation and temperature resources in rice production. To evaluate the influences of sowing date on radiation and temperature use efficiencies (RUE and TUE, respectively) and grain yield of rice in low-light regions, field experiments with three rice varieties and four sowing dates (S-0, S-10, S-30, and S-40) were conducted at Dayi, Anzhou, Nanbu, and Shehong, in Sichuan, China, in 2018 and 2019. The results showed that the yield, RUE, and TUE of rice were significantly and negatively correlated with delayed sowing dates across the study sites. Generally, delayed sowing dates increased the daily total solar radiation, daily mean temperature, and effective cumulative temperature before heading, but decreased the growth duration and cumulative total solar radiation before heading, which resulted in a reduction in the effective panicle number per unit area. Meanwhile, delayed sowing dates increased the growth duration after heading, but reduced the daily total solar radiation, daily mean temperature, cumulative total solar radiation, and effective cumulative temperature after heading, contributing to a decrease in both the seed setting rate and 1000-grain weight across study sites. Therefore, S-30 and S-40 markedly decreased the rice yield, RUE, and TUE at Anzhou, Nanbu, and Shehong in both years and at Dayi in 2019, compared to S-0 and S-10. Moreover, growth duration, solar radiation, and temperature parameters before and after heading could explain the 73.7 % variation in the relative grain yield, relative RUE, and relative RTUE across the study sites. Ensuring that the daily mean temperature after heading and growth duration before heading are greater than 25.8°C and 113 d, respectively, and the daily total solar radiation and mean temperature before heading and growth duration after heading are lower than 14.7 MJ m–2 d–1, 23.1°C, and 42 d, respectively, by earlier sowing, is required to improve the RGY, RRUE, and RTUE in the low-light regions of China.

Diapause Induction, Color Changes, and Supercooling Point of Diapause Larvae of Tetrastichus septentrionalis Yang (Hymenoptera: Eulophidae).

The chalcid wasp Tetrastichus septentrionalis Yang (Hymenoptera: Eulophidae) is one of the dominant pupal parasitoids of Hyphantria cunea (Drury) (Lepidoptera: Erebidae). In this study, the photoperiod's effect on diapause induction in T. septentrionalis using the alternative host Tenebrio molitor was measured, revealing that T. septentrionalis is of the long-day type. The critical photoperiods for diapause induction in T. septentrionalis were estimated to be between photoperiods of 13:11 and 14:10 (L:D) h at 18 °C, and between photoperiods of 12:12 and 13:11 (L:D) h at 21 °C and 24 °C. We also found that T. septentrionalis diapausing larvae were grey-brown, while normally developed (non-diapausing) individuals were light yellow. The diapause-sensitive insect state was the larval stage, and the short light exposure treatment had a significant cumulative effect on diapause induction. The least squares method was used to calculate a lower developmental threshold of 13.34 ± 0.50 °C and an effective cumulative temperature of 184.46 ± 11.46 d·°C for post-diapause development. The average supercooling point of diapausing mature larvae was significantly lower than that of non-diapausing ones. Our research on T. septentrionalis provides a reference for the biological control of H. cunea and other leaf-eating pests.

Assessment of Heat Risk of Winter Wheat Cropping Based on Long-Term Meteorological Data

The frequency of heat events is likely to increase due to global climate change, posing an increasing risk to wheat production. To optimize crop management strategies for coping with future climates, it is crucial to quantify the high-temperature occurrence during cropping seasons. Here, sixty-six years (1955~2020) of meteorological data during wheat reproductive growth were collected from six meteorological stations in the Huaibei Plain of Anhui Province. These data were analyzed to quantify the pattern and characteristics of post-anthesis heat stress for wheat crops. Five levels of annual mean daily maximum temperature (Tmax) were defined, from normal to extreme temperatures. Six crop developmental phases of winter wheat, i.e., phase i to phase vi, were divided from flowering to maturity. The data suggest an annual mean temperature of 17~24 °C from flowering to maturity, with an annual effective cumulative temperature ranging from 725 °C d to 956 °C d. The mean temperature and effective cumulative temperature increased as crop growth progressed, along with more frequent heat events during phase ii (8~14 days after anthesis) and phase iii (15~21 days after anthesis). We also found that the frequency of extremely high temperatures (≥33 °C) from 1990 to 2020 was significantly greater than that from 1957 to 1990. Interestingly, it was found that the intensity of post-anthesis night temperatures also increased with crop growth, i.e., from phase i to phase vi. Wheat grain yield increased with increasing effective accumulative temperature and Tmax, but it started to decline when thresholds of effective accumulative temperature and Tmax were reached. Overall, these findings could provide guidelines for winter wheat cropping in the Huaibei Plain, China, or similar climate and cropping regions.

