Key indicators affecting maize stalk lodging resistance of different growth periods under different sowing dates

The accurate evaluation of maize stalk lodging resistance in different growth periods enables timely management of lodging risks and ensures stable and high maize yields.Here,we established five diferent sowing dates to create diferent conditions for maize growth.We evaluated the effects of the different growth conditions on lodging resistance by determining stalk morphology,moisture content,mechanical strength and dry matter,and the relationship between stalk breaking force and these indicators during the silking stage(R1),milk stage(R3),physiological maturity stage(R6),and 20 days after R6.Plant height at R1 positively affected stalk breaking force.At R3,the cofficient of ear height and the dry weight per unit length of basal internodes were key indicators of stalk lodging resistance.At R6,the key indicators were the coefficient of the center of gravity height and plant fresh weight.After R6,the key indicator was the coefficient of the center of gravity height.The crushing strength of the fourth internode correlated significanty and positively with the stalk breaking force from R1 to R6,which indicates that crushing strength is a reliable indicator of stalk mechanical strength.These results suggest that high stalk strength and low ear height beneft lodging resistance prior to R6.During and after R6,the cofficient of the center of gravity height and the mechanical strength of basal internodes can be used to evaluate plant lodging resistance and the appropriate time for harvesting in fields with a high lodging risk.

Stability of growth periods traits for soybean cultivars across multiple locations

The growth periods（GPs, from planting/emergence to reproductive stage 8（R8） of soybean cultivars vary in different ecological regions, especially in China with a very complex soybean cropping system. In this study, a 3-yr experimental study was undertaken in three geographical locations of China from 2008 to 2010, including the Northeast（40.66-45.85°N）, Huang-Huai（34.75-38.04°N） and southern（22.82-30.60°N） eco-regions with about 250 accessions in each region to clarify the classification of maturity group（MG） and identify the cultivars with stable GP to increase the knowledge about the GP distribution of soybean cultivars in China. GPs of soybean cultivars in different eco-regions were significant different with a gradual decrease from 115-125 d in the Northeast part to the 85-100 d in the southern part of China. The geographical location was the major factor for GP of cultivars from the Northeast, while the year of planting was the major factor affecting the stability of GPs in Huang-Huai summer and southern summer soybean. AMMI2（additive main effects and multiplicativeinteraction）-Biplot analysis showed that the GPs of soybean cultivars from the Northeast eco-region have a comparatively satisfactory environmental stability. Moreover, soybean cultivars with moderate GP/MG and stable environment adaptability in different eco-regions were identified based on the linear regression and AMMI analysis, which was important for the accurate classification of soybean MGs in future. Taken together, our results reflected the genetic diversity, geographical distribution and environmental stability of the Chinese soybean GP trait. Soybean cultivars with stable GP for various Chinese eco-regions would be beneficial for Chinese soybean genetic improvement, varietal introduction, exchange, and soybean breeding program for wide adaptability.

Quantifying Multi-hazards and Impacts Over Different Growth Periods of Maize:A Study Based on Index Construction

Owing to the complexity and variability of global climate,the study of extreme events to ensure food security is particularly critical.The standardized precipitation requirement index(SPRI)and chilling injury index(I_(Ci))were introduced using data from agrometeorological stations on the Songliao Plain between 1981 and 2020 to identify the spatial and temporal variability of drought,waterlogging,and low-temperature cold damage during various maize growth periods.Compound drought and low-temperature cold damage events(CDLEs)and compound waterlogging and low-temperature cold damage events(CWLEs)were then identified.To measure the intensity of compound events,the compound drought and low-temperature cold damage magnitude index(CDLMI),and compound waterlogging and low-temperature cold damage magnitude index(CWLMI)were constructed by fitting marginal distributions.Finally,the effects of extreme events of various intensities on maize output were examined.The findings demonstrate that:(1)There were significant differences in the temporal trends of the SPRI and ICiduring different maize growth periods.Drought predominated in the middle growth period(MP),waterlogging predominated in the early growth period(EP)and late growth period(LP),and both drought and waterlogging tended to increase in intensity and frequency.The frequency of low-temperature cold damage showed a decreasing trend in all periods.(2)The CDLMI and CWLMI can effectively determine the intensity of CDLEs and CWLEs in the study area;these CDLEs and CWLEs had higher intensity and frequency in the late growth period.(3)Compared to single events,maize relative meteorological yield had a more significant negative correlation with the CDLMI and CWLMI.

