Nitrate/ammonium ratio effects on mineral element uptake by sorghum 1

Abstract

Experiments were conducted using different NO₃ ^–/NH₄ ⁺ ratios to determine the effects of these sources of N on mineral element uptake by sorghum [Sorghum bicolor (L.) Moench] plants grown in nutrient solution. The NO₃ ^–/NH₄ ⁺ ratios in nutrient solution were 200/0, 195/5, 190/10, and 160/40 mg N L^–1. Nutrient solutions were sampled daily and plants harvested every other day during the 12‐day treatment period.

Moderately severe Fe deficiencies were observed on leaves of plants grown with 200/0 NO₃ ^–/NH₄ ⁺ solutions, but not on the leaves of plants grown with the other NO₃ ^–/NH₄ ⁺ ratios. As plants aged, less Fe, Mn, and Cu were translocated from the roots to leaves and leaf/root ratios of these elements decreased dramatically in plants grown with 200/0 NO₃ ^–/NH₄ ⁺ solutions. Extensive amounts of Fe, Mn, and Cu accumulated in or on the roots of plants grown with 200/0 NO₃ ^–/NH₄ ⁺ solutions. Manganese and Cu may have interacted strongly with Fe to inhibit Fe translocation to leaves and to induce Fe deficiency. As the proportion of NH₄ ⁺ in solution increased, K, Ca, Mg, Mn, and Zn concentrations decreased in the leaves, and Ca, Mg, Mn, and Cu concentrations decreased in roots. Potassium and Zn tended to increase in roots as NH₄ ⁺ in solution increased.     

Efficiency of nitrogen fertilization in sweet sorghum

Abstract

In spite of a high N requirement, sweet sorghum hasn't shown a consistent response to N fertilization. This research was designed to study the effect of N fertilization on sweet sorghum as affected by rates and time of N application. Five experiments were conducted under field conditions, where 0, 50, 100 and 150 kg N/ha were applied at sowing, and 35, 40, 55, 60 and 80 days after plant emergence. The soil had textures varying from sandy loam to clay, and organic matter contents from 0.67% to 1.9%. The highest yields were observed when N was applied early in the season, showing that for sweet sorghum, sidedressing with N is not necessary. All the N can be applied at planting time, which allows the highest fertilizer use efficiency. On the other hand, late applications of N fertilizer (after 40 days), when the floral primordia is already visible, has little effect on stalk or grain yield. In this situation, a double or triple rate had to be applied to overcome the low efficiency of N utilization. There was no great advantage in splitting the sidedressed N rate. On the other hand, it was impossible to link the response to N to soil analysis as performed in most of Brazilian laboratories.     

Effects of solution pH on the growth and chemical composition of rice plants

Rice plants were grown in solution culture for a period of five weeks at pH's ranging from 3.5 to 8.5. Maximum dry matter was obtained at pH 5.5, but substantial reductions in the growth of tops and roots were observed at pH's of 3.5 and 8.5. At pH 3.5, both leaves and roots were short and unhealthy. The roots were thickened with lateral root growth severely inhibited. At pH 8.5, the youngest leaves developed chlorotic symptoms with roots being coarse and discoloured.

Plant concentrations of essential elements were adequate for normal plant growth at pH 5.5. Iron concentration in plant tops substantially decreased with increase in solution pH, but a reverse trend was observed for roots. The concentrations of other elements progressively increased in plant tops and roots with increasing pH.     

