| Jiangsu is an important wheat production province in our country.Due to stubble and climate factors,large area of wheat planting time has been delayed in this area.It is of great significance to explore the characteristics of yield,quality,nitrogen absorption and utilization and temperature and light utilization of late sowing wheat in different wheat areas,so as to further explore the temperature and light characteristics of wheat at different sowing dates and promote the improvement of the comprehensive productivity of late sowing rice stubble wheat.Therefore,the experiment was first carried out in Jianhu County,Jiangsu Province from 2016 to 2017.Semi-winter variety Nongmai 158and spring variety Yangmai 23 and Yangmai 25 were selected as experimental materials,and five sowing dates were set,which were October 31(S1),November 10(S2),November 20(S3),November 30(S4)and December 10(S5).The seedlings of each sowing period were 300×104 ha-1.To explore the forming factors of rice stubble wheat yield under different sowing dates.Based on this experiment and previous research results,in 2017 to 2020,Donghai County(N34°35’,E118°45’)in Huaibei wheat district and Jianhu County(N 33°47’,E119°77’)in Lixia River wheat district were respectively investigated.And the test will be conducted in Yangzhou(N32°37’,E119°43’),a wheat district along the Yangtze River from 2019 to 2021.On the basis of the original experiment,Huaimai 33 was added as a semi-winter variety,and the sowing date was added on December 20(S6).In order to make up for the difference of panicle number at different sowing dates,different planting densities were set.The seedlings in the first sowing period were 300×104 ha-1,and the seedlings were increased by 10%for each delayed sowing period.The changes of comprehensive productivity and temperature and light of rice stubble wheat under different wheat regions and sowing dates were studied,and their effects on wheat yield,quality and nitrogen absorption and utilization were studied from the point of view of temperature and light.The purpose of this study was to clarify the temperature and light requirements of yield,quality and nitrogen absorption and utilization of rice stubble wheat under late sowing in different wheat regions,and to provide a theoretical basis for making full use of temperature and light resources to achieve relatively high comprehensive productivity of rice stubble wheat under late sowing.The main research results are as follows:(1)The growth period of wheat was postponed with the postponement of sowing date,the days of each growth stage were reduced,the days of the whole growth period were also reduced,and the total growth days were shortened by 8-10d for each postponement of sowing date.The delayed sowing date resulted in the decrease of material accumulation at each growth stage,with the average decrease of 1.29t ha-1 per sowing date.The wheat yield decreased by 0.8t ha-1 for each sowing delay.From the analysis of yield components,the number of panicles,grains per spike and 1000-grain weight decreased gradually with the postponement of sowing date,in which the number of panicles decreased most significantly,and the number of panicles per plant per delayed sowing date decreased by 6.7%-10.25%compared with the previous sowing date.The protein and gluten were increased by delaying sowing date.The peak viscosity,trough viscosity,breakdown and final viscosity of flour increased by 103.7cp,55cp,48.7cp and 98.5cp,respectively,for each delay of sowing date.The sowing date was delayed and the dough formation time and stability time has an increasing trend.(2)The growth period and temperature and light characteristics of rice stubble wheat under different wheat area and sowing date were studied.The wheat area was the same,with the delay of sowing date,the growth period was delayed,and the fertility days were reduced.The sowing time is the same,with the increase of the latitude of the wheat area,the growth period of wheat is delayed,and the growth days are prolonged.When the wheat area moves northward,the total growth days increase by 6.63 days.The change of growth process led to the change of temperature and light corresponding to the growth period.The effective accumulated temperature and cumulative radiation during the whole growth period decreased by 55.25℃ d and 58.57MJ m-2 for each delayed sowing period.The mean daily temperature and radiation increased by 0.19℃ and 0.53MJ m-2 d-1 for each delayed sowing period,respectively.From seeding to seedling stage,with the delay of sowing date,the mean daily temperature decreased gradually,and the effective accumulated temperature increased gradually.The maximum effective accumulated temperature of S6 was 237℃ d.In the growth stage after seedling emergence,the later the sowing date,the higher the mean daily temperature and mean daily radiation,and the lower the accumulated temperature and cumulative radiation.The cumulative rainfall and humidity showed a significant change trend only from