Advances in Research on Water and Fertilizer Coupling and Its Effects on Rice Growth and Utilization Rate of Nitrogen

At present, the shortage of agricuItural water resources is worsening. In order to reduce the rice irrigation water and improve the utiIization of fertiIizers so as to achieve the high and stabIe yielding of rice, this report reviewed the research advances in water and fertiIizer coupIing, the conception of water and fertiIizer cou-pIing and its three kinds of effects （synergy, antagonism, superposition）, mechanism of water and fertiIizer coupIing, effects of water and fertiIizer coupIing on growth, deveIopment, yield and quality of rice and effects of water and fertiIizer coupIing on utiIization rate of nitrogen in rice. In addition, the deveIopment prospects of water and fertiIizer coupIing in China were described. It was proposed that the water and fertiIizer coupIing mode is an effective measure to achieve the high yield and quality of rice. According to actual demand, referring to the ideas of promoting fertiIizer with water and reguIating water with fertiIizer, reasonabIe water and fertiIizer cou-pIing mode can be estabIished, thereby improving the utiIization efficiencies of water and fertiIizer. In the premise of saving irrigation water and no increasing fertiIization amount, both high yielding and Iess poI ution can be achieved, providing theoretical and technical basis for water-saving agricuIture and cuItivation and management of rice in future.

Effects of the Spatial Coupling of Water and Fertilizer on the Chlorophyll Fluorescence Parameters of Winter Wheat Leaves

Wheat is an important agricultural crop in the Loess region of China, where there is drought stress and low availability of soil nitrogen and phosphorus. Using a pulse modulation fluorometer, we studied the effects of water, nitrogen, and phosphorus on the kinetic parameters of chlorophyll fluorescence in winter wheat. The wheat was grown in layered columns of Eum-Orthic Anthrosol （Cinnamon soil）, with the water content and nutrient composition of each layer controlled. The results showed that the kinetic parameters of chlorophyll fluorescence were sensitive to water stress. The basic fluorescence （F0） of leaves was higher in the dry treatment （0-30 cm layer at 40-45% of field capacity, 30-90 cm at 75-80% of field capacity） compared to the wet treatment （entire soil column at 75-80% of field capacity）. The maximal fluorescence （Fm）, the variable fluorescence （Fv）, the photochemical efficiency （Fv/Fm） and potential activites （Fv/F0） of photosystem 2 （PS2） were significantly lower in the dry treatment. Although drought stress impaired PS2 function, this effect was significantly ameliorated by applying P or NP fertilizer, but not N alone. P application increased FJFm, both in well-watered and water stressed plants, especially when fertilizer was applied throughout the column or within the top 30 em of soil. A combined fertilizer improved photosynthesis in well watered plants, with Fm and F,fFm being the highest when fertilizer was applied throughout the columns. For drought stressed, plants FJFm was significantly greater when combined fertilizer was added within the top 30 cm of soil. We concluded that, when growing winter wheat in both arid and semi-arid parts of the Loess region of China, it is important to guarantee the nutrient supply in the top 30 cm of the soil.

Spatial Variation of P and N in Water and Sediments of Dianchi Lake, China

Dianchi Lake is one of the most eutrophic lakes in China. In order to understand this eutrophication and to help control the pollution, this research investigated the spatial distribution of Kjeldahl nitrogen (K-N) and total phosphorus(TP) through analysis of bottom water and sediment (3 depths) samples collected at 118 sites around Dianchi Lake. The concentrations of K-N and TP for the lake bottom water in the Caohai part of the lake were much higher than those in the Waihai part, generally decreasing from north to south. In the sediments, the K-N concentration was higher in the Caohai part and the middle of the Waihai part. On the other hand, TP in the sediments was greater in the southern and western parts. Both K-N and TP had similar spatial distributions for the sediment samples of three different depths.Vertically, the K-N and TP concentration in the sediments decreased with an increase in depth. This was evidence that eutrophication and pollution of Dianchi Lake was becoming gradually more severe. Exterior factors including uncontrolled input of domestic and industrial effluents as well as non-point pollution around the lake were the main reasons for serious eutrophication; therefore, controlling these was the first step in reducing eutrophication of Dianchi Lake.

