高寒半干旱区水肥耦合对西芹收获期硝酸盐效应研究

为了探讨西芹水肥耦合作用,采用三因素(氮、磷和水)五水平(因子水平为-1.682、-1,0,1,1.682)二次通用旋转组合设计,在冀西北高寒半干旱区开展了水肥耦合对西芹硝酸盐效应的旱棚试验研究。结果表明,在该试验条件下水分对硝酸盐降低的作用最大,磷肥次之,氮肥最小;从卫生学角度考虑水肥耦合的硝酸盐效应最佳顺序依次为:中水中肥效应最佳,高水高肥次之,低水低肥较差;水肥交互耦合效应大小顺序是磷水耦合>氮水耦合>氮磷耦合。在西芹水肥管理方案中,硝酸盐不同取值区间内三因子的变化范围均相同,体现了因子间相互替代效应。从卫生学角度考虑,以中水中肥为宜。     

不同水肥耦合对西芹收获期土壤硝酸盐累积的影响

采用三因素五水平二次通用旋转组合设计,研究了冀西北高寒半干旱区不同水肥耦合对旱棚西芹收获期0 ～ 40 cm土层中硝酸盐累积的影响.结果表明:①在高中低不同水肥处理组合中,较高肥在较高水下可减少0 ～ 40 cm土层土壤硝酸盐的累积,较高肥在较低水下可使土壤硝酸盐相对累积增多;综合因子效应分析表明:随着单因子水平增加,N、P和水(W)对0 ～ 40 cm土层土壤硝酸盐的相对累积依次表现为:增加、不明显和减少.②三因子其他组合下,0 ～ 40 cm土层土壤硝酸盐的累积效应表现为: 在PW一致下,随N量的增加而增加;在NP一致下,随灌水量增加而减少;在NW一致下,随施P量增加而有不确定性.各处理硝酸盐的累积均随土壤深度的增加而增加,体现了水对土壤硝酸盐淋洗的特点.     

水肥(氮)条件对小麦产量综合效应研究

通过水、肥(氮)条件对小麦产量综合效应研究,综合评价作物产量、氮肥利用率、水分利用率和经济效益。从最佳水肥投入产出的经济效益分析来看,在所有各水肥组合处理中,以W3N3经济效益最高,其次为W3N2,再次为W4N3。因此在土壤含水量控制为22%,施氮量为12kg/亩,生育期灌水312mm/亩时,才能获得最佳的经济效益。     

玉米拔节期水肥耦合效应研究

采用正交设计玉米拔节期水肥耦合试验表明,不同水肥条件下水分是玉米生长发育的决定性因素.对玉米拔节期株高的影响,水分和钾均达到了极显著水平,且水分的影响大于钾,氮和磷影响不显著.土壤持水量对玉米拔节期单株叶面积的影响达到极显著的水平,氮和钾均达到显著水平,磷的影响不显著.磷对根长有显著的影响,对根重的影响不显著.水分、氮、钾对玉米拔节期生物量的影响为正效应,磷为负效应.玉米拔节期的灌水利用率表现为,低水高肥达到最大,高水控制条件下玉米拔节期的灌水利用率均低于低水和中水.其中处理3(W1N3P3K3)的灌水利用率达到最大,处理7(W3W1P3K2)的灌水利用率最低.     

水分胁迫条件下不同氮磷组合对小麦产量的影响

研究了在水分胁迫的条件下不同氮、磷组合对小麦生长发育的影响。结果表明 ,在 10.8%～ 14.4 %水分含量范围内 ,不同施肥处理的株高、小麦茎分蘖数、叶面积指数、成穗率以及小麦的子粒产量与生物产量均随水分含量的增加而增加。当水分含量为 10.8%和 12.5 %时 ,N1P1生物产量与子粒产量表现最高 ;水分含量为 14 .4 %时 ,N1P2处理的生物产与子粒产量最高。在所有施肥处理中 ,高氮高磷的处理均未表现出生物学效应的优势 ;低氮低磷组合和低氮高磷组合有利于小麦产量和其他产量因素的提高 ,在一定程度上提高了小麦的抗旱性。     

