减量控释氮肥对大棚甜椒产量及土壤硝态氮、铵态氮分布的影响

采用田间试验方法研究不同控释氮肥施用量对大棚甜椒生长及硝态氮、铵态氮含量分布的影响。结果表明,控释氮肥处理对大棚甜椒的产量、肥料利用率、氮肥农学效率、氮肥偏生产力较常规施肥有不同程度的提高,以RF30处理最佳。各施肥处理均显著增加了土壤全氮、甜椒Vc、可溶性糖、硝酸盐的含量,降低了可滴定酸的含量。施肥处理显著增加了0-60cm土层硝态氮含量,满足了甜椒在不同时期对氮素的需求。控释氮肥处理0-60cm土层铵态氮含量差异不大,常规施肥铵态氮含量明显下降。综合考虑在农民习惯性施肥基础上施用70%控释氮肥可以保证较高的产量和较好的果实品质。     

Leaf Chlorophyll Readings as an Indicator for Spinach Yield and Nutritional Quality with Different Nitrogen Fertilizer Applications

The objective of this study was to investigate the possibility of predicting the concentrations of total nitrogen (N), nitrate-nitrogen, and ascorbic acid in spinach (Spinacia oleracea) leaves using the pocket chlorophyll meter SPAD-502 (Minolta, Japan) in a pot experiment in a greenhouse. Spinach plants were grown in plastic pots filled with 0.5 kg of brown soil per pot with urea as N fertilizer at 0, 30, 60, 120, and 240 mg N/kg soil. SPAD readings of the two uppermost fully expanded leaves were recorded 18, 25, and 32 d after sowing and at harvesting (34 d). Dry-matter biomass and total N concentrations in leaves and roots, and NO₃-N, and ascorbic acid concentrations in leaves, were measured after harvesting. SPAD readings showed continuous reduction with increasing growth period irrespective of N applications. SPAD readings at harvest were significantly correlated with total N, leaf dry weight (DW), and NO₃-N concentration. However, this correlation did not exist between SPAD readings and ascorbic acid concentrations in leaves. The above results suggest that it is possible to apply SPAD readings to estimate NO₃-N concentrations in spinach plants, and that they may be applied for field assessments in decision-making and operational nutrient-management programs for the plant. Furthermore, the SPAD method may also be useful for ascertaining the harvest time. The results suggest that treatment with 120 mg N/kg significantly improved both leaf yields and leaf quality (i.e., leaf nitrate-N concentration and ascorbic acid). Too little and too much N fertilizer was not good for yield or spinach quality.     

Establishment of Chlorophyll Meter Measurements to Manage Crop Nitrogen Status in Potato Crop

Management of nitrogen (N) use is necessary to promote maximum development and production of tubers. For this reason, chlorophyll meters have been used to make N-fertilizer recommendations in potato. An assay was carried out with increasing doses of N. To define the thresholds IV for potato crops, correlations among IV, ISN, RR, and N content had been established. IV is the green index of the leaf measured by the chlorophyll meter. This index estimates the chlorophyll content in the leaf and through this the N concentration in vegetal tissue, based on the assumption that N and chlorophyll content have a strong correlation. ISN is the sufficiency nitrogen index. It was determined as the relation between the green index reading of each experimental unit and the highest average green index reading of the assay. RR is the relative yield. It was calculated as the ratio between the yield of each treatment and the highest average yield of the assay. The results had shown that varieties did not present N deficiencies during the vegetative growth phase, with IV and ISN values respectively equal to 41 SPAD units and 93 percent. During the tuber bulking phase, the necessary IV and ISN thresholds to reach maximum yields, for N content equal to 3 percent, were, respectively, between 38.5 and 40.5 SPAD units and between 84 and 94.8 at 70 and 89 days after planting. We concluded that the chlorophyll meter is an appropriate tool to determine the nutritional status in potato crops.     

