玉米耐旱相关基因dbf1的序列变异分析

玉米dbf1 基因在干旱胁迫下的编码产物与DIP₁蛋白相结合,调控植物激素脱落酸（ABA）响应基因rab17 的表达,从而提高耐旱性。以B73的dbf1 基因组序列为模板,对104个玉米自交系的dbf1 基因进行测序,研究玉米dbf1 基因的序列多态性。多态性分析表明,在全长为2 118 bp的序列中共发现48个SNP和12个InDel。尽管大部分变异位点集中在非编码区,但编码区的1个InDel和3个非同义突变位点的变异可以产生氨基酸序列改变。玉米dbf1 基因的全长序列和编码区序列的变异位点可以分别将该基因划分成33和11种单倍型,并且编码7种蛋白质。在供试材料中,dbf1 基因至少经历了9次重组,中性检测表明,该基因的进化没有偏离中性选择。     

Changes in Grain Yield of Rice and Emission of Greenhouse Gases from Paddy Fields after Application of Organic Fertilizers Made from Maize Straw

A field experiment was conducted at the farm of Yangzhou University, Yangzhou, China, to study the effects of organic fertilizers made from maize straw on rice grain yield and the emission of greenhouse gases. Four organic fertilizer treatments were as follows： maize straw （MS）, compost made from maize straw （MC）, methane-generating maize residue （MR）, and black carbon made from maize straw （BC）. These organic fertilizers were applied separately to paddy fields before rice transplanting. No organic fertilizer was applied to the control （CK）. The effects of each organic fertilizer on rice grain yield and emission of greenhouse gases were investigated under two conditions, namely, no nitrogen （N） application （ON） and site-specific N management （SSNM）. Rice grain yields were significantly higher in the MS, MC and MR treatments than those in CK under either ON or SSNM. The MS treatment resulted in the highest grain yield and agronomic N use efficiency. However, no significant difference was observed for these parameters between the BC treatment and CK. The changes in the emissions of methane （CH4） carbon dioxide （CO2）, or nitrous oxide （N20） from the fields were similar among all organic fertilizer treatments during the entire rice growing season. The application of each organic fertilizer significantly increased the emission of each greenhouse gas （except N20 emission in the BC treatment） and global warming potential （GWP）. Emissions of all the greenhouse gases and GWP increased under the same organic fertilizer treatment in the presence of N fertilizer, whereas GWP per unit grain yield decreased. The results indicate that the application of organic fertilizer （MS, MC or MR） could increase grain yield, but also could enhance the emissions of greenhouse gases from paddy fields. High grain yield and environmental efficiency could be achieved by applying SSNM with MR.     

Strategies for overcoming low agronomic nitrogen use efficiency in irrigated rice systems in China

Irrigated rice in China accounts for nearly 30% of global rice production and about 7% of global nitrogen (N) consumption. The low agronomic N use efficiency (AE_N, kg grain yield increase per kg N applied) of this system has become a threat to the environment. The objective of this study was to determine the possibility to improve the AE_N of irrigated rice in China by comparing the farmers’ N-fertilizer practices with other N management strategies such as real-time N management (RTNM) and fixed-time adjustable-dose N management (FTNM). Field experiments were conducted in farmers’ fields in four major rice-growing provinces in China in 2001 and 2002. The same experiment was repeated at the International Rice Research Institute (IRRI) farm in the dry seasons of 2002 and 2003. Agronomic N use efficiency was determined by the “difference method” using an N-omission plot. Maximum yield was achieved mostly at 60–120 kg N ha⁻¹, which was significantly lower than the 180–240 kg N ha⁻¹ applied in farmers’ practices at the Chinese sites. With the modified farmers’ fertilizer practice, a 30% reduction in total N rate during the early vegetative stage did not reduce yield but slightly increased yield and doubled AE_N compared with the farmers’ practice at the Chinese sites. The total N rate in RTNM and FTNM ranged from 30 to 120 kg ha⁻¹ at the Chinese sites, but their yields were similar to or higher than that of the farmers’ practice. Compared with the modified farmers’ practice, RTNM and FTNM further increased AE_N at the Chinese sites. Overall, FTNM performed better than RTNM at the Chinese sites because the total N rate of FTNM was closer to the optimal level than RTNM. A quantum leap in AE_N is possible in the intensive rice-growing areas in China by simply reducing the current N rate and by allocating less N at the early vegetative stage.     

