基于控制授粉技术的玉米籽粒建成与碳、氮供应关系

以郑单958和超试1号为材料,通过控制玉米果穗底部花丝不授粉使顶部籽粒正常结实,比较研究了玉米籽粒早期碳、氮含量动态变化及其与败育的关系。结果表明,控制底部花丝不授粉,提高了顶部穗轴的可溶性糖浓度,增加了对顶部籽粒的物质供应,顶部籽粒的可溶性糖、蔗糖含量提高,淀粉快速积累,顶部籽粒的氮含量增加,籽粒C/N比值提高,籽粒重量快速增加,发育转为正常,表现出与中部籽粒一致的碳、氮变化动态特征以及籽粒生长动态;相反,统一完全授粉处理顶部穗轴的可溶性糖浓度低,顶部籽粒的物质供应少,可溶性糖、蔗糖含量低,淀粉含量提高缓慢,氮含量也较低,籽粒的C/N比值偏低,表现为粒重增加缓慢,最后败育。2个品种表现出一致的规律性。总之,玉米顶部籽粒的正常发育伴随着碳、氮等物质的充足供应,物质供应不足可能是顶部籽粒不能正常发育的根本原因。     

施氮对不同氮效率玉米干物质形成及籽粒发育的影响

为了揭示不同氮效率玉米在不同氮素水平下籽粒发育和地上部干物质积累的差异,通过田间小区试验,在3个氮素供应水平N0、N1、N2（施纯氮量分别为0、140、210 kg/hm²）下,对6个不同玉米品种（‘屯玉99’(A),‘并单390’(B)、‘郑单958’(C)、‘晋单65’(D)、‘先玉335’(E)、‘潞玉19’(F)）干物质的积累变化和籽粒发育进行了对比分析。结果表明：这6个品种可以分为3种不同氮效率类型：高氮高效型（‘屯玉99’和‘并单390’）;双高效型（‘晋单65’和‘先玉335’）;低氮高效型（‘潞玉19’和‘郑单958’）。在N1(140 kg/hm²)水平下氮素能够明显促进玉米营养体干物质的积累,促进籽粒产量的增加。随着施氮量的增加,高氮高效型和双高效型品种光合碳量增加,为籽粒提供了充足的碳源;高氮高效性品种地上部干物质积累的增加大于籽粒干物质的积累的增加,而双高效品种籽粒干物质积累增加较快。同时,施氮还可以促进这2种类型玉米顶部籽粒发育,增加产量。而低氮高效品种在氮素作用下,营养体干物质有明显增加,籽粒没有明显变化;施氮会促进营养体干物质的转移;同时过高(N2)或过低(N0)的施氮量都会造成其顶部籽粒发育不完善,影响产量。     

氮素对高温胁迫下玉米籽粒发育的调控效应

明确籽粒建成期高温胁迫下氮素对玉米籽粒发育的调控效应,对合理施肥、缓解高温危害、实现玉米丰产稳产具有重要意义。以热敏感品种先玉335（XY335）和耐热品种郑单958（ZD958）为材料,设高温处理（T）和对照（CK）,研究不同施氮量（90,180,270 kg/hm²,分别记为N90、N180、N270）对籽粒建成期高温胁迫玉米籽粒发育及产量的影响。结果表明,高温胁迫打破了玉米籽粒内源激素间的平衡,使得2个玉米品种的N180和N270的籽粒脱落酸（ABA）含量、郑单958的N180和N270的生长素（IAA）含量降低;上部籽粒可溶性酸性蔗糖转化酶（SAI）活性降低,籽粒体积膨胀及干物质积累受阻,败育率增加,穗粒数减少,进而导致产量显著降低。热敏感品种先玉335受高温胁迫的影响程度高于耐热品种郑单958。随施氮量增加,高温对玉米籽粒发育的负面影响加剧。高温胁迫下,与低氮（N90）处理相比,中氮（N180）、高氮（N270）处理下,先玉335和郑单958籽粒ABA/GA₃降低,IAA和ZR含量升高,籽粒体积和干物质减少更加严重,败育率分别显著增...     

