Effect of applied nitrate on growth and N2-fixation inCicer arietinum L.

Summary Application of nitrate, either weekly or at the time of nodulation and pod-filling, significantly retarded nodule development and exerted a delay effect on the rate of N₂-fixating. However, after a certain period of time, its effect on nitrogenase became less conspicuous. Nitrate enhanced nitrate reductase activity in leaves as well as in nodules. At the initial stages, nitrate treated plants accumulated dry mass at a higher rate than those growing exclusively on atmospheric nitrogen. Nitrate induced premature senescence of plants towards the final stages of growth and lowered both the seed number per plant as well as weight of individual seed.     

基质氮素对大球盖菇生长及亚硝酸盐含量的影响

目的探索氮源对大球盖菇生长及亚硝酸盐、硝酸盐含量的影响。方法在培养基中添加不同含氮化合物,培养菌丝,定时测定生长量,并采用重氮偶合分光光度法测定其亚硝酸盐、硝酸盐含量。结果添加亚硝酸盐的基质,菌丝生长速度比对照慢。尿素、硫酸铵、硝酸铵和硝酸钾四处理之间差异无显著性,其生长速度最快。各处理间亚硝酸盐、硝酸盐含量差异均存在非常显著性。亚硝酸钾处理,亚硝酸盐含量高达402.03 mg/kg,不宜食用。硝酸钾处理,亚硝酸盐含量为30.87 mg/kg,食用100 g,就会超出亚硝酸盐日限量;硝酸铵处理,硝酸盐含量远远超过日常蔬菜,也不宜食用。结论在栽培大球盖菇时氮源不宜使用亚硝酸盐、硝酸盐,应使用尿素或硫酸铵,有机氮源也可以。     

Seasonal and diurnal variations in nitrate reductase activity of soybean (Glycine max (L.) Merr.)

Summary The seasonal and diurnal variations in nitrate reductase (NR) activity of field grown Altona soybean, with and without applied nitrogen, were determined. The NR activity in the fortnightly collected leaf samples was, on the average, 20 percent higher throughout the season in N-treated plants, the highest being early in the season and declining gradually in the samples of subsequent dates. Diurnal variations were marked by increase in the NR activity from 7 a.m. to 7 p.m. and then declining gradually to a minimum at 7 a.m. the next morning.     

Root contribution to nitrate reduction in barley seedlings (Hordeum vulgare L.)

Summary The leaf and root nitrate reductase activities were measured in 7 day-old barley seedlings by anoxic nitrite accumulation in darkness, during 48h after the transfer from a N-starved medium to a 1.5 mM K¹⁵NO₃ medium. Thisin situ nitrate reduction was compared with the¹⁵N incorporation in the reduced N fraction of the whole seedlings.The nitrate reduction integrated fromin situ measurements was lower than the reduced¹⁵N accumulation. The rootin situ nitrate reductase activity seemed to account for only the third of the real root nitrate reduction, which may have been responsible for the overall underestimation. This discrepancy was partly explained by the ability of the root to reduce nitrite in an anoxic environment.These results suggest that, after correction of thein situ estimation of the nitrate reduction. the roots contribute to about 50% of the total assimilation.     

Effect of vanadium on the growth,yield and chemical composition of maize (Zea Mays L.)

Summary The effects of application of vanadium on the growth, yield, and chemical composition of maize were compared in a series of pot experiments during several years. It was concluded that above a threshold value (0.05 ppm) vanadium was injurious to maize crop, but at milder dose it increased the yield of maize crop significantly. Quality of produce was also affected markedly by vanadium application.     