Effects of Calcium Element on Biomass and Effective Constituents Contents in Blumea balsamifera in Slow Growth Period of Winter

The one-year-old seedlings of Blumea balsamifera （L.） DC. were applied with CaCl2.H2O that supplied Ca in slow growth period of winter three times. The heights, ground diameters, leaf lengths, leaf widths and biomasses of B. balsamifera plants were measured. In addition, the relative contents of total flavones in different parts of B. balsamifera were determined by UV spectrophotometry, and the absolute contents of total flavones were calculated. The relative contents of L-borneol in leaves of B. balsamifera were determined by GC, and the absolute contents of L- borneol were calculated. The results showed that calcium element significantly in- creased the biomasses in leaves, stems and roots of B. balsamifera in slow growth period of winter. The leaf biomass of B. balsamifera in the 5 g/L CaCl2-H2O treat- ment group was significantly higher than those in the other three treatment groups. The leaf biomasses of B. balsamifera in the 10 and 15 g/L CaCl2.H2O treatment groups were significantly higher than that in the CK, with 3.03 and 2.65 times, re- spectively. The application of Ca inhibited the accumulation of total flavones relative contents, but significantly increased the total flavones absolute contents in different parts of B. balsamifera. The relative and absolute contents of L-borneol in the 5 g/L CaCl2 .H2O treatment group were 0.22% and 0.22 g, which were increased by 37.50%, 22.22%, 37.50% and 100%, 100%, 450%, respectively compared with those in the 0, 10 and 15 g/L CaCl2.H2O treatment groups. The Ca element could signifi- cantly promote the accumulation of biomasses in leaves, stems and roots, as well as the absolute contents of total flavones and L-borneol in B. balsamifera in slow growth period of winter.

Temporal and Spatial Characteristics of Rainstorm during the Crops Growth Period in North China Region

By using the daily precipitation data from 1961 to 2005 in North China region,the temporal and spatial distribution characteristics of rainstorm process occurrence and the rainstorm intensity during the crops growth period were studied.The results showed that the rainstorm intensity and the rainstorm process during the crops growth period in North China region both had the obvious annual fluctuations and era variation characteristics.Although the rainstorm and heavy rainstorm occurred in North China region every year,the annual variations were great,and the variation coefficients respectively reached 36.9% and 53.1%.The torrential rain occurred once in every 4-5 years,and the rainstorm process occurred once in every 11 years.Although the torrential rain and rainstorm process occurred in fewer years,their annual fluctuations were more obvious.The peak value zones of rainstorm intensity which was greater and the rainstorm process which occurred frequently were in the 1960s.After 1999,the rainstorm intensity and the rainstorm process were in low value zone of historical stage from 1961 to 2005.Moreover,the 1970s-1990s was between high value and low value,and the rainstorms in different intensities which weren't synchronous happened in the period.In addition,the spatial distribution of annual average rainstorm days presented the tendency which increased obviously from northwest to southeast in Northern China,and the variation coefficient of rainstorm days presented the tendency which increased gradually from southeast to northwest.Generally,the more the annual average rainstorm days are,the smaller the variation coefficient is,and vice versa.The statistics results also showed that precipitation in North China had obvious positive correlation relationship with the rainstorm days.

Study on the Influence of Climatic Change on Pasture Growth in Inner Mongolia Grassland

Through analyzing statistically metrological observation data from 1971 to 2010 and pasture data from 1983 to 2012 at 6 animal husbandry meteorological testing stations of Inner Mongolia grassland, the conclusions were drawn. Those were that annual average temperature rose in a straight line in Inner Mongolia grassland, and the increase rates of annual average temperature in meadow steppe and typical steppe were 0.40 and 0.34 ℃/10 a respectively. Annual rainfall had 10-year cyclical characteristics, and precipitation in the 1990s was the most but reduced significantly after 2000. Climate experienced the cold wet -cold dry -warm wet -warm dry periods. Warm and dry climate made the average heights of pasture in meadow steppe and typical steppe of Inner Mongolia cut down 2.4 and 9.3 cm in nearly 12 years than that in the 1990s; the average coverage of herbage decreased by 11% and 13%; the average hay yields reduced by 1 019.8 and 671.4 kg/hm^2.