Nitrogen Uptake and Allocation in Sweet Viburnum During a Root Growth Flush

Most woody ornamentals exhibit episodic growth flushes and nitrogen (N) uptake has also been demonstrated to be seasonal. However, there is little information on N uptake in relationship to plant growth cycle. In this study, N uptake and allocation of sweet viburnum during periods of low and high root elongation rates were studied. Plants were fertilized with ammonium nitrate (¹⁵NH₄ ¹⁵NO₃) and after 6 d N absorption was determined. Significantly more N was absorbed by plants with low root elongation rate compared with plants with high root elongation rate. About 70% of the N absorbed by plants with low root elongation rate was allocated to the mature leaves compared to 35% on plants with high root elongation rate. It was evident that root growth activity influenced N absorption and allocation. Although only a small amount of the N absorbed by plants with low root elongation rates was allocated to the immature leaves, significantly more N was allocated to the immature leaves by plants with high root elongation rates. It is possible that the N necessary to support immature leaf growth, when root elongation rate is low, is provided by mobilization from other parts, possibly mature leaves.     

Nitrogen Concentration and Dry-Matter Accumulation in Maize Crop: Assessing Maize Nitrogen Status with an Allometric Function and a Chlorophyll Meter

The ability to determine the optimal nitrogen (N) content in maize plants needed to obtain maximum growth is important to the management of the crop. It has been shown that N content declines as a function of aboveground biomass accumulation (W): [N] = 3.4W^–0.37. The goal of this study is to evaluate the applicability of relating chlorophyll meter readings with the optimal N content relationship to provide a tool for whole-plant N-status diagnosis in maize without the necessity of measuring N content. Biomass of shoot and specific organs, N concentration, and chlorophyll meter measurement of specific leaves were measured over several sites and years. Nitrogen-concentration measurements indicated that whole-plant N status can be represented by the N concentration of the topmost fully expanded leaf. A quantitative relationship between N concentration and chlorophyll meter measurement on the uppermost expanded leaf was established and validated.     

Seasonal Effect on Growth Parameters and Macronutrient Use of Sweet Pepper

ABSTRACT

Sweet pepper plants (Capsicum annuum L.) grown under greenhouse conditions differed widely in the rate of production of their total dry mass and their harvestable weight, although there was not shortage in water or nutrient supply. Plants were grown in aerated nutrient solutions along two different growing seasons. The differences in plant productivity were mainly due to the environmental conditions of the growth cycle. During the increasing day length season, from the beginning of spring to summer (13.0 to 14.8 h day^{? 1}), plants produced the largest amount of fruits, but with a 10% blossom-end rot incidence. In the season of short photoperiod, progressing from the beginning of autumn to winter with 13.3 to 10.3 light h day^{? 1}, the total dry weight and yields gradually decreased, but blossom-end rot in fruit did not appear. Different growth patterns were found for morphological and physiological parameters, because of the different light loads received by the canopy, being adjusted to the seasonal variables. Reduced light load markedly reduced leaf area and leaf thickness, but increased specific leaf area, which gave plants an increased ability to intercept light. Not only the amount of initial biomass, but radiation and the age of the pepper plants were the main growing driving factors, influencing relative growth rate, nitrogen (N)-use efficiency, and calcium (Ca) partitioning. Moreover, mathematical approaches for prediction of biomass production and N accumulation as a function of radiation are given in order to establish in the future a sweet pepper growth model.     

Reliability of Chlorophyll Meter Measurements Prior to Corn Silking as Affected by the Leaf Change Problem

The normal practice of using chlorophyll meters involves measuring the youngest fully developed leaf of a corn plant (Zea mays L.) before silk emergence and then switching to the ear leaf. A discontinuity exists of chlorophyll meter measurements associated with leaf change prior to the silking stage. The lag of silk emergence within a cornfield prior to silk emergence makes it practically impossible to take chlorophyll measurements on leaves at the same growth stage. Therefore, the change in leaves being measured introduces errors when chlorophyll meters are used prior to silk emergence to diagnose nitrogen (N) deficiencies. We report results from three field studies to assess the difference in chlorophyll measurements between the uppermost fully developed leaf and the ear leaf near the time of silk emergence and identify possible problems associated with the difference when chlorophyll meters are used to estimate the need for in‐season fertilization in cornfields.     

