施氮对旱地不同抗旱性小麦叶片光合色素含量与荧光特性的影响

在田间试验条件下,研究了不同抗旱性小麦品种全生育期叶片光合色素含量和叶绿素荧光参数的关系及其氮素响应。结果表明,光合色素各组分含量随施氮量增加有明显的升高趋势,品种间差异又因生育时期而不同;施氮显著提高了拔节期实际光化学效率(ФPSⅡ)和光化学猝灭系数(qP)、扬花期和灌浆期的最大光化学效率(Fv/Fm),降低了全生育期非光化学猝灭系数(qN)。提高叶绿素a含量能显著提高叶片ФPSⅡ、Fv/Fm、qP和降低qN;叶绿素b含量的升高能显著增强热耗散,增加类胡萝卜素含量则促进水地品种叶片光能的光合碳同化作用和旱地品种的热耗散。拔节期对照处理的旱地品种的ФPSⅡ和qN显著高于水地品种,在该时期品种抗旱性差异表现较为明显,能够通过提高光合机构实际光化学效率和热耗散来增强光合机构对干旱的适应能力。     

不同氮素形态下小麦叶片光合气体交换参数对蒸汽压亏缺的反应

利用溶液培养试验,研究了不同氮素形态下小麦叶片光合气体交换参数对蒸汽压亏缺(VPD)的反应,以揭示不同氮素形态影响水分利用效率(WUE)的生理机制。结果表明:铵态氮处理显著降低了小麦的叶面积和根长,提高了小麦的瞬时和长期水分利用效率。不同氮素形态下,叶片光合气体交换参数对蒸汽压亏缺的反应不同。随VPD增加,硝态氮处理的净光合速率无变化,但铵态氮和硝酸铵处理的净光合速率则明显下降。所有处理的叶片气孔导度均随VPD增加而下降,其中硝态氮和硝酸铵处理的下降幅度明显高于铵态氮处理。硝态氮和硝酸铵处理的细胞间隙CO2浓度也随VPD增加而下降,但铵态氮处理未发生变化。所有氮处理的蒸腾速率均随VPD增加呈现出二次抛物线变化,叶水势并未随VPD增加发生变化,表明气孔对VPD的反应符合前馈机制。3个处理的瞬时WUE均随VPD增加而下降,高VPD下铵态氮引起小麦叶片气孔的关闭是其WUE提高的重要原因之一。     

氮素水平对甜菜功能叶片光合特性的影响越

采用甜研七号(偏高糖型)和甜研八号(偏丰产型)甜菜作为试材,在5个氮素水平(0、60、120、180和240kg/hm2)下,研究了甜菜功能叶片(第15片真叶)在生育进程中和不同叶龄下的叶绿素含量、光合特性的变化动态及其对块根产量、含糖率及产糖量的影响。结果表明：随着生育进程,叶绿素含量、光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)等光合特性指标均为单峰曲线变化,在叶片完全展开后第21天达到最大值,而后逐渐降低,2个品种均表现为这一趋势。单一叶龄(以21d叶龄为例)在0~120kg/hm2施氮水平下,叶绿素含量、光合速率(Pn)随施氮量增加而增加,过量施氮则增长不显著。在生育进程中,叶绿素含量、光合速率(Pn)同块根产量均表现为极显著正相关。以甜研七号为例,相关系数分别为R=083**和R=093**;同产糖量呈显著正相关,相关系数分别为R=085*、R=086*;蒸腾速率(Tr)、气孔导度(Gs)同产质量的相关性基本与光合速率(Pn)相同,胞间CO2浓度(Ci)则与其他光合特性指标均呈极显著负相关;21d叶龄下,两品种的叶绿素含量、光合速率(Pn)同块根产量均表现为显著正相关或极显著正相关。     