Effects of aluminum on nutrient solution pH and nitrate/ammonium uptake by triticale

Aluminum (Al) plant tolerance has been frequently associated with a pH increase in the rhizosphere. The changes in pH are dependent on plant genotypes and ionic composition and strength of nutrient solutions. This work was performed in order to study in triticale (Triticosecale Wittm.) the association of pH change with nitrogen (N) uptake and growth performance in acid conditions. Three‐day‐old seedlings were treated with Al (185 μM) in solutions having different proportion nitrate/ammonium (NO₃/NH₄), 15/1 and 8/1, but the same total N content. Along the period with Al treatment, several measurements have been made: pH, every day; NO₃ and NH₄ uptake from the solution as well as shoot and root biomass production every two days (five and seven days of plant age). The maximum growth inhibition (30%) of fresh weight was found in roots of plants in the 15/1 (NO/NH,) nutrient solution. The presence of a higher proportion of NH₄ (8/1 solution) had a protective effect on Al damage as shown by less growth inhibition and less reduction in NO₃ uptake. Changes in pH apparently were not relevant for the tolerance. The results suggest that NH₄ fertilization may be useful for alleviating Al toxicity in triticale.     

Rice responses to single application of coated urea on yield,dry matter accumulation,and nitrogen uptake in Southern China

Nitrogen is the most important element for rice (Oryza sativa L.) growth. However, excessive use of conventional urea leads to serious environmental problems in China. The objective of this study was to evaluate the release patterns of coated urea and response of rice to coated urea on dry matter accumulation, nitrogen uptake, and nitrogen use efficiencies on a clay soil. A two single-year experiment was carried out in southern China to evaluate two coated urea, polymer-coated urea (PCU) and polymer-sulfur coated urea (PSCU). Nitrogen (N) release patterns of PCU and PSCU were determined in the laboratory and in the field. The release rate of PSCU in the field was much higher than that in the laboratory. And PCU had a similar release pattern both in the field and laboratory. Compared with urea, rice fertilized with PCU and PSCU had similar dry matter accumulation, but higher grain yield and N use efficiencies. Recovery efficiency of PCU treatment reached 50% in 2012 and 60% in 2013, around 40% for PSCU, which was only 16% for single application of urea.     

氮素运筹对玉米干物质积累、氮素吸收分配及产量的影响

田间小区试验,研究了氮素运筹对玉米干物质累积、氮素吸收分配及产量的影响。结果表明,施氮和有机肥可以延长干物质积累的旺盛时期,使玉米干物质总量积累速率最大的时刻推后1～3d,增加了玉米的干物质积累量。氮肥配施有机肥能延长氮素积累的旺盛时期,其中,N2+M处理氮素积累的旺盛时期△t分别比N0、N1、N2、N3和FP处理延长了6、4、6、1和7d,该时段吸N量比FP处理增加 0.25 g/plant,比等氮量的N2处理增加0.24 g/plant。播前施有机肥 30 t/hm2,在减 N 26.83%的情况下,玉米吸氮量比常规施肥（FP）提高 6.52%,氮素利用率达54.31%,高于常规施肥的 33.27%;玉米增产24.12%,比常规施肥增收2696元/hm2。     

氮肥用量与运筹对水稻氮素吸收转运及产量的影响

应用15N示踪技术研究了大田条件下氮肥用量与运筹对水稻氮素吸收、转运及籽粒产量的影响。试验分别设置3个氮肥水平(0、150和240 kg/hm2N)和两种基追比例(即基肥:蘖肥穗粒肥分别为40%︰30%︰30%(A)和30%︰20%︰50%(B)),共5个处理,依次记作N0、N150A、N150B、N240A、N240B。结果表明,在0~240 kg/hm2范围内,提高氮肥水平,显著增加水稻吸收的肥料氮素、土壤氮素数量以及肥料氮在土壤中的残留量。成熟期高氮处理(240 kg/hm2)水稻吸收的肥料氮素、土壤氮素及肥料氮在土壤中的残留量较多,分别为110.25、65.91、32.69 kg/hm2,而氮素的吸收利用率和土壤残留率下降,氮素损失率增加。在相同的氮肥水平下,采用基肥蘖肥穗粒肥比例为30%︰20%︰50%时,水稻吸收的肥料氮数量显著增加,氮素吸收利用率和土壤残留率提高,氮素损失率降低。适量施氮并增加穗粒肥的施氮比例,可以显著增加水稻产量。在本实验条件下,施氮量为240 kg/hm2及基肥蘖肥穗粒肥为30%︰20%︰50%的施氮处理是兼顾产量和环境的最佳氮肥运筹方式。     

