Vernalization Development Characteristics Of Wheat Cultivars In Huanghuai Wheat Zone And Regulative Effect Of Accumulated Temperature Before Winter

Wheat is one of important crop in China.With regulation of plantation structure,the acreage of wheat has significantly decreased in recent years at the end of "the Nineth Five-year Plan"and the beginning of "the Tenth Five-year Plan",though consumption amount increased.Security of wheat was faced with serious challenge. Raising the per unite yield is an important way to ensure total ouput and grain security. Increasing accumulation of photosynthetic product is beneficial to raising of the per unite yield.Improving ability to use solar radiation,temperature and water has significance for raising the per unite yield and benefit of wheat.The production system of wheat includes cultivar,environment and technology. Relationship between the growth and development of wheat and environmental factors,which includes fitness of environment for wheat and ability to use environmental factors of wheat,is the foundation of high yield and better benefit of wheat production as well as the important way of reducing production cost,reducing losses caused by natural calamity and gaining high yield.The proper population structure would promote coordinative development of individual and population, which is helpful for use of solar radiation and temperature resources and tapping production potentialities of cultivars.Proper cultivars,their suitable sowing dates and proper population structure are significant questions of better combination of cultivars, environment and technology,as well as of high yield,better benefit and ecological safety.In this study,twenty-nine wheat cultivars(Triticum aestivum L.)were used in sowing dates experiment and vernalization treatments experiment.Wheat cultivars in the wheat fields of Yellow River and Huaihe River area were classified according to their vernalization development character.The effects of vernalization treatments and accumulated temperature before wintering on growing period,initiation and duration of spike differentiation were investigated.The regulation effects of accumulated temperature before wintering on solar radiation use efficiency were also studied.The main results were as follows: 1 Vernalization development characteristics of different wheat cultivarsSeedling-heading period and duration from emergence stage to appearance of double ridge of spike differentiation were shorter with prolonging vernalization time. After vernalization treatment,there is larger difference in seedling-heading period and duration from emergence stage to appearance of double ridge among different cultivars.Twenty-nine cultivars in this experiment were classified to three types by means of cluster analysis,which are Spring-type,Semi-Winter-type and Winter-type. They can be further classified to five types,i.e.Spring(S),Poor Spring(PS),Poor Winter-Spring(PWS),Winter-Spring(WS)and Winter(W).Among five vernalization development types,Spring and Poor Spring cultivars can differentiate spike and head normally without vernalization treatment.Vernalization response of Spring cultivars was poor,coefficient of variation of seedling-heading period among four vernalization treatment of 0d,10d,20d and 30d was about 5%.Vernalization response of Poor Spring cultivars was more than Spring cultivars,coefficient of variation of seedling-heading period under different vernalization treatment was 8% approximately.Vernalization response of Poor Winter-Spring cultivars was richer than Poor Spring cultivars and was poorer than Winter-Spring cultivars.Spike differentiation of PWS and WS required low temperature at 0～2℃for 10d and 20d respectively.Coefficient of variation of seedling-heading period of PWS and WS under different vernalization treatment was about 18%and 25%respectively.As to Winter cultivars,spike differentiation can initiate but would stop in double ridges stage if cultivars were not treated at low temperature.Vernalization response of Winter cultivars was richer than four other types of vernalization development. Coefficient of variation of seedling-heading period of W under different vernalization treatment was more than 30%.Low temperature(0～2℃)for 30d was enough for spike differentiation of Winter cultivars.2 Corresponding relation between leaf and spikelet primordium differentiation of different development types of wheat cultivarsLeaf number and remaining leaf primordium.number are significantly influenced by accumulated temperature before winter and vernalization treatments,whereas leaf number index of different Accumulated temperature before winter and vernalization treatments is relatively stable.Difference of leaf number,remaining leaf primordium number and leaf number index among cultivars is larger than among different accumulated temperature before winter and vernalization treatments.Leaf number index in double ridges stage and glume stage is mainly determined by cultivar traits. These observations imply that corresponding relation between leaf number and spikelet primordium differentiation is markedly affected by ecological factors and cultivating conditions.As one of the standards of strong seedlings before wintering, leaf number is not suitable.The investigation concludes that there is definitely corresponding relation between leaf number index and spikelet primordium differentiation.Leaf number indices in double ridges stage of S and PS cultivars are 40%～45%and 45%～51%respectively,and those of PWS and WS cultivars are 50%～55% and 55%～59%.3 Effects of accumulated temperature before winter on spike differentiation of different vernalization development types of wheat cultivarsThe progress of spike differentiation of wheat depends on cultivar traits as well as accumulated temperature before winter.Accumulated temperature before winter mainly influence single ridge stage and double ridges stage of spike differentiation. The influence of accumulated temperature before winter on spike differentiation is getting smaller after glume differentiation stage.With decrease of accumulated temperature before winter,GDD in each stage of spike differentiation reduces.The effects of accumulated temperature before winter on accumulated GDD of spike differentiation vary with vernalization development types of wheat cultivars.GDD of Winter-Spring cultivars is more sensitive to accumulated temperature before winter than Poor Spring cultivars and GDD of Winter cultivars is most sensitive.The upper limits of suitable temperature in early stages of spike differentiation.for S and PS cultivars are 14℃.The upper limits of suitable temperature in early stages of spike differentiation for PWS and WS cultivars are 12℃.If accumulated GDD below 14℃reaches up to 232～264 and 236～280 respectively,the differentiation of spikelet primordia of S and PS cultivars would initiate.Accumulated GDD of 252～262 and 261～268 below 12℃is essential for initiation of differentiation of spikelet primordia of PWS and WS cultivars.The investigation concludes that the differentiation of spikelet primordia requires relatively stable accumulated GDD in specific temperature range in the fields and the requirement for temperature varies in vernalization characteristics of cultivars.4 Regulating effect of accumulated temperature before winter on solar radiation use efficiency of wheatAccumulated temperature before winter influenced solar radiation use efficiency of different types of vernalization development of wheat cultivars significantly.Accumulated temperature before wintering of 572℃for PS cultivar Lankao Aizao8 and 688℃for WS cultivar Zhoumai18 resulted in increased LAI, interception of solar radiation in canopy,spikes per unit area and Canopy photosynthesis rate.Fv/Fm was not influenced significantly by accumulated temperature before wintering.Fv/Fo of accumulated temperature before wintering of 688℃and 572℃of Lankao Aizao8 and 688℃of Zhoumail8 as well as qP and ETR were more than 462℃.With decrease of accumulated temperature before wintering, solar radiation use efficiency from sowing to erecting of two cultivars reduced.From erecting to mid grainfilling,solar radiation use efficiency of accumulated temperature before wintering of 572℃of Lankao Aizao 8 and 688℃of Zhoumail 8 was higher than two other accumulated temperature treatments.The investigation concludes that low solar radiation use efficiency from sowing to erecting is one of reasons of lower solar radiation use efficiency in growing season.572℃of Lankao Aizao8 and 688℃of Zhoumai 18 resulted in the highest solar radiation use efficiency of canopy and grain.According to vernalization development characteristics of varied cultivars and the upper limits of suitable temperature at double ridges stage,accumulated GDD of suitable stages(double ridges stage)of spike differentiation at varied districts can be calculated from mean temperature data.Under the condition of strong seedlings before wintering suitable sowing dates at different districts can be determined...