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1.
[Objective] The effects of nitrogen (N) application rates on cotton yield, nutrient uptake and utilization rate, soil available N and urease activity were investigated in low-fertility cotton fields of the Yellow River Basin. [Methods] Six N application rate treatments, 0, 90, 180, 270, 360 and 450 kg·hm－2 (N0, N90, N180, N270, N360 and N450, respectively), were established using cotton CCRI 79 in the field during 2016 and 2017. The cotton yield, dry matter quality, N, phosphorus and potassium accumulation levels, N use efficiency, 0–100-cm soil layer ammonium and nitrate N contents, 0–100-cm soil layer urease activity and other indicators were investigated. [Results] (1) Compared with N0, the N treatments significantly increased seed cotton yield, except the N90 treatment in 2016. Two years of N360 treatments significantly increased the number of bolls per cotton plant, while no significant differences were found among the seed cotton yields with other N treatments. The N application rates had no significant effect on lint percentage. (2) Compared with N0, N applications significantly increased the cotton dry matter accumulation. The accumulation of N, phosphorus and potassium in cotton increased along with the N application rates in the 90–360 kg·hm－2 range. The levels of N, phosphorus and potassium in N450-treated cotton decreased compared with N360-treated cotton. As the N application rates increased, the N agronomic efficiency and N fertilizer partial productivity of cotton decreased. When the N application rates exceeded 360 kg·hm－2, the N physiological efficiency began to decrease, but there were no significant differences among treatments. (3) The nitrate N contents in the 41–80-cm soil layers of the treatments, except for N90, significantly increased compared with N0. The nitrate N contents in the 41–80-cm soil layers of N270-, N360- and N450-treated cotton were significantly increased compared with those of N0, N90 and N180. However, N applications had no significant effects on the ammonium N contents in the soil. (4) The soil urease activities increased when N application rates were less than 360 kg·hm－2, and then decreased when the N application rates were greater than 360 kg·hm－2. [Conclusion] The optimum N application rate was 277.0 kg·hm－2. When the N application rates were greater than 360 kg·hm－2, the nitrate N contents in the soil increased. However, the nutrient accumulation levels and the N fertilization efficiencies decreased, and the soil urease activities were inhibited. No obvious increase in cotton yield was observed.  相似文献   

2.
[Objective] The optimum nitrogen rate of 300 kg·hm－2 is well documented for cotton in the Yangtze River Valley, China. It can be reduced to 225 kg·hm－2 without reducing yield in late sowing under high planting density. The aim of this study was to determine the possibility of further reducing the nitrogen application rate at the first flower stage, its residual effects and influence on cotton yield formation rule. [Method] A pot experiment was conducted with five nitrogen levels (120, 150, 180, 210 and 240 kg·hm－2) in 2014, but only 180 kg·hm－2(for studying nitrogen residual effect) in 2015, to study the cotton growth process, yield and its components and biomass accumulation. [Result] Nitrogen levels significantly affected the yield and biomass accumulation, but not the growth process and nitrogen residual effect. Maximum seed cotton yield (30.5 g·plant－1), boll weight (3.8 g) and biomass accumulation, especially in the reproductive and vegetative organs, was recorded in the 180 kg·hm－2 nitrogen treatment. In the rapid accumulation period, the proportion of biomass accumulation in the reproductive organs was the highest. [Conclusion] In a soil with medium fertility level, the application of 180 kg·hm－2 nitrogen was optimal, because the strength of biomass accumulation in reproductive organs increased during the rapid accumulation period.  相似文献   