根系分区交替灌溉条件下番茄果实硝酸盐含量的水肥耦合效应研究

为了解根系分区交替灌溉条件下灌水量和氮、磷、钾肥用量对番茄果实中硝酸盐含量的影响，通过盆栽试验，采用四元二次回归正交旋转组合设计，建立了硝酸盐含量与水肥因子的数学模型，并对各单一因素的效应及两两因素的耦合效应进行了分析。结果表明，在其他因子为0水平时，番茄果实中的硝酸盐含量，随灌水量、施磷量的增加均呈先增加后降低的变化趋势；随施钾量的增加呈先降低后增加的变化趋势；但不随施氮量而变化。灌水量与施氮量、施磷量与施钾量的交互作用均表现为阻碍番茄果实硝酸盐的积累。根系分区交替灌溉条件下，适当提高灌水量和施磷量,或者减少施钾量能有效地降低番茄果实的硝酸盐含量。     

氮肥不同用量及基追肥比例对芹菜产量和品质的影响

通过盆栽试验研究氮肥不同用量和基追比例对芹菜的产量效应和品质效应。本试验条件下,施氮量为150mg/kg土时(约相当于337.5 kg/hm2)芹菜产量最高,继续增施氮肥,产量显著降低。施氮量为100 mg/kg土时(约相当于225 kg/hm2),Vc含量和可溶性糖含量最高,施氮量增加,芹菜品质显著降低。芹菜叶绿素、硝酸还原酶活性和硝酸盐含量与氮肥用量呈极显著的线性正相关。不同氮肥用量处理的芹菜在不同生育期的硝酸盐积累量均呈明显的“S”曲线。基肥N占100%时,芹菜的生长情况最好,基肥N占50%时,芹菜的叶绿素含量,硝酸还原酶活性,Vc和可溶性糖含量均最大。追施一次肥处理的芹菜叶片硝酸盐含量显著低于追两次肥的处理。     

氮肥不同用量及基追肥比例对芹菜产量和品质的影响

通过盆栽试验研究氮肥不同用量和基追比例对芹菜的产量效应和品质效应。本试验条件下，施氮量为150mg／kg土时（约相当于337．5kg／hm^2）芹菜产量最高，继续增施氮肥，产量显著降低。施氮量为100mg／kg土时（约相当于225kg／hm^2），Vc含量和可溶性糖含量最高，施氮量增加，芹菜品质显著降低。芹菜叶绿素、硝酸还原酶活性和硝酸盐含量与氮肥用量呈极显著的线性正相关。不同氮肥用量处理的芹菜在不同生育期的硝酸盐积累量均呈明显的“S”曲线。基肥N占100％时，芹菜的生长情况最好，基肥N占50％时，芹菜的叶绿素含量，硝酸还原酶活性，Vc和可溶性糖含量均最大。追施一次肥处理的芹菜叶片硝酸盐含量显著低于追两次肥的处理。     