水氮调控对小油菜养分吸收、水氮利用效率及产量的影响

合理的灌水、施氮量对提高小油菜养分利用率、控制面源污染具有重要意义。本文采用盆栽试验,利用~(15)N同位素示踪技术,研究不同灌水水平(W_1:60%θ_f;W_2:75%θ_f;W_3:90%θ_f。θ_f为田间持水量)和施氮量(N_0:0 g·kg~(-1);N_1:0.1 g·kg~(-1);N_2:0.2 g·kg~(-1);N_3:0.3 g·kg~(-1))对小油菜养分吸收、产量及水氮利用率的影响。结果表明:灌水水平与施氮量对小油菜根系与叶片氮、磷、钾含量均有显著影响,且叶片含磷量受水氮交互作用的显著影响。叶片氮、钾含量显著大于根系。增加灌水,小油菜含磷量与根系含氮量增加,含钾量及叶片含氮量降低;施氮能增加小油菜氮、钾含量,降低含磷量。灌水与施氮对小油菜氮、磷、钾吸收总量均有显著影响,且磷、钾吸收量受水氮交互作用的影响显著,中水低氮处理(W_2N_1)各养分吸收量均最大。小油菜产量受灌水水平和施氮量的显著影响,表现为随灌水水平的提高而增加,随施氮量的增加呈先增加后降低的趋势。灌溉水分利用效率(IWUE)受施氮量及水氮互作的显著影响,随施氮量增加,IWUE变化与产量变化一致。灌水与施氮对~(15)N肥料去向有显著影响,且肥料利用率受水氮互作的显著影响。随灌水水平提高,肥料利用率呈增加趋势,中水处理肥料残留率最低,损失率最高。随施氮量增加,肥料利用率不断降低,损失率呈增加的趋势。本试验条件下,综合考虑小油菜养分吸收、产量及水氮利用率,W_3N_1、W_2N_1组合为推荐水氮处理。     

紫云英与氮肥配施对早稻干物质生产及氮素吸收利用的影响

为综合评价紫云英与氮肥配施对早稻干物质生产及氮素吸收利用的影响,筛选紫云英等量翻压条件下,较适宜的施氮水平,以冬闲常规施氮[150 kg(N)?hm~(-2)]处理为对照,在翻压紫云英22 500 kg·hm~(-2)条件下,设置90 kg(N)·hm~(-2)、120 kg(N)·hm~(-2)、150 kg(N)·hm~(-2)和180 kg(N)·hm~(-2) 4个施氮水平,研究紫云英和施氮量对早稻干物质生产及氮素吸收利用的影响。结果表明:紫云英与氮肥配施各处理的干物质积累量均高于对照,其中紫云英配施氮肥90 kg(N)·hm~(-2)和120 kg(N)·hm~(-2)的干物质积累量最多,分别达9.65 t?hm~(-2)和9.97 t?hm~(-2),比对照分别增加11.18%和14.86%。各处理在水稻播种—分蘖期及抽穗—灌浆期干物质积累量较大,占成熟期干物质量的19.26%~24.77%和45.23%~52.75%,这两个生育阶段是干物质主要积累时期。紫云英与氮肥配施各处理的氮素积累量均高于对照,增幅为6.95%~18.68%。氮素干物质生产效率和氮收获指数均以紫云英配施90 kg(N)·hm~(-2)处理最高,比其他处理分别增加3.94%~14.08%和6.65%~14.90%。紫云英配施氮肥有利于提高早稻的干物质积累量和氮素利用率,其中以紫云英配施氮肥90 kg(N)·hm~(-2)和120 kg(N)·hm~(-2)效果较优,可实现减氮增效目的,是较理想的施肥模式。     

