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1.
水稻生理生化特性对氮肥的反应及与氮利用效率的关系   总被引：37，自引：6，他引：37  
选用水稻氮高效基因型IR72和9311及氮低效基因型Lemont和PECOS,采用土培方法,在5个施氮量（0、0.51、1.02、1.53、2.04 g N 钵-1,分别相当于0、75、150、225、300 kg N hm-2）处理下,研究了生理生化特性对氮肥的反应及与氮效率的关系。结果表明,在幼穗分化期,氮高效基因型水稻的可溶性蛋白含量相对低,而谷氨酰胺合成酶（GS）活性高;不同氮效率基因型间1,5-二磷酸核酮糖羧化酶/加氧酶(Rubisco)含量的差异不大;两种氮效率基因型间的净光合速率（Pn）在幼穗分化期差异不明显。而在齐穗期,氮低效基因型的Pn比高效基因型的低28.66%左右;氮低效基因型在两个时期的单位叶绿素光合速率（Pn/Chl）比氮高效基因型分别低18.51%和29.67%左右。在成熟期,氮高效基因型干物质积累能力强,籽粒产量高。这些结果说明氮效率不同的基因型对氮肥的生理反应差异大。相关性分析表明,低氮水平时(0~1.53 g N 钵-1), GS酶活性与收获时生物量呈显著或极显著正相关;氮肥偏生产力（PFP）、氮肥农学利用率（AE）及氮素生理利用率（NUEb）分别与GS活性、Pn/Chl和齐穗期的Pn呈显著正相关,而与可溶性蛋白含量、Rubisco含量显著负相关;氮肥吸收效率（RE）与这些生理指标没有显著相关。结果表明水稻光合特征及氮代谢与水稻氮效率间存在紧密的关系,GS活性和可溶性蛋白含量对评价水稻氮肥利用率具有重要的参考价值。  相似文献   

2.
Sugarcane (Saccharum spp.) is increasingly exposed to periodic floods and shallow water tables on Histosols in Florida’s Everglades Agricultural Area (EAA). In the past, when these soils were usually well drained, they provided excess N for sugarcane through microbial oxidation. It is not known if supplemental N would now improve yields because microbial oxidation is reduced by shallow water tables and periodic floods. The purpose of this study was to evaluate the effects of N fertilizer rates on two sugarcane cultivars exposed to a 25-cm water-table depth with and without repeated 2-day floods. Two studies were planted in containers in 2001 and 2002 with two sugarcane cultivars and five equally spaced rates of N fertilizer from 0 to 200 kg ha−1. Leaf, stalk and root weights were reduced by periodic flooding and the magnitude of the reduction sometimes differed between cultivars. Plant weights, leaf chlorophyll content (SPAD) and leaf N content were often highest near an N rate of 100 kg ha−1. Usually, N fertilizer rate did not interact with water treatment. Nitrogen fertilization may be useful for sugarcane exposed to water-table depths of 25 cm with and without 2-day repeated floods on EAA Histosols.  相似文献   

3.
Twenty wheat ( Triticum aestivum L.) varieties differing in plant height were grown in soil culture and evaluated for differences in nitrogen uptake and nitrogen utilization efficiency (NUE) at limited (40 kg N ha−1) and normal (120 kg N ha−1) nitrogen supply. Nitrogen uptake showed 1.4- and 1.5-fold varietal variation at harvest for limited and normal N supply, respectively. NUE for dry matter production (NE1) exhibited 1.28- and 1.38-fold genotypic variation while NUE for grain production (NE2) varied by 1.25- and 1.21-fold at limited and normal N supply, respectively. Tall varieties were found to have higher N uptake and NUE for dry matter production, while dwarf cultivars had greater NUE for grain production. Nitrogen uptake was found to be strongly positively associated with dry matter production (r=0.85 and r =0.77 at limited and normal N supply, respectively), indicating an important effect of growth rate on N uptake. NUE for biomass production, as well as for grain production, was reduced as the supply of nitrogen was increased.  相似文献   

