Growth promotion by sodium in amaranthaceous plants

The amaranthaceous dwarf glasswort, Swiss chard, table beet, spinach and Mexican tea were grown in solutions containing 0, 20, 40, 80, 120, 160, 180 and 200 mol m^?3 sodium chloride (NaCl). Maximum growth and increase of biomass production compared to that at 0 mol m^?3 of dwarf glasswort was observed at 200 mol m^?3 (245%), and Swiss chard (146%), table beet (128%) and spinach (138%) at 80 mol m^?3. The growth of these species increased with increasing sodium (Na) concentration of shoot until it reached 4.18, 2.42, 1.60 and 1.58 mol kg^?1, respectively. These indicate that the order of Na-loving character is dwarf glasswort >> Swiss chard > table beet = spinach. The water contents increased with increasing Na concentration until growth reached maximum in dwarf glasswort and Swiss chard. In these highly Na-loving species, Na is activity transported to shoots and utilized for producing osmotic pressure to absorb water.     

Potassium recirculation in tomato plants in relation to potassium supply

The Ben Zioni ‐ Dijkshoorn hypothesis that NO₃ uptake by roots is regulated by NO₃ assimilation in the shoot was tested using the tomato plant. Plants were grown at three K levels and the fate of anion charge from NO₃,^‐ and SO₄ ^2‐. assimilation followed in its distribution between organic acid anion accumulation and HCO₃ ^‐ efflux into the nutrient medium. For the high K treatment almost all of this charge was directed towards organic acid accumulation with HCO₃ ^‐ efflux accounting for only 3% of the total charge. On the other hand for plants supplied at the low K level, a substantial proportion of the anion charge was excreted as HCO₃ ^‐ (32%).

Xylem sap analyses and NO₃ reductase assay results indicated that in the tomato plant the upper plant parts constituted the major site for NO₃ reduction. The quantitatively most important ionic constituents in the sap were K⁺, Ca²⁺ and NO₃ ^‐.

Results have been presented that indicate that when K is in short supply in the nutrient medium, K recycling occurs within the plant to facilitate the upward transport of NO₃ ^‐ from root to shoot.     

Influence of Pre-Plant Micronutrient Mixes and Ammonium to Nitrate Ratios in Fertilizer Solution on Growth and Micronutrient Contents of Marigold in Plug Culture

ABSTRACT

The purpose of this work was to determine the effects of pre-plant micronutrient mixes and various ammonium/nitrate (NH₄ ⁺/NO₃ ^?) ratios in a fertilizer solution on growth and the nutrient uptake of French marigold ‘Orange Boy’ in a plug culture. Two kinds of granular glass frits containing six micronutrients were produced and incorporated into peatmoss+vermiculite (1:1, v/v) substrate at a rate of 0.3 g · L^{? 1}. The five NH₄ ⁺/NO₃ ^? ratios in fertilizer solution were 0/100, 25/75, 50/50, 75/25, and 100/0, each giving a total nitrogen (N) supply of 80, 100, and 120 mg · L^{? 1}in the root substrate during stages 2, 3, and 4, respectively. The plants produced a significantly higher fresh and dry matter yield at 35 days after sowing when grown in 25/75 N nutrition in micronutrient fertilizer 1 (MF1) and 50/50 in micronutrient fertilizer 2 (MF2) than in the other NH₄ ⁺/NO₃ ^? ratios tested. Treatments of the highest accumulation of iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), and boron (B) in plants were 25/75, 50/50, 50/50, 25/75 and 50/50 in MF1 and 50/50, 25/75, 50/50, 50/50, 50/50 in MF2, respectively. The trends in accumulations of Fe, Mn, Zn, Cu, and B in plants were quadratic (Q), linear (L) and Q, L and Q, L and Q, and Q, respectively, in MF1. Those in MF2 were Q, Q, Q, L and Q, and Q, respectively.     