Natural abundance of 15N in sweet potato, pumpkin, sorghum and castor bean: possible input of N2-derived nitrogen in sweet potato

Two combinations of plant species, sweet potato (three cultivars) and pumpkin, and sweet sorghum (three cultivars) and castor bean were grown separately in three plots of alluvial soil from June to September 1996. The shoots (leaves plus stems) of sweet potato and pumpkin, and the whole tops (leaves plus stems and grains) of sweet sorghum and castor bean were harvested twice, once in August and once in September in order to analyze their natural abundance of ¹⁵N (δ¹⁵N). The δ¹⁵N values of two of the varieties of sweet potato harvested in September were significantly lower than those of pumpkin, while δ¹⁵N values of sweet potato and pumpkin harvested in August, as well as those of sweet sorghum and castor bean harvested in August and September, did not significantly differ. The lower δ¹⁵N values observed in the September-harvested sweet potato may indicate that as much as 40% of the N intake of this species is derived from dinitrogen. This species is known to have a high ability to take up N from undefined sources. Received: 23 February 1997     

栽培管理模式对冬小麦干物质积累、氮素吸收及产量的影响

为给小麦栽培管理提供指导,连续两个小麦生长季在河南省温县通过大田试验研究了农民习惯栽培(T1)、优化管理1(T2)、高产栽培管理(T3)、优化管理2(T4)4种栽培管理模式对冬小麦干物质积累、转运和氮素吸收、分配以及产量的影响。结果表明,与T1相比,T2通过基肥和拔节期追肥2次施肥,提高了干物质快速增长的时间和速率,增加了籽粒中干物质的积累和茎叶氮素向籽粒的转运,提高了穗粒数和粒重,从而达到产量和效率的提高;与T3相比,T4减少了氮磷钾用量,通过提高花后叶片中氮素的转运量和对籽粒的贡献率来增加粒重,在不降低产量的同时提高了养分效率。T3、T4模式与T1、T2模式相比,提高了干物质快速增长的时间和速率以及花后小麦茎叶贮存氮素向籽粒的转运量和对籽粒的贡献率。在本试验条件下,T2模式是目前生产情况下值得推广的优化栽培模式,T4模式是在产量进一步提高,达到高产条件下兼顾高产高效的最优栽培管理模式。     

Nitrogen uptake of sorghum (Sorghum bicolor L.) from tree mulch and mineral fertilizer under high leaching conditions estimated by nitrogen-15 enrichment

 The effects of applying either inorganic fertilizer or leaf mulch of Acacia saligna (Labill.) H.L. Wend. on yields of Sorghum bicolor (L.) were compared with an unfertilized control under the high leaching conditions of runoff irrigation in a dry tropical environment. The N use efficiency and transfer from ¹⁵N-labelled (NH₄)₂SO₄ or acacia leaves to the sorghum differed in quantity and quality. Only 6% of the applied mulch N was retrieved in the crop, in contrast to 21% of the fertilizer N. The proportions of N in the crop derived from the fertilizers were small, amounting to 7% and 28%, respectively, in the mineral fertilizer and mulch treatments. However, the application of inorganic fertilizer and mulch significantly increased crop grain yield (P<0.05 and P<0.1, respectively), biomass production and foliar N contents (P<0.05). The inorganic fertilizer improved crop yields to a larger extent than mulching. At the same time, more N was lost by applying (NH₄)₂ SO₄ than leaf mulch: only 37% of the N of applied (NH₄)₂ SO₄ was found in the crop and the soil (0–0.3 m), but 99% of the mulched N. High NO₃ ^– contents in the topsoil of the inorganic fertilized sorghum treatments indicated the risk of N leaching. However, more important may have been gaseous N losses of surface-applied NH₄ ⁺. From a nutrient conservation point of view, mulches should be given preferance to inorganic fertilizers under high soil pH and leaching conditions, but larger improvements of crop yields could be achieved with mineral fertilizers. Received: 29 July 1998     

