【作者】 赵丽；

【导师】 朱云集；

【作者基本信息】 河南农业大学 ， 作物学， 2018， 硕士

【摘要】 随着小麦生产的发展,提高小麦穗粒重成为当前小麦高产栽培中的主攻目标。提高小花结实率是增加小麦穗粒数进而提高穗粒重的重要途径。氮肥和密度是小麦栽培研究的重要内容,为探讨其对小麦小花发育成粒的影响,本研究于2015-2017年在河南农业大学科教示范园区设置试验,以大穗型小麦品种周麦16(V1)和多穗型小麦品种豫麦49-198(V2)为供试材料,设置 4 个氮水平 0 kg hm2(N1)、180 kg hm2(N2)、240 kg hm2(N3)和 360 kg hm2(N4),两个种植密度为每公顷2.25× 106基本苗(W)和每公顷4.5× 106(W2)基本苗,研究不同氮水平和密度对两种穗型小麦品种小花发育和结实的影响,探索不同施氮量和密度条件下物质积累分配、糖和激素变化对小花发育成粒的调控机理。主要研究结果如下:1不同施氮水平对两种穗型小麦品种小花发育的影响大穗型小麦品种表现出随施氮量的增加小花分化速率和退化速率增加,最终在180 kg.hm-2处理下结实粒数和产量最大,较不施氮分别提高了 47.26%和15.20%。两种穗型小麦品种相比,多穗型小麦品种豫麦49-198小花分化数量虽然比较少,但退化速率和败育速率较低,且在180 kg.hm-2处理下小花分化数与结实粒数均最高,每平方米的数量分别达到了143400个、19300个。不同部位小穗穗粒数分析结果也表明,两种穗型小麦品种均为180 kg.hm-2处理下达到最大,表明就最终的产量而言,两品种均以180 kg.hm-2处理较为适宜,结果还表明大穗型小麦品种周麦16还可通过降低小花的退化和败育速率来进一步提高产量,多穗型小麦品种豫麦49-198可在较低的退化和败育率基础上通过提高穗粒数来实现高产。2不同施氮水平对两种穗型小麦品种各部分蔗糖和可溶性糖的影响两种穗型小麦品种穗中可溶性糖和蔗糖与叶中可溶性糖变化趋势相同,与茎中可溶性糖含量变化趋势相反,而叶和茎内蔗糖的变化均是在一个范围内持续波动,最终在花后5d两品种茎、叶和穗中蔗糖和可溶性糖含量均在180 kg.hm-2处理下含量最高,其中大穗型和多穗型小麦品种茎内可溶性糖分别达到了 340.13mg.g-1与238.21 mg.g-1。表明施氮量对两种穗型小麦品种不同器官的蔗糖和可溶性糖有显著的调节作用,叶作为主要的光合作用器官承担起碳水化合物的合成与转运作用,合理的施氮水平能促进叶中和茎中的营养物质向穗中转运,开花后穗中的蔗糖和可溶性糖含量增加有利于后期籽粒中淀粉的合成,从而为小麦的高产提供理论依据。3不同施氮水平对两种穗型小麦品种干物质和氮素积累的影响通过对两种穗型小麦品种干物质积累与分配分析可知,在适宜的施氮水平180 kg.hm-2处理下大穗型小麦品种干物质积累量最大,从而保证了小花发育期间同化物的积累和分配,而多穗型小麦品种在较高施氮水平360 kg.hm-2处理下干物质积累量达到最大,说明不同穗型小麦品种地上部干物质积累对氮肥的响应不一致。花后同化干物质对籽粒产量的贡献率是小麦籽粒高产的主要决定因素之一,合理施氮水平180 kg.hm-2处理下两种穗型小麦品种花后同化干物质对籽粒产量的贡献率均最大,较不施氮处理分别提高了 12.15%11.23%,且在相同氮水平处理下大穗型小麦品种的花后同化干物质对籽粒产量的贡献率均比多穗型品种大,360 kg.hm-2处理下两者之间的差异最大达到750kg.hm2。通过进一步对比两种穗型小麦品种产量三因素可知,合理的施氮量能均衡协调三因素之间的关系,过高和过低的施氮水平打破三者之间的平衡,造成产量下降,说明花后同化干物质对籽粒产量的贡献率跟小麦产量及产量构成因素是密切相关的。4密度对两种穗型小麦品种小花发育的影响较高的种植密度使小麦植株之间的营养竞争加剧,这将直接影响后期小花的发育造成小花的退化和败育率增加,两种穗型小麦品种分化小花数、可孕小花数、结实粒数、小花结实率、可孕小花结实率以及小穗结实率均表现出4.5× 106/hm2基本苗处理小于2.25× 106/hm2基本苗处理,其中V1W1比 V1W2可孕小花结实率高55.29%,V2W1孕小花结实率比V2W高50.39%对于大穗型小麦品种周麦16来说增加密度不同部位的粒重都下降,而多穗型小麦品种豫麦49-198的中部和顶部粒重下降,基部变化不大,表明种植密度过大不利于产量的形成。2.2密度对两种穗型小麦品种C N物质积累转运的影响通过对地上部干物质和氮素的积累与转运分析,密度过高小麦地上部干物质积累、转运以及氮素的积累和转运都下降,其中多穗型小麦品种在成熟期在W处理下干物质积累、转运与氮素积累较W基本苗处理分别提高了 1 2.41%49.97%与 11.68%适宜的种植密度能够使小麦充分利用营养物质和光照条件,从而增加每个时期地上部分干物质量,协调各个器官之间营养元素的转运与分配,种植密度过大不仅造成资源浪费,还限制地上部分干物质和氮素的积累与转运,从而造成构成产量三因素之间的平衡被破坏,进一步导致单位面积产量急剧下降。3两种穗型小麦品种各部分器官内源激素含量差异由两种穗型小麦品种发育过程中旗叶和穗中的CTK和IAA含量变化分析可知,从小花退化的高峰期开始至花后5d,旗叶和穗中CTK含量表现出大穗型小麦品种低于多穗型小麦品种,而多穗型小麦品种在开花期后基部小穗内的CTK含量下降且低于大穗型小麦品种,两品种基部CTK含量相差16μ g/L。旗叶和穗中IAA含量正好相反,此时期是小花退化和败育的关键时期,说明不同穗型品种小麦各个器官内源激素含量与小花退化和败育速率有关,旗叶和穗中CTK含量高能减少小花的退化,较高的IAA含量易导致小花退化速率增加,多穗型小麦品种花后基部小穗内CTK含量下降可能与基部结实粒数较低关系密切。上述结果表明,合理的施氮水平以及适宜的种植密度有利于增加两种穗型小麦品种小花的分化数量,减少小花的退化和败育速率,增加小麦地上部干物质积累和氮素积累,从而提高了花后同化干物质对籽粒产量的贡献率。与其他处理相对比,合理的氮肥使用量能增加茎、叶和穗中蔗糖和可溶性糖的含量,有利于花后同化物向籽粒中转运,进而提高小麦籽粒产量。通过在小花退化的高峰期,对两种穗型小麦品种叶和穗中CTK和IAA的分析,发现大穗型小麦品种穗和叶中较低的CTK含量和较高的IAA含量可能是造成大穗型品种较高的小花退化和败育速率的原因。更多还原

【Abstract】 It has been agreed that main factor to limit wheat potential high yield were the grain number per spike and the weight per grain.According to the limited minimum factor of ecology law,the grain number of per spike had become a short board to limit the wheat grain yield.As research showed,the key to improve development and fructification of floret was promoting the yield of wheat.By contrasting conditions of different nitrogen levels(0 kg/hm2(N1)、180 kg/hm2(N2)、240 kg/hm2(N3)and 360 kg/hm2(N4))and different density levels(225×l04seedlings hm-2(W1)、450×l04seedlings