水氮协同对玉米光合特性及产量的影响

探求引黄灌区在水肥协同条件下影响玉米光合特性及产量构成的机理，为满足旱区作物优质高产提供理论依据。在2019—2020年开展大田试验，采用2因素裂区试验设计，主区为施氮量，分别为减氮30％(N0)、常规施氮(N1)；副区为滴灌量，分别为减少滴灌量30％(W0)、常规滴灌量(W1)和增加滴灌量30％(W2)，分析玉米关键生育时期光合特性和产量。结果表明:施氮量和滴灌量对叶片叶绿素相对含量(SPAD)、净光合速率(Pn)、光系统Ⅱ(PSⅡ)中P680反应中心吸收光能的大小(ABS/RC)、PSⅡ中最大光化学效率(Fv/Fm)、捕获光能与热耗散能量的比值(Fv/F0)、荧光参数(PI)、产量和产量构成因素影响显著。2年最高平均产量为N0W2处理。同一施氮量不同滴灌量下叶片SPAD值、净光合速率差异显著，且随着滴灌量的增加而增加，但N0W2与N1W2差异不显著。2年不同水氮处理下叶面积指数(LAI)随着生育进程推进呈先增后降趋势，在抽雄期达到最大值。Fv/Fm、Fv/F0、ABS/RC、PI随生育期推进呈先增后降趋势，滴灌量对其影响效应大于施氮量；各荧光参数在同一施氮量下随着滴灌量的增加而增加，在滴灌量W2下N0处理生育后期Fv/Fm、ABS/RC、PI与N1处理差异不显著，Fv/F0显著低于N1处理，说明适当施氮在保持捕获光能的同时可以增加热耗散，降低高温对叶片的损害。在宁夏引黄灌区采用水肥一体化模式配合水氮处理(全生育期施氮量292 kg/hm²和滴灌量4290 m3/hm²)，能够提高玉米产量和氮肥利用率，为当地玉米高产优质高效栽培以及水肥高效利用提供理论支撑和技术指导。     

不同施肥水平下粉葛氮磷钾吸收及干物质积累的特征

为探明赤红壤区粉葛生长发育中氮、磷、钾及干物质吸收积累的规律,采用“3414”随机区组设计,研 究不同施肥水平下粉葛关键生育期各器官的养分吸收积累特征。结果表明,粉葛氮、磷、钾积累量均在块根形成 至膨大阶段增幅最大,积累曲线呈近似“S 型”,其吸收能力为钾 > 氮 > 磷。不同施氮水平下,块根含氮量在苗 期和块根膨大期的氮肥调控效应较为明显,茎氮含量虽比对照显著提高,但施氮处理间无显著差异,各生育期氮 含量表现为叶 > 块根、茎,成熟期减量施氮(N1)处理的氮素积累量最大,为 19.91 g/ 株。不同施磷水平下,块 根形成及膨大期的块根磷含量、块根形成期的茎磷含量、成熟期的叶磷含量较对照显著提高,而其他生育期的磷 肥调控效应不明显,块根膨大期正常施磷(P2)处理的磷素积累达到了最高峰,为 2.04 g/ 株。不同施钾水平下, 块根形成以后 K2、K1 处理提高各器官含钾量的幅度要大于 K3、K0 处理,K3 处理甚至降低了成熟期块根含钾 量,钾积累量表现为 K2>K1>K0>K3>CK 处理,成熟期各处理钾积累存在较大差异。从苗期到成熟期,块根干物 质的量不断上升,而地上部分干物质的量表现先上后下的积累特征,随着生育期的推进,各处理均显示块根干物 质量的占比逐渐加大,成熟期块根占 68.54% ～ 78.56%,地上部分占 21.44% ～ 31.46%。不同施肥水平中,以减 量施氮(N1P2K2)处理的块根干物质分配最高,占 80.12%。     

Combined Effects of Water and Nitrogen on Growth,Biomass, and Quality of Spinach (Spinacia oleracea Linn.)

Water scarcity and nitrate contamination have caused considerable attention to environmental matters. Water and nitrogen interactions have critical impacts on their use efficiency, plant growth, and quality. In a field experiment, a combination of three water treatments and three nitrogen rates was applied to determine their interactive effects on the growth of spinach. Soil water supply that was too low [W₃N₁ (the combination of water treatment 3 and nitrogen treatment 1), W₃N₂] could cause an increase in nitrate content. Oxalate contents would increase when water and nitrogen were either inadequate (W₃N₀, W₃N₁) or too high (W₂N₂). The most profit from spinach was obtained in plots that received water treatment 2 and nitrogen fertilizer 78 kg N ha^?1. However, considering nitrogen treatments could affect the nitrate and oxalic acid, application of water treatment 2 and 39 kg N ha^?1 nitrogen fertilizer could get better spinach quality.     

