Effects Of Different Sowing Dates And Sowing Densities On Population Quality And Grain Yield And Quality In Winter Wheat

This paper systemically studied the Population-Quality indices,carbon and nitrogen metabolism,grain yield and main quality indices,with Massive-spike Winter Wheat cultivar Aizao 8 and intermediate-spike winter wheat cultivar Zhoumai 18 in different sowing dates and sowing densities treatments under field conditions in 2004-2005 and 2005-2006 growing seasons.The main results were as follows:1.Effects of different sowing dates and sowing densities on grain yields and yield components.The yield of two test wheat cultivars raised with the delay of sowing date and raised firstly and then fall with improving of sowing density.Decreased the number of basic seedling appropriately in early sowing and increased the number of basic seeding appropriately in late sowing would help improving the economic yield.Among three yield components,mature spike number of massive-spike winter wheat cultivar Aizao 8 was gradually decreased with the delay of sowing,but the results were opposite in grain number per spike and 1000 grain weight;the improving of sowing density has less effect on mature spike number,grain number per spike was increased a little while 1000 grain weight was decreased.The difference of Mature spike number,grain number per spike and 1000 grain weight of intermediate-spike winter wheat Zhoumai 18 were significant in different sowing dates.Mature spike number and grain number per spike were gradually decreased with the delay of sowing,but the results were opposite in 1000 grain weight;mature spike number and 1000 grain weight were increased with the improving of sowing density while grain number per spike was significant decreased.2.Effects of different sowing dates and sowing densities on population-quality indices. The results indicated that the population total tillering number was decreased greatly with the delay of sowing date while increased gradually with the improving of sowing density; Ear-bearing Percentage of Tillers Formed was increased gradually with the delay of sowing date while decreased greatly with the improving of sowing density.Dry matter weight of population before anthesis was decreased greatly with the delay of sowing and increased with the improving of sowing density;dry matter weight of population in early sowing was slightly decreased;the change of dry matter weight of population after anthesis was slowed down,but was increased gradually with the improving of sowing density.LAI was increased first,then decreased as the advance of growing and developing,and reached the peak level in booting stage.LAI after anthesis was increased first,then decreased with the delay of sowing,but decreased with the improving of sowing density.Grain leaf ratio changed with the delay of sowing:the grain weight per leaf area of massive-spike winter wheat cultivar Aizao 8 was decreased with the delay of sowing,while that was increased first,then decreased in intermediate spike winter wheat cultivar Zhoumai 18;effect of sowing date was less on grain number per leaf area.Only grain leaf ratio can't reflect high efficiency population-quality,it need the coordinated of grain number,grain weight and leaf area.3.Effects of different sowing,dates and sowing densities on characters of wheat plant shape.The top three leaf areas of main stem of Aizao 8 were increased slightly with the delay of sowing while decreased slightly with the improving of sowing density;the top three leaf length and area of tiller were increased slightly with the delay of sowing,but the leaf thickness were decreased,and all the leaf characters were decreased with the improving of sowing density.The flag leaf area and the second top leaf area of main stem of Zhoumai 18 were increased first,then decreased with the improving of sowing density; the top three leaf length,width and area were increased with the delay of sowing while decreased with the improving of sowing density.The leaf characters of Aizao 8 were longer,wider and thicker,and the percentage of the flag leaf area of main stem was higher than Zhoumai 18;but the top three leaf area were considerably below Zhoumai 18.The top three leaf length/width were the second top leaf＞flag leaf＞the third top leaf,while the specific leaf weight were flag leaf＞the second top leaf＞the third top leaf,the length/width of tiller stem were higher than main stem.Massive-spike winter wheat cultivar Aizao 8 has lower length/width and higher specific leaf weight,while the results were opposite in intermediate-spike winter wheat cultivar Zhoumai 18.The stem length of main stem were gradually decreased with the downward of inter-node,and the results were opposite in thickness of inter-node;with the downward of inter-node,the stem width were increased first,and then decreased.The length and thickness of inter-node were increased with the delay of sowing,and there was no large difference between early sowing and suitable sowing.The stem widths of upper inter-node in early sowing were higher,but that of lower inter-node in later sowing were higher.The stem lengths and widths of upper inter-node were decreased the improving of sowing density,that of lower inter-node were opposite;the stem thickness of inter-node were higher in intermediate sowing density.The stem length of tiller stem were increased first,and then decreased with the delay of sowing and the improving of sowing density,and there was no large difference among the stem width with the delay of sowing,but the stem thickness were