番茄基质通气栽培模式的效果

针对雾培模式在提高作物产量同时增加无土栽培成本的问题,研制了一种新型的珍珠岩通气栽培模式,探讨了其对番茄的栽培效果.试验设计3种栽培方式:全珍珠岩栽培(CK),珍珠岩通气栽培(T1)和气雾培(T2).结果表明:T1可显著改善番茄根际通气环境,其中根际CO2浓度仅为CK的1/5,O2浓度则为CK的1.17倍;显著增加了番茄的株高和茎粗,在定植后60d时,株高和茎粗分别比CK增加了5.1%和8.4%;植株净光合速率显著高于CK,在净光合速率达到最大值(定植后45d)时,比CK提高了13%;显著提高了植株根系活力和吸收能力,在定植后45d时,其根系活力为CK的1.23倍,在定植后60d时,根系钾、钙、镁含量分别比CK增加了31%、37%和27%,番茄产量为CK的1.16倍.且T1上述指标均与T2无显著差异;而CK、T1和T2在果实的可溶性糖、有机酸、糖酸比方面无显著差异.表明以珍珠岩为基质的通气栽培模式简便易行且可显著提高番茄产量.     

Accumulation and reduction of nitrate in cereal plants dependent on N supply

Summary In pot experiments the NO ₃ ^– accumulation and the occurrence of nitrate reductase (NR) capacity of wheat plants were investigated depending on late N applications at tillering, shooting and heading. NO ₃ ^– is preferentially accumulated in the stems, while NR dominates in the leaves. NO ₃ ^– accumulation is enhanced by late N treatments especially if N supply at seeding is sufficient. NR capacity of the plants is stimulated by late nitrogen supply, but its increment rates decrease with increasing NO ₃ ^– accumulation.     

Influence of phosphorus and sulfur nutrition on composition ofClitoria ternatea L.

Summary A greenhouse experiment on a silt loam surface soil (Typic Hapludult) was done to investigate effects of P and S on yield, quality aspects and sugar reserves in the tropical forage legumeClitoria ternatea L. Four levels of P and two N treatments (NH₄NO₃ vs symbiotic) were arranged in a factorial design with four replications. After the first cutting two levels of S were imposed on this design.Phosphorus enhanced dry matter yield in the first cutting. Its effect was smaller in the second cutting. Amount of P required to produce maximum plant yield dropped from 200 mg/kg soil (or more) at the first cutting to 50–100 mg/kg at the second. Added S improved growth at suboptimal levels of P. At optimal P and S, symbiotic and +N plants yielded alike.Phosphorus and S fertilization caused several changes in plant composition. Nitrogen concentration was raised by S treatment and lowered by P. Combined addition of P and S lowered plant nitrate content. In symbiotic plants, soluble sugar concentrations were higher than in N-treated plants, and were increased by P and S treatment. In N-treated plants, neither P nor S increased reducing sugar concentration, but they increased total sugar.     

Influence of phosphate and nitrate supply on root hair formation of rape,spinach and tomato plants

Summary Experiments with tomato, rape and spinach in nutrient solutions have shown that the formation of root hairs is strongly influenced by phosphate and nitrate supply. Decreasing the phosphate concentration of the nutrient solution from 100 to 2 M P resulted in an increase of root hair length from 0.1–0.2 to 0.7 mm of the three plant species. Root hair density also increased by a factor of 2–4 when the P concentration was lowered from 1000 to 2 M. The variation of these two root properties raised the root surface area by a factor of 2 or 3 compared to plants well supplied with P. Root hair length was closely related to the phosphate content of the root and shoot material. On the other hand, spinach plants grown in a split-root experiment produced root hairs in solutions of high P concentration (1000M P) if the major part of the total root system was exposed to low P concentration (2 M P). It is therefore concluded that the formation of root hairs does not depend on directly the P concentration at the root surface but on the P content of the plant.Similar experiments with nitrate also resulted in an increase in length and density of root hairs with the decrease of concentration below 1000 M. In this case marked differences between plant species occurred. At 2 M compared to 1000 M NO₃ root hair length of tomato increased by a factor of 2, of rape by a factor of 5 and of spinach by a factor of 9. Root hair length was correlated, but not very closely, to the total nitrogen content of the plants. It is concluded, that the influence of nutrient supply on the formation of root hairs is a mechanism for regulating the nutrient uptake of plants.Dedicated to Prof. Dr. E. Welte on the occasion of his 70th anniversary.     

