The effect of humus substances on the level of free amino acids in wheat plants

The presence of potassium humate (commercial sample of Humussäure Riedel-de Haën A. G., Seelze-Hannover) in distilled water led to an increase in the content of alanine, aspartic and glutamic acid in the overground parts of wheat plants as compared with the content of these substances in control plants grown in distilled water. In plants cultivated on nutrient solutions a higher level of alanine and glutamic acid and a considerably lower level of amides was found than in plants grown in distilled water and in water with humate. Generally the content of amino acids was higher in the overground parts than in the roots after a cultivation period of one week as well as of 14 day. In the overground parts of 1 days old plants the level of aspartic acid, asparagine and alanine was found to be higher and that of glutamine lower than in seven days old plants. In the roots of the examined plants a decrease of the amino acid content accurred almost in all cases after a cultivation period of 14 days as compared to one of 7 days.     

Effect of trophic conditions on aspartate transamination in wheat plants

The enzymatic transamination reactions between aspartic and α-ketoglutaric acid and between aspartic and pyruvic acid were studied in fresh dialysed extracts of young wheat plants cultivated under various trophical conditions, in mineral solution (Knop), in the solution of an soil organic substance (potassium humate) and without nutrients (H₂O). Simultaneously, the level of endogenic aspartic acid, glutamic acid and the growth values were determined. The enzymatic reactions were characterized by determining the optimum pH, the time course, and the effect of coenzyme and of inhibitors. The activity of the aspartate-glutamate transaminase from the root system of plants was considerably higher than the activity of the overground organs. The enzymatic activity from both parts of the plant was inversely proportional to the growth rate: intensive growth of the plants from the Knop variant was connected with their low enzymatic activity; the level of endogenic glutamic acid was high. The slow growth of the plants without nutrients was connected with a higher enzymatic activity; the level of endogenic glutamic acid was low. The plants from the potassium humate variant had an intermediate position between these two variants from the point of view of growth as well as from that of enzymatic activity. The plants with insufficient nutrition (slow growth, low level of endogenic glutamic acid) apparently have a low capacity for supplementing the glutamic acid deficit, which is essential for the metabolic processes, by increasing the activity of the reactions leading to glutamic acid synthesis (Asp-Glu) and, on the other hand, by decreasing the reactions utilizing it (Glu-Ala). For wheat plants the active aspartate-glutamate reaction is obviously physiologically more important than the direct reaction glutamate-aspartate and the reaction aspartate-alanine which in all cases had a very low activity.     

Influence of sodium humate and nutritive conditions on the content of nucleic acids,particularly on the ribosomal ribonucleic acid in wheat roots

Changes in the nucleic acid (NA) content were studied in roots of young wheat plants cultivated under various nutritive conditions, namely in a nutrient solution, in distilled water and in a solution of sodium humate in distilled water. Changes in the ribosomal ribonucleic acid (RNA) in particular and their connection with growth rate were investigated. The amount of the NA fraction investigated (more than 90 per cent of which is represented by the ribosomal RNA) changed substantially under the cultivation conditions studied. In roots of one plant cultivated in water the content of the NA fraction investigated was at the most about 25 μg and it began to decrease as early as from the second day of cultivation. After 12 days of cultivation it decreased to 15 μg. When cultivated in Na-humate the roots contained at the most 33 μg NA, between the 5th–7th day, followed by an intensive decrease after 12 days, to 17 μg. The content of the fraction investigated in wheat plants cultivated in a nutrient solution was about double the value in comparison to these two cases with the maximal value about 60 μg between the 7th–9th day. After 12 days this amount decreased to 45 μg. The ratio between the growth rate and the NA content presented positive values only when plants were cultivated in a nutrient solution and in Na-humate until the day when the NA content ceased to increase. In the case of Na-humate this took place on the 6th day and in the case of a nutrient solution on the 9th day. Under conditions favourable for growth (in a nutrient solution and in field conditions) the precultivation of wheat plants in Na-humate resulted in a more intensive growth of roots in comparison with the root growth of plants precultivated in distilled water. In plants precultivated in distilled water for 4 days the growth rate continuously increased under favourable nutrition conditions in contrast to plants transferred from distilled water as late as on the 6th day. Their growth stopped after the transplantation and was restored only after a 2 day lag phase. On the other hand, in plants precultivated in Na-humate the transfer to favourable nutritive conditions resulted in both cases in a short term cessation of growth.     