4.
[Objective] The aim of this study was to screen cotton varieties (lines) able to tolerate low nitrogen conditions, thereby tapping the potential of cotton to absorb and utilize nitrogen. [Method] This study analyzed the differences and correlations between the main cotton agronomic traits under two nitrogen levels using the sand culture method and 270 cotton varieties from different generations in three major cotton regions as materials. Principal component analysis and the membership function method were used to screen for low nitrogen-tolerant cotton varieties. [Result] The seven agronomic traits of 270 varieties varied greatly with different nitrogen levels. The coefficients of variation were all above 10 except for the SPAD value in four batches, and root biomass and cotton plant biomass in the first batch under low nitrogen level. The variation coefficient of nitrogen accumulation reached 60.02. The maximum relative value of SPAD, leaf area, and root biomass was greater than 80% in the first batch. The maximum relative values of SPAD, plant height, root biomass, shoot biomass, and cotton plant biomass were greater than 80% in the third and fourth batches, indicating that there are low nitrogen-tolerant genotypes in the selected materials. [Conclusion] Preliminary screening identified 32 low nitrogen-tolerant cultivars, including CCRI 35, CCRI 69, Yumian 12, Xinluzao 12, and Xinluzao 23. Furthermore, 32 varieties sensitive to nitrogen stress, including CCRI 64, CCRI 662, Xinluzhong 15, and Xinluzao 53, were identified.  相似文献   

5.
Two wheat genotypes viz. Uniculm 'gigas' (VI) and Kalyansona (V2) were raised till maturity with low (N1) and adequate (N2) nitrogen levels supplied at 30 and 120kg ha−1, respectively. Laminae, numbering 1–8 on the main shoot, were examined for various parameters at weekly intervals from emergence through senescence. N1 resulted in gradual reduction in laminae growth from 5th leaf onwards with maximum effect on flag and penultimate laminae of both the genotypes. Chlorophyll concentration, soluble protein, rubisco concentration and rubisco activity in response to low N supply was reduced in the top two laminae in V2. Pn rate varied little with leaf position in wheat at adequate N supply. In V2, low N supply resulted in the reduction of laminae N content by about 25% with corresponding reduction in Pn rates in the penultimate and flag laminae. VI, in contrast, exhibited no significant change in leaf N concentration and hence maintained similar Pn rates at both levels of N supply throughout the ontogeny.
It is concluded that the two genotypes responded differently to N supply in relation to laminae growth and photosynthesis. Uniculm 'Gigas' (VI) responded to low N with large reduction in laminae size, adequately maintaining the metabolic constituents such as chlorophyll, soluble protein, rubisco and laminae N concentration and Kalyansona (V2), in contrast, responded with small changes in laminae size and greater reduction in synthesis and maintenance of the metabolic constituents.  相似文献   

6.
Four bread wheat genotypes differing in salt tolerance were selected to evaluate ion distribution and growth responses with increasing salinity. Salinity was applied when the leaf 4 was fully expanded. Sodium (Na+), potassium (K+) concentrations and K+/Na+ ratio in different tissues including root, leaf‐3 blade, flag leaf sheath and flag leaf blade at three salinity levels (0, 100 and 200 mm NaCl), and also the effects of salinity on growth rate, shoot biomass and grain yield were evaluated. Salt‐tolerant genotypes (Karchia‐65 and Roshan) showed higher growth rate, grain yield and shoot biomass than salt‐sensitive ones (Qods and Shiraz). Growth rate was reduced severely in the first period (1–10 days) after salt commencements. It seems after 20 days, the major effect of salinity on shoot biomass and grain yield was due to the osmotic effect of salt, not due to Na+‐specific effects within the plant. Grain yield loss in salt‐tolerant genotypes was due to the decline in grain size, but the grain yield loss in salt‐sensitive ones was due to decline in grain number. Salt‐tolerant genotypes sequestered higher amounts of Na+ concentration in root and flag leaf sheath and maintained lower Na+ concentration with higher K+/Na+ ratios in flag leaf blade. This ion partitioning may be contributing to the improved salt tolerance of genotypes.  相似文献   