3.
[Objective] Phosphorus is one of three major required nutrients for cotton growth and development. A phosphorus deficiency will lead to retarded cotton growth, undeveloped roots, and the abscission of buds and bolls, which results in serious reductions in cotton yield and quality. While applied phosphorus is easily fixed in soils, it is mostly transferred to occluded P, which is not available to plants. Therefore, this study aimed to provide theoretical support for the study of response mechanisms to low phosphorus stress and the efficient phosphorus uptake and utilization of different cotton genotypes. [Method] The effects of phosphorus accumulation and utilization, leaf photosynthetic characteristics and root morphology of two genotypes of cotton (CCRI 79 and SCRC 28) were studied in hydroponic cultures having different phosphorus concentrations. [Result] CCRI 79 had higher phosphorus utilization rates of 90.92 mg·mg－1 at the low phosphorus level (KH2PO4 1.0×10－5 mol·L－1) and 23.09 mg·mg－1 at the high phosphorus level (KH2PO4 0.5 mol·L－1) compared with SCRC 28. When phosphorus was deficient, the total root length, total root surface area and total root volume of SCRC 28 increased by 13.05%, 18.78% and 10.50%, respectively, while the total root length, total root surface area and total root volume of CCRI 79 decreased significantly. [Conclusion] Here, we found that SCRC 28 had a root morphology and physiological characteristics that allowed it to adapt to low phosphorusstress, while CCRI 79 utilized phosphorus more efficiently.  相似文献   

4.
为探讨三江平原植被对不同形态氮的吸收偏好,以三江平原典型植物群落——草甸小叶章群落为研究对象,利用15N示踪技术,施加标记的NH+4-N和NO-3-N。结果表明：草甸小叶章群落5种植物均表现出喜硝性,且优势种小叶章吸收的铵态氮和硝态氮最多。优势种小叶章不同器官短期内偏好硝态氮的优先顺序为叶>茎>根。土壤中大部分外源氮被植物吸收,土壤残留的铵态氮多于硝态氮。  相似文献   

5.
【目的】为探讨土壤中的残膜含量对棉花根区环境及生长发育的影响。【方法】在大田条件下,以新陆中47号为供试材料,设置了0(CK)、225、450、675和900 kg·hm~(-2)共5个残膜量处理,于2013-2014开展2年小区模拟试验,研究了棉田土壤氮素、根系形态、产量性状随土壤中残膜含量的变化规律。【结果】随着残膜量的增大产量均呈下降趋势,450、675、900 kg·hm~(-2)残膜量处理的产量均显著(P0.05)低于0 kg·hm~(-2)(CK),其中900 kg·hm~(-2)处理的产量降低了22.2%。残膜阻碍根系生长,根长、根直径、根表面积、根体积、根尖数均随残膜量的增加而下降,其中,900 kg·hm~(-2)处理较0 kg·hm~(-2)(CK)分别下降了33.7%,24.3%,19.72%,66.4%和35.3%;0 kg·hm~(-2)与225、450、675、900 kg·hm~(-2)残膜量处理在花期和铃期均具有显著性差异(P0.05)。随着残膜量的增加土壤中的铵态氮和硝态氮呈增加趋势,与0 kg·hm~(-2)(CK)相比,900 kg·hm~(-2)处理在铃期铵态氮增加了36.6%、硝态氮增加了40.1%。【结论】残膜降低氮素利用率,阻碍了根系生长,不利于棉花产量的提高。  相似文献   

6.
土壤有效磷含量对棉花幼苗干物质积累和碳氮代谢的影响   总被引：5，自引：4，他引：1  
苗期为棉花对磷吸收最敏感时期,然而现有研究未能明确土壤有效磷含量对苗期棉花干物质积累和碳氮代谢的影响以及适宜的土壤有效磷含量。本研究以"中棉所79"为供试品种,采用盆栽试验,研究了不同土壤有效磷水平下,五叶期棉苗干物质质量、碳氮代谢、功能叶片叶绿素含量及磷的吸收和利用。结果表明,随着土壤有效磷含量的增加,棉苗干物质质量逐渐增加,根冠比逐渐降低;土壤有效磷含量在9.0 mg·kg~(-1)时,棉苗干物质质量达到最大值,根冠比最小;过高的磷素营养对干物质质量的积累没有显著促进作用。叶片叶绿素含量随着土壤有效磷含量的增加呈现出先增加后减少的趋势,在土壤有效磷含量为7.2 mg·kg~(-1)时达到最大值。各处理棉苗中的蔗糖、可溶性糖、淀粉和氨基酸总量先随着土壤有效磷含量的增加呈显著增加趋势,在9.0mg·kg~(-1)时达到最大值,随后开始下降但差异不显著。土壤有效磷含量的增加可以促进棉苗的磷吸收量和磷根效率比,抑制磷利用效率,但对磷转移效率没有显著影响。因此,低磷会降低棉花幼苗叶绿素含量、糖含量和氨基酸总量,导致棉花生长受到抑制,适宜棉花幼苗生长发育的土壤有效磷的临界含量为9.0 mg·kg~(-1)。  相似文献   

