Potassium Release from Soil Clays by Diammonium Phosphate, Ammonium Bicarbonate and Ammonium Chloride

We have studied the release of potassium (K) by diammonium phosphate, ammonium bicarbonate and ammonium chloride from Ca-saturated clay fractions of four Aridisols (Bhalwal, Gujiana, Miranpur and Pacca series), one Inceptisols (Miani series) and one Alfisol (Pindorian series). The six soil clay fractions contained mica, kaolinite smectites as their major mineral components and vermiculite and chlorite as minor constituents. Total K in the soil clays ranged from 2.65 to 3.55%. Of total K, 2–3% in the soil clays was extracted by the three extractants: diammonium phosphate, ammonium bicarbonate and ammonium chloride. However, there was significant (P < 0.01) main and interactive effect of soil x extractant on the amount of K extracted from soil clays. Potassium extracted from the soil clays was described by the Elovich equation. Amount of K extracted by the three extractants from six soil clays, except in Pindorian series, followed the order: ammonium bicarbonate > ammonium chloride > diammonium phosphate.
The profound influence of bicarbonate, chloride and phosphate anions on differential K replacement behaviour of NH₄ can be an important factor for K nutrition of plants in arid region soils.     

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.     

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.     

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.     

Effects of Salinity and Mixed Ammonium and Nitrate Nutrition on the Growth and Nitrogen Utilization of Barley

The absorption and utilization of nitrogen (N) by plants are affected by salinity and the form of N in the root medium. A hydroponic study was conducted under controlled conditions to investigate growth and N uptake by barley ( Hordeum vulgare L.) supplied with five different NH₄⁺-N/NO₃⁻-N ratios at electrical conductivity of 0 and 8 dS m⁻¹. The five NH₄⁺-N/NO₃-N ratios were 0/100, 25/75, 50/50, 75/25 and 100/0, each giving a total N supply of 100 mg N l⁻¹ in the root medium. A mixed N supply of NH₄⁺ and NO₃⁻ resulted in greater accumulation of N in plants than either NO₃⁻ or NH₄⁺ as the sole N source. Plants produced a significantly higher dry matter yield when grown with mixed N nutrition than with NH₄⁺ or NO₃⁻ alone. Total dry matter production and root and shoot N contents decreased with increasing salinity in the root medium. The interaction between salinity and N nutrition was found to be significant for all the variables. A significant positive correlation (r=0.97) was found between nitrogen level in the plant shoot and its dry matter yield.     

Nachweis des Strohabbaues über die Stickstoffreisetzung aus 15N-markiertem Stroh

Ten charges of ¹⁵N-labelled straw with different C/N ratios were incubated with lightly loamed sand at 25 °C and 50 % of the maximum water capacity. At the start of the 18-week incubation, mineral nitrogen was added and the ¹⁵N_min (NH₄ and NO₃-N) content was determined six times during the course of the experiment. A slow release of ¹⁵N was observed. After 111 days, between 2.5 and 13.0% of the total applied ¹⁵N was mineralized. The addition of ammonium sulphate caused an increasing degradation of organic N compounds of the straw material even during the first weeks. Finally, between 6.4 and 33.3 %¹⁵N was released. The ¹⁵N release only partially shows the straw degradation.     

Estimation and Partitioning of Nitrogen Fixed by Soybean in Mediterranean Climates

A field study was conducted to estimate the nitrogen fixation by soybean [ Glycine max (L.) Merr.], using the A-value and the N-difference methods, and to examine the N partitioning within the plant. The cultivar Clark and its non-nodulating isoline (as reference crop) were grown in a silty clay (Typic Xerothent) soil, in 1991 and 1992. ₁₅N-Labelled fertilizer was surface applied in solution, at rates of 20 and 100 kg N ha⁻¹ to the nodulating and non-nodulating soybean, respectively. Plant samples were taken at full bloom (R2), beginning of seed growth (R5) and physiological maturity (R7). There was little nitrogen fixation at the early growth stages but it increased rapidly during the seed filling period. At R7 nitrogen fixed was estimated by the A-value method as 155 kg N ha_-1 in 1991 and as 240 kg N ha⁻¹ in 1992. The corresponding estimates by the N-difference method were significantly smaller. The seeds had a higher, and the vegetative parts smaller, proportion of fixed nitrogen compared to the whole plant. During the seed filling period, the translocation efficiency for fixed nitrogen was greater (93 % in 1991 and 85 % in 1992) compared to the N derived from soil (75 and 56 %, respectively). It was estimated that, after the harvest of pods, the soil was depleted by a net amount of 121 kg N ha⁻¹ in 1991 and 90 kg N ha⁻¹ in 1992.     