施氮量对济麦20旗叶光合特性和蔗糖合成及籽粒产量的影响

在田间高产条件下,研究了施氮量对强筋小麦品种济麦20旗叶光合特性、蔗糖合成及籽粒产量的影响。结果表明,在0～168 kg hm^-2施氮量范围内,随施氮量的增加,旗叶蒸腾速率提高,气孔导度增大,细胞间隙二氧化碳浓度降低,旗叶净光合速率与蔗糖磷酸合酶活性显著提高,从而促进旗叶蔗糖合成,提高生物产量、籽粒产量和氮肥利用率;施氮量增加至240 kg hm^-2,旗叶净光合速率、蔗糖磷酸合酶活性、蔗糖含量和生物产量显著提高,但收获指数降低,籽粒产量和氮肥利用率无显著变化。施氮量继续增加至275 kg hm^-2,旗叶蒸腾速率、气孔导度、气孔限制值和净光合速率均显著降低,细胞间隙二氧化碳浓度则显著升高,旗叶光合作用受非气孔限制,蔗糖磷酸合酶活性、蔗糖含量、生物产量和收获指数均显著降低,籽粒产量减少,氮肥利用率降低。在本试验条件下,济麦20的适宜施氮量为168~240 kg hm^-2。     

施氮对不同氮效率玉米籽粒灌浆的影响

不同的玉米品种在吸收利用氮效率方面存在着显著差异,因此确定不同品种玉米的氮效率很有必要。玉米施氮后的生长效果可以在籽粒灌浆期表现出来。很多学者在对于相同的施氮条件下不同玉米品种间的灌浆特性差异方面做出了不少研究,然而对于不同施氮条件下的灌浆特性差异却鲜有报道。本试验通过观察玉米灌浆动态,旨在确定不同玉米品种氮效率差异的基础上,比较品种间的灌浆特性差异。试验于2013年5月1日—10月7日进行,在大田条件下,以‘屯玉99’、‘潞玉19’、‘先玉335’为材料,对不同供氮水平N0、N1、N2（施纯氮量分别为0、140、210 kg/hm²）下春玉米顶部、中下部籽粒的灌浆动态进行研究。结果表明,‘屯玉99’籽粒鲜重、干重表现为N2＞N1＞N0,‘潞玉19’表现为N1＞N2＞N0,‘先玉335’表现为施氮(N1、N2)＞无氮(N0),其中N1、N2间差别不大。N1条件下的‘潞玉19’发育优势最为显著,其次是N2条件下的‘屯玉99’,N1、N2条件下的‘先玉335’优势最不明显。施氮对顶部籽粒发育的促进作用明显高于中下部籽粒。     

不同耕作和有机培肥措施对土壤理化性质及小麦产量的影响

为探索黄淮海潮土区小麦最佳耕作和施肥模式,以河南省夏邑县潮土试验基地为平台设置了2种耕作方式（深耕和旋耕）和5种施肥模式（不施肥、单施化肥及3种化肥配施有机肥）,测定不同耕作和培肥措施下土壤理化性质、植株和籽粒氮、磷、钾含量及产量。结果表明,增施有机肥显著提高了表土层和犁底层土壤全氮、速效磷、速效钾和有机质含量;旋耕条件下土壤表层养分高于深耕。旋耕增施有机肥促进了植株和籽粒氮、磷、钾含量,籽粒氮和植株氮在化肥配施有机肥22 500kg/hm²时效果最佳;籽粒磷和植株磷含量在化肥配施有机肥7 500kg/hm²时效果最佳。深耕增施有机肥明显提高了小麦产量,最佳有机肥施用量为化肥配施有机肥15 280kg/hm²。     

灌浆结实期弱光对水稻籽粒蔗糖及其降解酶活性的影响

选用IR72（籼稻）和日本睛（粳稻）,在开花后遮光处理,对弱光条件下籽粒蔗糖含量的动态变化和降解酶的活性进行了研究。结果表明：两品种籽粒的蔗糖含量减少,蔗糖分解加快,蔗糖合成酶（SS）活性下降,液泡型转化酶（VCI）和细胞壁结合型转化酶（WCI）活性提高。即在弱光条件下,转化酶活性的提高加快了蔗糖的分解。相关分析表明,蔗糖合成酶活性、细胞壁结合型转化酶活性与淀粉积累速率显著正相关。说明这两种酶在蔗糖的分解和淀粉的合成过程中起着十分重要的作用。     

施钾对油菜酶活性的影响及其与产量品质的关系

研究了施钾对湘油13号的几种酶活性的影响及其与产量和品质的关系。结果表明：增施钾肥，促进油菜果壳和叶片的蔗糖磷酸合成酶（SPS）及籽粒的蔗糖合成酶（SS）和磷脂酸磷酸酯酶活性提高，使籽粒产量、收获指数和种子含油量增加；同时，促进油菜籽粒、果壳、叶片的谷氨酰胺合成酶（GS）活性和蛋白氮、非蛋白氮、总氮含量的提高，使种子蛋白质含量增加；增放钾肥有利协调油菜高产和高含油量及蛋白质含量的形成。     