7.
为探讨不同形态氮源对烟苗素质和生长发育的影响，以烤烟新品系HN2146为参试材料，采用水培试验研究硝酸铵、硝酸钙、硫酸铵和尿素4种不同形态氮源对烟苗生长发育特性的影响。结果表明，烟苗最大叶面积以硝酸钙处理最大，为100.4cm2；烟苗叶和根系蛋白质含量以硫酸铵处理最高，分别为151.452和79.367μg/g FW；硝酸还原酶活性表现为硝酸钙>硝酸铵>硫酸铵>尿素处理；烟苗对氮的吸收能力表现为硝酸铵>硫酸铵>硝酸钙>尿素处理。通过对不同处理烟苗相关农艺性状和生理特性指标的主成分分析，其综合得分表现为硝酸钙>硝酸铵>硫酸铵>尿素处理。可见以硝态氮和铵态氮作为唯一氮源对烟苗生长发育的效果较好，而以尿素作为唯一氮源的效果最差，本研究结果为不同氮源在烤烟育苗培育上的应用提供了理论依据。  相似文献   

8.
通过营养液浇灌盆栽试验，以晋谷21号为供试材料，基于总氮水平（5mmol/L）设置5个氮素形态配比，无氮素营养液处理作为对照，分析不同形态氮素配比对谷子幼苗生长、氮代谢关键酶活性及氮效率的影响。结果表明，与对照相比，施氮能显著促进谷子幼苗地上部和根系生长、氮代谢关键酶活性及氮素利用，且在硝铵比为50%:50%时达到最大；与单施一种氮源相比，硝铵氮源混施能显著促进谷子幼苗地下部生长和谷氨酸合成酶活性；与铵态氮占比在50%以上的处理相比，硝态氮占比在50%以上的处理更有利于促进谷子幼苗地上部生长、硝酸还原酶、谷氨酰胺合成酶活性及氮效率。隶属函数综合分析得出，氮源配施较单一氮源更有利于谷子幼苗的生长，且在硝铵比为50%:50%时效果最佳。  相似文献   