籼粳杂交稻甬优2640氮素吸收利用特点

【目的】探明籼粳杂交稻甬优2640的氮素吸收利用特点。【方法】籼粳杂交稻甬优2640、常规粳稻连粳7号和常规籼稻扬稻6号种植于大田,设置6种施氮量处理(0、100、200、300、400、500 kg/hm ²)和 ¹⁵N示踪微区试验。【结果】在0~400 N kg/hm ²范围内,甬优2640的稻谷产量随施氮量的增加而提高;连粳7号和扬稻6号的产量则是先增加后降低,在施氮量300 kg/hm ²时产量最高;相同施氮量下,甬优2640的产量均高于连粳7号和扬稻6号。甬优2640产量较高,这得益于地上部较高的干物质量和库容量(总颖花量)。适量增施氮肥提高了籽粒中 ¹⁵N积累量,但其在籽粒中的分配比例却随施氮量的增加而降低。甬优2640穗中的 ¹⁵N分配比例高于连粳7号和扬稻6号。高施氮量降低水稻氮收获指数。增施氮肥明显提高3个水稻品种穗分化期、抽穗期和灌浆中期叶片的硝酸还原酶、谷氨酰胺合成酶和谷氨酸合酶活性;相同施氮量下,甬优2640的各种酶活性显著高于连粳7号和扬稻6号。【结论】籼粳杂交稻甬优2640较常规水稻品种具有更强的氮素吸收与利用能力。     

不同氮利用率粳稻品种的碳氮积累与转运特征及其生理机制

【目的】探明不同氮利用率水稻品种的氮素积累与转运特征及其机制。【方法】2个氮高效品种(武运粳30号和连粳7号)和2个氮低效品种(扬粳4038和宁粳1号)种植于大田,设置2个施氮量：全生育期不施氮(0 N)和全生育期施氮180 kg/hm² (180N),比较分析了不同氮利用率粳稻品种干物质生产、氮素积累与转运差异及其机制。【结果】与氮低效品种相比,氮高效品种具有较高的产量、氮肥利用率、总颖花量和结实率,较高的花前干物质转运量和花后干物质积累量,分蘖至穗分化始期和抽穗至成熟期较高的净同化率和作物生长率,抽穗期较高的糖花比,灌浆期较高的籽粒库活性、籽粒中脱落酸与1-氨基环丙烷-1-羧酸含量的比值和茎鞘中较高的非结构性碳水化合物的转运和蔗糖合成相关酶活性以及蔗糖转运蛋白基因的表达量,抽穗后较高的氮转运、氮素吸收量,灌浆期较高的比叶氮含量、叶片中细胞分裂素含量、氮代谢酶活性以及氮素转运相关基因的表达量。【结论】氮高效品种穗分化前和抽穗后较高的物质生产效率以及灌浆期较高的碳氮转运与积累是产量和氮肥利用率协同提高的重要机制。     

稻田甲烷排放的微生物学机理及节水栽培对甲烷排放的影响

全球变暖是当前亟需解决的环境问题之一。甲烷是仅次于二氧化碳的第二大温室气体,其中稻田甲烷排放约占全球甲烷排放的10%~30%。稻田甲烷的产生与氧化是决定稻田甲烷排放的关键,其过程是在相关微生物参与下完成的,受多种环境条件影响。水分管理直接影响稻田土壤的通气状况,并对土壤微生物活动产生影响,从而直接或间接影响稻田甲烷的产生与排放。本文综述了稻田甲烷产生与排放的微生物学机理,并总结了干湿交替灌溉等常用节水栽培方式对稻田甲烷排放的影响。同时提出未来研究的重点方向。     

耕播方式与减氮对扬辐麦13氮素吸收利用的影响

为明确不同机械耕播方式下减氮对小麦氮素吸收利用的影响,在水稻秸秆全量还田条件下,以扬辐麦13为材料,研究两种机械耕播方式［板茬+2BMF-稻茬免耕条播机（NT）、旋耕+2BFG-10（8）230型播种机（CT）］和三个施氮模式［常规模式（N1）:施氮量270 kg·hm_-2,基肥∶分蘖肥∶拔节肥∶孕穗肥= 5∶1∶2∶2;减氮模式（N2）：施氮量225 kg·hm_-2,基肥∶分蘖肥∶拔节肥∶孕穗肥=5∶1∶2∶2;减氮减次模式（N3）：施氮量180 kg·hm_-2,基肥∶拔节肥=5∶5］对小麦氮代谢酶活性、氮素吸收利用特征以及籽粒产量的影响。结果表明,播种前土壤相对含水量为84%,与CT处理相比,NT处理提高了植株硝酸还原酶（NR）和谷氨酰胺合成酶（GS）活性,使花前氮素转运量增加和氮素在籽粒中的分配量分别增加10.78% (P<0.01)和7.56%（P<0.05）,获得较高的氮肥偏生产力和氮肥表观利用率,其最终籽粒产量提高5.36%（P<0.05）。N2处理在小麦生育中后期可维持较高的氮代谢酶活性,获得较高的氮肥利用效率,花后氮素积累量和籽粒产量与N1处理无显著差异;N3处理的氮肥利用效率最高,但氮代谢酶活性较低,影响氮素在植株中的积累和转运,且籽粒产量最低。因此,播前土壤偏湿条件下推荐采用NT耕播方式,配N2减氮模式,有利于小麦生育中后期维持较高的氮代谢酶活性和氮素的积累,促进氮素向籽粒转运,提升氮肥利用效率和籽粒产量,实现高产高效;若CT耕播方式下宜采用N1施肥方式才能实现稳产,但氮肥利用效率不高。     