氮密互作对夏玉米物质生产及氮素利用的影响

以夏玉米杂交种郑单958为材料,对不同种植密度和不同施氮水平下夏玉米的物质生产和氮素利用状况进行了研究。结果表明,在中(67 500株/hm2)、高(82 500株/hm2)密度下,氮肥对玉米单株物质生产能力的调控作用更为明显,并主要是通过影响穗粒数来实现的。适量施氮,可促进顶部子粒发育,减少败育,使秃尖缩短、瘪粒数减少,增加穗粒数,增加产量;促进植物体吸收的氮素高效地向籽粒中分配,提高氮肥的利用效率;使玉米叶片维持较高的光合性能,为籽粒形成提供充足的光合碳量,并促进营养体碳氮向子粒运转。     

CO2浓度升高加快了水稻灌浆前期籽粒的生长发育进程

本研究利用开放式空气中CO₂浓度增加（Free Air CO₂ Enrichment, FACE）试验平台，研究CO₂浓度升高200 µmol·mol^-1下，水稻灌浆早期籽粒大小、生长速率、可溶性碳水化合物和淀粉含量及蔗糖转化酶活性等在开花后20 d内的变化动态。结果表明，与对照相比，FACE处理加快了灌浆早期籽粒的发育进程，尤其加快了籽粒宽度达到最大的日程，籽粒大小和籽粒灌浆速率提前3 d达到最大值；成熟时籽粒的长宽积FACE下的比对照下的提高了4.5%，但粒重无差异；FACE下开花后2~5 d内籽粒中的还原糖和蔗糖的含量及细胞壁转化酶和细胞质转化酶的活性显著高于对照下的，但淀粉含量和可溶性酸性转化酶活性则无显著差异。从结果推论，FACE加速水稻灌浆前期籽粒生长发育与其花后早期颖果内蔗糖合成和转运水平之间可能存在内在联系。     

弱光胁迫对不同基因型玉米籽粒发育和碳氮代谢的影响

以不耐阴型玉米豫玉22和耐阴型玉米郑单958为试验材料,设置自然光照和弱光胁迫2个处理,研究弱光胁迫对不同基因型玉米籽粒建成和碳氮代谢的影响,探求弱光胁迫下碳氮代谢与籽粒建成的关系。结果表明,弱光胁迫下,玉米籽粒生长发育减缓,败育数增加,体积和干重降低;果穗顶部籽粒可溶性糖、蔗糖含量和全氮含量升高, 淀粉含量和碳氮比降低;豫玉22胚乳细胞中淀粉粒密度降低,郑单958与对照相近。弱光胁迫下,不耐阴型玉米豫玉22果穗籽粒的生长发育减缓程度大于耐阴型玉米郑单958,同一基因型果穗顶部籽粒生长发育减缓程度大于中部籽粒,耐阴型玉米郑单958在恢复自然光照后籽粒体积、干重、籽粒碳氮含量和碳氮比与对照之间的差异均小于豫玉22,表现出更强的补偿效应。淀粉合成能力和碳氮比的下降可能是弱光胁迫条件下籽粒发育不良以致最终造成败育的主要原因。     

不同产量潜力玉米籽粒胚乳细胞增殖与籽粒充实期的生理活性

不同产量潜力玉米间单籽粒的胚乳细胞数目差异显著,高产潜力玉米多于中产和低产潜力玉米,中产潜力玉米又多于低产潜力玉米。籽粒的生理状态影响着籽粒灌浆。籽粒灌浆速率、籽粒淀粉磷酸化酶活性及GA3含量的动态变化在时间进程上基本一致,籽粒淀粉磷酸化酶活性及GA3含量对籽粒物质充实有直接作用,其较高含量利于籽粒的干物     

Endosperm Development in Maize and Related to Photosynthate Supply

Maize ( Zea mays , L. Sweet Corn) plants were given shaded, partially shaded and control light treatments during 10 days or 20 days periods around the time of pollination. Glucose, sucrose, starch and dry matter (DM) contents were measured at intervals in composite samples of pericarp/nucellus (PN), and in endosperms taken from developing kernels. Total kernel DM per ear at maturity was higher in the partially shaded treatment than control and shaded treatments due to higher kernel set in apical regions of ears. In PN at 11 days after pollination (DAP), DM and sucrose contents were slightly greater in partially shaded than control and shaded plants. Glucose contents were substantially greater than controls in PN of partially shaded plants and were less than control in shaded plants. In endosperms from apical kernels at 5 to 10 DAP (during cell division), DM, glucose and sucrose contents were substantially less in shaded than control and partially shaded plants, sucrose contents were greater in endosperms of partially shaded than control plants. Sugar contents in endosperms from basal kernels were nearly the same in the three light treatments. At 10 DAP, apical and basal endosperms in shaded plants had fewer nuclei than those of the other light treatments. The light treatments appeared to effect apical kernel growth by influencing the extent of cell division.     