Response of cotton root growth and yield to root restriction under various water and nitrogen regimes

Water and nitrogen (N) are two major factors limiting cotton growth and yield. The ability of plants to absorb water and nutrients is closely related to the size of the root system and the rooting space. Better understanding of the physiological mechanisms by which cotton (Gossypium hirsutum L.) adapts to water and N supply when rooting volume is restricted would be useful for improving cotton yield. In this study, cotton was grown in soil columns to control rooting depth to either 60 cm (root‐restriction treatment) or 120 cm (no‐root‐restriction treatment). Four water–N combinations were applied to the plants: (1) deficit irrigation and no N fertilizer (W₀N₀), (2) deficit irrigation and moderate N fertilizer rate (W₀N₁), (3) moderate irrigation and no N fertilizer (W₁N₀), and (4) moderate irrigation and moderate N fertilizer rate (W₁N₁). Results revealed that root restriction reduced root length density (RLD), root volume density (RVD), root mass density (RMD), superoxide dismutase (SOD) activity, nitrate reductase (NR) activity, total plant biomass, and root : shoot ratio. In contrast, root restriction increased aboveground biomass and yield. The RLD, RVD, RMD, and root : shoot ratio decreased in the order W₀N₀ > W₁N₀ > W₀N₁ > W₁N₁ in both the root‐restriction and no‐root‐restriction treatments. However, the opposite order (i.e., W₁N₁ > W₀N₁ > W₁N₀ > W₀N₀) was observed for SOD activity, NR activity, aboveground biomass, and seed yield. Our results suggest that, when N and water supplies are adequate, root restriction increases both root activity and the availability of photosynthates to aboveground plant parts. This increases shoot growth, the shoot : root ratio, and yield.     

时空亏缺调控灌溉和施氮处理对番茄水氮利用的影响

为探索节水灌溉条件下蔬菜的水肥高效利用模式, 采用番茄盆栽试验, 以常规充分灌水为对照, 研究了时空亏缺调控灌溉和氮肥处理对番茄营养器官干物质累积、灌溉水分利用效率、氮素累积及土壤水氮分布的影响。在交替灌溉条件下, 设置控水时期、灌水水平和施氮水平3因素, 控水时期分别为开花座果期和结果期, 2个灌水水平分别为高水和低水, 3个施氮水平分别为高氮、低氮和无氮, 并以常规灌溉作为对照。结果表明: 与常规充分灌水处理相比, 交替灌溉持续高水处理、交替灌溉开花座果期低水处理、交替灌溉结果期低水处理及交替灌溉持续低水处理分别降低干物质累积总量4.52%、11.93%、17.76%和23.94%, 分别降低氮素累积总量1.74%、12.86%、15.50%和22.47%, 分别降低氮素干物质生产效率2.24%、3.93%、2.55%和0.89%, 而分别增加灌溉水分利用效率12.39%、8.99%、15.02%和12.96%。在交替灌溉条件下, 中氮处理的干物质累积、灌溉水分利用效率和氮素累积总量最大。与低氮处理相比, 中氮和高氮处理的氮素干物质生产效率分别降低6.87%~12.70%和17.81%~24.38%, 土壤硝态氮分别提高31.64%~159.58%和57.37%~297.37%。综合考虑干物质累积、水分利用及氮素累积等因素, 番茄适宜的水氮供给模式为交替灌溉持续高水中氮处理: 灌水定额为80%W₀(W₀为常规充分灌溉的灌水定额, 保持土壤含水量为田间持水量的70%~85%), 施氮量为0.30 g(N)·kg^-1(干土)。     