Correlation between nitrate uptake rate and nitrate inhibition of nitrogenase activity in Azotobacter chroococcum

In Azotobacter chroococcum cells exhibiting both nitrate (nitrite) assimilation ability and nitrogen fixation capability, the extent of nitrogenase activity inhibition by nitrate or nitrite positively correlated (r = 0.922) with the rate of nitrate (nitrite) taken up by the cells. These results corroborate our previous proposal that the anion must be assimilated to exert its inhibitory effect, and indicate that the inhibition is a graded rather than an all-or-none process.     

Influence of medium composition and aeration on the synthesis of biosurfactants produced by Candida antarctica

Candida antarctica synthesised surface-active mannosylerythritol lipids at 46 g l^–1 by adding 80 g soybean oil l^–1 to the medium and maintaining the pO₂ at 50% with an air flow rate 1 vvm. Two-stage culturing of C. antarctica avoided medium foaming but the yield of biosurfactants synthesis was 28 g l^–1. The biosurfactants decreased the surface tension of water to 35 mN m^–1.     

The effect of nitrate concentration in a flowing solution system on growth and nitrate uptake of twoPlantago species

Summary Juvenile plants ofPlantago lanceolata andP. major ssp.major were grown in a flowing solution system at 7.5 mM or 9.5 M NO₃. The parameters investigated were: RGR, shoot weight percentage, leaf length, length of main root axis, shoot concentrations of major ions and organic N, and the specific uptake rate for NO₃. At 9.5 M NO₃ growth ofP. major was not hampered, whereas shoot growth and leaf length ofP. lanceolata were reduced. The NO₃ concentration ofP. lanceolata decreased more than that ofP. major. The different performances of the species at 9.5 M NO₃ were associated with different specific uptake rates. In both treatments the root system ofP. major was shorter than that ofP. lanceolata. P. lanceolata accumulated more NO₃ in the leaves. The performance of thePlantago species is discussed in relation to the availability of nutrients in their habitats.Grassland Species Research Group. Publication no. 37.     

成垄压实施肥对氮素运移及氮肥利用率的影响

黄土高原地区夏玉米生长正逢雨季,是N素淋溶的主要时期,为此提出氮肥施用的成垄压实法,通过连续两年的田间小区试验,研究了夏玉米生长期成垄压实施肥方式下夏玉米产量和氮肥利用率,以及土壤NO3^--N迁移规律,并结合室内模拟实验探讨了该施肥法的影响因素。结果表明,在供水量接近研究区同期多年平均降雨量(370mm)的年份,平地施肥条件下,NO3^--N可被淋溶至90cm以下的土层;而成垄压实施肥可明显减少施肥区NO3^--N随入渗水分向土壤深层迁移,至60cm以下土层,土壤NO3^--N含量小于10mg·kg^-1,NO3^--N主要累积于近地表20～40cm土层,该土层土壤NO3^--N含量约为80～90mg·kg^-1。成垄压实施肥法局部存在的大容重障碍层对作物生长发育无影响在240.0kgN·hm^-2施氮量条件下,成垄压实较平地施肥没有显著提高玉米生物产量和经济产量,但却能极显著地增加作物吸氮量,使氮肥利用率提高9％左右。成垄压实施肥条件下,障碍层容重对NO3^--N迁移影响明显,随障碍层容重的增加,NO3^--N迁移深度减小,大田条件下,垄坡度对NO3^--N迁移影响不明显。     

施氮水平对高产麦田土壤硝态氮时空变化及氨挥发的影响

研究了不同施氮水平对高产麦田土壤硝态氮时空变化和氨挥发的影响.结果表明,高产麦田土壤硝态氮在播种至冬前阶段不断向深层移动,并在140cm以下土层积累.施纯氮96～168 kg·hm^-2处理,增加了60 cm以上土层土壤硝态氮含量,降低了土壤氮素表观损失量占施氮量的比例,提高了小麦籽粒蛋白质含量和籽粒产量,且土壤氨挥发损失较低,基施氮氨挥发损失占基施氮量的4.23%～5.51%;施氮量超过240 kg N·hm^-2,促进了土壤硝态氮向深层的移动和积累,基施氮氨挥发损失、土壤氮素表观损失量及其占施氮量的比例均显著升高,对小麦籽粒蛋白质含量无显著影响,但籽粒产量降低.高产麦田适宜的氮素用量为132～204 kg N·hm^-2.     