樱桃番茄叶片气孔特征和气体交换过程对NaCl胁迫的响应

为探讨樱桃番茄叶片气孔特征和气体交换过程对盐胁迫的响应机理,通过向营养液中添加NaCl盐,配制成0(对照)、0.05、0.10、0.15、0.20、0.25 mol/L浓度的Na Cl营养液,在人工气候箱条件下对樱桃番茄幼苗进行为期21 d的光照培养。结果表明,不同浓度NaCl溶液对气孔长度、气孔周长、气孔宽度和气孔形状指数均产生显著影响(P0.05),但其最大值均小于对照。随着Na Cl浓度的增加净光合反应速率(Pn)呈明显下降趋势,且在重度Na Cl胁迫(0.25 mol/L)下Pn同其他盐浓度处理的差异均为显著水平(P0.05)。同时,樱桃番茄叶片的蒸腾速率(T_r)、气孔导度(G_s)和细胞间CO_2浓度(C_i)随NaCl浓度的增加而降低,且与对照存在显著差异(P0.05)。另外,NaCl胁迫导致樱桃番茄叶片水平的水分利用效率(water use efficiency,WUE)降低,尤其是重度Na Cl胁迫(0.25 mol/L)的WUE比对照显著降低48%(P0.05)。此外,叶绿素含量随NaCl浓度增加先升高后降低。可见,NaCl胁迫条件下叶片通过调整单个气孔形态(气孔开度大小)和气孔分布特征(气孔密度和空间分布格局)优化气体交换效率,但其在重度盐胁迫下优化气体交换效率的能力却非常有限。研究结果可为樱桃番茄耐盐品种选育和盐碱地丰产增收提供依据。     

四种藤蔓植物幼苗气体交换特性研究

在土培条件下,对地锦(Parthenocissus tricuspidata)、五叶地锦(Parthenocissus quinquefolia)、扶芳藤(Euonymus fortunei)、树莓(Rubus idaeus)等4种藤蔓植物幼苗的生理指标作了测定。结果表明,4种幼苗的净光合速率日进程、蒸腾速率日进程和水分利用效率日进程均呈明显的单峰曲线。净光合速率相比较,扶芳藤>树莓>五叶地锦>地锦;蒸腾速率相比较,树莓>扶芳藤>五叶地锦>地锦。地锦、五叶地锦、扶芳藤、树莓4种幼苗的光饱和点均在1300μmolm-2s-1以上,光补偿点分别为414、15、0和80μmolm-2s-1,CO2补偿点分别为120、152、1251、14μmolmol-1,地锦和五叶地锦CO2饱和点分别为600、800μmolmol-1,扶芳藤和树莓均在1200μmolmol-1以上。4种幼苗的叶绿素含量相比较,树莓>扶芳藤>地锦>五叶地锦,叶绿素a/b值、叶绿素总含量、最大光合速率三者之间没有关联。     

氮素营养对旱作小麦光合特性的调控

水分和氮素营养对小麦光合特性具有明显的调控作用，其中土壤水分状况直接影响到氮素营养的作用强度。氮素营养在不同土壤水分条件下对作物光合的影响不同，表现在叶片气体交换参数值、光合受抑部位及冠层结构等有所不同。在干旱条件下，光合速率主要受制于非气孔因素，此时氮素可加剧对叶绿体光合能力的抑制。作物生产上的施肥与耕作等措施都应适宜于当时的田间水分状况，这样才能充分协调作物与环境的关系，使作物光合机构运转处于较高水平，以实现合理利用水肥资源和增加产量的目的。     

氮素营养对小麦群体光合碳同化作用的影响及其调控机制

小麦春季生育期间,群体光合速率(CPR)的动态变化呈单峰曲线,于孕穗至开花期达到最大值,不同氮素用量处理CPR的峰值大小、峰值出现时间和高值持续期不同。群体单位叶面积光合速率(CPR pa)与氮素用量呈显著负相关,高氮条件下CPR的提高主要起因于其群体叶面积的增大和冠层光截获率的增加。叶面积系数(LAI)随氮素用量增加呈逐渐增大趋势,但高氮处理生育后期LAI的衰减速率较快。CPR与同期及相邻生育时期的LAI呈显著正相关表明,CPR与LAI两者之间存在着相互制约关系。生育中后期 CPR 的日变化呈单峰曲线。不同氮素处理生育期间群体干物质的累积量与CPR的表现相似,CPR与同期及下一时期的群体干物质累积量成显著正相关。供试氮素范围内,整个春季生育阶段的群体叶源量(CKSC)随氮素用量增加呈抛物线型变化,施N 225kg·hm^-2处理群体叶源量最高,与开花期CPR、开花 蜡熟CKSC和同期CPR及LAI衰减速率的表现趋势相同。表明提高生育后期的群体光合速率,延长其高值持续时间,对于增加整个春季生育阶段的群体碳同化量具有重要作用。     