Ecology and behavioral patterns of Luciola cruciate in a restored forest in a chemical plant

Efforts to restore firefly populations are ongoing; these populations have been declining due to the development of cities and industries. The first step in restoration is the development of a breeding system that can accommodate approximately 5000 hatched larvae of Luciola cruciate, an aquatic firefly species, until they reach the last instar larval stage. The bred larvae are released into a river in a restored forest in a chemical plant, where they can breed naturally. Firefly-viewing events are organized so that people can experience the pleasure of watching fireflies. Such events can be successful if the peak flight season of fireflies can be predicted accurately. There is scope to improve the methods used for flight season prediction, which have impaired prediction accuracy owing to the variability of regional characteristics. In this study, data on fireflies and meteorological data accumulated for the restored forest over 11 years were analyzed and the peak flight days of L. cruciate adults and climbing by L. cruciate larvae were discussed. The new regression equation-based method proposed in this study, which used the breeding temperature and minimum humidity, can estimate the peak flight date of adult fireflies better than the conventional method based on the effective cumulative temperature. As part of the ecology of fireflies, statistical analysis on climbing by larvae revealed that minimum air temperature and cumulative precipitation were significant predictors of climbing and that climbing occurred on a rainy night with a minimum air temperature of ≥ 10 °C.

Latest potential sowing time of galega (Galega orientalis Lam.) for successful cultivation in the extreme winter conditions of northern Japan

AbstractMixed seeded plots of timothy (Phleum pratense L.) and galega (Galega orientalis Lam.) were established in multiple seeding times from 2014 to 2017 to determine the latest sowing limit in the Konsen region, northern Japan, where growing conditions are severe. Although low yields were observed in some cases when the soil freezing depth was deeper than average, the dry matter yield of the first crop of galega in the year after sowing was higher under conditions that ensured pre‐overwintering plant length growth of 30 cm or more, as compared with growth of less than 30 cm. Galega rhizomes were observed under conditions of pre‐overwintering plant length of 28 cm or more, but not under conditions of less than 28 cm in length. Therefore, achieving 30 cm plant length prior to overwintering is desirable when sowing galega in the Konsen region. Furthermore, the effective cumulative temperature (ECT) required for pre‐overwintering galega to reach 30 cm in plant length was 1079°C, for which seeding dates were calculated to be July 10 and June 29 in terms of calendar days, with 80% and 90% probability. In the Konsen region, galega should be sown earlier than in other regions of Hokkaido to ensure the growth rate because of the effects of soil freezing on overwintering performance.

The Estimation of an Effective Cumulative Temperature for Emergence of Rice Cultivar ‘Koshihikari’ without Heating in Ishikawa Prefecture

The Estimation of an Effective Cumulative Temperature for Emergence of Rice Cultivar ‘Koshihikari’ without Heating in Ishikawa Prefecture

Relationship between the Dynamic Characteristics of Tomato Plant Height and Leaf Area Index with Yield, under Aerated Drip Irrigation and Nitrogen Application in Greenhouses

The current study was undertaken to investigate the dynamic characteristics of the tomato crop, such as its plant height and leaf area index (LAI), based on the effective cumulative temperature. This was assessed under aerated drip irrigation (ADI) conditions and the application of a specific nitrogen (N) dose, and their relationship with the yield of the crop was formulated. The study was conducted in a greenhouse located in Zhengzhou, Henan province, China. The assessment conditions were the two irrigation methods, ADI and conventional drip irrigation (CK), and the three N application rates, i.e., 0, 140, and 210 kg ha−1. The logistic and Richards models were used to fit dynamic equations for plant height and LAI under the different treatments to quantify the characteristic parameters and understand their relationship with yield. The results revealed that the growth of the tomato plant fitted well with the logistic and Richards model at R2 > 0.98 (p < 0.01), regardless of the treatments. ADI and N application were found to significantly increase the maximum growth rate and average growth rate over the rapid growth period based on the tomato plant height and LAI. They were also noted to reduce the effective cumulative temperature at which plant height entered the rapid growth period (p < 0.05), thereby increasing the time spent in the nutritional growth phase. This is an essential precursor for the better development of subsequent reproductive organs. Tomato yields also confirm it: the highest yield of 85.87 t ha−1 was obtained with 210 kg N ha−1 for the ADI treatment, with an increase of 13.8%, 12.2%, and 39.6% compared to the CK–210 kg N ha−1, ADI–140 kg N ha−1, and ADI–0 kg N ha−1 treatments, respectively (p < 0.05). Grey correlation analysis showed that the characteristic parameters closely related to yield were all from the ADI and N application treatments. Furthermore, it was observed that the effective cumulative temperature and the maximum growth rate of the LAI at which the LAI entered the slow growth phase were the key growth characteristic parameters affecting tomato yield. This study provides a scientific basis for regulating the growth dynamics and yield of vegetables in greenhouse facilities under ADI and N application.

