Analysis on Absorption,Utilization and Transfer Efficiency of Nitrogen in High-yield Wheat Cultivars at Different Sowing Dates

This study aimed to analyze the absorption, utilization and transfer char- acteristics of nitrogen in high-yield winter wheat （Triticum aestivum） cultivars at dif- ferent sowing dates, so as to determine the optimum sowing dates for different high-yield wheat cultivars. A field experiment was conducted in the Shajiang black soil of Anhui Province with Jimai 22, Wanrnai 52 and Zhoumai 22, and the effects of early sowing （October 3）, optimum sowing （October 12） and late sowing （October 30） on wheat plant N content and accumulation, pre-and post-anthesis N accumula- tion （NA） of total plant, nitrogen remobUization to grain （NR）, N remobilization effi- ciency （NRE）, contribution of N remobilized to grain （NRC）, grain yield, N use effi- ciency （NUE） and N harvest index （NHI） of different wheat cultivar were investigat- ed. The results showed that sowing date had an impact on N content, absorption and utilization in wheat plants at various growth stages. The NA, NR and NRC of aboveground vegetative organs of wheat before anthesis were higher than those af- ter anthesis. Under the condition of late sowing, the grain N accumulation mainly depended on the N absorption by vegetative organs before anthesis. Under the conditions of optimum and early sowing, the absorbed N after anthesis accounted for a large proportion in grain N accumulation. The N uptake intensity and relative cumulative rate differed greatly among different growth stages and different-genotype wheat cultivars, and the pre-anthesis NA, pre-anthesis NR, pre-anthesis NRE, post- anthesis N assimilation amount and post-anthesis NRC showed significant differ- ences among different wheat cultivars. The grain yields of different wheat cultivars under the early and optimum sowing were all higher than those under the late sowing. The NHI and grain N accumulation were highest under the optimum sow- ing, and the latter significantly decreased with the delay of sowing dates. In con- trast, the NUE was highest under the late sowing, reaching 35.95%-41.32%. It indi- cated that under the condition of late sowing, most of the nitrogen was not ab- sorbed by wheat, but the use efficiency of the absorbed nitrogen significantly in- creased. In overall, the three high-yield wheat cultivars were all suitable for early and optimum sowing. Under the condition of late sowing, the yield of Zhoumai 22 showed the smallest differences with those under early and optimum sowing, and its NUE was significantly improved. Therefore, among the three high-yield wheat culti- vars, Zhoumai 22 was most suitable for late sowing.

Effects of Different Sowing Dates and Sites on Starch RVA Profile Characteristics of Different Ecotypes of Rice (Oryza sativa, L. japonica)