Promoting the production of salinized cotton field by optimizing water and nitrogen use efficiency under drip irrigation

Cotton is the main economically important crop in Xinjiang,China,but soil salinization and shortage of water and nutrients have restricted its production.A field experiment was carried out in the salinity-affected arid area of Northwest China from 2018 to 2019 to explore the effects of nitrogen and water regulation on physiological growth,yield,water and nitrogen use efficiencies,and economic benefit of cotton.The salinity levels were 7.7(SL)and 12.5 dS/m(SM).Drip irrigation was used with low,medium and adequate irrigation levels representing 60%,80%and 100%of cotton crop water demand,respectively,and three nitrogen applications,i.e.,206,275 and 343 kg/hm^(2),accounting for 75%,100%and 125%of local N application,respectively were used.The multi-objective optimization based on spatial analysis showed that,at SL salinity,water use efficiency(WUE),nitrogen use efficiency(NUE),economic benefit and yield simultaneously reached more than 85%of their maxima at 379.18-398.32 mm irrigation and 256.69-308.87 kg/hm^(2).At SM salinity,WUE,yield and economic benefit simultaneously reached more than 85%of their maxima when irrigation was 351.24-376.30 mm and nitrogen application was 230.18-289.89 kg/hm^(2).NUE,yield and economic benefit simultaneously reached their maxima at 428.01-337.72 mm irrigation,and nitrogen application range was 222.14-293.93 kg/hm^(2).The plants at SL salinity had 21.58%-46.59%higher WUE rates,14.91%-34.35%higher NUE rates and 20.71%-35.34%higher yields than those at SM salinity.The results are of great importance for the nutrient and water management in cotton field in the arid saline area.

Spatiotemporal Variation of Riverine Nutrients in a Typical Hilly Watershed in Southeast China Using Multivariate Statistics Tools

The water quality of lakes can be degraded by excessive riverine nutrients.Riverine water quality generally varies depending on region and season because of the spatiotemporal variations in natural factors and anthropogenic activities.Monthly water quality measurements of eight water quality variables were analyzed for two years at 16 sites of the Tianmuhu watershed.The variables were examined using hierarchical cluster analysis(HCA) and factor analysis/principal component analysis(FA/PCA) to reveal the spatiotemporal variations in riverine nutrients and to identify their potential sources.HCA revealed three geographical groups and three periods.Two drainages comprising towns and large villages were the most polluted, six drainages comprising widely distributed tea plantations and orchards were moderately polluted, and eight drainages without the factors were the least polluted.The river was most polluted in June when the first heavy rain(daily rainfall > 50 mm) occurs after fertilization and the number of rainy days is most(monthly number of rainy days > 20 days).Moderate pollution was observed from October to May, during which morethan 60% of the total nitrogen fertilizer and all of the phosphorus fertilizer are applied to the cropland, the total manure is applied to tea plantations and orchards, and a monthly rainfall ranging from 0 mm to 164 mm occurs.The remaining months were characterized by frequent raining(i.e., number of rainy days per month ranged from 5 to 24) and little use of fertilizers, and were thus least polluted.FA/PCA identified that the greatest pollution sources were the runoff from tea plantations and orchards,domestic pollution and the surface runoff from towns and villages, and rural sewage, which had extremely high contributions of riverine nitrogen, phosphorus,and chemical oxygen demand, respectively.The tea plantations and orchards promoted by the agricultural comprehensive development(ACD) were not environmentally friendly.Riverine nitrogen is a major water pollution parameter in hilly watersheds affected by ACD, and this parameter would not be reduced unless its loss load through the runoff from tea plantations and orchards is effectively controlled.