7.
热带水稻光合特性及氮素光合效率的差异研究   总被引：8，自引：0，他引：8  
曾建敏  彭少兵  崔克辉  黄见良 《作物学报》2006,32(12):1817-1822
在国际水稻研究所（IRRI）农场试验条件下,选用6个不同的热带水稻材料,其中包括2个常规籼稻、2个杂交籼稻和2个新株型稻（NPT）,研究氮肥农学利用率（AE）和氮素光合效率（PNUE）及其相关叶片参数的基因型差异,并探讨了它们之间的关系。结果表明,新株型稻的净光合速率(Pn)大于常规籼稻,杂交籼稻居中。各基因型间的气孔导度(Gs)、胞间CO2浓度(Ci)、蒸腾速率(Tr)和Ci/Gs的差异趋势不同。不同基因型叶片的氮浓度（N%）和比叶重（SLW）存在一定的差异。常规籼稻的单位叶绿素的净光合速率（Pn/Chl）较NPT低,杂交籼稻为中间类型;叶片净光合速率和单位面积含氮量（Na）之间存在显著的正相关;本研究所选用的热带杂交籼稻的PFP（氮肥偏生产力）和AE比新株型稻和常规籼稻高,两者最低的均为常规籼稻。氮素光合效率与AE间存在显著正相关,表明后期的氮素光合效率对氮肥利用率具有一定的指示和预测作用,这对于判断水稻品种氮肥利用率将具有重要的应用价值。  相似文献   

8.
An experiment was conducted under outdoor pot-culture conditions to determine effects of nitrogen (N) deficiency on sorghum growth, physiology, and leaf hyperspectral reflectance properties. Sorghum (cv. DK 44C) was seeded in 360 twelve-litre pots filled with fine sand. All pots were irrigated with half-strength Hoagland's nutrient solution from emergence to 25 days after sowing (DAS). Thereafter, pots were separated into three identical groups and the following treatments were initiated: (1) the control (100% N) continued receiving the half-strength nutrient solution; (2) reduced N to 20% of the control (20% N); and (3) withheld N from the solution (0% N). Photosynthetic rate (Pn), chlorophyll (Chl) and N concentrations, and hyperspectral reflectance of the uppermost, fully expanded leaves were determined at 3- to 4-day-interval from 21 to 58 DAS during the N treatments. Plants were harvested 58 DAS to determine effects of N deficiency on leaf area (LA), biomass accumulation, and partitioning. Nitrogen deficiency significantly reduced LA, leaf Chl content and Pn, resulting in lower biomass production. Decreased leaf Pn due to N deficiency was mainly associated with lower stomatal conductance rather than carboxylation capacity of leaf chemistry. Among plant components of dry weights, leaf dry weight had the greatest and root dry weight had the smallest decrease under N deficiency. Nitrogen-deficit stress mainly increased leaf reflectance at 555 (R555) and 715 nm (R715) and caused a red-edge shift to shorter wavelength. Leaf N and Chl concentrations were linearly correlated with not only the reflectance ratios of R405/R715 (r2 = 0.68***) and R1075/R735 (r2 = 0.64***), respectively, but also the first derivatives of the reflectance (dR/dλ) in red edge centered 730 or 740 nm (r2 = 0.73–0.82***). These specific reflectance ratios or dR/dλ may be used for rapid and non-destructive estimation of sorghum leaf Chl and plant N status.  相似文献   