Development of a Nocturnal Temperature Inversion in a Small Basin Associated with Leaf Area Ratio Changes on the Mountain Slopes in Central Japan

Nocturnal temperature inversion (NTI) is an important factor characterizing the local climate in mountainous areas. In central Japan, most of the mountain slopes are covered by forests, but the effects of their leaf expansion/fall on the NTI variations in basins have not been clarified. According to a three-year leaf area index (LAI) observation in the mixed forest of the Sugadaira Highland (1320 m a.s.l.), Nagano Prefecture, Japan, we identified weakening of the NTI associated with leaf expansion and strengthening after leaf fall in a small basin. Using digital elevation and land-cover data, we defined the distribution of the deciduous and mixed forests in the catchment area of nocturnal cold air drainage. The estimated timings of leaf expansion/fall at the catchment scale based on the effective cumulative temperature almost coincided with the NTI changes. Micrometeorology observations showed that NTI at the forest floor and downslope winds at the adjacent grassland strengthened during the dormant (leafless) season in the nighttime when the radiative cooling is strong. Calm and clear nights were chosen during the spring dormant season and the summer growing season for 22 and 30 nights, respectively. The heat loss during the cold-air pool development was estimated, and converted to storage heat flux in the forest areas. The storage heat flux was 3.8 W m−2 more on average in the growing season than the dormant season, and it was less than that of forests estimated in previous studies (several 10 W m−2), indicating that an increase in storage heat flux of the forests with leaf expansion could cancel nocturnal radiative cooling and weaken gravity currents at the forest floor.

Spatial Heterogeneity of Winter Wheat Yield and Its Determinants in the Yellow River Delta, China

Understanding spatial differences of crop yields and quantitatively exploring the relationship between crop yields and influencing factors are of great significance in increasing regional crop yields, promoting sustainable development of regional agriculture and ensuring regional food security. This study investigates spatial heterogeneity of winter wheat yield and its determinants in the Yellow River Delta (YRD) region. The spatial pattern of winter wheat in 2015 was mapped through time series similarity analysis. Winter wheat yield was estimated by integrating phenological information into yield model, and cross-validation was performed using actual yield data. The geographical detector method was used to analyze determinants influencing winter wheat yield. This study concluded that the overall classification accuracy for winter wheat is 88.09%. The estimated yield agreed with actual yield, with R2 value of 0.74 and root mean square error (RMSE) of 1.02 t ha−1. Cumulative temperature, soil salinity and their interactions were key determinants affecting winter wheat yield. Several measures are recommended to ensure sustainable crop production in the YRD region, including improving irrigation and drainage systems to reduce soil salinity, selecting salt-tolerant winter wheat varieties, and improving agronomy techniques to extend effective cumulative temperature.

Apple growth evaluated automatically with high-definition field monitoring images

During cultivation of agricultural crops, it is important to accurately evaluate crop growth and perform the appropriate work at the right time. However, because a system for inexpensively and accurately determining crop growth automatically over time has not been developed, it is generally difficult for farmers to decide when to perform agricultural work. Therefore, we developed a system that can inexpensively and accurately evaluate the growth of crops over time. First, we developed a high-definition image monitoring device and periodically took images of an apple tree from a fixed point for 2 years from 2016 to 2017. Then, to obtain apple growth information, the radii of the apples in the images were measured manually, and the average radius was standardized from data for both years. We assumed that metrics for evaluating apple growth could be calculated from high-definition field monitoring images of the apple tree. Then, we introduced the green–blue vegetation index (GBVI), which can be easily calculated from images taken with a visible light camera installed near an apple tree, and calculated the GBVI leaf area. Then, we analyzed the metrics that can evaluate apple growth. Specifically, logistic curve approximations were performed for both years with a standardized average apple radius as the dependent variable, and the effective cumulative temperature, cumulative sunshine duration, cumulative precipitation, cumulative maximum GBVI leaf area, cumulative average GBVI leaf area, and elapsed time were taken as independent variables. The obtained logistic curves were defined as growth curves. The results showed that when the cumulative maximum GBVI leaf area was used as an independent variable, the growth curves were almost the same in both years. Moreover, as a result of estimating the standardized average apple radius using each growth curve, the estimation error for the cumulative maximum GBVI leaf area used as an independent variable was the smallest among all the independent variables. These results suggested that the cumulative maximum GBVI leaf area calculated from images was the most useful metric for accurately evaluating apple growth. In addition, it was suggested that the harvestable apple radius could be predicted using the growth curve with the cumulative maximum GBVI leaf area as the independent variable. By incorporating the methods for calculating these metrics into the high-definition image monitoring device, we can develop an automatic apple growth evaluation system based on high-definition field monitoring images.