The integration of nitrogen dynamics into a land surface model. Part 1: model description and site-scale validation

Nitrogen cycling has profound effects on carbon uptake in the terrestrial ecosystem and the response of the biosphere to climate changes.However,nutrient cycling is not taken into account in most land surface models for climate change.In this study,a nitrogen model,based on nitrogen transformation processes and nitrogen fluxes exchange between the atmosphere and terrestrial ecosystem,was incorporated into the Atmosphere–Vegetation Interaction Model(AVIM)to simulate the carbon cycle under nitrogen limitation.This new model,AVIM-CN,was evaluated against site-scale eddy covariance–based measurements of an alpine meadow located at Damxung station from the FLUXNET 2015 dataset.Results showed that the annual mean gross primary production simulated by AVIM-CN(0.7073 gC m^-2 d^-1)was in better agreement with the corresponding flux data(0.5407 gC m^-2 d^-1)than the original AVIM(1.1403 gC m^-2 d^-1)at Damxung station.Similarly,ecosystem respiration was also down-regulated,from 1.7695 gC m^-2 d^-1 to 1.0572 gC m^-2 d^-1,after the nitrogen processes were introduced,and the latter was closer to the observed vales(0.8034 gC m^-2 d^-1).Overall,the new results were more consistent with the daily time series of carbon and energy fluxes of observations compared to the former version without nitrogen dynamics.A model that does not incorporate the limitation effects of nitrogen nutrient availability will probably overestimate carbon fluxes by about 40%.

Effects of water and nitrogen coupling on growth,physiology and yield of rice

Water and nitrogen fertilizer are two essential factors for quality and yield formation of rice.Experimental study was carried out to investigate the effects of water and nitrogen fertilizer coupling on yield-related factors,such as growth(height),physiological indicators(chlorophyll and leaf area index(LAI))and yield composition indicators(productive panicles,thousand grain weight and total grains per panicle).Results showed that,the height difference under two irrigation regimes was not significant,and it showed no difference until the tillering stage(p>0.05).The water control method for controlled and mid-gathering irrigation(CMI)was favorable for nutrients converting to rice grain.Meanwhile the height difference for CMI and conventional irrigation(CVI)was the biggest at 80 d after rice transplantation.Variance analysis showed the effect of fertilization on height was significant(p<0.05).With organic fertilizer application,it could control plant growth and promote the nutrients converting to the panicle.The change curve of LAI was similar to chlorophyll content.Organic fertilizer application could not only promote chlorophyll content and LAI,but also delay leaf fading and promote yield.Nitrogen fertilizer factors showed significant difference on rice yield,compared to irrigation regimes showing no significance.Considering the irrigation and fertilizer factors together,the interaction was significant.The descending orders for the effects of water and nitrogen on rice yield were fertilizer,water and fertilizer,water.Regression analysis showed that the productive panicles and total grains per panicle of rice were extremely significant on rice yield,and the direct effect of total grains per panicle on yield was greater than that of productive panicle.This study results could provide theoretical basis for water and nitrogen management to improve rice production.

山东沿海城市水环境氮输入时空分布特征及其驱动因素

人类活动导致氮在城市生态系统中大量聚集,进而加剧近岸海域的氮污染,氮污染治理面临挑战。选取作为国家发展重要引擎与对外交流窗口的山东沿海城市为研究对象,基于物质流分析构建山东沿海城市水环境氮负荷模型,量化沿海城市水环境氮输入特征及贡献率。利用氮代谢效率指标揭示各城市氮减排潜力和差异,进而识别各城市水环境氮输入的主要影响因素。结果表明:①2002-2021年山东沿海各城市中威海、青岛、潍坊以及滨州的水环境氮输入强度(NEI)较高,超过山东沿海各城市平均水平(35 kg/hm^(2))。各城市的NEI相对于各自年均值的偏离程度变化趋势呈现出显著差异,展现出氮污染控制的不稳定性。②从排放结构来看,作物种植、畜禽养殖及水产养殖业为主要排放源,且居民消费与废物处理子系统亦贡献显著。工业制造水环境氮输入得到控制,大气氮沉降趋势加剧。③畜禽养殖子系统氮环境损失率较高,具有显著的减排潜力。各城市水环境氮输入受到多种因素的差异化影响,但各城市的NEI均与单位农田面积施氮量呈正相关。研究显示,山东沿海城市水环境氮输入时空分布特征明显,我国的相关管理措施对其氮污染控制具有积极的促进作用。各城市应针对关键子系统制定有效策略,实现氮素的有效减排,促进水环境质量的改善。