Absorption and transport of Na and Cl in rice cultivars differing in their tolerance to salinity: An examination of the effects of ammonium and potassium salts

The absorption and transport of Na and Cl from 0.1 mM and 10 mM ²²Na labelled NaCl or ³⁶Cl labelled KCl were examined in 15 days old seedlings of 3 cultivars of rice differing in their tolerance to salinity. Furthermore, the effects of 10, 100 and 1000 ppm (N)₂S on their uptake were studied. It was found that in general, the salt‐tolerant cultivars BR and PNL‐1 absorbed more Na and translocated a lesser proportion of it to the shoot, compared to the salt‐sensitive IR‐8, from 0.1 mM NaCl. The presence of (N)₂S reduced the uptake of Na in all the cultivars. It was also found that the presence of 100 ppm K, KN or NNreduced Na absorption from 0.1 mM NaCl significantly in all the cultivars, and the translocation to shoot in BR‐ Chloride transport from 0.1 mM NaCl was reduced by (N)₂S in all the cultivars. The 3 cultivars differed significantly in the rates of absorption and transport of Na and Cl. The results indicate that PNL‐1 which is a cross of IR‐8 X BR, has inherited the salt tolerance trait from BR. Lower rates of Na translocation to the shoot can be used as an index of salt tolerance in rice.     

Tomato growth and mineral composition as influenced by nitrogen form and light intensity

Abstract

Tomato plants were grown in sand culture with NH⁺ ₄, and NO^? ₃, forms of N and three levels of light. Plants supplied with NH⁺ ₄, nutrition under high light intensity had symptoms of stunting, leaf roll, wilting, interveinal chlorosis of the older leaves, and one third the dry weight of N0₃‐fed plants. In contrast, growth of plants receiving NH⁺ ₄, nutrition under shade appeared normal although dry weight was reduced. NH₄‐N nutrition suppressed K, Ca and Mg accumulation in tissues and increased P contents as compared to NO₃‐N nutrition.     

氮钾水互作对玉米苗期植株生长及钾素吸收的影响

采用盆栽试验方法探讨了氮钾水互作对玉米苗期植株生长及养分吸收的影响。结果表明,水分适宜能明显增加玉米植株株高和干物重,水分适宜条件下玉米株高和干物重较水分亏缺条件的分别增加7.8%和13.8%。增施氮肥能显著增加玉米植株株高和干物重,水分适宜条件下中氮水平的玉米株高和干物重分别较低氮水平的增加10.4%和8.7%,而水分亏缺条件下株高和干物重均随施氮水平的增加而明显增加;水分亏缺条件下,中高量施钾能显著增加玉米植株干物重。水分适宜条件下增施氮肥能明显促进玉米对钾素的吸收,在水分适宜和亏缺条件下,不同氮水平的玉米钾素吸收均随施钾水平的增加而显著增加。     

The influence of calcium on growth of selected vegetable species in the presence of ammonium nitrogen

Growth of cabbage (Brasslca oleracea L.), cantaloupe (Cucumis melo L.), squash (Cucurbita pepo L.), chile pepper (Capsicum annuum L.), tomato (Lycopersicon esculentum Mill)., radish (Raphanus sativus L.), and Swiss chard (Beta vulgaris L.) was enhanced when supplied with additional Ca in the presence of NH₄‐N over those with normal Ca. Ammonium uptake as measured by residual NH₄ in soil leachate was lowered indicating possible increased uptake in the presence of additional Ca.     