有机无机肥料配合施用对设施菜田土壤N2O排放的影响

采用静态箱气相色谱法研究了有机无机肥料配合施用对设施菜田土壤N2O排放的影响。结果表明: 1）设施芹菜和番茄施基肥后57 d（灌溉后13 d）出现土壤N2O排放通量峰值,追肥后（施肥与灌溉同步）1 d出现土壤N2O排放通量峰值; 芹菜季和番茄季施用基肥后20 d内N2O排放量分别占当季总排放量的40%65%左右,是土壤N2O主要排放期。2）施用基肥后至定植灌水前各处理土壤N2O排放量逐渐降低,灌水后N2O排放通量迅速上升。各处理土壤N2O排放通量与土壤含水量之间呈显著相关,相关系数在0.43~0.72之间。3）土壤N2O排放主要发生在番茄季,番茄生育期各处理土壤N2O总排放量是芹菜生育期的3.1倍; 各处理土壤N2O排放通量与5 cm土层温度之间总体上呈显著相关,相关系数在0.40~0.58之间。4）设施菜田大幅减施化肥的有机无机肥配合施用模式可显著降低土壤N2O排放量和肥料损失率,芹菜季和番茄季土壤N2O排放量较习惯施肥处理分别降低66.3%和85.1%,肥料损失率分别降低45.2%和74.9%。5）等氮量投入时,施用秸秆较施用猪粪可有效降低土壤N2O排放,芹菜季和番茄季分别降低43.4%和74.2%。     

灌溉模式和有机肥配施对水稻产量、光合特性和氮肥利用率的影响

针对湘北地区农业水资源日益紧缺和水稻生产上滥施化学氮肥的现状，为了节约淡水资源、降低化肥用量、实现水肥协同和资源高效利用，设置2种灌溉方式(W₁：全生育期淹水灌溉；W₂：全生育期湿润灌溉)和4个施氮水平(N₀：不施氮肥；N₁：施N量150 kg/hm²，肥料为尿素氮100%；N₂：施N量150 kg/hm²，肥料为尿素氮80%+有机氮(菜枯)20%；N₃：施N量150 kg/hm²，肥料为尿素氮60%+有机氮(菜枯)40%)，分析水稻产量、光合特性、氮素代谢和氮肥利用率对灌溉模式和有机肥配施的响应规律。结果表明：与W₁相比，W₂显著增加水稻产量、氮肥利用率、净光合速率、蒸腾速率、气孔导度等；在不同施氮处理下，增加有机肥比例能显著提高产量，N₃、N₂、N₁分别比N₀增产28.32%、25.52%、18.88%，同时氮肥吸收利用率、氮肥农学利用率和氮肥偏生产力也表现为N₃>N₂>N₁，N₃的氮肥吸收利用率、氮肥农学利用率、氮肥偏生产力分别达到了78.52%、9.77 kg/kg、46.91 kg/kg。综合评分法表明，灌溉模式和有机肥配施的最佳模式为W₂N₃，即湿润灌溉、施N量150 kg/hm²、肥料为尿素氮60%+有机氮(菜枯)40% 组合。该研究结果可为湘北地区水稻水肥管理提供科学依据。     

Effects of different water regimes and nitrogen application strategies on grain filling characteristics and grain yield in hybrid rice

In order to optimize N application and understand how the different combinations of water and N management affect grain filling characteristics and yield, we designed three irrigation regimes (W₁ submerged irrigation, W₂ alternate irrigation, W₃ dry cultivation), and different N application strategies at 180 kg ha^?1 in 2010 and 2011. The relationship between grain filling characteristics and grain yield formation were respectively investigated. The results revealed that there were obvious interacting effects of irrigation regime and N application strategies on grain yield and grain-filling characteristics as well. Compared with W₁ and W₃ treatments, under W₂, the N-fertilizer should account for 30% base, 30% tillering, and 40% panicle fertilizer with the last being applied equally at 4th and 2nd leaves emerged from the top. Correlation analysis revealed that grain filling rate during middle grain-filling stage was the largest and contribute more than 50% to grain-filling. Grain yield was significantly related to grain filling rate (G_max or G_mean), final weight of a kernel (A), and mean grain filling rate (MGR) of the early, mid and late stages during grain filling in inferior spikelets, which is the important reason for water and N coupling effect further to increase yield and fertilizer use efficiency.     