不同氮素形态对茅苍术光合特性和光合氮素利用效率的影响

研究不同氮素形态对茅苍术光合特性和氮素吸收的影响,为其栽培氮肥高效利用提供理论依据。以一年生茅苍术为材料,研究不施氮肥、施用硝态氮、铵态氮和酰胺态氮对茅苍术叶片光响应曲线和光合氮素利用效率的影响。结果表明,施用氮肥可不同程度改善叶片光合特性,其中硝态氮处理的叶绿素含量、表观光量子效率、最大净光合速率,光饱和点、净光合速率、气孔导度、蒸腾速率均最高,但其光补偿点和胞间二氧化碳浓度显著低于铵态氮和酰胺态氮处理。同时,硝态氮处理能显著增大叶面积、降低比叶重,促进植株生长,使得其整株生物量比铵态氮和酰胺态氮处理提高6.89%和17.05%。此外,硝态氮处理还增加叶片氮素含量,提高光合氮素利用效率,分别比铵态氮和酰胺态氮处理提高2.43%和6.76%。可见,茅苍术光合特性对硝态氮更敏感,施用硝态氮肥能改善光能特性,促进氮素高效利用。     

不同灌水处理条件下不同小麦品种氮素积累、分配与转移的差异

利用15N同位素示踪技术,研究了不同灌水处理条件下2个高产小麦品种吸收利用不同来源氮素的差异。结果表明:1)同一灌水条件下,泰山23(T23)植株氮素总积累量、来自肥料氮的量、来自土壤氮的量、肥料氮和土壤氮开花期在营养器官中的总积累量及成熟期在子粒中的积累量均显著高于山农664(S664)。2)泰山23底墒水+拔节水处理(W1)营养器官中积累的肥料氮向子粒的转移量显著高于底墒水+拔节水+开花水处理(W2),土壤氮的转移量W1与W2处理无显著差异;山农664营养器官中积累的肥料氮和土壤氮的转移量均为W2显著高于W1处理。3)泰山23的子粒蛋白质含量、灌溉效益和水分利用效率为W1显著高于W2处理,子粒产量、蛋白质产量和氮素利用效率在W1与W2处理间无显著差异;山农664的子粒产量和蛋白质产量为W2显著高于W1处理,子粒蛋白质含量、氮素利用效率、灌溉效益和水分利用效率在W1与W2处理间无显著差异。从子粒产量、蛋白质含量和氮素与水分利用效率等方面综合分析,W1和W2处理分别是泰山23和山农664高产高效的灌水方式。     

WATER STRESS AND NITROGEN MANAGEMENT EFFECTS ON GAS EXCHANGE,WATER RELATIONS,AND WATER USE EFFICIENCY IN WHEAT

A field experiment was conducted over two years to evaluate the gas exchange, water relations, and water use efficiency (WUE) of wheat under different water stress and nitrogen management practices at Crop Physiology Research Area, University of Agriculture, Faisalabad, Pakistan. Four irrigation regimes and four nitrogen levels, i.e., 0, 50, 100, and 150 kg N ha^?1 were applied in this study. The photosynthetic gas exchange parameters [net carbon dioxide (CO₂) assimilation rate, transpiration rate and stomatal conductance] are remarkably improved by water application and nitrogen (N) nutrition. Plants grown under four irrigation treatments as compared with those grown under one irrigation treatment average stomatal conductance increased from 0.15 to 0.46 μ mol m^?2s^?1mol during 2002–2003 and 0.18 to 0.33 μ mol m^?2s^?1mol during the year 2003–2004 and photosynthetic rate from 9.33 to 13.03 μmol CO₂ m^?2 s^?1 and 3.99 to 7.75 μmol CO₂ m^?2 s^?1 during the year 2002–2003 and 2003–2004, respectively. The exposure of plants to water and nitrogen stress lead to noticeable decrease in leaf water potential, osmotic potential and relative water content. Relative water content (RWC) of stressed plants dropped from 98 to 75% with the decrease in number of irrigation and nitrogen nutrition. The higher leaf water potential, and relative water contents were associated with higher photosynthetic rate. Water use efficiency (WUE) reduced with increasing number of irrigations and increased with increasing applied nitrogen at all irrigation levels.     

