Ammonia Metabolism in the Leaves and Ears of Wheat (Triticum aestivum L.) During Growth and Development

The pattern of free NH₄⁺ accumulation and its metabolism was studied during the growth and development of field-grown wheat cv. HD 2204 at two applied N levels viz. 30 and 120 kg ha⁻¹. The study was confined to the 3rd, 5th and flag leaf blades and the developing ears, borne on the main shoot, during their ontogeny. The NH₄⁺ levels were considerably lower in young leaves and increased sharply as the leaves senesced when the activity of glutamine synthetase (GS) declined. In contrast to GS, glutamate dehydrogenase (GDH) remained active even during senescence. Concentrations of protein, free amino acid and total reduced N declined with age in the leaves. An assessment of free NH₄⁺ pool, free amino acid content and the activity of GS and GDH in the floral parts revealed that glumes, awns and grains also were active sites of NH₄⁺ turnover. Higher applied N level not only increased leaf and grain N concentration but also led to higher free NH₄⁺ levels in leaves and in developing ears. Presence of NH₄⁺ in the entrapped transpirate revealed that NH₄⁺ is released from both leaves and ears during senescence.     

Einfluß des Lichtangebotes auf das Wachstum und die biologische Stickstoff-Fixierung von Weißklee (Trifolium repens L.)

Influence of light quantity on growth and biological nitrogen fixation of white clover ( Trifolium repens L.)
The influence of photon irradiance (E_p; 100 to 500 μmol m⁻² s⁻¹) and of the photoperiod (16 or 11 h) on growth and nitrogenase activity of nodulated white clover plants was studied in growth chambers at two nitrate levels (1.0 and 7.5 mM NO₃⁻).
Total dry mass production, the root proportion and nitrogenase activity increased with increasing E_p and photoperiod. Nitrogenase activity generally increased proportionally to root mass. Only at low E_p (100 μmol m⁻² s⁻¹) and under a short photoperiod (11 h) was the specific nitrogenase activity per unit root mass reduced. An abrupt change in E_p led to a rapid and parallel change in nitrogenase activity and relative growth rate.
A higher NO₃⁻ concentration in the nutrient solution (7.5 mM) led to a marked decrease in specific nitrogenase activity, but increased growth between 200 and 500 μmol m⁻² s⁻¹ during early development only. At 100 μmol m⁻² s⁻¹, there was no growth response to nitrate, although its effect on nitrogenase activity was more marked than at a higher E_p.
The results show that with changing light quantity, biological nitrogen fixation of white clover adapts to the existing demand for nitrogen and does not limit growth except during early development, even when light supply is low.     

Morphogenetic Effects of Different Mineral N-compounds on Roots of Maize (Zea mays L.), Spring Barley (Hordeum vulgare L.) and Broad Bean (Vicia faba L.)

Plants of maize ( Zea mays L.), spring barley ( Hordeum vulgare L.) and broad bean ( Vicia faba L.) were raised in tubes filled with a soil-sand mixture and supplied with nutrient solution. The nutrient supply was varied with regard to concentration and typ of compound of "N". Due to the relatively high concentrations of "N", dry matter of shoots and roots was reduced in comparison to the control; root morphology was affected in terms of root length and root thickness. The N-compounds, used in the experiment, exerted quantitatively different influences on dry matter production and root morphology, NH₄NO₃ being the N-form which had the weakest detrimental effects. There was no specific response to NH⁺₄ or NO⁻₃ but a strong influence could be shown for NH₄Cl and N_aNO₃. Probably not only the concentration of "N" and the form of "N" have a specific influence, but also the cations and anions associated with the N-containing ion are effective.     

Differential Nitrogen Uptake, Utilization and Biomass Accumulation by Some Sorghum Cultivars

Five cultivars of sorghum viz: PU-7, Sarokartuho, Bagdar, Redjanpur and Potobar 4–8 were studied for their growth, N uptake and utilization efficiency at 5 mM N in solution culture. These cultivars differed significantly in their dry matter accumulation and relative growth rate of shoot. Differences in shoot/root of the cultivars were also notable. Markedly different mean N intake rate among the sorghum cultivars was 108 μmol g⁻¹ root dry wt. hr⁻¹ in Bagdar and 53 μmol g⁻¹ root dry wt. hr⁻¹ in PU-7 and Redjanpur. Both relative accumulation rate of N and efficiency of biomass accumulation per unit N absorbed also differed appreciably among the cultivars.     