BIOMASS ALLOCATION AND NITROGEN DISTRIBUTION IN RYEGRASS UNDER WATER AND NITROGEN SUPPLIES

Ryegrass (Lolium perenne L.) in grassland is known to sustain with water and nitrogen (N). This study investigates biomass and N partitioning in plant organs (roots, main and the youngest tillers) under water-nitrogen interactions. Nitrogen was applied at the rates of 50 and 100 mg N kg^?1 as N₁ (low N) and N₂ (high N) treatments, respectively, with uniform irrigation until 440 growing degree-days (GDD). Thereafter, the water supply was restricted to 50 mL on a weekly basis (W₁) against 50 mL on a daily basis (W₂) and concurrently, N enriched with 1 atom% ¹⁵N isotopes. Cumulative tillers’ biomass increased linearly from 1st to 8th order, but thereafter reached a plateau with further increases in number of negligible weights. Initially tiller mass and number per plan did not differ (P < 0.05) with water and/or N applications but changed at 788 GDD with clear differences at 911 GDD with the highest under N₂W₂ and lowest under N₁W₁. Nitrogen concentration sharply decreased from 530 to 700 GDD and then levelled off with age. The decline was more pronounced in tillers than roots. The high N treatment showed elevated N-concentration under both water treatments. Watering on a daily basis promoted vegetative growth. High water and N levels significantly (P < 0.05) influenced concentration of N absorbed during ¹⁵N labeling (N_L) in all organs with relatively pronounced N_L under N₂. The additive positive effect of W₂ and N₂ was obvious on N_L as compared to N_T, which showed that plants discriminate N-uptake on mass basis. Nitrogen (mobile) was higher in young and ¹⁵N (heavier) was low in young tillers and vice versa. Accumulation of N absorbed during ¹⁵N labeling (¹⁵N_A) was significant knowing that water is a strong determining factor of N concentration in ryegrass organs.     

水氮耦合对绿洲灌区土壤硝态氮运移及甜瓜氮素吸收的影响

在地处沙漠绿洲的甜瓜种植区,研究不同水、 氮输入量对土壤氮素平衡和运移的影响,为当地甜瓜生产的水肥管理提供科学依据。通过2009、 2010连续两年田间裂区试验,研究了不同灌水量（1500、 2100、 2700、 3300 m3/hm2,以W1500、 W2100、 W2700和W3300表示）和施氮量（N 0、 120、 240、 360 kg/hm2,以N0、 N120、 N240和N360表示）对土壤硝态氮分布、 累积和甜瓜的水、 氮吸收以及产量的影响。结果表明,甜瓜收获后各处理土壤硝态氮含量在040 cm土层最高, 0200 cm土层呈现先减少后增加再减少的变化趋势,且施氮量越大,硝态氮在80120 cm土层大量累积的趋势越明显。土壤硝态氮累积量随施氮量的增加而增加,随灌水量的增加而减少,灌水量超过2700 m3/hm2 时,仅有不到53%的硝态氮留存在0100 cm土层。甜瓜产量和果实氮素吸收量随灌水量和施氮量的增加而提高,但在W3300N360处理略有下降。氮素回收率随施氮量的增加持续降低,氮收获指数以处理W2700N240最大,水分利用效率以W1500N240处理最大。W2700N240处理能够兼顾甜瓜产量,平衡氮素吸收运移与土壤中硝态氮的留存空间3个方面,是绿洲灌区甜瓜种植的高产高效的水氮输入模式。     