9.
氮肥后移对不同氮效率水稻花后碳氮代谢的影响   总被引：9，自引：0，他引：9  
以氮高效品种(德香4103)和氮低效品种(宜香3724)为材料,利用~(13)C和~(15)N双同位素示踪技术和生理生化分析方法,采用盆栽及大田试验,在施氮量180 kg hm~(–2)条件下,设置3种氮肥运筹方式,基肥∶蘖肥∶穗肥比例分别为5∶3∶2(N_1)、3∶3∶4(N_2)、3∶1∶6(N_3),以及不施氮(N_0)处理;研究其对不同氮效率水稻花后氮碳代谢的影响,并探讨氮肥后移下花后光合同化物及氮素累积、转运、分配的共性响应机制及其与产量的关系。结果表明,品种、氮肥运筹对花后氮素利用特征、光合同化物分配、生理特性及产量均存在显著影响。氮高效品种与氮肥后移量占总施氮量的40%、氮素穗肥运筹以倒四、倒二叶龄期等量追施相配套(N_2处理),能促进花后氮素累积,提高剑叶光合速率和1,5-二磷酸核酮糖羧化酶、谷氨酰胺合成酶等碳氮代谢关键酶活性,促进叶片、茎鞘、根系、穗各营养器官光合同化物及氮素累积与转运,进而提高产量及氮肥利用率,为本试验氮高效品种配套的氮肥运筹优化模式。花后不同氮肥运筹下,氮高效品种光合同化物、氮素的累积与转运,分别较氮低效品种高7.78~12.75 mg ~(13)C株~(–1)、15.14~18.78mg ~(15)N株~(–1);且叶片转运量分别较氮低效品种高1.70~2.93 mg ~(13)C株~(–1)、2.21~4.55 mg ~(15)N株~(–1),茎鞘转运量分别较氮低效品种高1.70~2.93 mg ~(13)C株~(–1)、0.05~1.14 mg ~(15)N株~(–1);而穗部氮高效与氮低效品种~(13)C同化物分别增加31.04~44.68 mg ~(13)C株~(–1)(占~(13)C总量的42.04%~46.38%)、24.94~34.26 mg ~(13)C株~(–1)(占~(13)C总量的36.45%~41.36%),~(15)N则分别增加35.56~46.58 mg ~(15)N株~(–1)(占~(15)N总量的61.82%~82.93%)、27.37~31.57 mg ~(15)N株~(–1)(占~(15)N总量的58.04%~68.31%)。氮高效品种花后具有强光合碳同化、氮素的协同吸收转运特征,以及碳氮代谢能力,来满足籽粒灌浆期对光合同化物及氮素的利用,是氮高效品种相对于氮低效品种高产、氮高效利用的重要原因。此外,从花后不同器官碳氮比(C/N)变化值综合两品种高产及氮肥高效利用来看,N_2处理下,齐穗至成熟期叶片、穗部C/N提高幅度与该时期茎鞘、根系C/N降低幅度一致,据此可将C/N作为水稻高产及氮肥高效利用同步提高的评价指标,这具有重要的参考价值。  相似文献   

10.
为合理利用氮肥和隔根模式技术优化间作作物种间关系,进一步发挥种间优势提供理论依据,以胡麻间作大豆为研究对象,采用盆栽试验,研究不施氮(N0)和施15N 80 mg/kg(N80),根系完全分离(T1)、根系不分离(T2)、根系尼龙网分离(T3)3种隔根模式对胡麻/大豆间作优劣势和种间竞争力的影响。结果表明,间作胡麻干物质积累量在各处理间无显著差异,间作大豆全生育期干物质积累量表现为N80显著高于N0处理。间作胡麻单株有效蒴果数、每果粒数、千粒重和籽粒产量均在N80T2处理下最大,其中,籽粒产量较其他处理显著高出41.94%~137.84%。间作大豆根瘤数为N0>N80,单株结荚数、每荚粒数和百粒重均为N80T2处理最大,籽粒产量则为N80T3处理最大,但与N80T2处理差异不显著,较其他处理显著高出4.33%~13.99%。所有处理的土地当量比(LER)均大于2,N80T2时最大。不同施氮模式下,T2处理的种间竞争力表现为胡麻强于大豆(AF>0,CRF>1),T3处理则恰好相反(AF<0,CRF<1)。说明胡麻/大豆间作体系中施15N 80 mg/kg、根系不分离有利于协调胡麻和大豆种间关系,促进作物增产。  相似文献   