Effect of Homogeneous and Heterogeneous Soil Compaction on Shoot and Root Growth of Field Bean and Soybean

The study was done to observe the effects of soil compaction on field bean and soybean growth in greenhouse. Plastic cylindrical tubes of 58 cm height and 12 cm diameter were filled with silty loam soil with three bulk densities i.e., low (1.25 g/cm³), medium (1.45 g/cm³) and high (1.65 g/cm³) either separately or in combination of low/medium (level 1), low/high (level 2) and medium/high (level 3) as top and sub-soil densities.
General effect of compaction was a reduction in shoot and root growth and in yield of both the legumes; probable reason seemed to be mechanical impedance. At homogeneous compaction throughout the soil profile high bulk density decreased the root dry matter from 6 to 32 % and total root length from 30 to 57% but total root volume was not much affected due to thickening of the roots. From 4 to 31% reductions were also observed in shoot dry matter. Increase in only subsoil density from medium to high (level 2) decreased shoot and root dry matters (8 to 36% and 16 to 39%, respectively) but not the total root length. Plant growth was more hampered when both top and subsoil densities were increased (level 3) but the total root length was not highly affected in the upper (0 to 20 cm) and middle (20 to 40 cm) layer.     

Effect of NH4+ Nitrogen on Phosphorus Uptake by Canola, Lentils, Soybeans and Wheat

Phosphorus and ammonium nitrogen placed together has been shown to increase P uptake by crops, especially cereals, Thus, the objective of this study was to compare this effect on four crops grown in Manitoba. Plants harvested at flowering indicated greater P uptake in lentils, soybean and wheat, when P and NH₄⁺-N were placed on the same band. In contrast, canola did not respond to this treatment. Possible relationships of these ions are presented.     

Untersuchungen über die Wirkung von Ammonium- und Nitrat-Ernährung auf die Ertrags- und Proteinbildung bei Hafergenotypen

Investigations about the effect of ammonium- and nitrate nutrition on the formation of yield and protein of oats genotypes
The formation of yield and proteins of three different oats genotypes (cv. Gambo, Flämingskrone, Caesar ) in dependence on ammonium or nitrate nutrition was investigated in pot trials over 2 years (from 1982 to 1983). On oats the NH₄-nutrition showed in comparison to NO₃ nutrition increases in grain yield up to 20 % due to a favourable influence on the number of panicles per pot (s. Fig. 1).
Protein content and protein yield increased particularly by high fertilizing with NH₄-N (N₃- and Invariant); the best effect was ascertained by the N₄-variant increase of 4 % (D.M.). Among the protein fractions (albumins, globulins, prolamins, glutelins) the albumin- and prolamin-proteins increased after NH₄-fertilizing by 1–2 %, whereas at the same time the glutelins decreased by 1–4 %; the globulins showed no differences.     

Effect of NaCl Salinity and Putrescine on Shoot Growth, Tissue Ion Concentration and Yield of Rice (Oryza sativa L. var. GR-3)

Interactive effect of NaCl salinity and putrescine on shoot growth, ion (Na⁺, K⁺ and CI⁻) concentration in leaf, stem and inflorescence and yield of rice (Oryza sativa L. var. GR-3) were studied. When rice plants were subjected to salt stress (12 dS/m) the extension growth and dry weight of shoot system as well as total leaf area and chlorophyll content were found markedly reduced. Analysis of leaf, stem and inflorescence of salt-stressed plants showed higher concentration of Na⁺ and Cl ions and lower concentration of K⁺ ion compared to the control. Salinization also caused a considerable fall in grain yield.
Foliar application of putrescine (10⁻⁵M) significantly increased the growth and yield of salt-stressed plants. Putrescine treatment decreased the influx of Na⁺ and Cl⁻ ions and increased the K⁺ level in all the tissues of salinized plants examined. Putrescine also increased the chlorophyll content in salt-stressed plants. These results suggest that exogenous application of putrescine can be used successfully to ameliorate the stress injuries caused by NaCl salinity in rice plants to a considerable extent.     