La(NO3)3 对盐胁迫下黑麦草幼苗生长及抗逆生理特性的影响

为探讨稀土元素镧(La)对牧草盐胁迫伤害的缓解作用, 采用水培法研究了叶面喷施20 mg·L^-1La(NO₃)₃ 对NaCl 胁迫下黑麦草幼苗生长及其抗逆生理特性的影响。结果表明: 盐胁迫显著抑制黑麦草幼苗的生长, 提高叶片电解质渗漏率及丙二醛(MDA)、O₂^- 和H₂O₂ 含量, 其作用随盐浓度的增大而增强。超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)活性和抗坏血酸(AsA)、谷胱甘肽(GSH)、可溶性蛋白质、脯氨酸含量随盐浓度增大呈先升后降趋势, 可溶性糖和Na⁺/K⁺比逐渐增大, 质膜H⁺-ATP 酶活性逐渐降低, 过氧化物酶(POD)活性及POD 同功酶数量表达增强。喷施La(NO₃)₃ 处理可降低盐胁迫下黑麦草幼苗叶片的O₂^- 和H₂O₂ 含量, 提高SOD、CAT、POD、APX 和质膜H⁺-ATP 酶的活性及POD 同功酶的表达, 使AsA、GSH、可溶性蛋白质、可溶性糖和游离脯氨酸含量及幼苗生物量增加, Na⁺/K⁺比降低。表明La(NO₃)₃ 可通过提高抗氧化系统的活性和积累渗透溶质减轻盐胁迫伤害, 从而提高黑麦草的耐盐性。     

Effect of potassium on uptake and translocation of sodium and potassium in Chinese cabbage under NaCl stress

To investigate the influence of potassium (K⁺) on the salinity tolerance of Chinese cabbage (Brassica pekinensis Rupr.) seedlings, the plants were cultured at three K⁺ levels (0, 5, or 10?mM), under normal (0?mM NaCl) and high-salt (100?mM NaCl) conditions. The results indicated that the dry weight of Chinese cabbage increased with the application of K⁺ under salt stress. Addition of K⁺ increased K⁺ concentrations and suppressed sodium (Na⁺) concentration, which eventually increased the K⁺/Na⁺ ratios in roots or shoots. Application of K⁺ enhanced the uptake of K⁺ and suppressed the uptake of Na⁺. Moreover, the ratios of shoot-K⁺/root-K⁺ increased considerably, but the ratios of shoot-Na⁺/root-Na⁺ decreased in response to K⁺ application. It was concluded that the application of K⁺ could enhance the salt stress tolerance in Chinese cabbage because more K⁺ than Na⁺ was absorbed and translocated from roots to shoots.     

Grazing intensity and environmental factors effects on species composition and diversity in rangelands of Iran

The aim of this study was to analyze the effects of grazing, precipitation and temperature factors on plant species dynamics (diversity and composition) in the semi-steppe of Isfahan semi-arid rangelands, Iran. The effects of Sheep grazing were studied in a controlled experiment along grazing gradient with seven intensities (from very heavily grazed to nongrazed) during six consecutive years (2006–2011). The results show that plant species dynamics varied among years, but were only slightly affected by grazing intensity. Since the experimental years were much dryer than the long term average, the abiotic constraints may have overridden any grazing effect. The differences among the years were predominantly determined by the abiotic factors of temperature and precipitation. Most of the variations in species dynamics and coexistence between the C₄ and C₃ species were explained by seasonal weather conditions, i.e., temperature and precipitation regimes during the early season (March-June). The dominant C₃ species, Poa bulbosa, was highly competitive in March-June at low and high temperature and rainfall levels, respectively. In contrast, the most common C₄ species Cynodon dactylon benefited from high and low early season temperature and rainfall levels, respectively. However, biomass of P. bulbosa was positively correlated with temperature in March, when effective mean temperature ranges from 0 to 5°C and thus promotes vernalization and vegetative sprouting. Our results suggest that, over a six-year period, it is temporal variability in temperature and precipitation rather than grazing that determines vegetation dynamics and species distributions in grazed semi-steppe ecosystems. Our results also support that the variability in the dominant species biomass, rather than diversity, determine ecosystem functioning. This study provides fundamental knowledge on the complex interaction of climate, vegetation, and grazing.     