氮素营养对甜椒果实生长发育的影响

采用营养液培养试验,研究了氮素营养对甜椒果实生长发育的影响。结果表明,氮素营养过高,门椒难以座果,首次商品果实的上市时间推迟7d以上。氮素营养对甜椒前期商品果产量及产量性状的综合影响看出,中氮营养处理可获得最高的商品果产量,主要是各层位果实的高收果数,而与单果鲜重差异不明显;氮素营养过高或过低均导致商品果产量降低,因单株平均收果数降低,且单果重下降。高氮营养有利于提高后期幼果座果率。试验还发现,甜椒的结果习性在很大程度上取决于其植物学特性,氮素营养对果实发育进程的促进或延缓作用在某种程度上可能大于对结果数量的影响。中氮营养条件下,二分侧枝整枝方式对甜椒的结果数量和产量的影响符合等比数列Y=2(n-1)的理论模型。     

不同土壤肥力水平下施氮对甘薯产量与氮肥利用率的影响

为探明不同土壤肥力条件下施用氮肥对甘薯产量和氮肥利用率的影响,选取鲜食型甘薯品种烟薯25号为试验材料,采用大田试验,研究了施氮对不同土壤肥力下甘薯产量及产量构成因素、干物质积累规律和氮肥利用率的影响。结果表明:不施氮条件下,甘薯蔓数、最大蔓长度、叶面积指数和产量均表现为高肥力中肥力低肥力(P0.05)。3种土壤肥力条件下,增施氮肥均能显著增加甘薯蔓数、最大蔓长度和叶面积指数(P0.05),但对最大蔓节间数影响不显著。高肥力、中肥力和低肥力地块分别在施氮量为50,100,150kg/hm~2时获得最高产量,分别较不施氮处理(N0)增产16.06%,29.63%和33.33%。与地力条件无关,增施氮肥均能提高甘薯地上部干物质累积量。中、低土壤肥力条件下,甘薯氮累积量随施氮量增加逐渐增加,而高土壤肥力条件下呈先增加后降低的趋势;高肥力地块氮肥利用率随施氮量增加而逐渐降低,中肥力地块先增加后逐渐降低,在100kg/hm~2时氮肥利用率最高,低肥力地块逐渐增加。综合产量和氮肥利用率,可知高肥力、中肥力和低肥力地块甘薯适宜施氮量分别为50,100,150kg/hm~2。     

Relationship Between the Normalized SPAD Index and the Nitrogen Nutrition Index: Application to Durum Wheat

In a three-year field experiment in Toulouse (in Southwest France), two indicators of plant nitrogen (N) status were compared on five durum wheat cultivars: the normalized SPAD index and the nitrogen nutrition index (NNI). SPAD value is a non-destructive measurement of chlorophyll content from the last expanded leaf. The normalized SPAD index is expressed relative to SPAD reading on a fully fertilized crop. The NNI is calculated from the crop biomass and total plant N content using a universal N-dilution curve for wheat. The normalized SPAD index and NNI were closely related irrespective of year, cultivar, and growth stage. When N was a limiting factor, the SPAD index measured at anthesis predicted grain yield and protein content accurately. Unlike NNI, SPAD index cannot be used to predict these variables when wheat is over-fertilized.     

Nitrogen Uptake Efficiency and Growth of Bell Pepper in Relation to Time of Exposure to Fertilizer Solution

Irrigation of high‐value vegetable crops on sandy soils with poor water‐retention capacities may result in fertilizer nitrogen (N) displacement below the effective root zone prior to complete crop uptake. As a result, fertilizer N‐uptake efficiency (FUE) of vegetable crops is often relatively low, thereby increasing the potential risk of groundwater contamination. The objective of this study was to determine how time of exposure of the root zone to the N fertilizer (which is referred to as “fertilizer residence time” or t _R), as related to irrigation management, affects N uptake, FUE, growth, and yield of bell pepper (Capsicum annuum L.). Plants were grown in PVC columns with 45 kg of soil equipped with a drainage valve in the bottom of the column. Weekly irrigation with dissolved fertilizers (potassium nitrate; KNO₃) was applied 1, 3, or 7 d before weekly removal of residual soil N by leaching. Weekly N uptake rates were calculated by comparing total N recovery between unplanted (reference) and planted columns. At 77 d after planting, increasing the t _R from 1 to 3 or 7 d increased the weekly N uptake from 1.4 to 10.8 and/or 13.3 kg N ha^?1, respectively. Total calculated plant N accumulations were 19, 72, and 106 kg N ha^?1 for the 1‐, 3‐, and 7‐d t _R treatments, with overall FUE values being 8, 31, and 45%, respectively. It is concluded that during initial growth crop, uptake capacity is limiting, and more frequent (daily) fertilizer injection into the irrigation water may be required to enhance FUE. It is proposed also that via sound or innovative irrigation management practices, fertilizer retention in the root zone can be enhanced, thereby improving crop growth, yield, and FUE while reducing production cost and potential environmental impacts.     