Interactive Effects of Salinity and Biological Nitrogen Fixation on Chickpea (Cicer arietinum L.) Growth

The effect of salinity on the nodulation, N-fixation and plant growth of selected chickpea- Rhizobium symbionts was studied- Eighteen chickpea rhizobial strains were evaluated for their growth in a broth culture at salinity levels of 0 to 20 dS m⁻¹ of NaCl + Na₂SO₄. Variability in response was high. Salinity generally reduced the lag phase and/or slowed the log phase of multiplication of Rhizobium. Nine chickpea genotypes were also evaluated for salt tolerance during germination and early seedling growth in Petri dishes at five salinity levels (0–32 dS m⁻¹). Chickpea genotypes ILC-205 and ILC-1919 were the most salt-tolerant genotypes. The selected rhizobial strains and chickpea cultivars were combined in a pot experiment aimed at investigating the interactive effect of salinity (3, 6 and 9 dS m⁻¹) and N source (symbiosis vs. inorganic N) on plant growth. Symbiotic plants were more sensitive to salinity than plants fed mineral N. Significant reductions in nodule dry weight (59.8 %) and N fixation (63.5 %) were evident even at the lowest salinity level of 3 dS m-¹. Although nodules were observed in inoculated plants grown at 6 dS m-¹, N-fixation was completely inhibited. The findings indicate that symbiosis is more salt-sensitive than both Rhizobium and the host plant, probably due to a breakdown in one of the processes involved in symbiotic-N fixation. Improvement of salinity tolerance in field grown chickpea may be achieved by application of sufficient amounts of mineral nitrogen.     

Stickstoff-Eintrag und -Verbleib im Boden unter offenen und abgedeckten Mistmieten

Nitrogen penetration and persistence in soil under uncovered and covered farmyard manure heaps
After deposition of cattle manure for 308 days neither the total nitrogen nor the nitrate but onlv the ammonia content in the soil (0–70 cm) was significantly increased. During a 258 days period from autumn to spring the observed microbial oxidation of penetrated ammonia to nitrate was tardy and by no means quantitative. So leaching of nitrate was hardly to be detected during the whole period. In the soil layer 40–70 cm a maximum of 1.6 g NO₃⁻-N/m² was measured, which was in an equivalent range with the amounts detected by large scale investigations in agricultural soils at the same season. Therefore the manure heaps in question did not lead to an uncommon increase of nitrate in soil. The protection of the heaps against precipitation simply brought about small and only a few times significant reductions in soil N_min content.     

Comparative Responses of Wheat (Triticum aestivum L.) Cultivars to Salinity at the Seedling Stage

Seedling growth and ion content of Pakistani bread wheat cultivars was assessed in solution culture in the absence and presence of NaCl (100 and 200 mol m⁻³) to determine whether seedling traits could be used in breeding programs for salt-tolerance. Growth was recorded as seedling fresh weight, and the shoot and leaves analysed for major inorganic ions. Plants subjected to salt stress excluded Na⁺ and Cl⁻ ions from the shoot to varying extents. Exclusion preferentially maintained lower Na⁺ and Cl⁻ levels in the apical tissue, as the leaf to leaf gradient in Na⁺ and Cl⁻ became steeper as the external salinity increased, although there were significant differences between cultivars. Correlation analysis on individual plants indicated that excluding Na⁺ at low salinity, and Na⁺ and Cl⁻ at high salinity, were correlated significantly with growth performance, although it was clear that other factors were also involved. The relationship of tolerance to ion exclusion was stronger when the data were examined on an individual plant basis than when related to pooled cultivar data or to the cultivar rank order derived from field trials, probably due to large variations in Na⁺, and to a lesser extent, Cl⁻ transport in supposedly homozygous cultivars.     

Some Agronomic and Physiological Aspects of Salt Tolerance in Cotton (Gossypium hirsutum L.)