11.
营养液pH变化对刺梨苗吸收硝态氮和铵态氮的影响   总被引：1，自引：0，他引：1  
研究介质pH变化条件下刺梨(Rosa roxburghii)对不同形态氮素吸收特性的影响,能为不同pH土壤上刺梨的合理施肥提供科学依据。本研究以‘贵农5号’刺梨实生苗为材料,采用营养液培养和离子耗竭法,在分别供给硝态氮和铵态氮的条件下,设置营养液分别为pH 4、5、6、7、8、9的6个处理,测定不同pH营养液培养的刺梨苗对NO3-、NH4+的吸收动力学参数和刺梨苗的植株高度、干重生物量、氮含量及氮吸收量,分析营养液pH变化与NO3-、NH4+的吸收动力学参数的相关性和营养液pH变化与刺梨苗植株高度、生物量、氮含量和氮素吸收量的相关性。研究结果表明,刺梨根系对硝态氮、铵态氮及总氮的吸收规律均符合Michaelis-Menten酶动力学方程。营养液的pH变化能够改变刺梨苗根系对NO3-和NH4+的吸收特性。在营养液pH 4~9的范围内和供给硝态氮的条件下,刺梨实生苗的根系对NO3-的最大吸收速率(Imax)、根系与NO3-的亲和力、NO3-流入根系的速率(α)、植株高度、干重生物量、氮含量及氮的吸收量随营养液pH的增大而明显降低,营养液的pH变化与上述指标呈极显著负相关。在供给铵态氮的条件下,刺梨实生苗根系对NH4+的上述指标随营养液pH的升高而明显增大,营养液的pH变化与上述指标呈极显著正相关。在酸性条件下有利于刺梨苗对硝态氮的吸收,升高营养液的pH不利于刺梨苗吸收硝态氮。碱性条件有利于刺梨苗对铵态氮的吸收,酸性条件对刺梨苗吸收铵态氮有不利影响。  相似文献   

12.
氮素生物地球化学循环和减缓温室气体排放已成为全球（气候）变化研究的热点问题,氮素有效性是调控全球变化反馈机制的重要因子。本研究以东北三江平原小叶章湿地为研究对象,采用15N示踪技术,通过野外原位控制实验,研究湿地植物小叶章对不同氮素形态(NH+4、NO-3、NH+4-NO-3)的吸收及小叶章N2O排放通量特征。结果表明：(1)不同氮素形态处理下,小叶章叶生物量表现为处理A>NA>N>CK;A处理,茎生物量最大,比对照提高了35.7%;NA处理,地下生物量显著高于A和CK(P<0.05);NA处理,根冠比最大,是对照的1.82倍。(2)不同氮素形态处理下,小叶章叶、茎、地上以及根氮含量显著高于对照(CK)(P<0.05),不同处理之间氮含量差异不显著(P<0.05)。(3)不同氮素形态处理下,小叶章叶、茎以及地上部分Ndff和15N含量均表现为处理A>N>NA>CK,并且各处理极显著高于对照(P<0.01),各处理之间达到显著差异(P<0.05)。(4)不同氮素形态处理下,处理N湿地N2O排放量最多,且显著高于处理A和处理NA(P<0.05),处理N、A、NA显著高于对照(CK)(P<0.05)。阐释了不同形态氮素在植物-土壤-大气系统中周转与分配策略,以及对N2O排放的影响,为湿地氮生物地球化学和温室气体排放研究提供基础数据。  相似文献   

13.
保护性耕作是改善农田土壤肥力的重要举措,然而其对作物氮吸收与产量的作用尚不明确。为此,本试验于2016—2017年稻季在湖北省武穴市花桥镇,设置常规翻耕与免耕两种耕作方式以及前茬作物秸秆全量还田与不还田两种秸秆还田方法,研究耕作与秸秆还田方式对稻田土壤N_2O排放、根系酶活性、水稻氮吸收与产量的影响。结果表明,耕作方式显著影响土壤N_2O排放,但不影响根系硝酸还原酶与谷氨酰胺合成酶活性、水稻氮吸收与产量。与翻耕处理相比,免耕处理2016年和2017年土壤N_2O排放量分别显著提高了12.5%～18.2%和21.1%～38.6%。秸秆还田显著影响土壤N_2O排放量、根系酶活性、水稻氮吸收与产量。相对于秸秆不还田处理,秸秆还田处理2016年和2017年土壤N_2O排放量分别显著提高了38.5%～45.5%和13.1%～29.5%。秸秆还田处理相对于不还田处理根系硝酸还原酶与谷氨酰胺合成酶活性分别显著增加了6.7%～45.9%和9.0%～46.7%,水稻氮吸收量提高了12.5%～26.0%,产量增加了9.4%～12.6%。本文认为,虽然秸秆还田提高了水稻氮吸收与产量,但也促进了土壤N_2O的排放,因此在评估保护性耕作稻田温室效应时应加强对温室气体(CH4和N_2O)排放和土壤碳固定影响的长期监测,以期为发展低碳稻作提供理论依据和技术支撑。  相似文献   