[Objective] This study aimed to investigate the effects of different sowing dates and sites on starch RVA profile characteristics of different ecotypes of japonica rice. [Method] Five different ecotypes of japonica rice were sown at seven different dates in four rice planting regions in Jiangsu Province to analyze the differences in starch RVA profile parameters among different rice varieties. [Result] Among eight parameters of rice starch RVA profile, peak time exhibited no significant differences among different sites, while other seven parameters varied significantly or extremely significantly among different sites, sowing dates and varieties. Specifically, rice variety exerted the most significant effects on rice starch RVA profile parameters. Starch RVA profile characteristics varied significantly among different ecological conditions but exhibited no significant differences among different latitudes. To be specific, in different sites, peak viscosity （PKV）, hot paste viscosity （HPV） and breakdown viscosity （BDV） demonstrated a descending order of Huai＇an 〉 Suzhou 〉 Lianyungang 〉 Yangzhou. Cool paste viscosity （CPV） and consistence viscosity （CSV） were higher in the north than in the south; specifically, CPV and CSV were significantly higher in Lianyungang and Huai＇an than in Yangzhou and Suzhou. Setback viscosity （SBV） showed an increasing trend with increasing latitude; specifically, SBV was significantly lower in Suzhou than in other three sites. Pasting temperature （PAT） and peak time （PET） changed slightly among different latitudes. With the postponing of sowing date, peak viscosity （PKV）, hot paste viscosity （HPV）, cool paste viscosity （CPV） and peak time （PET） showed a decreasing trend, setback viscosity （SBV） and consistence viscosity （CSV） increased, breakdown viscosity （BDV） increased first and then decreased, whereas pasting temperature （PAT） decreased first and then increased. Furthermore, rice starch RVA profile parameters showed the same variation trend with sowing date in different sites; early sowing within suitable sowing dates could effectively improve the parameters of rice starch RVA profile. However, different parameters exerted different variations among different sites and most parameters were higher in the north than in the south, which indicated that starch RVA profile parameters were significantly affected by sowing date in the north of Jiangsu Province. Among eight starch RVA profile parameters, setback viscosity exhibited the maximum variation coefficient, while peak time exhibited the minimum variation coefficient. Among five rice varieties, Nanjing 46 exhibited the highest peak viscosity and breakdown viscosity and the lowest setback viscosity and consistence viscosity, suggesting that Nanjing 46 had the most appropriate starch RVA profile characteristics and the best cooking and eating quality. Lianjing 4 exhibited relatively high peak viscosity and breakdown viscosity, and relatively low setback viscosity and consistence viscosity, suggesting that Lianjing 4 had good starch RVA profile characteristics. Different sowing dates and sites exerted significant effects on starch RVA profiles of different eco- types of japonica rice. Rice starch RVA profile characteristics varied significantly among different sites but exhibited no significant variations among different latitudes. In addition, starch RVA profile characteristics varied significantly among different sowing dates. Therefore, early sowing of the same variety was conducive to improving starch RVA profile characteristics in appropriate planting regions. [Conclusion] This study provided a theoretical basis for producing high-quality rice and improving the eating quality of rice in Jiangsu Province.

Study on Sowing Date for Mechanicaltransplanting Rice under Wheat-Rice Cropping System in Chengdu Basin

Nurturing sturdy mechanical-transplanting seedlings is the key to achieve high yield using mechanical-transplanting technology under wheat-rice cropping conditions in Chengdu Basin. In this study, super hybrid rice II You 602 was adopted as experimental material, to investigate the effects of sowing date on seedling growth,transplanting quality, growth process and yield of mechanical-transplanting seedlings in wheat-rice cropping region of Chengdu Basin, thus exploring supporting high-yield cultivation techniques for mechanical-transplanting technology in Chengdu Basin, Results showed that the appropriate sowing date for mechanical transplanting in wheatrice cropping region of Chengdu Basin was April 10-15, and the appropriate seedling age was 45-50 d, which led to the highest yield of mechanical-transplanting seedlings. Although postponing sowing was conducive to improving transplanting quality and increasing the percentage of earbearing tillers, it would result in lagged group growth, poor spike quality and reduced effective number of panicles, grain number, seed-setting rate, 1 000-seed weight and other yield components, thus declining the yield. Yield reduction rate would be above 10% with sowing date postponed by 15 d.

Effect of Different Sowing Dates and Densities on Individual Morphological Development of Super Short-season Insect-resistant Cotton

[Objective] The paper was to explore the effect of different sowing dates and densities on individual morphological development of super short-season insect-resistant cotton,confirm their effects on vegetative and reproductive growth of cotton,so as to provide theoretical and practical guidance for sowing date and density management of cotton planting in Jidong cotton growing region in Yellow River Basin.[Method] With super short-season insect-resistant cotton＂546＂as materials,the effects of different sowing dates（sowing dateⅠ：May 20;sowing dateⅡ：June 2;sowing date Ⅲ：June 14）and densities（low density：120 000 plants/hm2;middle density：150 000 plants/hm2;high density：180 000 plants/hm2）on individual morphological development of super short-season insect-resistant cotton were explored.[Result] Different sowing dates and density treatments significantly affected the individual morphological development of super short-season insect-resistant cotton＂546＂.The effectiveness of sowing date was higher than the effectiveness of density,and the effectiveness of sowing date on development of number of individual fruit branches was higher than that on plant height and stem diameter.[Conclusion] The regulation of sowing date and density during the cultivation process of super short-season insect-resistant cotton ＂546＂ in Jidong cotton growing region in Yellow River Basin could effectively promote vegetative and reproductive growth of cotton,strengthening its production base.