Prediction of the Emergence Date of Small Brown Plant Hopper (Laodelphax striatellus) by the Effective Cumulative Temperature Method and the Agro-meteorological Grid Square Data System

Prediction of the Emergence Date of Small Brown Plant Hopper (<i>Laodelphax striatellus</i>) by the Effective Cumulative Temperature Method and the Agro-meteorological Grid Square Data System

Method for Collecting Eggs of &lt;i&gt;Scepticus uniformis&lt;/i&gt;（Coleoptera: Curculionidae）without Sand or Soil and Development of Their Eggs

We developed a new method for collecting eggs of Scepticus uniformis Kono without the use of sand or soil and investigated the development of the collected eggs. Weevils presented with a kidney bean leaflet and a piece of kitchen paper deposited most eggs on the kitchen paper, which proved to be a suitable substrate for oviposition. The developmental period of the eggs differed between 20 and 32°C. We estimated the lower developmental threshold（T0）as 13.9°C and the effective cumulative temperature of eggs（K）as 104.2 degree-days. It might be possible to set the timing of egg hatch by controlling the rearing temperature in the above range.

Upstream migration mechanisms of juvenile temperate sea bass Lateolabrax japonicus in the stratified Yura River estuary

Hydrographic conditions and distributions of juvenile temperate sea bass Lateolabrax japonicus were observed in early spring from 2009 to 2012 in the Yura River estuary, which is highly stratified due to its small tides and consequent seawater intrusion into the bottom layer of the river as a salt wedge. In all four studied years, the upstream expansion of their distribution coincided with the timing of the salt wedge intrusion from the lower to upper estuary, indicating that juvenile fish used salt wedge intrusions to ascend the estuary in early spring. However, juveniles sometimes remained in the nearshore area even when the salt wedge intrusion had already occurred, indicating that other triggers are also likely to be necessary. We therefore evaluated the effects of temperature on upstream migration behaviors. The relationship between the mean temperature they experienced from hatch until starting the ascent and mean age of each cohort at the upstream migration fitted with the law of effective cumulative temperature. Most cohorts ascended the river at an effective cumulative temperature of approximately 500 °C–days. This suggests that higher temperatures would lead to a shorter period prior to the upstream migration.

Soybean aphid, Aphis glycines (Hemiptera: Aphididae), developmental and reproductive capacity on white clover, Trifolium repens (Rosales: Leguminosae), in northeast China

Nymphs of Aphis glycines Matsumura were individually reared to adults in the laboratory on detached leaf discs of Trifolium repens L. (white clover) mounted on agar medium. Adults of A. glycines were fed T. repens within small clip cages in the field. Development, reproduction and intrinsic rates of increase of A. glycines were studied. These data were compared to those of controls fed known host plants including cultivated soybean Glycine max (L.) Merr. and the wild soybean species Glycine soja Sieb & Zucc. The results demonstrated that nymphs of A. glycines successfully developed into adults and reproduced efficiently when reared on T. repens in the laboratory. The lower development temperature threshold for nymphs fed T. repens was estimated as 8.27 °C, and the effective cumulative temperature for A. glycines development from nymph to adult was 90.91 degree-days. Adults of A. glycines could also survive on T. repens in the field, but only a few nymphs were produced.

Maize kernel weight responses to sowing date-associated variation in weather conditions

Variation in weather conditions during grain filling has substantial effects on maize kernel weight (KW). The objective of this work was to characterize variation in KW with sowing date-associated weather conditions and examine the relationship between KW, grain filling parameters, and weather factors. Maize was sown on eight sowing dates (SD) at 15–20-day intervals from mid-March to mid-July during 2012 and 2013 in the North China Plain. With sowing date delay, KW increased initially and later declined, and the greatest KW was obtained at SD6 in both years. The increased KW at SD6 was attributed mainly to kernel growth rate (Gmean), and effective grain-filling period (P). Variations in temperature and radiation were the primary factors that influenced KW and grain-filling parameters. When the effective cumulative temperature (AT) and radiation (Ra) during grain filling were 950°C and 1005.4MJm−2, respectively, P and KW were greatest. High temperatures (daily maximum temperature [Tmax]>30.2°C) during grain filling under early sowing conditions, or low temperatures (daily minimum temperature [Tmin]<20.7°C) under late sowing conditions combined with high diurnal temperature range (Tmax-min>7.1°C) decreased kernel growth rate and ultimately final KW. When sowing was performed from May 25 through June 27, higher KW and yield of maize were obtained. We conclude that variations in environmental conditions (temperature and radiation) during grain filling markedly affect growth rate and duration of grain filling and eventually affect kernel weight and yield of maize.