13N-nitrate uptake sites and rhizobium-infectible region in a single root of common bean and soybean

The positron emitting tracer-imaging system (PETIS) was used to determine whether it was possible to obtain on image of ¹³N-distribution in common bean in which a single root was fed with a liquid medium containing nitrate at different concentrations with different ¹³N specific activities. The distribution of the images of the ¹³N atoms in the root could be obtained over a wide range of nitrate concentrations and ¹³N specific activities in the medium. As for nitrate stress on leguminous root nodulation, the positional relationship between the nitrate uptake sites and root hair just elongating area, where rhizobia capably initiate their infection, was studied in common bean and soybean. PETIS gave direct evidence that single roots of both common bean and soybean showed one or two dense ¹³N-distribution areas after 2 min pulse-feeding of ¹³N0₃ ^-. These areas remained stable over 30 min, and the first dense site, which was common in all the examined roots, extended over ca. 1 cm above the root apex. Microscopic observation revealed that this area covered both sites of rhizobium infection and of early nodule development in a common bean and soybean single root.     

土壤非交换态钾与结构态钾能够区分吗？

Nonexchangeable K (NEK) is the major portion of the reserve of available K in soil and a primary factor in determining soil K fertility. The questions of how much NEK is in soils and how to quantify total NEK in soils are so far still unclear due to the complicated effects of various minerals on K fixation. In this study, the NEK in 9 soils was extracted with sodium tetraphenylboron (NaBPh₄) for various time periods longer than 1 d. The results showed that the NEK extracted by NaBPh₄ gradually increased with time, but showed no more increase after the duration of extraction exceeded 10--20 d. As the temperature increased from 25 to 45 ^oC, the duration to obtain the maximum extraction of NEK was reduced from 20 to 10 d, and the maximum values of NEK released at both temperatures was almost the same for each soil. The maximum NEK (MNEK) of the 9 soils extracted by NaBPh4 varied from 3 074 to 10 081 mg kg^-1, accounting for 21%--56% of the total soil K. There was no significant correlation between MNEK released by NaBPh₄ and other forms of K, such as NH₄OAc-extracted K, HNO₃-extracted K and total K in soils, which indicates that NEK is a special form of K that has no inevitable relationship to the other forms of K in soils. The MNEK extraction by NaBPh₄ in this study indicated that the total NEK in the soils could be differentiated from soil structural K and quantified with the modified NaBPh₄ method. The high MNEK in soils made NEK much more important in the role of the plant-available K pool. How to fractionate NEK into different fractions and establish the methods to quantify each NEK fraction according to their bioavailability is of great importance for future research.     

Differential growth responses of agaves to nitrogen,phosphorus, potassium,and boron applications

Nutrient effects on the growth of Crassulacean acid metabolism plants have received little attention. Agave deserti and A. lechuguilla were therefore selected for study because their rate of leaf unfolding from the central spike relates closely to growth, thus providing a convenient means for monitoring the effect of nutrient applications. The greater fractional influence of nitrogen fertilization on leaf unfolding for A. deserti can be explained by its lower soil level of N than for A. lechuguilla; high application levels of N near 500 kg ha^‐1 proved slightly inhibitory compared with 100 kg N ha^‐1 during the first year after application but not during the second year for A. deserti. Agave deserti occurred in soils much higher in phosphorus, potassium, and boron than for A. lechuguilla; consistent with this, application of these three nutrients in the field had little influence on the rate of leaf unfolding for A. deserti tut could significantly increase the leaf unfolding rate for A. lechuguilla. Applications of nutrient levels that greatly stimulated leaf unfolding for A, lechuguilla, such as 100 kg N ha^‐1 or 500 kg P ha^‐1 , led to large increases in net COg uptake over 2k h; applications of 500 kg K ha‐¹ or 100 kg B ha"¹ led to lower enhancements in CO₂ uptake and in the leaf unfolding rate, but again prevented any major decrease in net COg rate during the night. In agreement with studies on other CAM plants, the macronutrients N, P, and K and the micronutrient B can enhance the growth of agaves, depending on the relative level of these nutrients in the soil.     

The effect of an NH4 +‐enhanced nitrogen source on the growth and yield of hydroponically grown maize (Zea mays L.)

Increased above‐ground dry matter and grain yields were found for two hydroponically grown maize hybrids (Pioneer‐3925 and Pioneer‐3949) when plants were supplied with an NH₄ ⁺‐enhanced nutrient solution (31 percent of total N) compared with a control (4 percent of total N as NH₄ ⁺). The major difference in yield developed between silking and 2 weeks post‐silking and silking and 4 weeks post‐silking for the P‐3925 and P‐3949 respectively. The reduced nitrogen content of the stover (leaves plus stalk) was consistently higher on the NH₄ ⁺‐enhanced nutrient solution. The decreased production of the control treatment may have resulted from a reduced photsynthetic capacity.     