hm-2(W2))with two wheat of different spike types(large-spike cultivar zhoumail6(V1)and multl-spike cultivar yumai49-198(V2))The dynamic models and characteristics of florets development and grain set characteristics were studied in the experiment station of Henan Agricultural University in 2015～2017 growing seasons.The experiment analyzed the relationship between different nitrogen levels and density.Meanwhile,the regulation mechanism of florets development was determented by different cultivation measures.The main results were as follows:1 The effect of different nitrogen levels on the characteristics of floret development and grain set of two spike-types wheat1.1 The effect of different nitrogen levels on the characteristics of floret development of two spike-types wheatResearch pointed out that wheat material production,accumulation and transportation can reach the top when the nitrogen application in 180～270 kg·hm-2 in Henan Province.There should be obvious positive correlation between accumulation of nitrogen in the plant and grain number per spike of wheat.GDD(growing-degree-day)was used to calculate the growth of plants,harvest time and quality.In this report,GDD(growing-degree-day)was an important merit to study the relationship between floret development and hit source.Experimental investigation showed that rising curing can be described the dynamic of floret differentiation between two cultivars and straight line can be described the degeneration and infertility in relation to the growing-degree-days(GDD).With the creasing of nitrogen application amount,large spike type wheat has more floret differentiation number,fertile florets differentiation number,fertile spikelet number,floret differentiation rate and degeneration rate.multi spike type wheat turns out more florets in middle nitrogen levels.It was clearly indicated that the number of florets was not the only factor to decide the grain number,more attention should be paied on the cultivation of regulation at the later stage of floret development1.2 Difference of the content of sucrose and soluble sugar of two spike-types wheat under different nitrogen levelsAnalyzing the content of sucrose and soluble sugar in stems and leaves,we can find that The stems and leaves acted as storage organs in the early stage and the storage organs played as the transportation when the florets and spikelets get into the rapid developing stage.Soluble sugar in stems was continuously increasing from the JS to AS,while sucrose was decreasing at begining and then increasing.The soluble sugar in the stem is a continuously decreasing process from the JS to 5d post-AS,but The change of sucrose was continuously fluctuating within a range.1.3 Difference of dry matter and nitrogen accumulation of two spike-types wheat under different nitrogen levelsResults showed that from WS to MS,dry matter and nitrogen accumulation in wheat were gradually increasing,and two cultivars in dry matter and N accumulation are in obvious differences after jointed,Between JS and AS,the contribution rate of post-anthesis assimilated dry matter to grain yield was a major determinant of wheat grain yield,and they were the biggest when the nitrogen levels were reasonable.At the same nitrogen level,the contribution rate of post-anthesis