Evaluation of commonly grown cotton (Gossypium hir-sutum L.) genotypes under saline environment may help to cope with the venture of the crop failure in salt-affected soils. In a pot experiment, four cotton genotypes (MNH-93, NIAB-78. S-12, and B-557) were grown to compare their relative performance on a sandy clay loam soil (original ECe = 1.9 dS m⁻¹) salinized with a salt mixture (Na₂SO₄, NaCl, CaCl₂, MgSO₄ in the ratio of 9:5:5:1 on equivalent basis) to EQ levels of 10 and 20 dS m⁻¹. The crop was raised to the flower initiation stage. The imposed salinity stress exhibited deleterious effect on the germination and vegetative growth with significant differences among the genotypes. Leaf area, stem thickness, shoot (stem + leaves) and root weights decreased with the increase in substrate salinity. NIAB-78 showed the least decline followed by MNH-93. Leaf thickness showed an opposite trend as an increase in this parameter was observed with the rising salinity, the maximum increase being in the case of NIAB-78. Analysis of the leaf sap showed increased Na⁺ and Cl⁻ concentrations and decreased K⁺ concentration with the increase in substrate salinity. A better osmotic adjustment, a lower Na⁺/K⁺ ratio and a lower Cl concentration were found in the leaves of NIAB-78 followed by MNH-93. This contributed towards their better growth performance under saline conditions.     

Untersuchungen zum Wurzelwachstum von Jungpflanzen alter und neuer Winterweizensorten sowie eines Spelzweizens bei variierter N-Versorgung

Root growth of seedlings of old and new winter wheat cultivars and a spelt wheat at varying levels of nitrogen
Root growth of five old (time period 1882–1920) and five new (time period 1975–1982) winter wheal cultivars and a spelt winter wheat cultivar was investigated in two greenhouse trials. Nitrogen (NH₄NO₃) was supplied at six (Exp. I) and two (Exp. II) levels (sub- to supraoptimal for shoot growth). The seedlings were grown in sand-filled polyethylene tubes of 4.5 cm diameter and 50 cm length at 20 ^oC. The plants were harvested 11 (Exp. I) and 12 (Exp. II) days after emergence. At this early stage of development root growth o: old and new cultivars differed only slightly. The old T. aestivum cultivars had more seminal roots. The longest roots of the modern cultivars penetrated into deeper layers of the substrate. For some traits, cultivar: seemed to respond specifically to the varying N-supply. However, there were no significant difference: between old and new cultivars. Neither were old cultivars better adapted to low N-fertilization nor were modern cultivars superior in tolerating toxic concentrations of NH₄NO₃. Increasing N supply changes root growth as follows: decline in root dry matter, increase in shoot/root ratio of dry weight, decrease in number of seminal roots, shortening of axes and more laterals, increase in diameter of the laterals and less significantly of the main roots, increase in density of laterals, decline in root surface area. The number of apices was affected only to a very small degree.     

Response of Rainfed Sunflower (Helianthus annuus L.) to Nitrogen Rates and Plant Population in the Semi-arid Savanna Region of Nigeria

Field experiments were conducted during the wet seasons of 1991,1992 and 1993 at the Abubakar Tafawa Balewa University Farm, Bauchi (10 ° 22'N, 09 ° 47'E) to study the response of sunflower ( Helianthus annaus L.) to N rates and plant population under rainfed conditions. Four N rates (0, 50, 100 and 150 kg N ha ^-1) and four plant populations (40000,80000,120000 and 160000 plants ha^-1) were factorially combined in a randomized complete block design with three replications. Leaf area index, shoot dry weight and seed yield (kg ha^-1) increased significantly with increasing N rates from 0 to 100 kg N ha^-1. The growth and yield parameters per plant decreased significantly with increasing plant populations from 40000 to 160000 plants ha^-1, but the seed yield (kg ha^-1) obtained at 80000 plants ha^-1 was significantly higher than all the other plant populations. The interactions of N x plant population confounded the main effect of each factor on the growth and yield of sunflower. The seed yield (3425 kg ha^-1) obtained from the use of 100 kg N ha^-1 at 80000 plants ha^-1 was significantly higher than those obtained from all other combinations of N x population and out-yielded the main effects of 100 kg N ha^-1 and 80000 plants ha^-1 by 18 % and 25 %, respectively. The use of 100 kg N ha^-1 at 80000 plants ha^-1 is therefore recommended for maximum yield of sunflower in Bauchi.     