Digestive Rate of Dongtian F_1 Red Dear in Weaning Period and Growth Period

in this paper, 4N-HCLAIA method was adopted to conduct digestive tests in young female and male Dongtian F1 red deer (Cervus elaphus) of rearing seperatefy in growth period and mixed raising in weaning period in Harbin Specialty Research Institute. Results indicated that digestive rate of crude protein and crude fiber were 95.35% and 73.68% respectively when rational protein content was 26.8% in growth period. Digestive rate was not significantly different between female and male(P>0.05)i During weaning period, When rational crude protein content is 22.06%, digestive rate of crude protein and crude fiber were 93.05% and 63.96%, respectively. The tests suggest that higher rational protein can be effective in accelerating groWth of young Dongtian F1 red deer during growth period and weaning period(before 10 months old).

Analysis on Change Tendency of the Precipitation Resource during Growth Period of the Conventional Crops in Plain Area before Taihang Mountains

[Objective] The aim was to study change tendency of the precipitation resource during growth period of the conventional crops in plain area before Taihang Mountains. [ Method] Based on daily precipitation data at Shijiazhuang meteorological station in recent 51 years, average rainfall dudng growth periods of the 9 kinds of conventional crops was obtained. Precipitation tendency dudng growth periods of the 9 kinds of conventional crops in plain area before Taihang Mountains was analyzed by Mann-Kendall nonparametric test. [ Result] Seen from rainfall during growth pedods of the different crops, rainfall was the least during the growth period of winter wheat, followed by summer corn. Rainfall during growth peri- ods of the cotton, oil plant, vegetable, fruit tree, potato, rice and legumes was more. Under different guaranteed rates, precipitation change also had difference. Rainfall change during growth periods of the wheat and corn was bigger, and rainfall change during growth period of the rice was smaller. Change degree of the precipitation during growth periods of the cotton, oil plant, vegetable, fruit tree and legumes was equivalent, while precipitation change during growth period of the potato was the biggest. Seen from change tendency of the precipitation during growth periods of the different crops, precipitation in the growth period of winter wheat was increasing at a speed of 0.62 mm/a. However, precipitation in growth periods of the other crops had a decreasing tendency. Precipitation in the growth periods of summer corn and legumes decreased at the same speed which was 2.11 mm/a, while precipitation in growth periods of the cotton, oil plant, vegetable, fruit tree, potato and rice decreased insignificantly. [ Con dusion] The study laid foundation for determination of the agricultural irrigation water and provided theoretical reference for regional agricultural water-saving.

GROWTH OF MONGOLIAN OAK

The height fast growing period of oak seedling (Quercus mongolica) was between 25 to 30 years old but the diameter varied greatly. The maximum diurnal height increment of the investigated oak tree reached 3. 3 cm, but at daytime it was much greater than at night. The oak trees usually sprouted twice and even treble in the growing season. In natural oak stands. the volume rarely exceeded 200 m3/hm2 and the mean volume increment was only about 2 m3/hm2

The Variation Rule and Anomaly Features of the Available Precipitation in the Growth Period of Crops in the Middle and Southern Part of Ningxia

[ Objective] The aim was to study the available precipitation and its abnormal characteristics during the growth period of crops in the mid- dle and southern part of Ningxia. [ Methed] Through Takahashi＇s evaporation equation, linear trend analysis, Mann -Kendall, Lepage, wavelet analysis, the characteristics of available precipitation and its abnormal characteristics during its growth period in Ningxia were analyzed based on monthly precipitation （March- September）, temperature, and NCAR/NCEP reanalysis data in 9 observation stations from 1961 to 2010. E Result l In recent 50 years, the available precipitation during the growth period of crops in central drought area and south hilly area varied a lot, more in the south and less in the north. The available precipitation in these two areas was reducing and varied a lot in different ages. The available precipitation was less in the middle drought region after 1970s and in the southern hilly region after 1990s and the available precipitation in middle drought area changed significantly. The available precipitation in the two areas appeared in July, August, and September, above 76% of general growth period, while that in March, April and May was 14% lower than that in growth period. No abrupt changes in central drought area and south hilly area. There were the periods of 5 -7 a and 2 -3 a oscillations in the middle drought region, 2 -3 a and 10 -12 a oscillations in the southern hilly region. There were negative anomaly field at 500hPa height in high-precipitation years between the Baikal and the China＇s northwestern, and there were positive anomaly field in low-precipitation years. [ Cenclusion] The study provided reference for the reasonable utilization of available water resources in cen- tral and south Ningxia.