不同形态氮对掌叶半夏生长及块茎主要化学成分影响研究

【目的】本文利用盆栽试验,探讨了不同铵态氮、 硝态氮供应比例对掌叶半夏生长、 相关生理指标及块茎中主要活性成分含量的影响,以期为掌叶半夏的合理施肥、 科学种植提供技术依据。【方法】盆栽试验以蛭石为栽培基质,以掌叶半夏为试验材料,采用不同铵态氮、 硝态氮比例处理,分析不同铵硝比例处理下掌叶半夏叶片中抗氧化保护酶（SOD、 CAT）, 叶片、 块茎中氮代谢关键酶（NR）的活性及块茎中次生代谢产物（MDA、 硝酸盐及主要活性成分）的含量变化。【结果】 1）叶片鲜重、 块茎鲜重及总叶绿素含量总体均随铵态氮比例的升高而呈逐渐增加趋势,其中在全铵营养下,块茎鲜重和总叶绿素含量均达到最高值。2）随着铵态氮比例的升高,植株叶片中SOD、 CAT酶活性呈先升高后降低趋势; 当铵硝比为50∶50时,SOD、 CAT酶活性最高,此时,叶片中NO-3-N含量也达到最高。3）在全铵营养或全硝营养下,MDA含量均高于其他处理; 当铵硝比为50∶50时,MDA累积量最低。4）在全硝营养下,叶片、 块茎中的NR活性均达到最高值,同处理水平下叶片中NR活性要高于块茎; 并且随着铵态氮比例的增加叶片中NR活性呈逐渐降低的趋势,而块茎中的NR活性则呈逐渐增加的趋势。5）块茎中主要活性成分的累积更依赖于两种氮素的配施作用,在较高的铵态氮配施处理下（75∶25时）,总生物碱、 总有机酸及腺苷的积累量均取得最高值。【结论】适宜比例的铵硝配比可以促进掌叶半夏生长及产量的形成,其促进效果也显著高于全硝营养; 当铵硝比为50∶50时,其植物体内的相关酶活性也达到最高,说明适宜的铵硝配比能减轻膜质过氧化对植株细胞膜造成的损伤; 同时,较高的NH+4-N也有利于块茎中主要活性成分的积累,尤以铵硝比为75∶25时,累积效果最显著。     

Differences in short-term responses of rice and tomato to sodium salinization and supplemental potassium and calcium

Short-term (72 h) responses of the water and nutritional status to Na-salinization were investigated in rice (Oryza sativa L. cv. Koshihikari) and tomato (Lycopersicon esculentum Mill cv. Saturn). The short-term effect of supplemental K and Ca to the nutrient solution on the water status and absorption and transport of ions in the plants was also investigated. In both species, Na salinity resulted in the deterioration of the water status of tops and in nutritional imbalance. However, in rice, it was possible to prevent the deterioration of the nutrient status by enhancing the transport of cations, especially K, while tomato could maintain an adequate water status by inhibiting the water loss associated with transpiration. On the other hand, the water status in rice and the nutritional status in tomato markedly deteriorated by high Na level in the solution. Supplemental K and Ca could not ameliorate th.e water status in both species, and even worsened the status in rice. In rice, a close relationship was observed between the osmotic potential (OP) of the solution, water uptake and water content. The water status of rice, therefore, seemed to depend on OP of the solution. Supplemental K and Ca, on the other hand, were effective in the amelioration of the nutritional status. In tomato, supplemental Ca could improve the nutritional balance by suppressing the transport of Na and enhancing that of the other cations in avoidably the deterioration of the water status. Thus, the differences in the responses of the water and nutritional status of rice and tomato to high Na salinization and to supplemental K and Ca were evident in a short-term study and supported a similar tendency observed in a long-term study.     