1958—2017年江西省水稻需水量与有效降雨量耦合关系分析

基于江西省15个气象站点1958—2017年逐日气象数据,利用Penman-Monteith方法、Mann-Kendall趋势检验、气候倾向率和ArGIS空间插值分析等方法,分析了早稻和晚稻生育期内有效降雨量(P_(e))、需水量(ET_(c))及需水量与有效降雨量耦合度(λ)时空分布特征。结果表明:江西省早稻和晚稻生育期内平均有效降雨量分别为186.69和119.26 mm,早稻和晚稻有效降雨量分别以1.00和1.31 mm/10a的平均速度增加,赣北有效降雨量及其上升趋势均大于赣南;早稻和晚稻生育期多年平均需水量分别为335.77和381.20 mm,早稻和晚稻需水量最大值均出现在赣州、吉安站附近区域,最小值均出现在庐山、修水站附近区域,早稻需水量和晚稻需水量变化趋势分别为-3.09和-7.95 mm/10a;早稻和晚稻需水量与有效降雨量耦合度多年平均值分别为0.57和0.33,早稻和晚稻耦合度均以0.01/10a呈不显著增加趋势。早稻和晚稻耦合度最大值均出现在庐山站,早稻和晚稻耦合度较小值均在赣州、吉安、南昌和波阳站,总体上,早、晚稻耦合度及耦合度倾向率均为赣北大于赣南,赣南地区水稻缺水情况比赣北更严重,尤其要关注赣南地区晚稻缺水情况,并做好水资源规划及制定灌溉措施。

基于多要素耦合的水网空间格局设计思路与方法

水网建设需要规划先行,水网空间格局设计是各层级水网规划编制的重中之重。针对水网空间格局设计的研究通常聚焦于水资源要素或某一层级、区域,存在与其他行业协同谋划不足等问题,从多要素空间耦合系统、自然-人工复合系统、多功能网络系统等内涵特征出发,结合空间格局设计理论方法对水网空间格局设计的启示,提出了以水系布局为基础、以经济社会水安全保障重点区域为核心、以支撑优化国土空间格局为前提的水网空间格局设计总体思路,统筹考虑经济社会布局、生态保护布局、其他行业发展布局和水系空间布局,提出了水网空间格局设计方法,进而分析了省级水网和市县级水网空间格局设计重点。

西南季节性干旱区夏玉米水氮耦合效应与水氮生产函数研究

【目的】探究西南季节性干旱区夏玉米关键生育期适宜的水氮耦合模式。【方法】于2022年6—10月在四川省都江堰灌溉试验站测桶区遮雨棚内开展夏玉米水氮耦合试验,以仲玉3号夏玉米为研究对象,采用桶栽方式种植夏玉米,以充分灌水(100%ET)和当地高水平施氮量(300 kg/hm2)为对照(CK),在拔节—抽雄期(Ⅱ)、抽雄—灌浆期(Ⅲ)分别设置2个灌水水平:HW(75%CK)、LW(50%CK)和3个施氮水平:N1(85%CK)、N2(70%CK)、N3(55%CK),共计13个处理,研究不同关键生育期的水氮耦合对夏玉米生长、产量、水分利用效率(WUE)、氮肥偏生产力(NPFP)的影响,基于Jensen模型构建水氮生产函数。【结果】拔节—抽雄期为夏玉米营养生长的关键时期,适宜的水氮耦合模式能在节水节氮条件下获得较高的产量并提高WUE和NPFP,Ⅱ-HWN2、Ⅲ-HWN1处理和Ⅲ-HWN2处理较CK分别节水12.78%、9.77%和9.77%,节氮9.0%、4.5%和9.0%,增产1.31%、4.32%和4.50%,WUE较CK分别提高28.39%、14.83%和8.52%,NPFP较CK分别提高11.33%、10.42%和8.52%;基于Jensen模型构建的水氮生产函数拟合度较好(R2=0.7619),拔节—抽雄期水氮敏感指数为0.152,大于抽雄—灌浆期的水氮敏感指数0.074。【结论】从提高水肥资源利用效率和保障产量的角度出发,推荐Ⅱ-HWN2处理和Ⅲ-HWN2处理为西南季节性干旱区适宜的水氮耦合模式。