Research on the Influence of Early Experience on the Growth Rate of Science and Engineering Graduate Supervisors

This research is based on three northeastern double first-class polytechnic universities.A total of 1628 science and engineering graduate supervisors?resumes were referred to from an official website by the random sampling method,of which only 500 supervisors were included in consideration of complete information,key events,and time in terms of the educational background(undergraduate school,graduate school,doctoral school,number of masters,number for Dr.),early work background(number of postdocs,number of overseas visits,numbers of research work),and the growth rate(period from graduation to associate professor title).The higher education background and early work background were defined as early experience,and the database of these 500 science and engineering graduate supervisors with complete resume information from three double first-class universities in northeastern China was established.In this study,the growth rate of the growth period was divided into two at the critical period:the growth rate of the graduate supervisor to associate professors.Through stepwise multiple regression analysis,it was found that higher education background(undergraduate schools,graduate schools,doctoral schools,as well as the number of master's and doctorate degrees)as well as early work background(number of postdoctoral work,research work,and overseas visits)have a significant impact on the growth rate of graduate supervisors to associate professors.

Extreme Climatic Characteristics and Their Effects on Maize Yield in Hei-longjiang Province from 1961 to 2020

This paper analyzed the extreme climatic characteristics of maize in Heilongjiang Province during different growth periods using the climate data and maize yield data from 1961 to 2020,and applied the principal component analysis to analyze the extent of different extreme climatic events affecting maize yield.The results showed that the extreme cold events showed a decreasing trend,and the extreme warm events showed an increasing trend,and the trend of extreme precipitation change was not obvious.Maize yield was negatively correlated with TN10p(cold nights),TX10p(warm days)and T8(days below the lower temperature limit),and positively correlated with TN90p(warm nights).T34(days above the upper temperature limit)and TX90p(warm days)during the tasseling-milking period were negatively correlated with the maize yield,and this part was concentrated in the southern part of Heilongjiang Province.The maize yield was positively correlated with the extreme precipitation during the seedling period and negatively correlated with the extreme precipitation during the filling-maturity period of maize,but the correlations were not significant.The effects of extreme weather events on maize yield were higher during the seedling and the filling-maturity periods than those during the jointing-tasseling and the tasseling-milking periods.The effects of extreme precipitation on the maize yield were less than those of the extreme temperature during different growth periods in all regions,but the effects of the extreme precipitation on maize yield were significantly higher in the Songnen Plain than those in other regions.There were regional differences in the impact of climate extremes on maize during different growth periods.The area with the greater impact of climate extremes during the seedling period was the Songnen Plain,the areas with the greater impact of climate extremes during the jointing-tasseling period were the northern part of the Sanjiang Plain,and the areas with the greater impact of climate extremes during the filling-maturity period were the Lesser Khingan Mountains and the semi-mountainous areas of Mudanjiang.

Adaptability Comparison of Chinese Milk Vetch (Astragalus sinicus) Varieties for Double-rice Cropping System in Hunan

Five Chinese milk vetch（Astragalus sinicus） varieties were selected to make a comparison in order to screen effective varieties which could suit for the double-rice cropping system of Hunan Province. The results showed that the growth period of Xiangzi 2 is shorter than that of Xiangfei 2, Xiangfei 3 and Yujiangdaye,and is similar to that of Xinyang Chinese milk vetch. The full-bloom stage of Xiangzi 2 is also similar to Xinyang variety and obviously earlier than that of the other three varieties. The fresh grass yield of Xiangzi 2 in full-bloom stage is 23 842.5kg/hm^2, which increases by 39.9% compared with Xinyang variety. Nitrogen content in the fresh grass of Xiangzi 2 is higher than that of the other four varieties. In conclusion, Xiangzi 2 is an extremely early-blossoming and early-maturing Chinese milk vetch variety with moderate fresh grass yield, high nutrient contents, stable characters and wide adaptability. So, Xiangzi 2 is suitable for planting in double-rice cropping region in Hunan Province and other same latitude regions which have similar ecological conditions.