不同生态类型大麦品种(系)杂交后代主要农艺性状的分析

为了解不同生态类型大麦品种(系)杂交后代主要农艺性状的分离规律,以美国引进的优质啤酒春大麦品系ABI 18-152为母本、江苏主推冬啤酒大麦品种扬农啤7号为父本配制的杂种F1、F2群体及亲本为材料,测定株高、穗长、穗下节间长、单株穗数、主穗粒数、千粒质量、单株产量、粒长、粒宽、粒长宽比10个农艺性状,对各性状的杂种优势及分离规律进行分析。结果表明:除主穗粒数和粒宽在亲本间差异不具统计学意义,其余8个性状在亲本间均具有统计学意义(P<0.05)或高度统计学意义(P<0.01)。杂种F1的10个性状大多存在正向中亲优势和负向高亲优势,优势大小在性状间存在较大差异。株高类性状和单株产量性状在杂种F2群体内变异程度高,变异系数均在10%以上,单株产量的变异系数最大(58.65%);籽粒粒型性状在杂种F2群体内的变异程度较低,其变异系数在5%左右,粒长的变异系数最小(4.52%)。降低单株株高,对影响单株产量的性状加强选择,可实现矮秆高产品种的选育。     

淮北地区麦茬机插优质食味粳稻氮肥减量的精确运筹

当前"减氮"成为优质食味粳稻种植措施之一,但减氮后的氮肥科学运筹方案尚不够明确,需进一步研究。2018—2019年,选用优质食味粳稻品种‘南粳505’和‘南粳2728’为材料,前茬麦秸秆全量还田,采用机插方式,在总施氮量较当地常规施氮量减少20%条件下,设置基蘖肥和穗肥比例分别为5∶5、6∶4、7∶3和8∶2四种氮肥运筹比例,研究了淮北地区麦茬机插优质食味粳稻氮肥减量精确运筹。结果表明,随着基蘖肥占总施氮量比例增加,产量呈先增后降趋势, 7∶3处理产量最高, 2年达11,134.80～11,280.19 kg hm–2,较CK增产1.23%～2.54%,但差异不显著; 7∶3处理群体高产,在于能获得充足的群体颖花量、较高的结实率和千粒重。随着基蘖肥比例增加,有效分蘖临界叶龄期、拔节期群体干物质积累量呈增加趋势;抽穗期、成熟期、抽穗至成熟期的干物质积累量、最终氮素积累量及氮素利用率,呈先增后降趋势,均以7∶3处理最高。与常规施氮处理相比,减氮处理通过增加前期施氮肥比例(7∶3),能确保群体后期获得较高的干物质积累量;成熟期氮素积累量较小,但显著提升了氮素吸收利用率,较CK高14.10%～...     

不同机械化栽培方式下控释肥配比对迟熟中粳水稻产量形成及氮素吸收利用的影响

以优质食味粳稻南粳9108为材料,纯氮270 kg hm–2施氮条件下,设置了钵苗机插、毯苗机插2种栽培方式,将控释肥与速效氮肥以5∶5的比例混合,其中控释肥由4种不同释放期(40、80、100、和120 d)肥料按照1∶4的比例混合形成了3种配比方式,分别为40+80、40+100、40+120,同时设置常规分次施肥(CK)为对照,研究不同机械化栽培方式下控释肥配比对迟熟中粳水稻产量形成以及氮素积累的影响。结果表明,相同肥料处理下,钵苗机插2年产量较毯苗机插分别增加了3.9%和4.9%,其原因是钵苗机插能够提高中后期的光合物质积累,获得较大的穗型,具有更高的每穗粒数、结实率以及千粒重。钵苗机插与毯苗机插栽培方式下,40+80和40+100控释肥处理2年产量均高于CK, 40+100控释肥处理产量最高, 2年较CK分别显著增加7.3%和9.2%,其原因在于40+100控释肥处理具有更高的有效穗数和群体颖花量。与40+80和40+120控释肥处理相比,40+100控释肥处理与南粳9108的养分吸收规律更为匹配,即保证了前期分蘖的发生,又保证了后期稳定的光合物质生产,获得稳定的穗数、穗粒数...