Influence Of Accumulated Temperature Between Sowing And Wintering On The Spike Differentiation And Growth And Photosynthesis Of Two Kinds Of Wheat Varieties

Abstract:The experiment uses the spring variety such as Yumai 18,Lankaoaizao 8, and the weak winter variety such as Zhoumai 18,Yumai 49 as material,which are widely sowed in Henan.Adopting the analytical method of the crops growth,for different sowing times,it takes real-time records on changes of the temperature during the wheat's development;for different ecological conditions,it systematically observes and determines the spike differentiation,population development, photosynthesis,grain filling rate.So that it can prove up the forming regulation of wheat's growth and production on the condition of the different accumulated temperatures before winter and the requirements to the environment for wheat field of high production and high efficiency.The results of the experiment is stating as below:1.As the delay of sowing time,the fringe spike's differentiation procession of two different ecotype wheat varieties delays.But in any phase,the differentiation procession of the weak winter variety is later than the spring variety(delay 8.5d on average).From the differentiation rate of the fringe spike,the processions in the three sowing treatments all have the tend of low to fast and then to slow.The spike differentiation of springiness wheat does not require low temperature strictly, but need a bit in double ridges.Weak winter variety need rigorous low temperature to pass single ridge.The differentiation times of the two varieties expresses as:treatmentⅠ＞treatmentⅡ＞treatmentâ…¢;The differentiation procession of treatmentâ…¡and treatmentâ…¢of spring variety is faster and 12.5d shorter than that of the same treatment of weak winter variety on average.2.The spike differentiation of different varieties has different requirements to the accumulated temperature.Weak winter variety needs the general accumulated temperature of about 852℃.d,and the spring variety needs the general accumulated temperature of about 735℃.d.With the delay of the sowing time and the reduction of the accumulated temperature,the reducing rate of the spring variety is larger than the weak winter variety.From the accumulated temperature and final production of the young ears,if the production of spring variety up to 000kg/hm^-2,it needs 690℃·d(total time need about 135 days),and the accumulated temperature should be about 471℃·d before winter;While if the production of weak winter variety up to about 8200kg/hm^-2,it needs above 900℃·d(total time need up to 151 days),and the accumulated temperature should be above 581℃·d before winter.3.The sowing time influences the wheat's individual and population development. In the different growing periods,the single plant's rooting numbers and area coefficient of weak winter variety(Zhoumai 18,Yumai 49)are treatmentⅠ＞treatmentⅡ＞treatmentâ…¢.While before winter,those of the spring variety(Yumai 18,Lankaoaizao 8)are also treatmentⅠ＞treatmentⅡ＞treatmentâ…¢.With the growing procession,the treatmentâ…¡grows well,and it is treatmentⅡ＞treatmentⅠ＞treatmentâ…¢.The dynamic changes of population numbers also have similar regulations.The treatmentâ… of weak winter variety is the largest, the treatmentâ…¡is larger and the treatmentâ…¢is the least large.Before winter, the treatmentâ… of spring variety is the largest,but after shooting,the amount of middle sowing is the largest.In the combination of the management to the 12 kinds' treatments,the amount of treatmentâ… about Yumai 49(10/15)is the largest,up to 719×10⁴·hm^-2,the amount of treatmentâ…¢about Lankaoaizao 8 (10/31)is the smallest,up to 385×10⁴·hm^-2.4.The sowing time and the combination of the management to the varieties control the accumulation of dry matter and the grain filling rate of the wheat. Before blooming,the weight of single dry matter continually increases with the growing accession.In early sowing,weak winter variety has the fastest increasing rate,largest dry matter weight,then is middle sowing,and last is the late sowing; for spring variety,the middle sowing is the largest and late sowing is the smallest. After blooming,the filling rate of these four kinds is all expressed as unimodal curve,and the peak value is 25d after blooming.Before peak value,the filling rate of spring variety(Yumai 18,Lankaoaizao 8)is higher than weak winter variety(Zhoumai 18,Yumai 49),and after the peak value,its reducing rate is also larger than weak winter variety.For the spring variety,the grain filling rate of middle sowing is the largest;while for the weak winter variety,the early sowing is the largest. 5.Analyze the photosynthesis and the solar energy utilization rate of different varieties in different sowing times.The result shows that:middle sowing is more useful for improving the Pn,CAP,Fv/Fm,Fv/Fo and group solar energy utilization rate of Lankaoaizao 8,while early sowing is more useful for these above items to Zhoumai 18,Yumai 49.The comprehensive research shows that:the sowing time of spring variety-Yumai 18,Lankaoaizao 8 should be later than weak winter wheat.In usual cases,it is suitable to sow at the accumulated temperature of 471℃·d(about Oct. 23)before wintering and average temperature at 13.79℃to the south area in Henan.For weak winter variety-Zhoumai 18,Yumai 49,it is suitable to sow at the accumulated temperature of 581℃·d(about Oct.15)before wintering and average temperature at 14.80℃,so that it can have enough accumulated temperature before winter for spike differentiation and its production is 13.33%higher than that of middle sowing and late sowing.