土壤中不同含量Cd2+对大麻、大豆幼苗生育的影响

探究大麻耐重金属能力,为今后植物修复重金属污染土壤提供数据支持。以‘龙大麻5号'和‘黑农84'为试验材料,通过盆栽试验,研究土壤中喷施不同含量Cd²⁺对大麻、大豆幼苗生长发育的影响。结果表明,低含量的Cd²⁺(≤0.6 mg/kg)对大麻和大豆的根系活力及干物质积累略有促进作用,差异不显著。当土壤中20.0 mg/kg≥Cd²⁺≥2.0 mg/kg时,2种作物的生长均受到抑制,与对照处理相比,大麻出苗率降低6.3%~100%,根系活力下降5.8%~77.8%,干物质积累降低6.6%~40.2%;与对照处理相比,大豆出苗率降低21.6%~100%,根系活力下降8.9%~100%,干物质积累降低27.4%~50.1%。当土壤中Cd²⁺含量≥100 mg/kg时,大麻、大豆的出苗率均为零。对相同含量的Cd²⁺大麻耐受能力要强于大豆;对于重金属污染严重的地块,建议大麻优先于大豆种植。     

Evaluation of N Fertilizer Rate and Timing and Wheat Cultivars on Soil Residual Nitrates

Nitrogen (N) fertilizer management for production of bread quality wheat may increase nitrate residues in the soil. To assess soil nitrate levels associated with bread quality wheat ( Triticum aestivum L.) production in Eastern Canada, an experiment was conducted for 2 years at each of two sites in Québec. Four cultivars (Columbus, Katepwa, Max and Hege 155-85), four N levels (0, 60, 120 and 180 kg N ha⁻¹) and two N timings (all at seeding time or 60 % at seeding and 40 % at anthesis) were combined in a factorial arrangement on a Bearbrook clay and a Ste-Rosalie clay. Residual soil NO₃-N levels were measured in the 0–20 and 20– 60 cm soil layers. The cultivars used have potential as bread wheats. Cultivar effects on soil nitrate levels existed only in the Ste-Rosalie soil, suggesting that the cultivars used were better adapted to the conditions on the Bearbrook soil. Changes in soil NC₃N levels over winter indicated that mineralization had occurred. Calculated balance-sheet values were larger than measured residual NO₃-N in the autumn of each year, indicating that NO₃-N was lost from the systems, possibly due to denitrification. Potential increases in, and thus potential pollution from, residual soil NO-N existed only at the 180 kg N ha⁻¹ level. Overwinter changes in soil NO₃-N levels were proportional to the inverse of the fall NC₃N levels. Differences between sites were large for many of the variables measured.     

Effect of Inoculant Rate on Nodulation and Various Agronomic Traits of Soybean

In a soil lacking indigenous Bradyrhizobium japonicum , soybean ( Glycine max [L.] Merr.) nodulation depends upon the number of rhizobia applied with the inoculum. This field study reports the effect of different rates of applied rhizobia on nodulation, dry matter and nitrogen content in soybean in a Mediterranean soil lacking B. japonicum.
Treatments included six rates of B. japonicum , ranging from 2.5 × 10⁴ to 6.075 × 10⁶ rhizobia cells per seed applied to the seed as peat inoculant at planting, 100 kg N ha⁻¹ and an uninoculated control. The experiment was conducted in an Entisol soil. Regression analysis showed linear relationship between the rate of applied rhizobia and the number of the nodules per plant or the dry weight per nodule. In early stages of development (32 and 68 days after planting) plant dry weight was not affected by inoculation rate. At harvest a rate of 7.5 × 10⁴ rhizobia cells per seed was necessary for maximum total and stover dry weight. A higher rate, 6.75 × 10⁵ rhizobia cells per seed, was required to obtain maximum grain yield, total N content in plant tops and grain N content. Grain percentage N was increased up to 2.025 × 10⁶ rhizobia cells per seed. Nitrogen application increased grain yield, total N content and grain N content at the same level as the lower inoculation rate.     