Conversion of SO2−4-S and Changes in Glucosinolate Content in Leaves of Rape Seedlings Transplanted

The conversion of SO^2-₄ -S and changes in content of S in various constituents in leaves of rape seedlings transplanted were investigated by using (NH₄)₂³⁵SO₄ as a tracer to exploit formation and accumulation of glucosinolates in oilseed rape. Seedlings grown under sandy culture absorbed ³⁵SO^2-₄ which was added to the cultural solution and incorporated into amino acids, glucosinolates and proteins rapidly. Distribution of extractable ³⁵S with 70 % methanol in glucosinolates in leaves declined with time from labelling, while those in amino acids rised correspondingly. Per cents of ³⁵S incorporated into bound form in total ³⁵S increased linearly and those of ³⁵S into glucosinolates and amino acids decreased with time within five days from labelling. After that the relative amounts of ^3SS in three constituents was basically constant. Content on dry weight basis of labelled glucosinolates and amino acids expressed as μmol S/g.d.w. increased linearly with time from labelling with absorption of ³⁵SO^2-₄from soil by the seedlings under soil culture. Compared with seedlings grown under sandy culture, more ³⁵S was incorporated into glucosinolates in leaves of seedlings grown under soil culture.     

Nitrogen Fixation by Hybrids of White Clover (Trifolium repens L.) and Trifolium nigrescens

Development of hybrids between white clover ( Trifolium repens L.) and Trifolium nigrescens provides a novel route for genetically improving the reproductive capacity of white clover, provided the hybrids are agronomically viable, particularly with respect to N₂ fixation. A comparative study of growth and rates of N₂ fixation over 21 days was conducted with the parental species, F ₁ hybrids and backcross hybrids, in flowing solution culture, without a supply of mineral N to the plants. T. nigrescens was unable to fix N₂ in association with the strains of Rhizobium leguminosarum biovar. trifolii selected for inoculation. Rates of N₂ fixation per plant increased in the order T. nigrescens < F ₁ hybrid < T. repens < backcross 1. Specific rates of N₂ fixation (days 0–21) increased in the order T. nigrescens < F ₁ hybrid < backcross 1 <  T. repens . Dry matter production and nodule biomass per plant increased at a higher rate in backcross 1 hybrids than in T. repens. The results suggest that the potential for N₂ fixation by backcross 1 hybrids is at least as great as that by T. repens .     

Soybean Genotypic Variation for Nitrogen Fixation

Eighteen soybean ( Glycine max [L.] Merr) cultivars from maturity groups V and VI were screened with two Bradyrhizobium japonicum strains (USDA 110 and TAL 378) in the greenhouse to determine N₂ fixation (C₂H_2: reduction) rates. Antibiotic resistant markers were used for observing nodule occupancy. Cultivars L.-76-0132, PI 159319, Hoberland, Lee, PI 22173 and Centennial showed high nitrogenase activity of 6.25, 5.54, 17.43, 4.73, 6.94, and 4.81 μM C₂H₄/Pl/hr, respectively. Cultivars PI417419, PI 230978, Ogden , and FC 31665 showed low nitrogenase activity of 1.51, 0.80, 0.62 and 0.94 μM C₂H₄/Pl/hr, respectively. The data from this screening experiment suggest that the N₂ fixation varied among genotypes and all the nodules were occupied by the inoculated strains only. Rhizobial strain effect was observed among soybean cultivars (MGVI).     