9.
Drought is the single most important factor limiting soya bean (Glycine max L. Merr.) yields in the field. The following study was therefore undertaken to identify phenotypic markers for enhanced drought tolerance in nodulated soya beans. Leaf and nodule parameters were compared in three genotypes: Prima 2000, glyphosate‐resistant A5409RG and Jackson, which had similar shoot biomass and photosynthesis rates at the third trifoliate leaf stage under water‐replete conditions. When water was withheld at the third trifoliate leaf stage, photosynthesis, nodule numbers, nodule biomass and symbiotic nitrogen fixation (SNF) were greatly decreased. Significant cultivar–drought interactions were observed with respect to photosynthesis, which also showed a strong positive correlation with nodule SNF, particularly under drought conditions. Prima leaves had high water‐use efficiencies, and they also maintained high photosynthetic electron transport efficiencies under long‐term drought. Moreover, Prima had the highest shoot biomass under both water‐replete and drought conditions. A‐5409RG was the most drought‐sensitive genotype showing early closure of stomata and rapid inhibition of photosynthesis in response to drought. In addition to classifying the genotypes in relation to drought tolerance, the results demonstrate that the ability to sustain shoot biomass under nitrogen limitation is an important parameter, which can be easily applied in germplasm screening for drought tolerance in soya bean.  相似文献   

10.
Spinach is a leafy vegetable that requires a high N fertilization to have a satisfactory yield and quality, in part because it has poor nitrogen use efficiency (NUE). Therefore, there is a need to breed for cultivars with an excellent NUE. To this end the genetic diversity for NUE-related traits was studied in a diverse set of commercial cultivars. This set was evaluated in a hydroponic system using the Ingestad model; the system was set at a relative growth rate of 0.14 and 0.18 g g?1 day?1 (low and high N, respectively). Experiments were performed at low and high plant density. Traits monitored for single plants included fresh and dry weight, leaf area, specific leaf area, dry weight ratio between root and shoot, and chlorophyll content. The high density experiment showed more genotypic variation for the observed traits than the low density one. Biomass production was considerably lower at low than at high N. Path analysis revealed that leaf area had the highest direct effect on NUE, while specific leaf area was an important trait determining variation in NUE at low N. Slow and fast growing genotypes were shown to use different strategies to utilize N, and these strategies are expressed differently at high and low N availability. This indicates that improving spinach for NUE is feasible using the analysed genotypes as source material, and different strategies can be targeted for adaptation of spinach cultivars to low N conditions.  相似文献   

11.
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12.
苗期耐低氮基因型苦荞的筛选及其评价指标   总被引：3，自引：0，他引：3  
张楚  张永清  路之娟  刘丽琴 《作物学报》2017,43(8):1205-1215
土壤缺氮是造成我国黄土高原冷凉地区农业低产的主要原因。为了筛选耐低氮苦荞基因型及适宜鉴定指标,采用苗期水培方式,测定9个不同基因型苦荞在不同氮水平下的农艺性状、生理特性及植株氮素利用等指标,采用隶属函数法计算各指标耐低氮指数,通过主成分分析与聚类分析评价各基因型苦荞综合耐低氮能力。结果表明,低氮胁迫下,苦荞地上部生长受抑制程度大于根系,株高、茎粗、叶面积、地上部干重、根系体积、根系表面积及根系平均直径均呈下降趋势,主根长和根冠比呈上升趋势;根系活力、根系硝酸还原酶(NR)活性及可溶性蛋白含量有所下降,而根系超氧化物歧化酶(SOD)、过氧化物酶(POD)活性、丙二醛(MDA)、可溶性糖及游离脯氨酸含量有所升高;叶片叶绿素含量、Fm和Fv/Fm降低,而Fo升高;植株全氮含量及氮积累量降低,而由于植株氮积累量降幅明显大于生物量降幅,导致氮利用效率显著升高。将25个单项指标转化为4个相互独立的综合指标(累计贡献率达87.44%),并将9个苦荞基因型划分为耐低氮型、中间型和不耐低氮型。为了预测苦荞基因型的耐低氮能力,将D值作因变量,各指标耐低氮指数作自变量进行逐步回归分析,建立最优回归方程,筛选出株高、茎粗、叶面积、根冠比、叶绿素含量、Fm、根系超氧化物歧化酶(SOD)活性及氮利用效率8项对苦荞耐低氮能力有显著影响的指标,并且9个苦荞基因型的苗期耐低氮能力预测值Y与D值显著相关(R2=0.998,P0.01),表明这8个指标可用于耐低氮苦荞基因型的快速鉴定。  相似文献   