Comprehensive Assessment of Drought Resistance of Proso Millet Germplasm Resources in Shanxi

In order to clarify drought resistance of proso millet applied in field production in Shanxi, we identified its drought resistance during the whole growth period and measured nine traits, including plant height, panicle length, stem diameter, panicle weight, grain weight per spike, straw weight per plant, node numbers of main stem, 1 000-grain weight and effective panicles, under different treatments. Principal component analysis and stepwise regression analysis were used for comprehensive evaluation of drought resistance during the whole growth period and screening the drought index. The results showed that there were correlations among 9 phenotypic traits. The coefficient of variation of panicle weight and straw weight per plant sharply reduced under normal water supply and drought stress. Landrace ＂yellow millet＂ had the strongest drought resistance（D =0.87）, integrated drought D value and membership function value of yield had significant correlation（r =0.515 9, P〈0.05）. Panicle weight and straw weight per plant had significant impact on drought resistance and could be taken as comprehensive indexes of drought resistance identification in growth period.

Variation Dynamics of Total Nitrogen and Nicotine of Burley Tobacco at Various Growing Stages under Different Nitrogen Nutrition Levels

[Objective] This study aimed to investigate the variation dynamics of total nitrogen and nicotine of burtey tobacco at various growing stages under different ni- trogen nutrition levels to provide reference for optimizing fertilization technologies for burley tobacco. [Method] Fresh burley tobacco leaves were collected at various growing stages and dried to measure the content of total nitrogen, protein and nico- tine by using INTEGRAL automated chemical analyzer and analyze the correlation with nitrogen application level. [Result] Regardless of the nitrogen application level, the content of total nitrogen and protein showed a downward trend since root ex- tending stage and reached the minimum at mature stage; the content of nicotine showed an upward trend since early vigorous growing stage and increased to the maximum at mature stage; the content of total nitrogen, protein and nicotine all in- creased after air curing; the content of total nitrogen, protein and nicotine showed positive correlation with nitrogen application level, while total nitrogen/nicotine was negatively correlated. The results indicate that nitrogen level is closely related to the total nitrogen and nicotine of burley tobacco at growing period and post-air curing, rational application of nitrogen is an important measure to regulate the content of total nitrogen and nicotine of tobacco. [Conclusion] This study provides scientific ba- sis for rational fertilization of burley tobacco.

Spatial Characteristics of Temperature Indices of Climate Change in China

Based on the temperature indices established by expert group on the detection,monitoring and indices of climate change,spatial characteristics of temperature indices from 278 meteorological stations in China during 1961-2008 were studied.The results showed that day number of freezing point went down gradually from northwest to southeast,as well as the most regions of China.Day number of summer was mostly over 50 d in China and over 100 d in Eastern China except for the most part of Northeast China,while there was an increase trend in the most regions of China.Growth period was generally above 150 d in China and increased with the decrease of latitude from north to south,while the trend coefficient of growth period in 236 stations was positive.

Studies on the Super-high-yield Cultivation Techniques for Oats in Tibet

[Objective] The aim was to explore the optimal levels of different factors influencing oat yield in Lhasa, Tibet. [Method] Orthogonal test was conducted to analyze oat cultivation technology in Tibet. [Result] Qingyin No.2 and Baiyan No. 8 were proved the optimal species to be grown in Lhasa with optimal sowing quantity at 150-180 kg/hm2. Sowing term is an extremely significant factor affecting growing season, and species and N fertilizer are significant factors. Al factors have none significant effects on hay yield. [Conclusion] The research provides theoretical refer-ences and technological supports for large-scale planting.