Metabolism of nucleic acids in wheat roots in dependence on nutritive conditions

Influence on individual types (fractions) of nucleic acids (NA) was studied in roots of wheat plants grown in various cultivation media, namely in distilled water, in sodium humate and in a nutrient solution. NA’s were prepared by means of the phenol technique. Using separation on a methylalbumine column (MAK) five fractions were obtained, namely: fraction I.— low molecular weight substances, fraction II.—soluble RNA, fraction III.—DNA-RNA, and the ribosomal RNA in two fractions, IV.—(l r-RNA) and V.—(h r-RNA). Of the NA fractions investigated, the r-RNA fraction was noticeably influenced by the kind of nutrition, its amount varying in a certain proportion to the growth intensity affected by the cultivation medium. The other NA fractions were not apparently affected. The metabolical turnover of the individual NA types (as observed from the specific³²P activity) was considerably influenced by the kind of nutrition as well. The specific³²P activity in all NA fractions of wheat roots cultivated in a nutrient solution was approximately double that in roots of wheat plants cultivated in distilled water and Na-humate. Changes in the specific³²P activity of r-RNA were again considerably evident. With regard to root growth their relative values appeared in an inverse proportion to the changes in the r-RNA content. The specific³²P activity decreased with increasing growth intensity. Besides changes in the r-RNA fraction, changes in fraction I. were apparent. An especially striking decrease in the specific³²P activity was found in roots of plants grown in H₂O, namely by about one order in comparison with its specific activity in fraction I. from roots of plants grown in Na-humate and in a nutrient solution.     

Effect of trophic conditions and humic acid on alanine transamination in wheat plants

In dialyzed extracts from winter wheat plants an intensive enzymatical transamination reaction occurred between L-α-alanine and α-ketoglutaric acid (L-α-alanine + + 2-oxoglutarate = pyruvate + L-glutamate, EC 2.6.1.2) as well as a weak nonenzymatical transamination reaction, practically immeasurable. Pyridoxal-5’-phosphate strongly affected the reaction rate. Besides the transamination product-glutamate, γ-aminobutyric acid was formed in this reaction. This amino acid could have originated neither via proteolysis of the enzyme extract, nor via decarboxylation from glutamate formed, nor via transamination of succinic-γ-semialdehyde after α-ketoglutarate decarboxylation. This was the only case of its formation in the transamination reactions investigated in our laboratory — it originated from the alanine-glutamate reaction only, and the mechanism of its biosynthesis cannot be elucidated for the present. Dialysates from shoots exhibited a significantly higher enzymatic activity in comparison with those from roots. The effect of trophic conditions (Knop’s nutrient solution, a water solution of potassium humate, water) was not revealed when calculating per dry weight unit. However, when calculating per protein unit an increased activity was found in the dialysates from shoots of both nutrient — deficient variants. Roots of plants cultivated in potassium humate had the lowest activity. The discussion concerns the possibility of an adaptive use of this transamination for increasing the essential glutamate level in green parts of the plants cultivated under unfavourable nutritive conditions, and also deals with a further characteristic of the differing metabolism of plants cultivated in humate.     

Transaminase studies in germinating seeds

The changes in glutamic-alanine and glutamic-aspartic transaminase during the germinating period of the seedling have been studied with plants from three plant families. It was found that in the germinating seed embryo the glutamic-aspartic transaminase activity was in general higher than the glutamic-alanine transaminase activity. At the beginning of germination all plants studied contained approximately the same amount of transaminase: i.e., about 5–10 units/embryo. However after 120 hr. of germination there were wide variations in the amount of transaminase found in the different species. In most of the plants studied the transaminase activity/mg. protein nitrogen revealed a proportionally greater increase in the enzymatic activity than that of the protein nitrogen.Stimulation of growth and metabolism of the embryo by the use of a mineral supplement for germination of the seeds produced an increase in the rate of formation of both transaminase and protein nitrogen. However, the production of the enzyme was relatively greater than the formation of protein nitrogen.The results indicated that no definite relationships existed between the changes in glutamic-alanine or glutamic-aspartic transaminase activity and the formation of protein. This would suggest that in plants, protein synthesis is not a direct function of transaminase activity; it may play an indirect role in protein synthesis by its action on the interconversion of amino and keto acids.     

Maize growth and ion absorption in Richter's solution at different flow rates

By comparing maize plants cultivated in standing nutrient solution with those from solutions flowing at different flow rates it has been established that absorption of nitrogen, potassium and especially of phosphorus was increased owing to the flow. There was likewise a relative rise in the distribution of nutrients to the overground parts of the plants. The content expressed per unit dry matter was increased only in the case of phosphorus; with nitrogen and potassium it was slightly lower than in the standing solution. Increasing amounts of iron were required under the conditions of flowing nutrient solutions to prevent chlorosis of the plants. The production of dry matter,NAR andRGR was also increased because of the flow. The flow considerably changed the habitus of the primary roots of the maize plants. The roots were longer, thinner and on the whole they contained relatively less dry matter (RWR). The lengthening of the roots is explained as a response to stimulation by the solution flow—the rheotropism.     