assimilated dry matter to grain yield of zhoumail6 was higher than yumai 49-198.Reasonable application of nitrogen fertilizer was also beneficial to the accumulation and transportation of the aboveground nitrogen in wheat and is the foundation for getting high yield.Through further analysis of three factors make up the grain yield on two spike type wheat,it conducted that a balanced amount of nitrogen can coordinate the relationship between the three factors.High and low nitrogen levels breaked the balance between the three factors and caused the decline in grain yield.2 The effect of different density levels on the characteristics of floret development and grain set of two spike-types wheat2.1 The effect of different density levels on the characteristics of floret development of two spike-types wheatThe result showed that total florets,fertile florets,grains total florets set,fertile florets set and spikelets set of W1 treatment were more than W2 treatment of two spike-type wheat.Among them the fertile florets sets of V1W1 treatment was 55.29%higher than that of V1W2,and the fertile florets sets of V2W1 was 50.39%was higher than that of V2W2.The higher density levels increased the nutrition competition among the plants,which directly influent the development of florets and the formation of yield.While high planting density made a decrease of spikelet number in different parts of the spikelet,The grain weight in different parts of spikelet was also decreased for large spike-type wheat.There was no obvious change of grain weight in the middle and top parts for multi spike-types wheat yumai49-198.2.2 The effect of different density levels on the dry matter and nitrogen accumulation of two spike-types wheatFrom the date of accumulation and transportation of dry matter and nitrogen in the ground,it conducted that suitable planting density enables wheat to make full use of nutrients and light conditions,by increasing dry matter quality and coordinating nutrient elements transportation and distribution among organs.However,excessive planting density not only leads to waste of resources,but also restricts the accumulation and transport of some dry matter and nitrogen in the ground.Thus,the destruction of the balance of the three factors of grain yield causes the decrease of the yield per unit area.3 Difference of the content of endogenous hormone(CTK,IAA)in different organs of two spike-types wheatFrom analyzing changes of the content of endogenous hormone CTK and IAA in leaves and spikes from jointing past,it showed that the contents of CTK in leaves and spikes of multl-spike cultivar were generally higher than that of large-spike cultivar.The content of IAA of large-spike cultivar was higher than that in the early stage,but it was lower than that latter.It was indicated that there were differences in the contents of endogenous hormones of different spike types wheat in different organs.The contents of CTK and IAA in the leaves and spikes of large-spike cultivar get to the top when the degeneration and infertility of florets achieved their peak.However the degradation and abortion rate of the arge-spike cultivar higher than that.It showed that the degradation and abortion of florets were related to the content of endogenous hormones in wheat.更多还原