玉米灌浆期果穗不同部位籽粒碳水化合物积累与淀粉合成相关酶活性变化

玉米果穗顶部籽粒通常较中、下部籽粒充实差,粒重轻,其机制不清楚。本研究旨在探明玉米果穗不同部位籽粒淀粉合成相关酶活性变化及其与籽粒灌浆的关系。以玉米品种登海11为材料,分别进行春播和夏播试验,观察果穗不同部位籽粒中可溶性糖、蔗糖和淀粉的含量及淀粉合成相关酶活性变化。结果显示,与夏播玉米相比,春播玉米具有较多的每穗粒数、较高的百粒重和产量。虽然产量在春播和夏播间有差异,但两季玉米籽粒的最大灌浆速率、平均灌浆速率、百粒重、可溶性糖和蔗糖含量、最大淀粉积累速率、平均淀粉积累速率均表现为果穗下部籽粒中部籽粒上部籽粒。灌浆期果穗不同部位籽粒腺苷二磷酸葡萄糖焦磷酸化酶(AGPase)、淀粉合酶(St S)和淀粉分支酶(SBE)活性变化均呈单峰曲线,果穗上部籽粒AGPase、St S和SBE活性峰值和平均值均显著低于果穗中、下部籽粒。相关分析表明,淀粉积累速率、籽粒灌浆速率与AGPase、St S和SBE活性均呈极显著正相关。说明玉米果穗顶部籽粒较低的AGPase、St S和SBE活性是其灌浆较差、粒重较低的重要原因。春播玉米粒重较高,与其灌浆期较强的淀粉合成能力有关。     

油菜素内酯对春玉米灌浆期叶片光合功能与产量的调控效应

以玉米品种"郑单958"为材料,在大田条件下,采用植物生长调节物质油菜素内酯(brassinolide,BR)对苞叶和穗位叶喷施处理,研究了BR对玉米穗位叶功能、籽粒灌浆及产量的调控作用。结果表明,灌浆期随生育进程,玉米穗位叶叶绿素含量、光合速率、磷酸烯醇式丙酮酸羧化酶(PEPCase)、1,5-二磷酸核酮糖羧化酶(Ru BPCase)以及蔗糖磷酸合酶和蔗糖合酶的活性均显著下降。同时,籽粒蔗糖含量显著降低,但淀粉含量和粒重均显著增加。与对照相比,BR处理显著增加玉米穗位叶叶绿素含量,提高光合速率,增强PEPCase、Ru BPCase、蔗糖磷酸合酶和蔗糖合酶的活性。BR处理显著增加籽粒蔗糖和淀粉积累,提高玉米籽粒干物质积累。在产量构成上,BR显著缩短秃尖长度,增加穗粒数和千粒重,显著提高产量。本研究说明,灌浆期喷施BR可提高玉米叶源的活性,延长叶片光合功能持续期,促进籽粒灌浆和物质积累,从而实现增产。     

基于控制授粉技术的玉米弱势粒发育与库特征的关系

明确弱势粒败育和灌浆受限与其库容量或库活性关系,对于探讨弱势粒调控途径、实现密植群体产量挖潜具有重要意义。本研究以典型玉米杂交种郑单958和先玉335为材料,在控制授粉条件下(不完全授粉IcP、完全授粉CP),比较成功发育弱势粒(IcP处理)和发育不良弱势粒(CP处理)的库容量和库活性及籽粒灌浆参数的差异。结果表明,不同控制授粉处理下,玉米弱势粒胚乳细胞增殖过程和最大胚乳细胞数无显著差异;IcP处理弱势粒可溶性酸性蔗糖转化酶(SAI)活性显著高于CP处理,平均差异和最大差异分别达12.6%和21.8%,且实测百粒重、籽粒终极生长量、最大灌浆速率和平均灌浆速率皆表现为IcP处理高于CP处理。可见,玉米果穗顶部弱势粒败育或灌浆停滞不受其库容量的限制,籽粒形成期的库活性是弱势粒败育或灌浆受限的核心限制因子。     