Effects of Different Sowing Dates and Sites on Grain Quality and RVA Profile of Nanjing 46,a Popular Cultivar of Japonica Rice(Oryza sativa L.)

[Objective] This study was performed to determine the effects of sowing dates and sites on grain quality and Rapid Viscosity Analyzer （RVA） profile of Nan-jing 46. [Method] The field experiments were carried out at five sites in Jiangsu Province, and in every site, the seeds were sowing on seven different dates. RVA related indices were measured after harvest. [Result] Along with the delay of sowing date, the mil ing quality of Nanjing 46 increased at first and then reduced, while its appearance quality went up and the cooling and edible quality decreased. With the sowing sites moving southward, the rice mil ing quality, appearance quality, and cooling and edible quality of Nanjing 46 decreased at first and then increased. Grain traits responded variably to the sowing dates and sites. The brown rice rate, grain width, grain length, length/width, mil ed rice rate and head mil ed rice rate were less affected, while the chalky rice rate and chalkiness degree were more af-fected. The gelatinization temperature, protein content, amylose content, gel consis-tency and eating value were in-between. The RVA profile analysis revealed that the breakdown value, setback value and pasting temperature were affected by the sow-ing date and geographical environment. The peak viscosity, hot viscosity, cool vis-cosity and peak time were influenced more by geographical environment. With the delay of the sowing date, peak viscosity, hot viscosity, cool viscosity, setback value and pasting temperature decreased at first and then increased, while the breakdown value changed inversely, and the peak time did not exhibit a regular trend. With the decrease of latitude, the peak viscosity, hot viscosity, breakdown and cool viscosity declined at first and then increased, the setback value and peak time decreased, while the pasting temperature increased. [Conclusion] This study wil provide refer-ences for the effective production of Nanjing 46.

Maize kernel weight responses to sowing dateassociated 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 1005.4 MJ m-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.

Effect of Rice Sowing Date on Occurrence of Small Brown Planthopper and Epidemics of Planthopper-Transmitted Rice Stripe Viral Disease

To understand the relationship between rice sowing date and occurrence of the rice small brown planthopper （SBPH） Laodelphax striatellus Fallen and the epidemics of the planthopper-transmitted rice stripe viral （RSV） disease, four sowing dates of rice were evaluated in 2006 and 2007. The results showed that the peak density of SBPH and RSV incidence in the nursery and in the transplanted field decreased with the delay of sowing date in single crop of japonica rice in north Zhejiang Province of China. The relationship between seedling RSV incidence at the end of the nursery trial with sowing date was well described by Weibull equation. The area under the curve of population dynamics （AUCPD or planthopper-day accumulation） or the peak density of the planthopper in the nursery could be summarized by a logistic equation. RSV incidence in the transplanted fields could be characterized quantitatively by a multivariate regression equation, including the variables of sowing date, peak density of the vector, and RSV incidence at the end of the nursery trial. That the descriptive model excluded the AUCPD in transplanted field implies that this variable is not necessary in forecasting disease epidemics in the field. The 2-year experiments sufficiently indicated that suitable sowing of rice could be used as one of the effective measures to control the vector population and therefore the planthopper-transmitted RSV on a larger scale. The optimal sowing date for the single-cropped transplanted japonica rice is recommended from late May to early June in north Zhejiang, China.

Adaptation of potato production to climate change by optimizing sowing date in the Loess Plateau of central Gansu, China