13.
水稻氮高效基因型及其评价指标的筛选   总被引：20，自引：1，他引：20  
以48份不同水稻基因型为供试材料，研究了它们的氮素吸收和利用率，及其与主要农艺性状之间的关系。结果表明，水稻基因型在氮素吸收利用率方面间存在明显差异，从现有的材料中可筛选出氮高效基因型。长伦占不论在低氮处理还是高氮处理均表现出氮高效利用特性，为典型的氮高效基因型。此外，还筛选了适于低氮条件种植的广恢128和茉莉占选；适于高氮条件种植的97香、2466和银花占。低氮高效型适合在贫瘠地区种植，而高氮高效型适合在肥沃地区种植。结果表明，水稻氮素利用率与抽穗期及乳熟期倒2、倒3叶的叶绿素含量呈显著或极显著负相关；与收获指数、稻谷产量和穗数之间均呈极显著正相关，它们可作为水稻氮素利用效率的评价指标。但是水稻氮素吸收率与利用率之间存在极显著负相关，因此，如何协调二者关系，既能提高稻谷产量和氮素利用率，又减少施氮量是急需解决的问题。  相似文献   

14.
Temperature and other abiotic factors, such water and nutrient availability, play an important role for plants in response to the changing environments. At this regard, both warming and drought might affect the nutrient use efficiency (NUE) and growth of Megathyrsus maximus a C4 forage grass of high interest for cattle feeding. However, the nutrient requirements of this species under climate change are unknown. Therefore, we aimed to evaluate the individual and combined effects of two levels of temperature: ambient and elevated temperature (2°C above ambient temperature), and two levels of soil water availability: irrigated plants and non‐irrigated plants on accumulation of leaf nutrients, NUE and biomass production of M. maximus. Temperature control was performed by a temperature free‐air‐controlled enhancement (T‐FACE) system under field conditions. In general, we observed that warming under well‐irrigated conditions increased the leaf accumulation of most nutrients, improving the NUE of N, P, K, Ca, Mg, Cu, Mn and Zn. Plant growth was also enhanced under warming effects, with higher leaf dry mass accumulation and root development. Meanwhile, drought decreased NUE of K, Ca, B and leaf dry biomass, while root growth was stimulated. The combined effects of warming and drought on nutrient accumulation, NUE and plant growth tended to be greater than the individual effects expected from a single factor; thus, warming mitigated the negative impacts of individual drought. In summary, our findings suggest that warming and drought, both as individual and combined factors, will change the nutrient requirements of M. maximus in tropical ecosystems.  相似文献   

15.
棉花氮素和SPAD值叶位分布规律研究   总被引：16，自引：1，他引：15  
 在盆栽和大田氮肥试验的基础上,研究棉花氮素和叶绿素含量（SPAD值）随叶位的空间分布特征,并对不同叶位叶片的含氮率、SPAD值之间及其与总叶片含氮率和植株含氮率之间的相关性进行了分析。结果表明棉花不同叶位叶片含氮率、叶绿素含量、SPAD值均存在差异,增加施氮量能提高叶片含氮率、叶绿素含量和SPAD值,同时减小叶位间的差异;SPAD值对氮素的敏感性为倒4叶最高,倒2叶最低,而倒1、倒3叶的敏感性排序因品种不同而不同;蕾期、初花期和盛花期均以倒4叶与总叶片及植株含氮率相关系数最高;且适宜氮素水平下,初花期倒4叶SPAD值的变异系数最小。以某一特定叶片的SPAD值或以叶色差的大小来诊断棉花氮素营养状况时,倒4叶是较为理想的指示叶。  相似文献   