seeding to seedling stage,and the other periods showed different laws between treatments and years.With the same sowing date,the effective accumulated temperature and mean daily temperature during the whole growth period decreased gradually as the wheat area moved northward.With each increase of latitude,the effective accumulated temperature and mean daily temperature during the whole growth period decreased by 63.61℃ d and 0.82℃,respectively.The cumulative radiation amount and mean daily radiation amount during the whole growth period increased by 282.44MJ m-2 and 1.1MJ m-2 d-1,respectively.Compared with other periods,the latitude had the most significant effect from seeding to seedling stage.Cumulative rainfall and relative humidity were not significantly different between latitudes.In conclusion,the influence of wheat area and sowing date on temperature and radiation is the most significant.(3)In the same wheat area,wheat yield decreased gradually with the delay of sowing date,and wheat yield decreased by 0.29t ha-1 on average for each delay of sowing date.From the analysis of yield components,there was no significant difference in panicle number between sowing treatments by increasing seedlings by 10%every 10 days delayed.The decrease of grain number per spike was mainly due to the delay of sowing date,which led to the increase of mean daily temperature and decrease of accumulated temperature from jointing to heading,which accelerated the formation of spikelet and shortened the differentiation time of spikelet,thus affecting the decrease of grain number per spike.The main reason for the decrease of wheat grain weight was that the mean daily temperature from heading to maturity increased gradually with the delay of sowing date,and the effective accumulated temperature and cumulative radiation decreased gradually,which affected the grain filling.The mean daily temperature from jointing to heading increased with the delay of sowing date and the northward movement of wheat area,and the number of grains per ear decreased gradually.From heading to maturity,the mean daily temperature increased and the effective accumulated temperature decreased as the wheat area moved northward.There was no significant difference in cumulative radiation with wheat area moving northward.The 1000-grain weight of wheat decreased gradually with the delay of sowing date and the northward movement of wheat area.Dry matter accumulation decreased gradually with the delay of sowing date,and the dry matter accumulation decreased by 0.41t ha-1 for each delay of sowing date.The effective accumulated temperature and accumulated radiation were positively correlated with dry matter accumulation,while the daily temperature was negatively correlated with dry matter accumulation.The increase of temperature and the decrease of accumulated temperature and accumulated radiation led to the decrease of dry matter accumulation.(4)In the same wheat area,plant nitrogen content increased gradually with the delay of sowing date.With the same sowing date,nitrogen content in wheat growth stage increased gradually with the northward movement of wheat area.From sowing to jointing stage and heading to maturity stage,nitrogen accumulation in S1 was 1.06-11.35kg ha-1 and 0.3311.32kg ha-1 more than that in S2-S6,respectively.From jointing to heading,nitrogen accumulation in S1 was 0.16-5.97kg ha-1 lower than that in S2-S6.The nitrogen accumulation of plants during the whole growth period decreased by 2.66kg ha-1 for each latitude moved northward.The grain production efficiency of S1 was 0.3-6.05kg kg-1 higher than that of S2S6.There was a significant negative correlation between effective accumulated temperature and nitrogen accumulation from seeding to seedling stage,and a significant positive correlation between accumulated temperature and nitrogen accumulation at other growth stages.The mean daily temperature from seeding to seedling stage was significantly positively correlated with nitrogen accumulation,while the mean daily temperature from seedling to maturity stage was significantly negatively correlated with nitrogen accumulation.There was a significant positive correlation between cumulative radiation and nitrogen accumulation at other growth stages except from seeding to seedling stage.The increase of effective accumulated temperature and cumulative radiation after jointing was conducive to the improvement of plant nitrogen accumulation and grain production efficiency,while the increase of mean daily temperature after jointing was not conducive to the improvement of plant nitrogen accumulation and grain production efficiency.