Potato grows in most part of China, it achieves higher yield and better quality in Gansu Province than in others. With global warming, its growth duration has been prolonged and sowing date become earlier than before. Therefore, to regulate its sowing date and growing period is of great significance for better harvest. In this study, experiments were conducted with six sowing-date treatments of potato in Dingxi, which is in the Loess Plateau of central Gansu Province in Northwest China in 2010. The growth period, morphological index and change in yield and their relationships with temperature, precipitation, and other climatic factors were investigated for each treatment. Results show that the crop with different sowing dates experienced different climate conditions, leading to distinct growth duration, plant height, and leaf area index. The growth duration was shortened due to a delay in sowing date. For each 15-day delay in sowing, the growth duration was reduced by 12 days on average. A significant linear relationship was found between numbers of days either from seeding to emergence or from flowering to harvest and mean temperature over the corresponding period. Dry matter accumulation, tuber fresh weight, and final yield were all decreased because of insufficient cumulative temperature over the shorter growing periods. Marked differences in tuber yield were discovered among the six treatments of sowing date, the potato planted on May 27 giving the highest yield. The potato planted either earlier or later would produce invariably lower yield than the treatment of May 27. Late May therefore can be taken as the optimum sowing time of potato in this region because the crop can fully utilize thermal resource. We conclude that to postpone sowing time is a good practice for potato production to adapt to climate warming in the Loess Plateau of central Gansu, China.

Protein and hordein fraction content in barley seeds as affected by sowing date and their relations to malting quality

The effect of sowing date on grain protein, hordein fraction content and malting quality of two-rowed spring barley was investigated by using ten commercial cultivars with different grain protein content and the relationships among these traits were examined. The results showed that grain protein content and B hordein content increased as the sowing date postponed and were significantly affected by sowing date, while C and D hordein contents were less influenced by sowing date. There were significant differences in grain protein and hordein fraction content among the ten cultivars. The coefficient of variation of D hordein content was much larger than that of B and C hordein contents, suggesting its greater variation caused by different sowing dates. Beta-amylase activity and diastatic power were also significantly affected by sowing date, with malt extract being less affected. Significant differences in measured malt quality were found among the ten cultivars. Grain protein was significantly correlated with B hordein and malt extract positively and negatively, respectively. There was no significant correlation between beta-amylase activity or diastatic power and grain protein content. B hordein was negatively and significantly correlated with malt extract, but no significant correlations between C hordein, D hordein and malting quality traits.

A Dynamic Knowledge Model for Design of Suitable Sowing Date and Sowing Rate in Winter Wheat

Based on research concerning dynamic relationships of winter wheat growth to environments and production conditions, a winter wheat model for selecting suitable sowing date, population density and sowing rate under different varieties, spatial and temporal environments was developed. Case studies on sowing date with the data sets of five different eco-sites, three climatic years and soil fertility levels, and on population density and sowing rate with the data sets of two different variety types, three different soil types, soil fertility levels, sowing dates and grain yield levels indicate a good model performance for decision-making.

The effects of sowing date on cottonseed properties at different fruiting-branch positions

A two-year field experiment was conducted to illustrate the effects of sowing date on cottonseed properties at different fruiting-branch positions（FBPs）.Two cotton cultivars（Kemian 1 and Sumian 15）were sowed on 25 April,25 May,and10 June in 2010 and 2011,respectively.The boll maturation period increased with the delaying of sowing date.Normal sowing treatment（25 April）had higher seed weight,embryo weight,embryo oil content and protein content than late sowing treatments（25 May and 10 June）.The flowering date,seed weight,embryo weight,embryo oil and protein contents,and the dynamic changes of embryo oil and protein contents were altered by different FBPs.A significant interaction of sowing date×FBP was observed on embryo weight,embryo oil content,embryo protein content and the dynamic changes of embryo oil and protein contents,but was not observed on seed weight.Seed weight,embryo weight,embryo oil and protein content had significant positive correlations with the mean daily temperature（MDT）,mean daily maximum temperature（MDTmax）,mean daily minimum temperature（MDTmin）,and mean daily solar radiation（MDSR）,indicating that temperature and light resources were the main reasons for different sowing dates affecting the cottonseed properties at different FBPs.Moreover,the difference in MDT was the main difference in climatic factors among different sowing dates.