Interactive Effect of Nitrogen and Sulphur on Growth and Yield of Rape-seed-Mustard (Brassica juncea L. Czern. and Coss. and Brassica campestris L.) Genotypes

A simple randomized field experiment was conducted to assess the growth and yield of rape-seed-mustard in relation to sulphur and nitrogen interaction. Three levels of sulphur (0, 40 and 60 kg ha⁻¹) in combination with three levels of nitrogen (60, 100 and 150 kg ha⁻¹) were tested as treatments, T₁, T₂, T₃, T₄, and T₅. Results indicated significant favourable effects of sulphur and nitrogen, when applied together, on yield components, seed and oil yield. Maximum response was observed with treatment T₃ (having S and N of 40 and 100 kg ha¹, respectively). Percentage oil content of seed was maximal at T₄ (having S and N of 60 and 100 kg ha¹) in both cultivars. The increase in N dose from 100 to 150 kg ha⁻¹ without any change in applied S, i.e. 60 kg ha¹ (T₅), decreased the percentage oil content. The seed and oil yield, however, were similar to T₃. Favourable responses of S and N interaction on leaf area index, rate of photosynthesis and biomass production were also observed.     

Effects during Period of Siliqua Developing of KH2PO4 and MgSO4 Application on Nitrogen Transportation in Pods of Oilseed Rape(Brassica napus L.)

An experiment was conducted in field experiment plot to investigate nitrogen transportation from hulls of pods in different periods at early stage of siliqua developing and effect of KH₂PO₄ and MgSO₄ application on it using ¹⁵N-urea.
More than 80 % of ¹⁵N applied on the surface of pods at lower terminal during flowering was recovered from all pods one month after flowering, most of them were still in the hulls of labelled pods, 17-27 % of ^l5N applied was transported into seeds, a small amount was transported to pods at upper terminal, a little amount was found in pods at branch. More ^l5N applied in middle period of flowering was transported to pods at upper terminal and branch than those applied in early period of flowering. It should be further investigated to conclude how will be going on transportation of nitrogen from hulls as preceding of siliqua developing towards maturity of seeds and its difference between ¹⁵N applied in more different periods.
Application of KH₂PO₄ and MgSO₄ with ¹⁵N-urea of surface of pods promoted transportation of ¹⁵N into seeds from hulls, effect of MgSO₄ was more notable.     

Effect of Sulphur and Foliar-applied Chemicals on Cold Tolerance in Chickpea (Cicer arietinum L.)

In a field study it was observed that sulphur fertilization of chickpea at 100 kg S ha⁻¹ imparted cold tolerance under low temperature stress conditions. Further, foliar sprays of DMSO, H₂SO⁴, KCl and H³BO³ proved effective in alleviating cold injury. Glucose spray also showed efficacy in this regard. The effects of sulphur fertilization and foliar applied DMSO and H²SO⁴ were largely associated with improved sulphur nutrition of plants, while improvement in K content under KCl treatment and B content under H₃BO₃ treatment was responsible for cold tolerance effects. Improvement in overall soluble carbohydrate and protein status of plants was held responsible for glucose effects possibly associated with osmoregulation.     

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.     

Effect of Gibberellic Acid Spray and Basal Nitrogen and Phosphorus on Productivity and Fatty Acid Composition of Rapeseed-Mustard

Two field experiments were conducted during] 994-95 to study the effect of spray of 10⁻⁵ M GA3 at 40 days after sowing on mustard ( Brassica juncea (L.) Czern & Coss.) cv. Varuna grown with basally applied 0, 40, 80 and 120 kg N ha⁻¹ (Expt. 1) and 0,15, 30 and 45 kg P ha⁻¹ (Expt. 2) on pod number per plant, seeds per pod, 1000 seed weight, seed yield, biological yield, harvest index and fatty acid composition of oil. No significant difference between water and GA3 spray was found when basally applied nitrogen was 0 or 40 kg N ha⁻¹. N₈₀ proved to be the best for yield characteristics. In another experiment on phosphorus, GA₃ and 30 kg P ha⁻¹ individually enhanced the yield, but interaction of GA₃ and P remained non-significant. The fatty acid composition of oil in both experiments was significantly affected only by nitrogen and phosphorus treatments for oleic acid and erucic acid. It was found that return in the form of yield was more for every kg applied fertilizer under GA, spray treatment. The response was more for N fertilizer in comparison to P. GA₃ at a low level of fertilization significantly increased the return from fertilization.     