Effects of Fulvic Acid on Agronomic Traits and Yield of Autumn Potato

[Objective] This study was to investigate the effects of fulvic acid on agronomic traits and yield of autumn potato. [Method] The effects of fulvic acid on growth period, plant morphology, tuber, net photosynthetic rate, chlorophyll content, leaf area index （LAI） and yield of autumn potato were investigated. [Result] The application of fulvic acid prolonged the growth period and increased the plant height, stem diameter, leaf chlorophyll content, LAI, net photosynthetic rate, tuber number per plant, tuber weight per plant and marketable tuber rate of autumn potato, thus increasing the yield. Applying fulvic acid prolonged the growth period of autumn potato by 1-3 d and significantly increased the plant height, net photosynthetic rate, tuber weight per plant and yield of autumn potato （P〈0.05, P〈0.01）. When the application amount of compound fertilizer was reduced by half, applying fulvic acid almost showed the same seedling emergence stage, mature stage, growth period and net photosynthetic rate with applying full amount of compound fertilizer. In particular, no significant difference was found in the yield of autumn potato between fullamount and half-amount compound fertilizer treatment groups in the premise of solid- liquid fulvic acid combined application. [Conclusion] In the premise of unchanged yield, applying fulvic acid can reduce the application of chemical fertilizers and reduce the non-point source pollution of chemical fertilizers.

Variations in stem radii of Larix principis-rupprechtii to environmental factors at two slope locations in the Liupan Mountains,northwest China

Relationships between stem growth and climatic and edaphic factors,notably air temperatures and soil moisture for different slopes,are not completely understood.Stem radial variations were monitored at the bottom and top slope positions in a Larix principis-rupprechtii plantation during the 2017 and 2018 growing seasons.Total precipitation during the growing season in 2017 and 2018 was 566 mm and 728 mm,respectively.Stem contractions typically occurred after mid-morning followed by swelling in the late afternoon in both plots,reflecting the diurnal cycle of water uptake and loss.Trees at the two locations showed the same growth initiation(mid-May)because of the small differences in air and soil temperatures.There were no significant differences in cumulative stem radial growth between the bottom plot(1.57±0.34 mm)and the top plot(1.55±0.26 mm)in 2018.However,in 2017,the main growth period of the bottom plot ceased 17 days earlier than in the top plot,while cumulative seasonal growth of the bottom plot(1.08±0.25 mm)was significantly less than the top plot(1.54±0.43 mm).Maximum daily stem shrinkage was positively correlated with air and soil temperatures,solar radiation,vapor pressure deficits,and negatively correlated with volumetric soil moisture content.The maximum daily shrinkage reflected transpiration rates as affected by environmental factors.Daily radial stem increment was correlated with precipitation and volumetric soil moisture in both years,but with air temperatures only in 2017.The seasonal growth of L.principis-rupprechtii Mayr thus shows interannual dynamics,while precipitation constitutes a key driving factor.

Characteristics of root pullout resistance of Caragana korshinskii Kom.in the loess area of northeastern Qinghai-Tibet Plateau,China

Roots exert pullout resistance under pullout force,allowing plants to resist uprooting.However,the pullout resistance characteristics of taproot-type shrub species of different ages remain unclear.In this study,in order to improve our knowledge of pullout resistance characteristics of taproot systems of shrub species,we selected the shrub species Caragana korshinskii Kom.in different growth periods as the research plant and conducted in situ root pullout test.The relationships among the maximum pullout resistance,peak root displacement,shrub growth period,and aboveground growth indices(plant height and plant crown breadth)were analyzed,as well as the mechanical process of uprooting.Pullout resistance of 4-15 year-old C.korshinskii ranged from 2.49(±0.25)to 14.71(±4.96)kN,and the peak displacement ranged from 11.77(±8.61)to 26.50(±16.09)cm.The maximum pullout resistance and the peak displacement of roots increased as a power function(R^(2)=0.9038)and a linear function(R^(2)=0.8242)with increasing age,respectively.The maximum pullout resistance and the peak displacement increased with increasing plant height;however,this relationship was not significant.The maximum pullout resistance increased exponentially(R^(2)=0.5522)as the crown breadth increased.There was no significant relationship between the peak displacement and crown breadth.The pullout resistance and displacement curve were divided into three stages:the initial nonlinear growth,linear growth,and nonlinear stages.Two modes of failure of a single root occurred when the roots were subjected to vertical loading forces:the synchronous breakage mode and the periderm preferential breakage mode.These findings provide a foundation for further investigation of the soil reinforcement and slope protection mechanisms of this shrub species in the loess area of northeastern Qinghai-Tibet Plateau,China.