Effects of Sowing Dates on Yield,Agronomic Traits and Resistance of Millet in Yan'an

[ Objective ] This study aimed to investigate the appropriate sowing dates of different millet varieties and analyzed the yield, agronomic traits and resist- ance of millet. [ Method ] Split-plot design was employed with sowing date and millet variety assigned to the main plot and sub-plot, respectively, to investigate the effects of sowing dates on yield, agronomic traits and resistance of millet. [ Result] The results showed that early or late sowing would lead to yield reduction. Changsheng 07, Jingu 36 and Changnong 35 exhibited higher yield. Based on the yield, agronomic traits and resistance, the appropriate sowing date of Changsheng 07, Jingu 40 and Jingu 36 was May 13 ; the appropriate sowing date of Yangu 13 and Changnong 35 was May 20. [ Conclusion] The most appropriate sowing date of millet in Yan＇an was May 10 to May 20. Key words Millet; Sowing date; Yield; Agronomic traits ; Resistance

Effect of Sowing Date on Growth,Yield and Diseases and Pests Occurrence in Sunflower Helianthus annuus L.

Effect of sowing date on growth, yield and diseases and pests occurrence in sunflower Helianthus annus L. were compared and the relationship between sowing date and occurrence degree of diseases and pests or yield were analyzed in the paper, aiming to reduce the occurrence of diseases and pests in sunflower by adjusting sowing date. The results showed that sowing date was obviously correlated with occurrence of diseases and pests in sunflowers, and appropriate sowing date could effectively reduce the occurrence degree of diseases and pests, beneficial to high yield and good quality. In the main sunflower producing area in Changji Hui Autonomous Prefecture of Xinjiang, it is more appropriate to sow sunflower in early and mid May, resulting in lighter occurrence of diseases and pests, and better yield and quality.

Effect of Dates and Methods of Sowing with and without Hydropriming on Growth,Phenology and Yield of Sorghum under Semi Arid Conditions of Eritrea

A study was carried out at the research farm of Hamelmalo Agricultural College during summer 2015 to study the effect of dates and methods of sowing with and without hydro-priming on growth,development and yield of sorghum.The experiment consisted of 2 factors-three dates of sowing viz.D0(Sowing before the onset of first summer rain,June 30),D1(Sowing with the onset of first summer rains,July 7)and D2(Sowing after the onset of summer rains,July 14)and three methods of sowing viz.SP(Direct sowing with hydro seed priming),TR(Transplanting)and DS(Direct sowing without hydro seed priming).The experiment was conducted in split plot design with 4 replications by keeping dates of sowing in the main plots and methods of sowing in the sub plots.The data on growth parameters,crop phenology,yield components and yield were recorded.The data were analysed using GENSTAT software and inferences were drawn by using LSD at 5%level of significance.Sowing methods significantly affected leaf area and leaf area index but sowing dates and their interaction with sowing methods did not show significant difference.Stand count,plant height,phenological parameters,thousand grain weight,grain and biomass yield were significantly affected by the sowing dates and methods but no significant difference in their interaction on all the parameters except in stand count and phenological parameters.Sowing before the onset of first summer rains(D0)resulted in significantly highest grain yield.Among the sowing methods,transplanting resulted in significantly higher grain yield seconded by direct sowing with hydro seed priming.Transplanting is less profitable and practicable as it is more laborious and difficult to apply in larger areas.

The environment,especially the minimum temperature,affects summer maize grain yield by regulating ear differentiation and grain development

Ear differentiation,grain development and their interaction with factors in the growing environment,such as temperature,solar radiation and precipitation,greatly influence grain number and grain weight,and ultimately affect summer maize production.In this study,field experiments involving different sowing dates were conducted over three years to evaluate the effects of temperature factors,average solar radiation and total precipitation on the growth process,ear differentiation,fertilization characteristics,grain filling and yield of summer maize varieties with different growth durations.Four hybrids were evaluated in Huang-Huai-Hai Plain(HHHP),China from 2018 to 2020 with five different sowing dates.The results showed that the grain yield formation of summer maize was strongly impacted by the environment from the silking(R1)to milking(R3)stage.Average minimum temperature(AT_(min))was the key environmental factor that determined yield.Reductions in the length of the growing season(r=–0.556,P<0.01)and the total floret number on ear(R^(2)=0.200,P<0.001)were found when AT_(min) was elevated from the emerging(VE)to R1 stage.Both grain-filling rate(R^(2)=0.520,P<0.001)and the floret abortion rate on ear(R^(2)=0.437,P<0.001)showed quadratic relationships with AT_(min) from the R1 to physiological maturity(R6)stage,while the number of days after the R1 stage(r=–0.756,P<0.01)was negatively correlated with AT_(min).An increase in AT_(min) was beneficial for the promotion of yield when it did not exceeded a certain level(above 23°C during the R1–R3 stage and 20–21°C during the R1-R6 stage).Enhanced solar radiation and precipitation during R1–R6 increased the grain-filling rate(R^(2)=0.562,P<0.001 and R^(2)=0.229,P<0.05,respectively).Compared with short-season hybrids,full-season hybrids showed much greater suitability for a critical environment.The coordinated regulation of AT_(min),ear differentiation and grain development at the pre-and post-silking stages improved maize yield by increasing total floret number and grain-filling rate,and by reducing the floret abortion rate on ear.