16.
A pot‐culture experiment was conducted under outdoor conditions to determine effects of nitrogen (N) deficiency on big bluestem (Andropogon gerardii Vitman, cv Bonelli) growth, photosynthesis and leaf reflectance (R) properties. Big bluestem was seeded on 14 May 2004 and grown in 120 twelve‐litre pots filled with fine sand and irrigated with Hoagland’s nutrient solution (with 81 mg L?1 as N). Treatments initiated at 60 days after sowing (DAS) included: (1) the control (100N) continued receiving the Hoagland’s nutrient solution; (2) reduced N to 20 % of the control (20N); and (3) withheld N from the solution (0N). Chlorophyll (Chl) and N, and reflectance of the uppermost fully expanded leaves were determined at 10‐d intervals from 60 to 115 DAS during the N treatments. Plant growth and developmental parameters were measured at the end of the experiment, 115 DAS. Nitrogen deficiency caused a reduction in leaf Chl content, rate of photosynthesis (A), and dry weight (DW) of biomass components. Deficit N increased leaf reflectance at 555 (R555) and 715 (R715) nm and caused a shift in red‐edge (685–745 nm) to shorter wavelengths. Leaf N and Chl concentrations were linearly correlated with not only the reflectance ratios of R545/R1605 (r2 = 0.82) and R555/R405 (r2 = 0.81), respectively, but also the first derivatives of the reflectance (dR/dλ) in red‐edge centred 690 or 700 nm (r2 = 0.74–0.83). Leaf and panicle DW had the greatest, while root DW had the smallest decrease under N deficiency. It was concluded that the specific reflectance ratios or dR/dλ may be used for rapid and non‐destructive estimation of leaf Chl and plant N status of big bluestem to detect changes in N for appropriate nitrogen management strategies during the growing season.  相似文献   

17.
采用砂培试验研究了不同小麦基因型对施锌的反应.通过比较小麦幼苗根冠比的大小(是否大于1),以及根据培养过程中植株的生长表现,将供试的25种小麦基因型划分为两类:即缺Zn敏感型和非敏感型.结果还表明,供Zn可以促进小麦地上部和根系的生长,均较大幅度提高了叶绿素SPAD值(25个小麦基因型中18个的增幅都超过10%),而根冠比则相对保持稳定.小麦种子中的锌含量、幼苗根冠比与小麦叶片叶绿素SPAD值之间均无显著性相关关系.由于地上部积累了较高浓度的Zn,缺Zn非敏感型可有效减轻缺Zn对其造成的危害.非敏感型与敏感型相比较,缺Zn条件下地上部和根系锌含量平均值分别高出96.6%和28.8%,而在供Zn条件下则高出47.6%和10.9%.施Zn对敏感型与非敏感型小麦体内磷含量并无显著性影响.小麦幼苗中P/Zn的大小主要受到小麦体内Zn含量变化的影响,与磷含量则无明显的关系.  相似文献   

18.
为探讨生物质炭输入对盐胁迫下玉米幼苗生长和光合生理特性的影响,在温室以轻、中、重度盐渍化土壤模拟盐胁迫环境,设置0(CK),1%,2%,4%,8%生物质炭输入水平,进行玉米盆栽试验。对玉米幼苗生长、SPAD、净光合速率(Pn)等光合参数进行测定。结果表明:盐胁迫条件下玉米幼苗叶片叶绿素含量、光合作用等均受到抑制,进而影响玉米幼苗生长,干物质累积量、单株叶面积均显著降低。生物质炭输入能有效缓解盐胁迫对玉米幼苗生长的抑制。8%生物质炭输入水平对轻度盐胁迫下玉米幼苗生长的促进作用最显著:干物质累积量、SPAD、叶面积分别较对照增加116.22%,36.09%,107.67%,Pn、Tr、Gs分别较空白对照处理高76.60%,57.76%,17.33%;2%生物质炭水平下中度盐胁迫干物质累积量、SPAD、叶面积最高,分别较空白对照处理增加138.04%,18.92%,23.50%,Pn、Tr、Gs分别较空白对照处理高78.48%,55.56%,26.23%;8%生物质炭输入重度盐渍化土壤玉米幼苗干物质累积量、单株总叶面积最高,分别较空白对照处理高483.33%,92.32%,但SPAD在4%输入水平最高,较空白对照处理高71.50%。8%生物质炭输入重度盐渍化土壤玉米幼苗叶片Pn、Tr、Gs分别较CK处理高120.00%,88.78%,17.39%。生物质炭输入盐渍化土壤可通过自身特性增加土壤中矿质养分含量,改善土壤持水能力,提高植株叶绿素含量,促进光合作用,缓解盐胁迫对玉米幼苗生长的抑制作用,可应用于盐渍化土壤的改良。  相似文献   