14.
[Objective] Under the same cultivation conditions, we explored the differences in photosynthetic characteristics between upland cotton and sea-island cotton, and their dry matter and nitrogen accumulation and distribution patterns during the blooming period, to provide a theoretical basis for irrigation and fertilization of island cotton. [Method] Using Xinluzhong 75, Xinluzhong 54, Xinhai 35 and Xinhai 48 as materials, we tested the net photosynthetic rate (Pn), leaf temperature, dry matter accumulation and nitrogen absorption and distribution characteristics under the same management conditions. [Result] After the flowering stage, when compared with island cotton, the Pn of upland cotton was higher, but the leaf temperature and light illumination were lower. However, the difference in effect of stomatal conductance (Gs) on Pn between island cotton and upland cotton was small. The dry matter accumulation of shoots and the daily accumulation of shoots and reproductive organs in the whole growth period were higher for upland than for island cotton, with a lower dry matter proportion of reproductive organs in the early growth period, and higher in the late period for upland than for island cotton. When compared with Xinhai 48, the initiation of rapid nitrogen accumulation of Xinluzhong 54 was later and its duration was shorter, but the maximum nitrogen accumulation rate was higher; however, the initiation of rapid accumulation time of reproductive organs was later, and its rapid accumulation duration was longer. [Conclusion] The dry matter output efficiency, accumulation in reproductive organs and nitrogen accumulation in the later growth period of island cotton were lower than those in upland cotton. Therefore, under production conditions, the proportions of water and fertilizer use should be increased for island cotton according to different regions.  相似文献   

15.
Nitrogen (N) transfer from legume trees to associated crops is a key factor for the N economy of low-input agroforestry systems. In this work, we presented a new approach to estimate N transfer based on the 15N content of root exudates and N released by root turnover of the donor plant (Gliricidia sepium) and the temporal change of the 15N content of the receiver plant (Dichanthium aristatum). The study was carried out in greenhouse using two isotopic methods: 15N leaf feeding (LF) and the natural 15N abundance (NA). Measurements of exudate 15N were made at several dates before and after tree pruning. A time-dependent box model was devised to quantify N transfer in time and to make comparisons between the isotopic methods. In NA, although tree roots and exudates presented a similar 15N signature before tree pruning, exudates were strongly depleted in 15N after pruning. In LF, exudates were always depleted in 15N in relation to tree roots. Hence, the current assumption used in N transfer studies concerning the equal 15N/14N distribution in tissues of the donor plant and in its excreted N was not confirmed in our study. Before pruning, N transfer functioned as a two-N-source system (soil N and exudates N) and both isotopic methods provided similar estimates: 11–12% for LF and 10–15% for NA. Calculations performed with the model indicated that N transfer occurred with small or nil fractionation of 15N in exudates. After pruning, there was a third N source associated with N released from tree root turnover. During this period, the isotopic signature of the receiver plant showed a transient state due to the progressive decrease of 15N content of that N source. The amount of N derived from the tree represented 65% of the total N content of the grass at the end of the experiments.  相似文献   