水氮耦合对膜下滴灌红花生长发育及产量的影响

【目的】研究水氮耦合对膜下滴灌红花生长发育、干物质积累量和产量的影响。【方法】采用裂区试验设计,以灌水量水平为主区。播前施基肥磷酸二铵(总养分64%,N-P_(2)O_(5)=18-46)150 kg/hm^(2),氧化钾(30%)75 kg/hm^(2)。设灌水量(W)和施氮量(N)2个因素,3个灌水量水平:W_(1):1200 m^(3)/hm^(2)(低灌量)、W_(2):1500 m^(3)/hm^(2)(中灌量)和W_(3):1800 m^(3)/hm^(2)(高灌量);3个施氮量水平:N_(0):不施氮(空白)、N_(1):300 kg/hm^(2)(传统施氮量)和N_(2):600 kg/hm^(2)(高施氮量)。测定不同处理下红花的农艺性状、干物质积累量和产量,评估不同水氮耦合处理对红花生长发育和产量影响。【结果】适宜的灌溉量和施肥量对红花生长发育有显著的促进作用,W_(2)N_(0)和W_(2)N_(1)处理下红花的株高、分枝数和叶片数等农艺性状均显著高于其他处理,其中W_(2)N_(1)处理下红花干物质积累速率及积累量、单株果球数和每果粒数均达到最高水平,花丝产量和籽粒产量在W_(2)处理下均比W_(1)和W_(3)处理显著增加了8.09%和20.84%,但在N_(1)和N_(2)处理下差异较小,却均比N_(0)处理显著增加了10.69%和25.66%。【结论】中灌量和传统施肥量处理W_(2)N_(1)(灌溉量1500 m^(3)/hm^(2)及施肥量300 kg/hm^(2))最优,可以促进红花的生长发育、提高水肥利用效率、增加干物质积累、协调产量构成因素,达到高产优质。

石漠化地区土壤界面水氮耦合研究进展

为探讨石漠化地区土壤界面下的水氮耦合影响因素,本文从石漠化程度、地形异质性、植被恢复措施和土地利用4个方面进行综述,总结出土壤水分和氮素的迁移规律。(1)轻度石漠地区含水量和土壤氮含量较高,导致植物内养分运输快,水氮耦合效果最佳;其次是重度石漠地区;中度石漠地区通常是耕地聚集地,其土壤水氮含量较低,水氮耦合效果也最差。(2)随着海拔的降低,土壤水氮耦合效应增强,但这种效应随土壤深度的增加而减弱;不论是在高原的山地、峡谷、盆地还是洼地,石漠化地区的土壤水分和养分的流失都十分严重;不同植被恢复类型和恢复年限对当地的土壤水及氮素均有影响。(3)植树造林显著提高石漠化土壤的含水量和全氮含量;退耕还林不仅提升土壤肥力和环境质量,还有助于土壤氮库恢复和碳氮平衡维持;封山育林能在一定程度上改善土壤中的氮含量。(4)不同的耕地利用类型和作物选用都会对水氮耦合产生影响;园地通过减少翻耕次数,导致土壤紧实化,从而提高水土保持效果。根据以上研究,今后可针对综合治理策略、生态恢复与水资源综合管理策略、高效植被恢复策略、优化土地管理和利用策略等方面开展研究。