19.
采用SPAD仪进行甜菜氮素营养诊断技术研究   总被引：2，自引：2，他引：2  
为研究甜菜大田栽培及生产过程中氮素的营养状态,以便及时补充氮素亏缺,使用SPAD-502仪(soil plant analysis development)测定了甜菜叶片不同叶位和叶序的SPAD值,发现SPAD值的分布特点及其规律性,建立了基于SPAD值的氮素营养快速诊断方法。试验设计了室内盆栽及田间试验,对不同基因型、不同发育阶段甜菜叶片不同叶位叶序的SPAD值进行测定,统计并分析SPAD值与叶片的叶绿素含量及植株全氮含量的相关性。结果表明：甜菜叶片SPAD值在不同叶位及叶序上有差异,其中叶片尖部SPAD最大值出现的次数与叶片侧缘部和叶片基部相比较有较明显优势,施氮及不施氮处理均达到50%以上;4~6片真叶期后最高叶片SPAD值与测得的同株叶片的SPAD值有较显著的相关性,所以最高叶片的叶片尖部可作为甜菜叶片SPAD值的最适测定部位;增加施氮量能提高叶片SPAD值;不同品种间叶片SPAD值也有差异;SPAD值与不同发育阶段甜菜叶片的叶绿素含量以及植株全氮含量分别建立线性方程,拟合后发现叶片SPAD值和总叶绿素含量之间为极显著相关,与植株含氮量之间为相关性显著。因此,利用叶片SPAD值可实时监测甜菜生长与光合效应,进行氮素营养的快速诊断。  相似文献   

20.
The main objective of this study was to compare the relationship between biomass yield and nutrient uptake in salt-stressed maize ( Zea mays L.) following nitrogen (N) nutrition in a greenhouse. Three forms of N were applied, each at the rate of 100 kg ha−1: urea-N, nitrate-N, 1/2 urea-N + 1/2 nitrate-N (mixed-N) and no N application (control). Maize was grown as a test crop for 6 weeks. All N sources greatly stimulated crop growth and nutrient uptake compared with the control. The biomass (shoot and root) of maize was significantly greater in mixed-N treatment than in single sources in saline soil whereas it varied in the order of urea-N > mixed-N > nitrate-N > control in non-saline soil. Under both soil conditions, the concentration of Ca, Mg and Na in shoot was highest in nitrate-N treatments while that of K was highest in the control. Shoot nitrogen concentration was not significantly different among N sources under non-saline treatment, whereas under saline conditions, the concentration varied markedly in the order of nitrate-N > urea-N > mixed-N > control. The mineral concentrations in the shoot increased under salt treated soil when compared with non-saline soil. The ratios of Na/K, Na/Ca and Na/Mg were also higher under salt stress due to higher accumulation of Na ion in the shoot. Among N-fertilizer sources, Na/Ca and Na/Mg ratios were highest in control whereas Na/K ratio was the highest in nitrate-N treatment. The lowest cation ratios were noted in mixed-N-treated plants under both soils. Regression analysis showed that maize biomass was related to N concentration by the following equations: Y = −4.54 + 0.97N for the non-saline soil and Y = 0.89 + 0.25N for the saline soil. Nitrogen use efficiency for non-saline soil exceeded that of saline soil by 15 %.  相似文献   

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