水蚀条件下硝酸铵施用对黄绵土氮素流失的影响

研究结果表明不同坡度谷子地,高N处理小区径流中铵态氮、硝态氮和有效氮浓度平均为1.06、0.76和1.82mg/kg,低N分别为0.64、1.29和1.93mg/kg;高氮处理土壤铵态氮、硝态氮和有效氮平均流失量分别达到17.90、12.93和30.84kg/(km²·a),低N流失量为11.90、23.86和35.77kg/(km²·a)。高氮处理小区泥沙中有机质和全氮浓度平均为5.21和0.536g/kg,而低氮处理分别为4.94和0.481g/kg;高氮和低氮处理土壤有机质流失量分别为5702和5743kg/(km²·a),土壤全氮流失量为498和559kg/(km²·a)     

Availability and extractability of soil manganese in a liming experiment

Abstract

The availability of soil Mn to corn in relation to extractability of soil Mn by EDTA, Mg(NO₃)₂, CH₃COONH₄, hydroquinone, H₃PO₄, and NH₄H₂PO₄ as affected by liming was evaluated under field conditions on a single soil type. EDTA, Mg(NO₃)₂ and CH₃COONH₄‐extractable Mn were related inversely to available Mn. No useful relationships were found between hydroquinone, H₃PO₄, and NH₄H₂PO₄‐extractable soil Mn and Mn uptake by sweet corn.     

Growth,Nitrate Accumulation,and Macronutrient Concentration of Pakchoi as Affected By External Nitrate-N: Amino Acid-N Ratio

ABSTRACT

A study was carried out to determine the influence of nitrogen (N) sources on the growth, nitrate (NO₃ ^?) accumulation, and macronutrient concentrations of pakchoi (Brassica chinensis L.) in hydroponics. Plants were supplied with NO₃ ^? and two amino acids (AA), glutamic acid (Glu), and glutamine (Gln), at six NO₃ ^?-N/AA-N molar ratios: (1) 100:0, (2) 80:20, (3) 60:40, (4) 40:60, (5) 20:80, (6) 0:100. The total N concentration was 12.5 mmol/L for all treatments in nutrient solutions. Both AAs reduced plant growth with decreasing NO₃ ^?-N/AA-N ratios, but the reduction was for Gln than for Glu. At 80:20 NO₃ ^?-N: Gln-N ratio, the Gln had no significant effect on pakchoi fresh weights. Decreasing NO₃ ^?-N/AA-N ratios reduced NO₃ ^? concentrations in the plant, regardless of AA sources. Adding an appropriate portion of AA-N to nutrient solutions for hydroponic culture increased concentrations of N, phosphorus (P), and potassium (K) in pakchoi shoots. Substituting 20% or less of NO₃ ^?-N with Gln-N in hydroponic culture will increase the pakchoi quality by reducing NO₃ ^? concentration and increasing mineral nutrient concentrations in shoots without significant reduction of crop yields.     

PERFORMANCE OF DUALEX IN SPRING WHEAT FOR CROP NITROGEN STATUS ASSESSMENT,YIELD PREDICTION AND ESTIMATION OF SOIL NITRATE CONTENT

Dualex and SPAD are devices developed for the purpose of testing crop nitrogen (N) status. These instruments were used in a wheat experiment in order to compare their respective performance in assessing leaf nitrogen (N) concentration, response to N topdressing application, soil nitrate (NO₃)-N levels and in predicting grain yield. The experiment included different N rates in 2005 and 2006 in the Montérégie region of Quebec, Canada. Dualex readings correlated negatively with SPAD readings, leaf N concentration, soil NO₃-N content and wheat grain yield. SPAD alone and the ratio of SPAD to Dualex measurements (Chl/Phen) were linearly related to N application rate but no effect of N application rate was found for individual Dualex parameters. However, both SPAD and Dualex readings were affected by year effects. The Dualex was also capable of indirect evaluation of in-season soil NO₃-N accumulation and the prediction of wheat yield, but more so as Chl/Phen.