氮肥管理对小麦产量和氮肥利用效率的影响

氮肥过量施用造成环境污染和生产成本增加等问题已成为限制我国农业可持续生产的主要因素。为实现氮素化肥的高效利用,连续2年在山东省农业科学院作物研究所试验地同一地块利用氮肥梯度带,进行了基于小麦叶片SPAD值的氮素实时管理。结果表明,在基施区随着施肥量的增加,小麦籽粒产量增加,二者呈线性关系,但施氮量207kg/hm2(N207)和276kg/hm2(N276)处理间差异不显著;追施区小麦的2个生长季籽粒产量均以不施基肥拔节期追氮207kg/hm2(N0+207)处理最高,分别为7649kg/hm2和7522kg/hm2,基施氮肥207kg/hm2拔节期不追肥(N207+0)处理最低,仅为7318kg/hm2和7388kg/hm2,差异达显著水平(P<0.05)。基施区各氮肥处理的氮肥表观利用率(RE)和氮肥偏生产力(PFP)均存在显著性差异,均是随着基施量的增加而显著降低。追施区N0+207、N69+138、N138+693个处理的PFP、AE和RE均高于或显著高于N207和N276 2个处理。因此在确定总施氮量的条件下实行基、追肥分施能够显著提高小麦的氮肥表观利用率、氮肥农学效率和氮肥偏生产力。     

ENHANCING NITROGEN USE EFFICIENCY BY COMBINATIONS OF NITROGEN APPLICATION AMOUNT AND TIME IN WHEAT

Nitrogen (N) is one of the most important impact factors on development and growth of wheat. In this study the effects of nitrogen use efficiency on quantity and quality of grains were studied by agronomic management of N fertilizers on spring wheat (Triticum aestivum L.) grown under field conditions for two years. The experiments were performed at 16 combinations of N application amount and time, including four levels of N at 0, 60, 120 and 180 kg N ha^?1 that were used as pre-plant fertilizers, sub-treated with four levels of the same N amount used as top-dress fertilizers. As a result, with an increase in total N fertilizers, grain yield increased in a cubic equitation, but partial factor productivity (PFP_N, kg grain yield per kg N applied) decreased exponentially. With total fertilizers, N content and accumulation in vegetative tissues and grains increased linearly, but N uptake efficiency (UtE_N, kg nutrient taken up per kg N applied) decreased exponentially. When N was over-applied (>360 kg N ha^?1 in this study), grain yield clearly declined, due to decrease in productivity from per unit N. The high N level (240～300 kg N ha^?1), the reasonable distribution between pre-plant and top dress from the same amount N fertilizer not only increased grain yield but also enhanced N use efficiency.     

EFFICIENCY OF PRE-PLANT,TOPDRESS, AND VARIABLE RATE APPLICATION OF NITROGEN IN WINTER WHEAT

Past research about the efficiency of nitrogen application in winter wheat (Triticum aestivum L.) based on source and timing has produced inconsistent results. The majority of the literature used data from few locations over short time periods. This study used a unique data set of yields and nitrogen quantities from 2002–2009 at ten different locations in Oklahoma, USA. The objective of this research was to determine wheat yield response for granular pre-plant, uniform foliar topdress, and variable rate foliar topdress. Topdress liquid nitrogen had a 19% higher NUE than pre-plant urea, and was the most profitable source of nitrogen.     

COURSE OF DRY MATTER AND NITROGEN ACCUMULATION OF SPRING WHEAT GENOTYPES KNOWN TO VARY IN PARAMETERS OF NITROGEN USE EFFICIENCY

Field experiments were conducted for two years to compare and identify bread spring wheat (Triticum aestivum L.) genotypes which make the most efficient use of nitrogen (N). Such information is required for breeding strategies to reverse the negative relationship between yield and protein content. Three Swiss spring wheat cultivars (‘Albis’, ‘Toronit’, ‘Pizol’) and an experimental line (‘L94491’) were grown without (N0; 0 kg N ha^?1) and with high fertilizer N [(NH₄NO₃); (N1; 250 kg N ha^?1) supply on a clay loam soil with low organic matter content. Biomass and nitrogen accumulation in biomass as well as the leaf growth and senescence patterns (SPAD) were investigated in an attempt to explain the physiology of growth and N translocation of these genotypes. The pre-anthesis accumulation of biomass and N in the biomass depended on genotype only at N1 in 2000. In this year, conditions were less favorable for the pre-anthesis accumulation of biomass and N, which was, on average, 10 and 20% lower, respectively, of the total than in 1999. The contribution of pre-anthesis assimilates to the grain yield (CPAY) was higher in 1999 for all genotypes (36.9%) compared to 2000 (13.5%) except ‘Toronit’. Between anthesis and maturity the climate influenced the genetic variability of some N use efficiency components: N translocation efficiency (NTE) and dry matter translocation efficiency (DMTE). NTE was higher in 1999 (68.1%) compared to 2000 (50.7%); 1999 was a year in which the post-anthesis period was drier and warmer than usual. ‘Toronit’ produced the highest biomass by maturity due mainly to greater and longer lasting green leaf area after anthesis. ‘Albis’ performed relatively well under low input conditions, with considerable amounts of N being re-translocated to the seeds at maturity (NHI), whereas ‘Pizol’ accumulated in grains N as high as for ‘L94491’. In a humid temperate climate breeding for greater N uptake and partitioning efficiency may be a promising way to minimize N losses and produce high phytomass and grain yields. Using high protein lines as selection material and combining them with high biomass genotypes may lead to high protein contents without decreasing yield.     