春玉米产量、氮素利用及矿质氮平衡对施氮的响应

通过在辽宁省昌图县的田间试验,研究了不同施氮水平(0、60、120、180、240和300 kg hm-2)对春玉米产量、氮素利用及农田矿质氮平衡的影响。结果表明:春玉米产量随施氮量增加而显著提高,当施氮量高于N 240 kg hm-2时,产量有减少趋势;氮素当季利用率随施氮量增加先增加后降低,在施氮量180 kg hm-2时达到最大,为27.95%。随着施氮量增加,氮肥农学利用率、氮素吸收效率和氮素偏生产力均显著降低,而氮肥生理利用率和氮肥表观残留率均先增加后降低,这与氮肥表观损失率的变化正好相反。作物吸氮量随施氮量增加而显著增加,氮盈余主要以土壤残留为主,表观损失在氮盈余中的比例虽小,但随着施氮量增加而明显增加。低量施氮(<180 kg hm-2)主要引起土壤矿质氮残留量的显著增加,而高量施氮(240 kg hm-2和300 kg hm-2)主要引起土壤氮素表观损失量的显著增加。在本试验条件下,合理施氮量应控制在180～209 kg hm-2左右。     

Leaf elemental concentrations and grain yield of sorghum grown on an acid soil

Abstract

Determination of the nutrient requirements of sorghum [Sorghum bicolor (L.) Moench] grown on acid soils is, a critical step in the development of plants which are adapted to these problem soils. Sorghum genotype, environment, and soil type interact with the uptake of elements and affect plant growth and production. This study compared the yields of a sorghum grain hybrid grown on a sandy loam soil at four acid pH levels. Nutrient concentrations in sorghum leaves on these soil regimes were also investigated. Grain yields declined 96% as soil pH decreased from 5.5 to 4.4. Leaf element analysis revealed that as pH decreased from 5.5 to 4.4, there was an increase in plant Al, Fe, Mn, K, P and a decrease in Cu, Zn, Mg, Ca. Interactions among several of these elements were readily apparent. Additional data involving different sorghum genotypes and different soil types are needed to establish a consistent pattern of element uptake on acid soils in relation to yield and plant production.     

施肥方式对滴灌加工番茄干物质积累、养分吸收和产量的影响

通过加工番茄大田试验,研究了不同施肥方式下,膜下滴灌加工番茄的干物质积累与养分吸收规律及产量构成。结果表明,在滴灌追施100%氮肥和初果期之后滴灌追施70%钾肥的基础上,基施65%磷肥和初果期之前滴灌追施35%磷肥(优化处理)比100%磷肥基施的加工番茄干物质增加11.51%,产量提高3.59%,氮、磷、钾肥的利用率分别增加了6.06、4.15和5.26个百分点。氮肥和磷肥在初果期之前滴灌追施,氮肥和钾肥在初果期之后滴灌追施的滴灌配方肥处理的产量显著低于优化处理,且优化处理的肥料效益也好于滴灌配方肥处理。加工番茄在初果期之前滴灌追施氮与磷,在初果期之后滴灌追施氮与钾可以提高加工番茄产量,增加肥料利用效率。     

An examination of Fe deficiency stress response in relation to Fe uptake in two sorghum hybrids and their parent cultivars

Two sorghum (Sorghum bicolor L. Moench) hybrids CSH‐10 and ‐ 11 and their parent cultivars 296‐A, SB‐1055 and MR‐715 were examined for their tolerance to Fe‐deficiency stress, and also Fe uptake. It was observed that there was greater reduction of pH of the nutrient media and more rapid recovery from chlorosis only in the female parent 296‐A, and to some degree in the hybrids, but not in the male parents. The results indicated that Fe uptake‐translocation were inversely related to their Fe stress tolerance.     