16.
行距对机采棉干物质积累及氮磷利用效率的影响   总被引：1，自引：0，他引：1  
【目的】新疆棉花生产的主要环节均已实现机械化,但采摘环节仍大量使用人工,农机农艺不协调是导致机收比例低的主要原因。优化机采棉行距配置是实现农机农艺融合的有效途径,因此本研究通过设置不同的机采棉行距,探究其对棉花产量形成及养分利用的影响,为机采棉行距配置的优化提供理论依据。【方法】采用随机区组设计,选择生产中最佳密度,在密度一致基础上,设置"一膜三行"(S1,平均行距76 cm)、"一膜四行"(S2,平均行距57 cm)、"一膜六行"(S3,平均行距38 cm)3种行距,其中S3处理为常规机采行距(CK),研究行距对棉花干物质积累、分配以及对产量形成及氮、磷养分吸收利用的影响。【结果】不同行距下棉花干物质的积累符合Logistic生长函数模型。2年均值表明随着平均行距的降低,单株干物质积累总量降低43.3%,干物质最大积累速率降低(1.4 g·株-1·d-1),快速积累期起始时间从出苗后51.4 d逐渐推迟至62.5 d,但快速积累持续时长从19.7 d增加至35.1 d。增加行距显著提高单株成铃(0.9个),对铃重及衣分无显著影响,籽棉及皮棉产量显著增加16.7%和17.4%。行距对植株养分积累与分配有显著的影响,S1处理氮积累总量(907.0 kg·hm-2)、磷积累总量(58.3 kg·hm-2)、吐絮期经济器官氮分配率和磷分配率(N 55.7%和P2O569.1%)、每100 kg皮棉氮素吸收量(32.1 kg)均最高;而S3处理氮积累总量(664.5 kg·hm-2)、磷积累总量(38.9 kg·hm-2)最低,S2处理吐絮期经济器官氮分配率和磷分配率(N 48.5%和P2O560.3%)、每100 kg皮棉氮素吸收量(28.6 kg)最低。【结论】综合来看,一膜三行下植株养分指标及产量均优于其他行距,更适宜作为高效机采的行距。  相似文献   

17.
[Objective] The aim of this study is to evaluate nitrogen efficient cotton germplasms and improve nitrogen use efficiency. [Method] Eighty cotton germplasms were selected and evaluated in the hydroponic experiment under low (0.25 mmol·L－1) and high (5 mmol·L－1) nitrogen concentration. Different traits for screening were identified and nitrogen use efficiency types were classified. Field experiments were also performed for comparison and confirmation of the identified germplasms. [Result] The results showed that there were significant differences in the total plant dry matter, shoot nitrogen accumulation and nitrogen absorption efficiency in cotton germplasms at the two nitrogen levels. Based on coefficient of variation, principal component analysis and correlation, six traits including total plant dry matter, shoot dry matter, root dry matter, total nitrogen accumulation, shoot nitrogen accumulation and nitrogen absorption efficiency were used as screening indicators. According to the Heatmap clustering analysis and the nitrogen efficiency comprehensive index, two germplasms (Lu05R59 and CCRI 69) were identified as low nitrogen tolerant and nitrogen efficient, and two germplasms (Coker 201 and Xinluzhong 30) as low nitrogen sensitive and nitrogen inefficient. The results of field experiment were consistent with the results of the hydroponic culture at the seedling stage. [Conclusion] It was finally determined that Lu05R59 and CCRI 69 were the low nitrogen tolerant and nitrogen efficient germplasms, and Coker 201 and Xinluzhong 30 were low nitrogen sensitive and nitrogen inefficient germplasms. The results of these studies provide the possibility for screening and rapid identification of nitrogen use efficiency in cotton at the seedling stage, and provide the ideal materials and theoretical basis for further study of cotton nitrogen efficient.  相似文献   