Plant biomass partitioning and chemical defense: Response to defoliation and nitrate limitation

Summary Plant growth and allocation to root, shoot and carbon-based leaf chemical defense were measured in response to defoliation and nitrate limitation inHeterotheca subaxillaris. Field and greenhouse experiments demonstrated that, following defoliation, increased allocation to the shoot results in an equal root/shoot ratio between moderately defoliated (9% shoot mass removed) and non-defoliated plants. High defoliation (28% shoot mass or >25% leaf area removed) resulted in greater proportional shoot growth, reducing the root/shot ratio relative to moderate or non-defoliated plants. However, this latter effect was dependent on nutritional status. Despite the change in distribution of biomass, defoliation and nitrate limitation slowed the growth and development ofH. subaxillaris. Chronic defoliation decreased the growth of nitrate-rich plants more than that of nitrate-limited plants. The concentration of leaf mono- and sesqui-terpenes increased with nitrate-limitation and increasing defoliation. Nutrient stress resulting from reduced allocation to root growth with defoliation may explain the greater allocation to carbon-based leaf defenses, as well as the defoliation-related greater growth reduction of nitrate-rich plants.     

Influence of soil applications of nitrogen on nitrate reductase activity,leaf and grain protein content in sorghum

Summary Three sorghum genotypes, L.187, SK5912 and RCFA×L.187 (the latter being a hybrid) were field grown under four nitrogen application rates and replicated four times. The experiments were of complete randomized plot design and conducted in 1976, 1977 and 1978.Nitrate Reductase Activity (NRA) was measured at 5, 7, 9, 11, 13, and 15 weeks and at 18, 19, 20 and 21 weeks after planting in 4th vegetative leaf and flag leaf respectively. Flag leaf, 4th leaf and grain protein contents were also measured.Nitrogen application generally increased NRA in both 4th leaf and flag leaf in the 3 genotypes at all the sampling dates.NRA of the hybrid, RCFA×L.187 was consistently higher than those of SK5912 and L.187 (both straight varieties).NRA of 4th leaf was negatively correlated with leaf protein but flag leaf protein tended to increase with applied nitrogen.Flag leaf NRA was positively and significantly correlated with grain protein indicating an important part played by the flag leaf relative to protein accumulation of the developing grain.     

Nitrate,nitrate reduction and organic nitrogen in plants from different ecological and taxonomic groups of Central Europe

Summary 48 plant species of the families Asteraceae, Chenopodiaceae, Ericaceae, Fabaceae, Lamiaceae, Polygonaceae and Urticaceae were investigated in 14 natural habitats of Central Europe having different nitrate supplies, with respect to their nitrate content, nitrate reductase activity (NRA) and organic nitrogen content. Plants that were flowering were selected where possible for analysis. The plants were subdivided into flowers, laminae, petioles+shoot axes and below-ground organs. Each organ was analyzed separately. Differences among species were found for the three variables investigated. Apart from the Fabaceae, which had particularly high concentrations of organic N, these differences reflect mainly the ecological behaviour, i.e. high nitrate and organic N contents and NRA values per g dry weight were found in species on sites rich in nitrate, and vice versa. Nitrate content, NRA and organic N content were correlated with nitrogen figures of Central European vascular plants defined by Ellenberg (1979). By use of regression equations this correlation was tested with species from other systematic groups. Some species were attributed with calculated N figures for the first time.     

Foliar and fine root nitrate reductase activity in seedlings of four forest tree species in relation to nitrogen availability

Summary Seedlings of red maple, white pine, pitch pine and red pine were fertilized with nutrient solutions containing 4 levels of nitrate or ammonium additions. These levels corresponded to approximately 0.5, 1, 2 and 4 times normal availability of nitrogen in northeastern forests. Nitrate reductase (NR) activity was assayed in roots and leaves. Red maples treated with nitrate showed much higher leaf activities and higher ratios of leaf NR activity to root NR activity than any other species. Ammonium additions to red maple and white pine appeared to inhibit NR activity in leaves. With high nitrate additions, NR activity was induced in roots and leaves of pine species, but activity in roots remained much higher than in leaves.