Nitrogen Fixation, Growth and Yield of Intercropped Mungbean (yigna radiata L.) and Groundnut (Aracbis bypogaea L.) as Affected by the Genotype

¹⁵N-aided investigations were conducted to ascertain the Nj fixation and the nitrogen (N) contribution by mungbean ( Vigna radiata L.) and groundnut ( Aracbis hypogaea L.) when intercropped with maize ( Zea mays ). The study involved growing seven genotypes of the above legumes with maize in alternate rows in two separate experiments. A sole crop of maize was used as the reference crop to determine N2 fixation by the ¹⁵N methodology. Significant genotypic differences in pod yield and stover N content were observed in intercropped mungbean and groundnut. The percentage N derived from the atmosphere showed a genotypic variation of 31 to 45 % (7 to 10 kg N₂ fixed ha⁻¹O in mungbean and 47 to 69 % (9 to 18 kg N₂ fixed ha⁻¹) in groundnut. Harvest index for N varied from 58 to 77 % in mungbean and 55 to 75 % in groundnut. In groundnut, the uptake of soil N was significantly affected by the genotype. Assuming that the N contribution to the soil by the helow-ground plant parts was negligible, the removal of seeds at maturity resulted in a negative N balance in the soil in all the genotypes of mungbean. In groundnut, some genotypes produced a positive N balance in the soil. Owing to high N₂ fixation capacity and low harvest index for N, groundnut showed a greater N supplementing ability than mungbean.     

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.     

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.     

Identification of AFLP and RAPD markers linked to anthracnose resistance in grapes and their conversion to SCAR markers

Resistance to anthracnose or black spot ( Elsinoe ampelina ), a serious fungal pathogen in viticulture and table grape production, was investigated on 25 grape cultivars. Bioassays performed with culture filtrates produced by the pathogen revealed 14 resistant genotypes. In most plants resistance originated from Vitis labrucsa but also genotypes with V. rupestris and V. riparia  ×  V. rupestris background showed resistance. Genetic analysis was conducted in F₁, S₁ and BC₁ plants developed from various cultivars. In total, 326 F₁ plants were evaluated, 172 genotypes proofed to be resistant, whereas 154 were susceptible to anthracnose. A Mendelian segregation ratio of 1 : 1 (χ² = 0.30–0.65) indicating that anthracnose resistance is controlled by a single dominant gene. To facilitate the use of marker-assisted selection in grape-breeding PCR-based markers were developed by random amplified polymorphic DNA and amplified fragment length polymorphism in bulk segregant analysis. Finally, OPB 15₁₂₄₇ was developed as a sequence characterized amplified region marker being diagnostic for the locus of resistance to anthracnose in all resistant genotypes tested. Within the 25 grape cultivars OPB 15₁₂₄₇ is diagnostic in the genetic background of both V. labrucsa and V. rupestris and V. riparia  ×  V. rupestris .     

Molecular mapping of genic male-sterile genes ms15, ms5 and ms6 in tetraploid cotton

Two genic male sterile (GMS) lines, Lang-A conditioned by ms ₁₅ and Zhongkang-A conditioned by ms ₅ ms ₆ duplicate recessive genes in Gossypium hirsutum L., were chosen to map GMS genes. These two lines were crossed with Gossypium barbadense cv. 'Hai7124' to produce segregating populations. The ms ₁₅ gene was mapped on chromosome 12, and was flanked by two simple sequence repeat (SSR) markers, NAU2176 and NAU1278, with a genetic distance of 0.8 and 1.9 cM respectively. The ms ₅ and ms ₆ genes were mapped to one pair of homoeologous chromosomes, ms ₅ on chromosome 12 flanked by three SSR markers, NAU3561, NAU2176 and NAU2096, with genetic distances of 1.4, 1.8 and 1.8 cM, respectively, and ms ₆ on chromosome 26 flanked by two SSR markers, BNL1227 and NAU460, with a genetic distance of 1.4 and 1.7 cM respectively. These tightly linked markers with the ms ₁₅ , ms ₅ and ms ₆ genes can be used in the marker-assisted selection among segregating populations in a breeding programme, and provide the foundation for gene isolation by map-based cloning for these three genes.