Assessing the effects of urea and nano-nitrogen chelate fertilizers on sugarcane yield and dynamic of nitrate in soil

ABSTRACT

The aim of this study was to evaluate the effect of urea and Nano-Nitrogen Chelate (NNC) fertilizers on yield of sugarcane (Saccharum Officinarum) and nitrate leaching from soil. The treatments included urea (U) and NNC at five levels of nitrogen (0, 80, 112, 137 and 161 kg N ha^?1). This experiment was carried out during 2017 and 2018 in Khuzestan province, Iran. The results showed that the average of soil nitrate concentration during the sugarcane growth period in urea and NNC treatments were 10.2 and 12.8 mg kg^?1 respectively. The highest and lowest nitrate leaching (699.0 mg l^?1 and 183.0 mg l^?1) belongs to the highest level of urea fertilizer and the lowest level of NNC. In urea treatments, the lowest amount of nitrate was observed in the topsoil (0-30 cm depth) whereas in NNC fertilizer maximum value was achieved in topsoil. The height of sugarcane stem in both fertilizers increased with increasing rate of fertilizer, but there was no significant difference between two types of fertilizer. Yield of sugarcane (fresh weight of stem) increased significantly by increasing of fertilizer application, but there was no significant difference between two types of fertilizer. In terms of sugar content, there was a significant difference between treatments. The order of nitrogen use efficiency (NUE) for stems and sugar yield from high to low was as NUE (fresh stem): U₁ > N₁ > N₃ ≥ U₃ ~ U₂ > N₄ ~ U₄ > N₂ and for NUE (sugar): N₁ > U₁ > N₃ ≥ N₂ > U₂ ~ N₄ ≥ U₃ > U₄. This study showed that application of nano nitrogen fertilizer (NNC) had significant effects on reducing nitrate leaching and increasing sugar production in sugarcane. However, when nitrate leaching and its effects on human health and the environment are in view, nano fertilizers are valuable.     

模拟降水和氮沉降对准噶尔盆地南缘梭梭光合生理的影响

氮沉降和降水格局变化是目前全球气候变化背景备受关注的热点研究课题,也是荒漠生态系统的两个主要限制因子。因此,研究两者对荒漠植物的效应有助于深入了解荒漠生态系统对全球变化的响应。本文选择准噶尔盆地南缘荒漠地区的建群种梭梭(Haloxylon ammodendron)作为研究对象,设置自然降水(W0)与增加降水30%(W1)两个水分条件和自然氮沉降(N0)、增加氮素30 kg(N)·hm~(-2)·a~(-1)(N1)与增加氮素60kg(N)·hm~(-2)·a~(-1)(N2)3个施氮水平,连续处理2年,以探究降水、氮沉降及其交互作用对梭梭光合日变化及生理生态特征的影响。结果表明:降水、氮沉降及其交互作用对梭梭的净光合速率(Pn)日变化产生极显著正相关影响;同时根据梭梭Pn、胞间CO2浓度(Ci)及气孔限制值(Ls)的变化方向,推测梭梭光合"午休"主要由非气孔因素引起。此外,W0条件下,梭梭丙二醛(MDA)含量、抗氧化酶(POD、CAT、SOD)活性、可溶性蛋白(Pr)和可溶性糖(SS)含量均随施氮量增加而显著降低,脯氨酸(Pro)含量则呈先降低后增加的趋势;而W1条件下,梭梭MDA含量、抗氧化酶(POD、CAT、SOD)活性及渗透调节物质(Pro、Pr、SS)含量均随施氮量增加呈显著先增加后降低的趋势。两种水分条件下,除W1N1处理梭梭的Pro含量高于对照组外,其余处理均显著低于对照组;同时梭梭的MDA含量、抗氧化酶活性、Pr及SS含量也均显著低于对照组。综合分析结果表明:降水、增氮及其交互作用均有利于梭梭的生长,但其交互作用效应的强弱则取决于二者间的比例。