玉米籽粒突变体dek101的表型分析和精细定位

As the storage organ of maize, kernel development and accumulation of storage production directly determines maize yield and quality. In this study, a stable defective kernel mutant, named as defective kernel 101 (dek101), was identified during the development of double haploid (DH) lines in maize. The dek101 kernels displayed severely shrunk kernel appearance, significantly reduced kernel weight, lethal embryo, defective endosperm and were incapable of germinating. The dek101 showed obvious developmental abnormalities at 12 days after pollination (DAP). The fresh weight, dry weight and volume of the kernels were no longer increased after 21 DAP. Scanning electron microscopy (SEM) observation revealed that the starch granules of dek101 were significantly smaller compared with wild-type kernels. Genetic analysis demonstrated that the mutant trait was controlled by a recessive single gene. Using 441 F₂ individuals and 1648 F₃ individuals, dek101 was narrowed down to a genomic region of about 300 kb between the InDel marker IDP2182 and IDP4600 on chromosome 1, which contains five predicted genes. These results laid the foundation for mining functional genes related to maize kernel development and deciphering the mechanism of grain development.     

Agronomic Performance and Nutrient Concentration of Maize (Zea mays L.) as Influenced by Nitrogen Fertilization and Plant Density

A field experiment was conducted at Samaru, Nigeria to study the influence of nitrogen fertilization and plant density on the agronomic performance and nutrient concentration of maize ( Zea mays L.). The treatments were factorial combinations of five nitrogen fertilization rates (0, 50, 100, 150 and 200 kg N/ha) and three plant density levels (25000, 50000 and 75000 plants/ha).
Nitrogen fertilization up to 150 kg N/ha enhanced grain and stover yields and increased kernel number and weight up to 100 kg N/ha. Nitrogen supply also increased maize ear length. Increased N fertilization rates increased concentrations of N, K and Mg but had no effect on P and Ca concentrations. Higher grain yield was closely associated with higher N concentration in ear leaf; with 0.1 % change in N concentration causing 177 kg/ha change in grain yield. Increased plant density increased stover yield up to 50 or 75 thousand plants/ha but depressed kernel number and weight and ear length.     

Yield Components of Apical and Subapical Ear Contributing to the Grain Yield Responses of Prolific Maize at High and Low Plant Populations

Subapical ears are largely responsible for grain yield variations in prolific maize (Zea mays L.) grown under conditions favourable for the expression of prolificacy trait, but limited information exists on yield components contributing to yield responses. A field experiment was conducted to determine the yield components of apical and subapical ear in prolific maize after various pollination treatments at two plant populations. Hybrid Pioneer 3733 was grown in the perfect stands of 71 428 and 35 714 plants ha^?1. Three pollination treatments were carried out: (i) free pollination; (ii) subapical earshoots were covered to prevent pollination; and (iii) apical earshoots were covered to prevent pollination. Grain yields of free pollinated plants were by 50.1 % larger at low plant population (265 g per plant) than at high plant population (177 g per plant) due to a 45.3 % increase in kernels per plant, whereas 1000‐kernel weight slightly increased by 3.3 %. These increased kernels per plant at low plant population were, in part, the result of kernel increments on apical ear (10.1 %), and mainly associated with kernels from subapical ears that did not occur at high plant population. At low plant population, the total grain yield per plant was reduced by 94 g (35.5 %) after the apical ear was bagged to prevent pollination, but only 52 g (19.6 %) when the subapical ear was bagged. When subapical ear development was stopped at low plant population, grain yield on apical ears increased by only 3.9 % as a result of heavier 1000‐kernel weights, clearly demonstrating limitations in kernel set and size. After grain development on apical ear was prevented, subapical ear enlarged to 80.3 % of maximum apical ear yield because the former had, on average, 2.5 % lighter 1000‐kernel weight and 17.5 % fewer kernels than the latter. Ears did not differ in row number when only apical or subapical ear was developed on plant, whereas subapical ears tended to have fewer rows than apical ears when both were present on the same plant. Our results showed that: (i) plant population affected all yield components on both apical and subapical ear except row number; (ii) the occurrence of subapical ear is triggered by achieving maximum potential kernel set on apical ear; and (iii) subapical ear is inferior in potential grain yield to apical one even when the latter was prevented from pollination.