(5)The grain filling characteristics of wheat were analyzed by fitting Logistic growth curve.From the perspective of temperature and light,the mean daily temperature increased by 0.32℃,the grouting time decreased by 1.5 days,and the grouting rate increased by 0.018 mg d-1.Effective accumulated temperature and cumulative radiation were negatively correlated with grain filling rate.The effects of temperature and light on the basic quality characters of wheat in the three wheat districts showed similar rules.The increase of mean daily temperature,maximum daily temperature and minimum daily temperature after flowering was not conducive to the increase of bulk density and yield of wheat,while the increase of effective accumulated temperature and cumulative solar radiation was conducive to the increase of bulk density and yield of wheat.The effective accumulated temperature decreased by 20.57℃ d when the mean daily temperature increased by 0.43℃,protein content increased by 0.24%,wet gluten content increased by 0.45%,sedimentation value increased by 1.33ml,amylose increased by 0.45%,but total starch content and amylopectin content decreased by 1.09%and 1.54%,respectively.According to the correlation analysis,the protein related quality of wheat could be improved by delaying sowing date,increasing mean daily temperature after flowering and decreasing effective accumulated temperature.The increase of mean daily temperature was beneficial to the improvement of starch gelatinization parameters,water absorption,dough development time,dough stabilization time and farinograph quality number.The effective accumulated temperature and accumulated radiation were negatively correlated with starch gelatinization parameters,water absorption surface,development time,dough stability time and farinograph quality number.In conclusion,with the delay of sowing date,the increase of mean daily temperature and the decrease of effective accumulated temperature and cumulative radiation after flowering had adverse effects on the formation of wheat milling quality,but was beneficial to the formation of wheat nutritional quality and processing quality.(6)Under the treatment of wheat plot and sowing date,the comprehensive productivity of wheat was evaluated by the analytic hierarchy process(AHP)considering yield,quality and nitrogen absorption and utilization.According to the comprehensive score,the comprehensive productivity of wheat decreased gradually with the delay of sowing date,and the comprehensive score of different wheat districts was as follows:Lixia River wheat district>Huaibei wheat district>wheat district along the Yangtze River.According to the correlation between the comprehensive score and temperature and light,the suitable sowing date of different wheat areas could obtain relatively higher productivity,and the suitable temperature and light range of each wheat area could be determined according to the suitable sowing date.The effective accumulated temperature,mean daily temperature,cumulative radiation amount and mean daily radiation amount in the whole growth period of East China Sea were 1803.32088.3℃ d,8.66-9.21℃,2408.9-2627.9MJ m-2 and 11.69-12.18MJ m-2 d-1,respectively.The effective accumulated temperature,mean daily temperature,cumulative radiation and mean daily radiation of Jianhu during the whole growth period were 1831.1-2203.1℃ d,9.3410.11℃,1939.1-2326.1MJ m-2 and 9.91-10.98MJ m-2 d-1,respectively.The effective accumulated temperature,mean daily temperature,cumulative radiation and mean daily radiation during the whole growth period in Yangzhou were 1926.5-2244.9℃ d,10.5210.81℃,1841.5-2041.5MJ m-2 and 9.67-10.22MJ m-2 d-1,respectively.The effective accumulated temperature from sowing to seedling stage increased with the northward movement of wheat area,while the mean daily temperature showed the opposite effect.The effective accumulated temperature from heading to maturity and the whole growth period decreased gradually with the northward movement of wheat area,while the mean daily temperature showed the opposite effect.The cumulative radiation and the mean daily radiation during the whole growth period increased with the northward movement of wheat area.In conclusion,the delay of sowing date resulted in the decrease of ear number,grain number per ear and 1000-grain weight of wheat,and improved the nutrition and processing quality of wheat.Delayed one sowing date increased the seedlings by 10%,so that the number of ear under sowing date treatment had no significant difference.From the perspective of temperature and light,the increase of mean daily temperature and the decrease of accumulated temperature and cumulative radiation during the whole growth period were not conducive to the formation of yield,nitrogen absorption and utilization and the formation of milling quality,but had a certain promotion effect on nutrition quality and processing quality.The increase of mean daily temperature and the decrease of accumulated temperature and cumulative radiation from seeding to seedling stage were beneficial to the formation of yield,nitrogen absorption and utilization and the formation of milling quality,but were unfavorable to the formation of nutrient quality and processing quality.Earlier sowing of rice-stubble wheat can obtain higher overall wheat productivity. |
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