Effects of Sowing Periods on Growth and Development,Yield and Quality of Maize in Cold Area

In order to determine the most suitable sowing periods for maize in the cold area of Harbin City,the field test method was adopted.From 2018 to 2019,the main maize variety Xianyu 696 which was planted in Harbin City,Heilongjiang Province,was used as the test material for the six-sowing-period treatment experiments.The sowing period settings were as the followings:April 20(T1),April 24(T2),April 27(T3),May 4(T4),May 11(T5)and May 18(T6).In the experiment,the effects of different sowing periods on the growth and development,yields and quality of maize were studied.The results showed that the maize through T1 treatment had the longest growth period,the lowest height and the highest ear height,and the highest grain protein content.The maize through T6 treatment had the highest height and ear height,as well as the highest starch and oil content.And the grain crude fat,soluble protein,soluble sugar and the moisture content increased and then decreased with the delay of the sowing period.The maize through T4 treatment had the highest content of soluble protein.However,other quality indicators and the number of rows,the length of the bald tip,the number of grains per spike and the weight of 100 grains first increased and then decreased with the delay of the sowing period.The dry matter accumulation through T4 treatment was significantly higher than the ones through five treatments,and the 100-kernel weight and other ear-grain traits were the highest,the maizes through T4 treatment increased the yield by 21.54%compared with that through T1 treatment.Thus,the most suitable sowing period for the maize in the cold area of Harbin City was from May 4 to May 11.It provided technical supports for guiding maize planting in the cold area of Harbin City.

RITSD Analysis of the Agronomic Traits of Somaclonal in Rice

[Objective]The aim was to study the sensitive response characteristics of the main agronomic traits of somaclonal and the variation of sensitive response of the lines of somaclonal to sowing date. [Method]The RITSD changing of agronomic traits was studied by using 24 rice somaclonal and its donor parent under two sowing dates. [Result]The average values of RITSD were higher （over one） for the traits of pant height （PH）,density of spikelets （DS）,filled spikelets per panicle （FSP）,spikelets per panicle （SP） and grain weight per plant （GWP）,but lower for days of sowing to heading （DSH）,effective panicles （EP）,panicle length （PL）,seed setting rate （SS） and 1 000-grain weight （1 000-GW）. These showed that PH,DS,FSP,SP and GWP were easily affected by sowing date and tended to higher with the later sowing; the RITSD of somaclonal changed with the agronomic traits. The frequency of RITSD＇ variation of DSH and PH was higher than that of PL. The RITSD＇ value of EP,PL,DS,FSP,SP and SS became higher,and higher or lower for DSH and GWP in different somaclonal; compared with the donor,20 of 24 was significantly different,and the frequency of RITSD variation was over 83. 3%,however,RITSD of the most lines （75%） changed only for 1-2 characters; cluster analysis showed that the RITSD of agronomic traits belonged to different combinations of somaclonal in rice. [Conclusion]the study had provided a theoretical basis for the screening and using of the somaclonal.