increased first,and then decreased with the improving of sowing density.With the delay of sowing,the grain number per spike,spike length and single panicle weight of main stem spike were increased sharply,while total spikelets per spike and fertile spikelets per spike were increased first,and the decreased,but the sterile spikelets per spike were decreased;with the improving of sowing density,grain number per spike,spike length,single panicle and grain number per spikelet were decreased,but the results of the bottom sterile spikelets per spike were opposite,meanwhile,total spikelets per spike and fertile spikelets per spike were increased first,and then decreased.The grain number per spike,single panicle weight and grain number per spikelet of tiller spike in early sowing were higher,but the total spikelets per spike and fertile spikelets per spike were lower,those characteristics were fluctuated with the delay of sowing;with the improving of sowing density,grain number per spike,single panicle weight and grain number per spikelet were decreased,but the total spikelets per spike and fertile spikelets per spike were increased first,and then decreased.4.Effects of different sowing dates and sowing densities on carbon and nitrogen assimilation,translocation and distribution.The results indicated that appropriately delay sowing lead to stimulating the assimilation of dry matter per plant,decrease sowing density lead to stimulating dry matter weight per plant.With the delay of sowing the dry matter assimilation of anthesis and maturity and single panicle weight were gradually increased, meanwhile,the transportation ratio of per-anthesis stored dry matter of the vegetative organs to grain were increased,but the move ratio were opposite.With the improving of sowing density,the anthesis store dry matter,the transportation ratio of per-anthesis stored dry matter of the vegetative organs to grain and single panicle weight were decreased slightly.Early sowing and appropriate decrease sowing density lead to rising the transportation ratio of per-anthesis stored dry matter,while appropriate delay sowing date and decrease sowing density lead to stimulating translacation of per-anthesis stored dry matter and rising grain weight.5.Effects of different sowing dates and sowing densities on some physiology indices of flag leaf.The NR activity of massive-spike winter wheat cultivar Aizao 8 were increased first,and then decreased with the advance of filling;that of intermediate-spike winter wheat cultivar Zhoumai 18 was highest on the day of flowering,and then declined slowly. Appropriate sowing date and later sowing lead to prolonging the duration of high NR activity of flag leaf after anthesis,while decreased the sowing density lead to keeping higher NR activity of flag leaf,thus to enhance the Photosynthetic Characters.With the delay of sowing,the peak value of Chl content of flag leaf were increased,and the duration of peak value were prolonged,so there can maintain higher Chl content in later filling stage; with the improving of sowing density,the peak value of Chl content of flag leaf were increased first,and then decreased,but the entirety tendency were decreased.In appropriate sowing period,soluble protein content of flag leaf has higher initial point,but has decreased quickly in later filling stage;later sowing and appropriately decrease sowing density lead to increasing peak value of soluble protein content of flag leaf after anthesis and prolonging peak period.In early sowing period,GS activity of flag leaf was higher,but has decreased quickly in later filling stage,while later sowing period lead to prolonging peak period of GS activity of flag leaf;appropriately decrease sowing density lead to increasing GS activity of flag leaf after anthesis and prolonging peak period.With the delay of sowing,the entire tendency of net photosynthesis(Pn)of flag leaf was increased first, and then decreased,appropriately sowing and later sowing maintain higher Pn in later filling stage;with the improving of sowing density,the entire tendency of net photosynthesis(Pn)of flag leaf was increased first,and then decreased,high sowing density maintain higher Pn in later filling stage,but that can't make up for the lower Pn initiate in anthesis.6.Effects of different sowing dates and sowing densities on grain starch and protein content and yield.The results indicated that the grain starch content of two test wheat cultivars were gradually increased with the delay of sowing and increased first,and then decreased with the improving of sowing density,later sowing has highest starch yield. Early sowing with appropriately decreased sowing density and later sowing with appropriately improving sowing density lead to rising grain starch content and yield.With the delay of sowing and the improving of sowing density,the grain protein content of two test wheat cultivars were increased first,and then decreased;appropriately increased sowing density in Aizao 8 and keep appropriately sowing density lead to rising grain protein content.Early sowing has highest protein content,and increased first,and then decreased with the improving of sowing density.Early sowing with appropriately decreased sowing density and later sowing with appropriately improving sowing density in massive-spike winter wheat cultivar lead to rising grain protein content.Early and appropriately sowing with appropriately decreased sowing density and later sowing with appropriately improving sowing density in intermediate-spike winter wheat cultivar lead to rising grain protein content.