Effect of Nitrogen on Yield and Some Quality Parameters of Sweet Corn

Sweet corn consumption has increased considerably worldwide. Sweet corn is produced for human consumption as either a fresh or a processed product. The nutrient composition of sweet corn is very important for human health and diet. This study aimed to determine the best nitrogen (N) dosage for sweet corn. Kernel mineral composition and protein content were determined for different N rates. The research was carried out during 2003 and 2004 in Sanliurfa, Turkey. Nitrogen application rates were 120, 160, 200, 240, 280, 320, and 360 kg N ha^?1 with control. The fresh ear yield per hectare and the protein and mineral contents of kernel were significant (P < 0.01). The lowest yield was obtained at low N applications, whereas increasing N applications increased the fresh ear yield and protein content of kernel. Nitrogen-use efficiency increased up to 320 kg ha^?1 N dosage (60.2% and 58.6% for 2003 and 2004, respectively), and a decrease was seen at 360 kg ha^?1 N dosage. Leaf area index and root dry matter increased with increasing N supply. The copper concentration of the kernel was generally positively affected by increasing N application. Iron and zinc contents of kernels increased, whereas manganese content decreased, with increasing N doses. At the focus of regression analysis, the best N dosage was 320 kg ha^?1 along with the soil N content for Vega sweet corn variety grown in the southeastern Anatolia region of Turkey.     

Optimizing Nitrogen Fertilization for Production of White and Orange-Fleshed Sweet Potato in Southeast Nigeria

ABSTRACT

Two field experiments were used in 2005–2006 to study the effects of nitrogen (N) on light interception, weed biomass, and yield of white and orange-fleshed sweet potato varieties in southeastern Nigeria. Treatments comprised four N levels (0, 40, 80, 120 kg N ha^?1) and four varieties of sweet potato (White-fleshed TIS 87/0087 and TIS 8164, orange-fleshed Ex-Igbariam and CIP Tanzania), arranged in randomized complete block design with three replications. Nitrogen application up to 120 kg N ha^?1 increased light interception, leaf area index and shoot dry matter. Regardless of rate, N application reduced weed growth at 12 weeks after planting. On average, the storage root yield increased with N application up to 80 kg N ha^?1 when the background soil N was 0.056% in 2005, but not beyond the rate of 40 kg N ha^?1 when the background N was 0.104% in 2006. The white-fleshed TIS 87/0087 followed by orange-fleshed Ex-Igbariam out-yielded other varieties and intercepted over 70% of the incident radiation.     

Boron Nutrition of Four Sweet Pepper Cultivars Grown in Boron-Deficient Soil

ABSTRACT

In a greenhouse study, boron (B) application significantly increased dry-matter yield of sweet pepper (Capsicum annum L.) cultivars (‘California Wonder,’ ‘Anahein,’ ‘Narwala,’ and ‘2573’) grown in a B-deficient (hot-water extractable, 0.28 B mg kg^?1), calcareous soil of the Shujabad series (Typic Ustochrepts). Five rates of B, ranging from 0 to 8 mg B kg^?1 soil, were applied as H₃BO₃ along with adequate basal fertilization of nitrogen (N), phosphorus (P), potassium (K), and zinc (Zn). Four plants of sweet pepper were transplanted in each pot, two of which were harvested after three weeks of transplanting and the other two after six weeks. Maximum crop biomass was produced with ～1 mg B kg^?1, but application of higher rates proved toxic, resulting in dry-matter yield reductions. The four cultivars significantly differed in relative growth rate (RGR) and relative accumulation rate of B (RARB). Cultivar ‘2573’ showed the highest RGR while ‘Anahein’ showed the highest RARB. Relative accumulation rate was positively correlated (R² = 0.83) with dry-matter yield of four cultivars. Critical B concentration in sweet pepper whole shoots was 69 mg B kg^?1 for three-week-old plants and 49 mg B kg^?1 for six-week-old plants.     