18.
Rice ( Oryza sativa cv. Koshihikari) seedlings were grown in a sandy dune soil in pots with a basal dressing of N (0.5 g N), P and K. Two N treatments were applied, a +N treatment in which a top dressing of 15N-labeled 0.5 g N was supplied on July 20 and a −N treatment in which no additional fertilizer was supplied. During the grain-filling stage from August 6 to 13, plants were subjected to one of three temperature treatments; controlled low temperature, LT (day/night 28/23 °C), controlled high temperature, HT (35/30 °C) and uncontrolled glasshouse temperature, UT (day/night averages, 38/26 °C). All plants were then exposed to 13CO2 for 1 h on August 11 in a growth chamber at 25 °C. On August 13, all plants were harvested and the 13C and 15N abundances and starch and sugar concentrations in the ears, shoots and roots were determined. The 13C content of the ear was lower in UT than in LT irrespective of the +N or −N treatment. The translocation of 15N to the ears was also slightly depressed in UT compared with LT. Under high-temperature conditions (HT and UT), the starch content per plant was reduced for −N, but for +N, it was not significantly different among the temperature treatments. A high accumulation of sucrose was observed in all plant parts under UT conditions. It is suggested that extreme high day temperatures during the grain-filling period may reduce starch synthesis in the grains and, especially so under N-deficient conditions. High temperatures also induce an accumulation of sucrose and a decrease in carbon and nitrogen transport from the shoots to the ears via the phloem.  相似文献   

19.
旨在研究影响小麦产量的最佳灌溉与施氮方式组合。以‘定西42号’春小麦为材料,采用水氮互作的方法,设4种灌溉量（单位面积水深50 mm、100 mm、150 mm、200 mm）和3种施肥方式（拔节期施纯氮肥40 kg/hm 2、开花期施纯氮肥40 kg/hm 2、拔节期和开花期施纯氮肥40 kg/hm 2和50 kg/hm 2）。（1）灌溉量150 mm与开花期施氮肥40 kg/hm 2处理时,小麦产量都最高。（2）灌溉量150 mm时各个土层含水量最高,不同施氮处理,各个土层含水量高低顺序为分蘖期<开花期<拔节期。（3）小麦植株耗水量随灌溉量增加而增加、水分利用效率随灌溉量增加而减少。（4）分蘖期灌溉量150 mm时各个土层硝态氮含量最高;拔节期,0~10 cm土层铵态氮和硝态氮含量最高;开花期,灌溉量150 mm和追施纯氮肥40 kg/hm 2时各个土层硝态氮和铵态氮含量最高。灌溉量150 mm和开花期施纯氮肥40 kg/hm 2方式搭配,对甘肃陇中黄土高原春小麦产量、土壤有效氮含量和水分节约最有益。  相似文献   

20.
为了研究施氮对冬小麦生长前期叶片和根系活性氧代谢差异的影响,以‘百农207’为材料,进行根箱培养试验,设置7个氮素水平:N0（不施氮）、N1 (120 kg/hm 2)、N2 (150 kg/hm 2)、N3 (180 kg/hm 2)、N4 (240 kg/hm 2)、N5 (270 kg/hm 2)、N6 (300 kg/hm 2),分析了不同氮处理下‘百农207’生长前期叶片和根系中丙二醛(MDA)、可溶性蛋白(WSP)、总抗氧化能力(T-AOC)、超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)活性及与根系生长发育特性的关系。结果表明在冬小麦生育前期,叶片和根系的MDA含量在低氮处理下最高。在一定范围增施氮肥,中氮(N2)处理下叶片和根系WSP含量最高,T-AOC在高氮(N6)处理下最大。根系对胁迫环境的响应比叶片敏感,施氮提高了小麦根系活力,降低了根冠比,增加了叶片和根系生物量。随着施氮的增加,叶片和根系MDA含量、根系APX酶活性降低,叶片和根系的TAOC、叶片CAT酶活性和根系SOD酶活性增加。小麦叶片和根系酶促系统反应机制各自独立又相互协作,施氮量过高对酶促系统中部分抗氧化酶活性起抑制作用。在本实验条件下,施氮量在中氮范围内(150~240 kg/hm 2)时,冬小麦植株中酶活性指标相对最优,有利于冬小麦的前期生长发育,符合减肥增效的原则。  相似文献   

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