施氮量对间作玉米土壤硝态氮累积量及氮肥利用率的影响

通过田间定位试验,监测了不施氮和不同施氮水平(分别为210、420和630kg.hm-2)下间作玉米各关键生育时期0～200cm土层硝态氮累积量的动态变化、玉米产量及其构成,计算分析了间作玉米的氮肥利用率。研究结果表明,间作玉米0～200cm土层土壤硝态氮累积量总体表现为0～60cm土层>60～200cm土层。0～60cm土层土壤硝态氮累积量呈"M"形变化,即玉米播种前和玉米大喇叭口期出现高峰,小麦播种前、玉米拔节期和玉米收获后出现低谷。60～120cm和120～200cm土层土壤硝态氮累积量呈倒"V"形变化,总体在玉米大喇叭口期前后出现高峰值,210～630kg.hm-2施氮处理下120～200cm土层的硝态氮累积量较不施氮处理分别高出149.1%、115.6%和126.3%。随着施氮量的增加,间作玉米穗长、穗粒数、穗重呈增大趋势,秃顶呈降低趋势,增产幅度依次减小,氮肥利用率依次降低。     

不同产量水平小麦的氮吸收利用差异

在土培盆栽条件下,以130份小麦为材料,测定了不同生育时期小麦的干物质量、氮素含量和籽粒产量,将供试品种按籽粒产量由低到高低依次分为I、II、III、IV、V、VI等6类型,研究了各类型氮素吸收利用的差异。结果表明：（1）供试品种籽粒产量差异较大（CV=3316%）,氮素籽粒生产效率随籽粒产量水平提高呈增加的趋势(r=02740**),提高氮素吸收量和籽粒氮素利用效率均可提高籽粒产量。（2）不同生育时期,不同籽粒产量水平类型小麦植株含氮量存在显著或极显著差异,但与籽粒产量的相关性不密切。抽穗期和成熟期植株吸氮量与籽粒产量极显著相关(r=02890**、09175**)。（3）不同生育时期氮素干物质生产效率在类型间的差异均达到显著水平,但其与籽粒产量相关性不显著。提高氮素收获指数和拔节期氮素干物质生产效率均可提高籽粒产量。（4）拔节期-成熟期不同类型间小麦干物质量随籽粒产量的增加而增加,成熟期表现尤为突出。籽粒产量水平较高的品种在拔节期后有较强干物质和籽粒产量形成能力。（5）氮素吸收量和氮素籽粒生产效率是影响籽粒产量的重要因素。     

LEAF PHOTOSYNTHESIS,BIOMASS PRODUCTION AND WATER AND NITROGEN USE EFFICIENCIES OF TWO CONTRASTING NAKED VS. HULLED OAT GENOTYPES SUBJECTED TO WATER AND NITROGEN STRESSES

Water and nitrogen (N) are the two most important factors influencing the growth and yield of oat (Avena sativa). A pot culture study was conducted to determine the physiological and biomass production of contrasting oat genotypes to water and N supply conditions. With sufficient water, biomass yield of the naked ‘Shadow’ was 12.4% and 10.0% greater than ‘Bia’ in the treatments 750 and 1250 mg N pot^?1, respectively, but ‘Bia’ produced greater grain yield than ‘Shadow’. Under severe water stress conditions, increasing N supply decreased P_N mainly due to the reduction of g_s and E. ‘Shadow’ had higher chlorophyll and leaf N than ‘Bia’, while there were no differences in plant total N, NuptE and NUE. With increasing N application and water stress, WUE_L and WUE_P both increased. NUE was inversely related with increasing N rates and water stress levels, resulting in a trade-off relationship between WUE_P and NUE.