镉污染水稻土中水稻氮素营养的SPAD诊断

治理和安全利用重金属污染水稻土过程中,氮素营养的快速诊断是制定合理施肥措施的基础。叶绿素测定仪SPAD已广泛应用于非污染耕地土壤中玉米、小麦和棉花等作物的氮素营养诊断,然而针对镉污染条件下的不同类型水稻土,SPAD在诊断水稻氮素营养的适应性方面仍然缺乏系统研究。本研究采集了我国水稻主产区的21种典型水稻土,以德农2000为供试水稻品种,设置无镉污染、轻度镉污染、重度镉污染处理的水稻盆栽试验,研究水稻叶片SPAD值对镉污染水稻土氮素供应诊断和水稻产量预测的能力。结果表明:水稻土类型影响了水稻叶片SPAD值对不同水平镉污染的响应,土壤p H是主控因子,其相对影响的平均值为20%。水稻叶片SPAD值与不同生育期水稻籽粒氮素含量显著正相关,其中拔节期的相关系数最大;同时水稻叶片SPAD值与水稻营养生长期(苗期至拔节期)土壤溶液总氮和铵态氮含量呈显著正相关,且不受镉污染程度和土壤类型的影响。总体上,不同生育期(尤其是拔节期)水稻叶片的SPAD值可以表征镉污染条件下不同类型水稻土氮素养分供应对水稻氮素营养的影响。     

旱地不同冬小麦品种氮素营养的叶绿素诊断

通过田间试验研究了叶绿素仪用于西北旱地主栽的10个冬小麦品种氮素营养诊断的效果。结果表明,冬小麦SPAD值与子粒产量、生物学产量有很好的相关性,尤其以拔节期和开花期相关性较高。不同施氮量下的SPAD值有明显的不同,施氮量为180kg/hm2时,SPAD值达到最大。在同一施氮水平下,开花期的SPAD值均最高。拔节期之前冬小麦不同品种间SPAD值的差异较小,拔节期以后差异较大,最大可达9.2个SPAD单位。小偃22在每个时期的SPAD值都最高,并且与陕253、陕229和小偃503之间的差异均达显著水平,而陕253、陕229和小偃503之间的差异不显著。可见,小偃22与其它3个品种对氮素反应分属于不同类型,应根据不同品种类型建立相应的诊断指标。     

Effect of Salt Stress on Growth and Chlorophyll Content of Some Cultivated Cotton Varieties Grown in Syria

Five upland cotton varieties (Gossypium hirsutum L.) (Aleppo 118, Aleppo 33/1, Aleppo 90, Raqqa 5, and Deir-Ezzor 22) were evaluated under different salinity indices [0, 50, 100, and 200 mM sodium chloride (NaCl)] for 56 days. During the course of the experiment, plant size (HT), leaf number (LN) and leaf area (LA), chlorophyll SPAD (Soil Plant Analyses Development), chlorophyll (Chl) a and b content, and osmotic potential were measured in both control and salt-stressed plants for all tested varieties. Salt-stress application reduced the HT and LN of all varieties, whereas LA decreased as salinity level increased for all tested varieties comapared to their respective control expect for Deir-Ezzor 22 variety. Our data showed that LA, Chl a and b, and chlorophyll SPAD can be used to discriminate between salt-tolerant varieties and salt-sensitive ones. In this respect, Deir-Ezzor 22 variety differed by showing high salt tolerance relative to Aleppo 118 and Aleppo 33/1 varieties. Therefore, this investigation aimed for a better understanding of the different responses presented among these varieties toward salt treatment.     

Effect of Different Nitrogen Doses on Dry Matter Ratio,Chlorophyll and Macro/Micro Nutrient Content in Sweet Herb (Stevia rebaudiana Bertoni)