Variation in Salt Tolerance Among Some Wheat and Triticale Genotypes

The identification of genotypes having potential salt tolerance is an effective approach to solve the problems of saline soils.
Seed germination and seedling establishment are limiting factors in crop production. Seven wheat ( Triticum aestivum L.) and one Triticale (X Triticosecale Wittmak) genotypes were evaluated for salt tolerance at emergence and early seedling growth in solution culture with NaCl salinities up to 300 mM L⁻¹ (electrical conductivity equals 27.6 dS m⁻¹).
Seedling emergence was delayed by increasing NaCl in nutrient media. At 200 mM L⁻¹ NaCl, the emergence percentages of wheat genotypes ranged between 68.7 % and 91.3 % after 7 days and 79.3 % and 98.7 % after 15 days. While at 300 mM L⁻¹, the emergence percentages of the wheat genotypes were 0.0 % after 7 days. After 15 days the emergence percent ranged between 24 % and 72 %. The emergence percent of the Triticale line was 88.7 after 7 days and 89.3 after 15 days at 200 mM L⁻¹, while it was 25.3 % and 84 % after 7 and 15 days, at 300 mM L⁻¹, respectively. Root and shoot dry weight were greatly reduced by increasing NaCl, however, the Triticale line showed less reduction in growth compared to the wheat genotypes. K⁺, Ca²⁺ and Mg²⁺ were decreased with increasing salinity levels while Na⁺ content was decreased in the shoot tissues of wheat and Triticale genotypes.     

Stickstoffaufnahme und Stickstoffrückstände von Hauptfrucht-und Ausfallrapsbeständen

Nitrogen Uptake and Nitrogen Residuals of Winter Oil-Seed Rape and Fallout Rape
The objective of the investigation was a study of the relationship between seed dry-matter production and vegetative dry-matter production in oil-seed rape crops and their dependence on the production conditions. In addition to the relationship between the N-uptake during the vegetation period and the N-residue after harvest was of major interest. Furthermore the potential for N-uptake in fallout rape was measured. Over two vegetation periods factorial field experiments with winter oil-seed rape, cv. Lirabon, different drilling techniques and different nitrogen fertilization levels were tested. Measured traits were: the dry-matter accumulation including root mass and fall-off leaf-material mass, the N-uptake of both the oil-seed crops and the fallout rape stands, and, simultaneously, the soil NO₃-N content. Finally the harvest indices and the N-harvest indices were calculated.
Combined with a N-uptake of up to 330 kg N/ha, oil-seed rape crops produced up to 200 dt dry matter/ ha. At seed yield levels of 33dt/ha (d.m.), harvest indices varied from 0.14—0.23 and N-harvest indices varied from 0.30–0.50. As a result of the residue of vegetative plant material at harvest, leaf losses before harvest and the soil NO₃-N-contents at harvest up to 275 kg N/ha remained in the field. After the harvest of oil-seed rape, the soil NO₃-N-contents were quickly reduced by emerging and growing fallout rape stands. However, following soil-preparation measures in the autumn, a continuous rise in the soil NO₃-N-content was observed.     

Effects of NaCl Salinity on Growth and Production of Young Cladodes of Opuntia ficus-indica

The effects of salinity on the growth and production of `nopalitos' (young cladode sprouts) of Opuntia ficus-indica (L.) Mill. cv. Copena V-1 were investigated. Salinity (NaCl) irrigation levels with electrical conductivities of 2, 5, 10, 13, 18 and 21 dS m^–1 were used. In general, all cladode variables (stem area, number of young cladodes, length and width of cladodes, and fresh and dry weights) decreased with increasing salinity. The root-to-stem ratio and young cladode water content decreased significantly as salinity increased. Other variables that decreased with increasing salinity included harvest index, relative growth rate, stem area ratio, dry mass accumulation, and Na⁺ and Cl^– concentrations. For rooted cladodes, increased salinity decreased fresh weight, succulence, and root fresh weight, dry weight and length. Our conclusions suggest that this species is salt sensitive; however, there is some indication that it could be effectively managed in saline environments. Further studies and evaluation of different cultivars are needed to identify the mechanism of adaptation of salt tolerance in this species.