Phosphate buffer–extractable organic nitrogen as an index of soil‐N availability for sorghum and pearl millet

The availability of soil nitrogen (N) is usually quantified by the amount of mineralized N as determined after several weeks of soil incubation. Various alternative methods using chemical solvents have been developed to extract the available organic N, which is easily mineralized. We compared one such solution, neutral phosphate buffer (NPB), with conventional incubation and 0.01 M–CaCl₂ extraction, as measures of soil N available to two major cereal crops of the semiarid tropics, based on the total N uptake by plants in a pot experiment. Mineralized N had the highest correlation with N uptake by pearl millet (Pennisetum glaucum L., r = 0.979***) and sorghum (Sorghum bicolor [L.] Moench, r = 0.978***). NPB‐extractable N was also highly correlated with N uptake (pearl millet, r = 0.876***; sorghum, r = 0.872***). Only one major peak was detected when NPB extracts were analyzed using size‐exclusion high‐performance liquid chromatography, regardless of soil properties. In addition, the organic N extracted with NPB was characterized by determining the content of peptidoglycan, the main component of bacterial cell walls. Although the characteristics of NPB‐extractable organic N are still unclear, it offers a promising quick assay of available N.     

氮肥运筹对棉花干物质积累、氮素吸收利用和产量的影响

通过膜下滴灌田间试验,研究不同氮肥运筹模式对棉花干物质积累、氮素吸收利用及产量的影响。结果表明,各处理棉花干物质及氮素积累均符合Logistic方程;棉花干物质积累最快时期出现在出苗后83～139 d。不同的氮肥运筹可明显影响到棉花氮素吸收最大速率及其出现日期,以有机无机氮肥配施（N2+M）处理的氮素吸收最大速率较高,且其出现日期相对较早。棉株对干物质分配中心与氮素吸收分配中心一致。各施氮处理氮肥利用率在32.11%～49.24%之间,N2+M处理氮肥利用率最高,其它处理氮肥利用率随施氮量的增加而降低。本试验中,N2+M处理产量达1890 kg/hm2,显著高于其它处理。     

Subsoil compaction effects on crops in Punjab, Pakistan:II. Root growth and nutrient uptake of wheat and sorghum

Crop yields can be reduced by soil compaction due to increased resistance to root growth, and decrease in water and nutrient use efficiencies. A field experiment was conducted during 1997–1998 and 1998–1999 on a sandy clay loam (fine-loamy, mixed, hyperthermic Typic Haplargids, USDA; Luvic Yermosol, FAO) to study subsoil compaction effects on root growth, nutrient uptake and chemical composition of wheat (Triticum aestivum L.) and sorghum (Sorghum bicolor L. Moench). Soil compaction was artificially created once at the start of the study. The 0.00–0.15 m soil was manually removed with a spade. The exposed layer was compacted with a mechanical compactor from 1.65 Mg m⁻³ (control plot) to a bulk density of 1.93 Mg m⁻³ (compacted plot). The topsoil was then again replaced above the compacted subsoil and levelled. Both compacted and control plots were hoed manually and levelled. Root length density, measured at flowering stage, decreased markedly with compaction during 1997–1998 but there was little effect during 1998–1999. The reduction in nutrient uptake by wheat due to compaction of the subsoil was 12–35% for N, 17–27% for P and up to 24% for K. The reduction in nutrient uptake in sorghum due to subsoil compaction was 23% for N, 16% for P, and 12% for K. Subsoil compaction increased N content in wheat grains in 1997–1998, but there was no effect on P and K contents of grains and N and P content of wheat straw or sorghum stover. During 1997–1998, K content of wheat straw was statistically higher in control treatment compared with compacted treatment. In 1998, P-content of sorghum leaves was higher in compacted treatment than uncompacted control. Root length density of wheat below 0.15 m depth was significantly reduced and was significantly and negatively correlated with soil bulk density. Therefore, appropriate measures such as periodic chiselling, controlled traffic, conservation tillage, and incorporating of crops with deep tap root system in rotation cycle is necessary to minimize the risks of subsoil compaction.