With this study, the effect of different nitrogen (N) doses applied to sweet herb (0, 50, 100, 150 and 200 N kg ha^?1) on the macro/micro nutrient element content, dry matter ratio and on the chlorophyll amount in the plant leaves is examined. The research was carried out in the research and trial field of Faculty of Agriculture Agronomy department, Akdeniz University, during the 2012–2013 growing season under field conditions for 2 years with four replications according to the randomized block trial design. Chlorophyll amounts were determined and the average was obtained with three readings from each leaf by a chlorophyll meter when the plants were in the beginning of flowering. Post-harvest macro and micro nutrient elements of the sweet herb were also investigated. According to the obtained data, while the highest chlorophyll and N amounts in the leaf for both the first and second years were determined as 46.97 SPAD (Minolta Corp, NJ, USA) and 1.34 N% 44.9 SPAD, 1.42 N%, respectively, under 200 kg ha^?1 N application, the lowest chlorophyll and N amounts were determined in the control group. In addition, N application in different doses for both years increased the phosphorus (P) and potassium (K) contents and increased the microelement contents, especially in the second year. At the same time, a correlation between the chlorophyll content in the plant leaves and the N amount was determined and a linear increase was observed in the chlorophyll amount with the increased green part.     

补光时间及光质对温室甜椒矿质元素吸收与分配的影响

为探究发光二极管(LED)补光对温室甜椒矿质元素吸收及分配的影响,以甜椒品种奥黛丽为试材,设置红光(R)和蓝光(B)组合2∶1(2R1B)、4∶1(4R1B)、8∶1(8R1B) 3种光质,2 h(18:00-20:00)、4 h(18:00-22:00)和8 h(18:00-02:00) 3个补光时间,以不补光为对照(CK),研究补光时间及光质对甜椒N、P、K、Ca、Mg、Mn、Zn积累及分配的影响。结果表明,光质与补光时间显著影响矿质元素在甜椒中的积累与分配,且二者存在显著的交互作用。与CK相比,LED补光显著促进了甜椒全株中N、P、K、Ca、Mg和Mn的积累,光质对N、P、K、Mg、Mn积累总量的影响无显著差异,但补光时间会显著影响矿质元素的积累,以补光8 h的元素积累量最高,其N、P、K、Ca、Mg和Mn的单株积累量分别较CK增加51.82%、55.56%、47.55%、50.00%、56.76%和36.23%,补光4 h的N、Ca、Mn积累总量与补光8 h无显著差异。从分配比例来看,与CK相比,补光2 h降低了N、P、Mg、Mn在果实中的分配比,补光4 h提高了N、P、K、M...     

施用生物质炭和生石灰对连作辣椒生长的影响

为探究生物质炭和生石灰对连作辣椒生长的影响,以辣椒为材料,采用大田方式,设置8个处理,即对照处理(不加任何生物质炭和生石灰的辣椒连作土,CK);单施生物质炭处理(1.5 kg·m^-2,T2);生物质炭+生石灰处理(1.5 kg·m^-2生物质炭+0.15 kg·m^-2生石灰,T3;1.5 kg·m^-2生物质炭+0.225 kg·m^-2生石灰,T4;3.0 kg·m^-2生物质炭+0.3 kg·m^-2生石灰,T5);单施生石灰处理(0.15 kg·m^-2生石灰,T6;0.225 kg·m^-2生石灰,T7;0.3 kg·m^-2生石灰,T8),研究各处理对连作辣椒生长指标、果实特征及产量疫病发病率以及土壤理化性质的影响。结果表明,在辣椒连作土壤中添加适量的生物质炭和生石灰能够显著促进辣椒的生长发育,改善辣椒根际土壤环境。单施生石灰或生物质炭对辣椒的各项生长指标促进效果差异较大,而适量的组合施用生石灰和生物质炭处理(T4)的辣椒株高、茎粗以及壮苗指数总体上高于其他处理,对辣椒生长促进作用最为明显。单施生物质炭处理(T2)并不能显著增加辣椒植株的鲜重和干重,而单施生石灰处理后随着施用量的增加会表现出抑制作用。T4对辣椒植株鲜重和干重增加效果明显,定植90 d时,辣椒地上部干重和鲜重、辣椒根系干重和鲜重分别增加了21.34%、21.34%、14.40%、13.34%;同时,辣椒的单株产量和总产量较CK均增加了23.37%,但与其他处理差异不显著。施用生物质炭和生石灰能够显著降低辣椒疫病的发生率,与CK相比,T5的发病率和病情指数均最低,分别为8.33%和3.47,对病害的控制作用最显著。施用生石灰和生物质炭对辣椒土壤中养分含量的增加有促进作用;各处理对土壤pH值无显著性差异(P>0.05),均在6.3~6.8之间。本研究结果为缓解辣椒连作障碍及生产实践提供了理论指导。