水氮耦合对滴灌玉米光合特性及产量的调控效应

探索水氮施用对玉米光合参数及产出指标的影响规律,寻求适宜水氮耦合量,为西辽河流域水肥管理提供理论和应用参考。膜下滴灌田间试验设置三种灌溉水平与三种施氮量组合形成9个处理,对比分析不同水氮组合作用效果。结果表明,水氮两因素对玉米光合速率Pn、蒸腾速率Tr、气孔导度Gs、胞间二氧化碳浓度Ci影响程度表现为灌水>施氮,对叶片水分利用效率WUE影响程度表现为施氮>灌水。对于Pn,W_(2)N_(2)(中水中氮)显著高于W_(3)N_(1)(高水低氮)、对于Tr,W_(2)N_(2)和W_(3)N_(1)差异不显著,因此灌溉量由中水至高水(1802~2315 m^(3)·hm^(-2))对Pn提升作用无法补偿中氮240 kg·hm^(-2)降至低氮192 kg·hm^(-2)对Pn的削弱作用,但可补偿对Tr的负效应。中高灌溉水平下氮肥192~240 kg·hm^(-2)可有效提升Pn、Tr、百粒重、穗粒重(W_(2)N_(2)显著高于W_(2)N_(1)、W_(3)N_(2)显著高于W_(3)N_(1)),继续施氮无显著作用。玉米产量提升与Pn、Tr增大呈正相关,水分亏缺时中氮240 kg·hm^(-2)至高氮288 kg·hm^(-2)无明显增产作用,中等灌溉水平下氮肥增产效果显著。W_(3)N_(2)(高水中氮)耦合下玉米可获得最佳光合能力及产量水平,但超过W_(2)N_(2)(中水中氮)的耦合量对WUE无增效、降低光合产物在籽粒中的分配比例。综合考虑光合参数及产量,推荐中等至较高的灌溉水平1802~2315 m^(3)·hm^(-2)(W2~W3)与中等施氮水平240 kg·hm^(-2)(N2)为最优水氮耦合量。

黄河三角洲湿地柽柳周边土壤的水盐耦合关系

为揭示滨海湿地植物对土壤水盐的影响机制,以黄河三角洲湿地柽柳(Tamarix chinensis Lour.)周边土壤水、盐为研究对象,分析柽柳周边土壤水盐相互影响的耦合关系。结果表明:距柽柳远近不同,土壤含水率的差异明显不同,冠下表层土壤含水率明显大于冠缘和裸地,呈现由冠下至裸地逐渐减小的趋势,尤其是柽柳西、南两侧的变化趋势最为明显;20 cm土层以上水分聚集率为冠下大于冠缘,呈现明显的“水岛”效应,而20 cm以下水分聚集率的变化则相反;土壤盐分表聚性显著,远离柽柳的裸地表层土壤含盐量较高,西、南两侧最为明显;土壤总盐与Cl^(-)、Na^(+)、Mg^(2+)3种离子相关性极显著,这些离子在近柽柳周围土壤的变化幅度及含量均较小,盐分富集率明显为冠下小于冠缘,呈现“盐谷”效应;土壤水盐耦合度在柽柳周边表现为西侧>南侧>北侧>东侧,水、盐呈显著负相关;西、南两侧较高的土壤含盐量出现在低含水率的条件下,呈现高含盐量+低含水率为高耦合度的特征,这种高耦合度情况还出现在柽柳周边的表层土壤与远离柽柳的裸地。在柽柳的影响下,水盐耦合度呈现距柽柳由近及远逐步增大、随着土层深度的增加而逐渐减小的趋势。