Combined Impact of Climate Change, Cultivar Shift, and Sowing Date on Spring Wheat Phenology in Northern China

Distinct climate changes since the end of the 1980s have led to clear responses in crop phenology in many parts of the world. This study investigated the trends in the dates of spring wheat phenology in relation to mean temperature for different growth stages. It also analyzed the impacts of climate change, cultivar shift, and sowing date adjustments on phenological events/phases of spring wheat in northern China （NC）. The results showed that significant changes have occurred in spring wheat phenology in NC due to climate warming in the past 30 years. Specifically, the dates of anthesis and maturity of spring wheat advanced on average by 1.8 and 1.7 day （10 yr）-1. Moreover, while the vegetative growth period （VGP） shortened at most stations, the reproductive growth period （RGP） prolonged slightly at half of the investigated stations. As a result, the whole growth period （WGP） of spring wheat shortened at most stations. The findings from the Agricultural Production Systems Simulator （APSIM）-Wheat model simulated results for six representative stations further suggested that temperature rise generally shortened the spring wheat growth period in NC. Although the warming trend shortened the lengths of VGP, RGP, and WGP, the shift of new cultivars with high accumulated temperature requirements, to some extent, mitigated and adapted to the ongoing climate change. Furthermore, shifts in sowing date exerted significant impacts on the phenology of spring wheat. Generally, an advanced sowing date was able to lower the rise in mean temperature during the different growth stages （i.e., VGP, RGP, and WGP） of spring wheat. As a result, the lengths of the growth stages should be prolonged. Both measures （cultivar shift and sowing date adjustments） could be vital adaptation strategies of spring wheat to a warming climate, with potentially beneficial effects in terms of productivity.

Impacts of climate warming and crop management on maize phenology in northern China

Climate warming has and will continue to exert a significantly impact on crop phenology in the past and coming decades.Combining observed data of phenology and a crop growth model provides a good approach for quantitating the effects of climate warming and crop management on crop phenology.The purpose of this study is to determine the impacts of temperature change, sowing date(SD) adjustment and cultivar shift on maize phenology in northern China during 1981–2010.Results indicated that climate warming caused anthesis date(AD) and maturity date(MD) of maize to advance by 0.2-5.5 and 0.6-11.1 d/10 a, respectively.Due to climate-driven changes in maize phenology, three growth periods of maize, i.e., vegetative growth period(VGP;from sowing to anthesis), reproductive growth period(RGP;from anthesis to maturity) and whole growth period(WGP;from sowing to maturity) shortened by 0.2-5.5, 0.4-5.6 and 0.6-11.1 d/10 a, respectively.With SD adjustment(i.e., SD advancement), AD and MD occurred early by 0.5-2.6 and 0.1-3.4 d/10 a, respectively.SD adjustment caused duration of VGP of maize to prolong.However, duration of RGP slightly shortened by 0.1-1.3 d/10 a.Furthermore, due to cultivar shift, MD of maize significantly delayed by 4.9-12.2 d/10 a.Durations of VGP, RGP and WGP of maize prolonged by 0.2-4.1, 1.6-8.4 and 4.3-11.8 d/10 a, respectively.In conclusion, our results indicated that cultivar shift, to some extent, could mitigate the negative impact of climate warming on maize phenology.

The Variation of β-glucan and Protein Content in Barley as Affected by Agronomic Practices

The influences of N application rate, timing, sowing date and seeding rate on β-glucan and protein content in barley grains were studied through the field experiments in Hangzhou, China during 1997 -2001. Protein content increased with N application rate and with N proportion applied at late stage. β-glucan content also responded significantly to N application rate and timing, but with different pattern with protein content. Of three N rate treatments, the medium N rate (135 kg ha-1) had the highest β-glucan content, being significantly higher than low N rate (90 kg ha-1) and no difference with high N rate (180 kg ha-1). A-mong three N timing treatments, two times of N top-dressing at both tillering and booting stage had significantly higher β-glucan content than once N top-dressing at tillering or booting stage. Sowing date has the dramatic effect on both β-glucan and protein content. Protein content decreased with the delayed sowing, and kernel weight showed opposite tendency. Either earlier or later sowing caused increased β-glucan content relative to sowing in early November, which is the normal date for barley sowing locally. Seeding rate had no significant influence on both β-glucan and protein content.