水氮耦合对陕南烤烟渗透调节物质及抗逆生理特性的影响

以云烟99为材料,采用双因素完全组合法,设置W1(土壤相对含水量75%~85%)、W2(土壤相对含水量55%~65%)、W3(土壤相对含水量35%~45%)3个土壤水分条件和N1(4 g)、N2(5 g)、N3(6 g)3个单株施氮量,共9个处理,进行盆栽试验,旺长期控水15 d后测定烟叶过氧化氢酶(CAT)、过氧化物酶(POD)、超氧化物歧化酶(SOD)活性及可溶性蛋白、可溶性糖、脯氨酸(Pro)、还原型谷胱甘肽(GSH)、抗坏血酸(AsA)、丙二醛(MDA)、超氧阴离子自由基(O2-)含量,分析水氮耦合对烤烟渗透调节物质及抗逆生理特性的影响。结果表明:在W3条件下,增施氮可提高可溶性蛋白含量,与W3N1处理相比,W3N2、W3N3分别提高25.36%和42.86%,能降低可溶性糖含量,分别降低3.85%和12.32%;W2N2、W2N3与W2N1处理相比,SOD活性分别提高20.29%和31.19%,POD活性分别提高24.60%和44.89%;N2条件下,与W1N1处理相比,W1N2和W2N2处理的CAT活性分别提高40.26%、43.58%;W3处理增加了烟叶Pro、GSH、MDA及O2-含量,与W1N1处理相比,增幅分别达69.69%~222.49%、15.2%~89.36%、155.15%~162.37%、24.89%~72.34%。分析互作效应发现,土壤相对含水量对SOD、POD活性及Pro、GSH、MDA、O2-、可溶性糖含量的影响较大;而施氮量对可溶性蛋白含量、CAT活性的影响较大;二者的互作效应对AsA含量的影响较大。综合来看,轻度缺水时株施氮量6 g的处理对烤烟抗氧化酶活性的提升效果较好,而重度缺水时株施氮量为5 g的处理对烤烟渗透调节物质和抗氧化物质含量的提升效果较好。

元宝槭幼苗光合生理的水氮耦合效应研究

研究元宝槭幼苗光合生理的水氮耦合效应可以为元宝槭苗木水肥管理提供科学依据,有利于元宝槭产业发展。以1 a生元宝槭实生苗为材料,设置田间持水量(FC)的10%~20%(W1)、40%~50%(W2)、70%~80%(W3)3个水分梯度,施氮0 g/株(N0)、2 g/株(N1)、4 g/株(N2)和6 g/株(N3)4个氮肥梯度的二因素完全随机盆栽实验,通过测定不同水氮处理下元宝槭幼苗的光合参数、叶绿素含量、叶绿素荧光参数,分析其变化规律,揭示水氮耦合对元宝槭苗期光合生理的影响机制。结果表明,水氮耦合对元宝槭的光合生理有显著影响:(1)元宝槭幼苗的Pn、Gs、Ci、Tr等4个光合参数总体变化趋势表现为随着土壤含水量的增加而增加,而iWUE、LS则与之相反;施氮对元宝槭光合参数的影响较复杂,W2N2处理Pn最高,为8.84μmol/(m^(2)·s)。(2)水氮对元宝槭幼苗的光系统II的实际光化学效率(ΦPSII)、非光化学猝灭系数(qN)影响较大,而对光系统II的最大光化学效率(Fv/Fm)、光化学猝灭系数(qP)无明显影响。(3)水分是元宝槭叶绿素含量的主要影响因素,随土壤水分含量升高,元宝槭总叶绿素含量提高,叶绿素a/b值下降,叶绿素b的比例显著增大。(4)元宝槭Pn与Ci、Gs、Tr、Fv/Fm、Chl显著正相关,与iWUE、LS则呈现出显著负相关性。综上所述,提高土壤含水量能显著提高元宝槭幼苗的光合作用,土壤含水量较低时,水分是影响元宝槭光合生理的主导因素,土壤含水量为中、高水平时,其光合生理由水氮共同决定,该结论可为元宝槭苗期水肥管理体系建立提供理论参考。

水氮耦合对金线莲生长和品质的影响

【目的】探究不同水氮耦合处理对金线莲生长和品质的影响,为确定金线莲栽培的适宜水氮耦合方案提供参考。【方法】以大叶金线莲为试材,采取裂区设计,设置3种施氮量(N1:3.3 g/m^(2);N2:6.6 g/m^(2);N3:9.9 g/m^(2))和4种灌水量(W1:(45±5)%θ_(f);W2:(55±5)%θ_(f);W3:(65±5)%θ_(f);W4:(75±5)%θ_(f);其中θ_(f)为田间持水量)组合处理,以不施肥、不灌溉为对照(CK),栽培5个月后,测定13个处理金线莲的生长指标(保存率、株高、单株叶片数、叶长和叶宽、茎节数、节长、根长、根数、单株鲜质量及干质量、折干率)、生理指标(总叶绿素、可溶性蛋白、可溶性糖含量和过氧化物酶、超氧化物歧化酶活性)和品质指标(总黄酮含量及总多糖、金线莲苷、总生物碱和总氨基酸质量分数),分析灌水量和施氮量对金线莲生长及活性成分的影响。【结果】(1)与CK相比,除N1W1、N3W1处理外,其余处理均可以提高金线莲单株鲜质量、干质量、折干率、茎节数、节长和株高,其中N2W3处理金线莲的单株鲜质量、茎节数、节长、株高均达最大值,较CK分别提高了35.67%,33.18%,16.14%和35.45%。在30~60 d的较短栽培时期内,金线莲栽培的保存率在各处理之间差异不明显,但随着栽培时间延长,N1、N2条件下的水氮耦合优势逐渐显现。与CK相比,各处理金线莲的单株叶片数、叶长、叶宽、根长和根数无显著差异。(2)与CK相比,除N2W1处理外,其余处理均可以提高金线莲可溶性糖含量、SOD活性和总叶绿素含量;除N1W4和N3W4处理外,其余处理均可以降低金线莲的POD活性。与CK相比,各处理对金线莲可溶性蛋白含量有显著影响,同一施氮水平下,W1条件下的可溶性蛋白含量显著高于其他处理。(3)与CK相比,各处理对金线莲总氨基酸和总多糖质量分数均有显著影响,其中N2W3处理的总氨基酸质量分数最高,为9.18%;N1W3处理的总多糖质量分数最高,为45.08%。在W2、W3条件下,金线莲的总黄酮含量和金线莲苷质量分数随施氮量的增加均呈先增后减趋势,施氮效果均表现为N2>N3>N1,且均以N2W3处理最高,分别为25.04 mg/g和19.36%。(4)熵权系数法分析结果显示,12种肥水组合中,耦合作用效果排名前5的处理为N2W3>N2W2>N3W1>N2W4>N3W2。【结论】适宜的水氮耦合处理有利于金线莲生长及活性成分的积累,金线莲较优的肥水组合是灌水量为田间持水量的60%~70%,施氮量为6.6 g/m^(2)。

不同灌溉方式下水氮供应对冬小麦水氮利用效率的影响

【目的】探究不同灌溉方式下水氮耦合对冬小麦产量、产投比(VCR)、土壤氮素残留(NR)、水分利用效率(WUE)和氮肥偏生产力(NPFP)的影响,进而优化河南省冬小麦水氮管理制度。【方法】本研究以济麦22为研究对象,设定2种灌溉方式(宽垄沟灌(F),畦灌(Q)),3个灌水下限(60%田间持水率(W1)、70%田间持水率(W2)、80%田间持水率(W3)),3个施氮量水平(120 kg/hm^(2)(N1)、220 kg/hm^(2)(N2)、320 kg/hm^(2)(N3)),建立综合评价小麦产量、灌溉方式、水分利用效率、氮肥偏生产力、土壤氮素残留以及产投比的多目标优化模型,使用遗传算法进行寻优。【结果】①灌溉方式、灌水下限和施氮量对冬小麦水分利用效率、氮肥偏生产力、0~100 cm深度土壤硝态氮残留和产量均有极显著影响(P<0.01)。产量和水分利用效率均随灌水下限和施氮量的增加呈现先增加后降低的趋势。②FW2N2处理的产量、水分利用效率以及净利润达到最大值,分别为9686.93 kg/hm^(2)、1.97 kg/m^(3)、15142.93元/hm^(2),相较于FW1N1处理分别增加了44.71%、56.65%、56.59%,这说明恰当的水氮供应具有增产与节水有机统一的良好潜力。【结论】冬小麦最优的水氮耦合管理措施为:灌溉方式采用宽垄沟灌,灌水下限为70%田间持水率,施氮量232.64 kg/hm^(2)。