The effect of various microelements on changes in the activity of certain enzymes in hydroponically cultivated barley during the first period of growth

The paper deals with the effect of the application of certain ions (Zn²⁺, B₄O₇ ^2- Mn²⁺, Cu²⁺, MoO₄ ^2-,) on the development of the activity displayed by amylase, urease, and glutamate-oxalacetate (GOT) in hydroponically cultivated barley during the first seven days of ontogenesis. The enzymes were studied separately in the overground and root parts of the plants. The following main conclusions can be drawn from the findings made: The amylase activity of the control plants in connection with their development diminished slightly in the overground part, while it was relatively constant in the roots. Due to the effect of certain elements tested, this activity increased pronouncedly (significant differences were confirmed in variants containing MoO₄ ^2-, Zn²⁺, and Co²⁺). The urease level in the overground part of the control plants remained low throughout the entire experimental period and was only little influenced by the individual microelements under study (with the exception of B⁴O₇ ^2-). On the other hand, the urease activity in the root system increased markedly, the B₄O₇ ^2- ions exhibiting a significantly stimulating effect. The activity of glutamate-oxalacetate transaminase (GOT) in the overground part of the control plants increased only slightly in the course of the initial development, while in the root system it grew relatively more pronouncedly. In the overground part of the plants all the microelements administered displayed a significantly depressive effect on the development of this enzyme activity; in the roots, the inhibitory action was maintained only in the last experimental period in variants with Zn²⁺ ions.     

The effect of foliar application of urea on the root fungi of wheat growing in soil artificially contaminated withFusarium spp.

Repeated treatment of overground parts of wheat with a solution of urea was reflected in an increased count of bacteria and a decreased count of fungi on the roots of plants grown in soil contaminated with the fungusFusarium spp., which is known to be noxious to plants. The occurrence of some fungal genera on the roots of plants growing in contaminated and uncontaminated soil after foliar application of urea was also changed. The roots of treated planted were found to contain more bacteria with a lytic effect and retarding the growth of the fungus used for the contamination. The favourable effect of foliar application of urea on wheat was reflected in an increased dry weight of plants even if growing in a soil contaminated withFusarium.     

野生与栽培乌拉尔甘草不同部位甘草酸含量分析

采用超声提取法结合高效液相色谱(HPLC)对黑龙江省西部野生与栽培乌拉尔甘草不同部位的甘草酸含量进行测定,结果表明:超声方法提取甘草酸是便捷、有效的方法之一,最佳提取条件为50%甲醇提取液,超声提取45m in。甘草地下部分甘草酸含量较高,野生甘草的甘草酸含量主根 > 横根茎 > 不定根 > 垂根茎;栽培甘草则为不定根 > 主根 > 横根茎;总体上看地上部分甘草酸含量是微量的,其中叶的甘草酸含量相对较多,地上茎、种子等器官甘草酸含量较低。无论野生甘草还是栽培甘草, 10月份甘草地下部分甘草酸含量大于5月份,并且这种差别在栽培甘草中表现更明显。人工管理措施对甘草酸含量具有较大影响,野生甘草和栽培甘草经过土壤翻松和良好的田间管理模式反而使甘草酸含量下降,按种植农作物模式对栽培甘草进行管理对提升甘草酸含量效果不佳,给予一定的环境胁迫可以提高甘草酸的含量。在黑龙江省西部,野生甘草主根在1.0~2.0 m深度为甘草酸含量分布较高的部位;栽培甘草主根甘草酸含量随土壤深度的增加而增加,其根尾的甘草酸含量最高,表明栽培甘草主根尚未伸长到其甘草酸含量最高的土壤深度。     

Wheat (Triticum aestivum) seedlings secrete proteases from the roots and, after protein addition, grow well on medium without inorganic nitrogen

This paper reports on the role of proteases secreted by roots in nitrogen capture by plants. The study was conducted on aseptically cultivated wheat seedlings (Triticum aestivum cv. Tacher) obtained from embryos isolated from grains. Seedlings were cultivated for 21 days on deionised water, Murashige Skoog medium (MS), MS without inorganic nitrogen (IN), and MS without IN, in which IN was replaced by casein (0.01%, 0.1% or 1%). Comparison of seedlings grown on these media showed that casein entirely compensated for the lack of inorganic nitrogen in the medium. Shoots and roots of seedlings cultivated on MS medium with this protein had higher fresh weight than those cultivated on MS medium without casein. The increase in fresh weight of seedlings was correlated with casein concentration and proteolytic activity in the medium. In conclusion, wheat that uses proteases secreted by the roots can directly utilise proteins in the medium as a source of nitrogen without prior digestion by microbial proteases and without protein mineralisation. These results suggest the important role of organic nitrogen fertilisers in increasing wheat yield.     

Biological changes in the rhizosphere of wheat after foliar application of chlorocholinechloride,urea and 4-chloro-2-methylphenoxyacetic acid

In field experiments wheat in the phase of shooting was sprayed with solutions of chlorocholinechloride (CCC) and urea, CCC and ammonium salt MCPA (Aminex) or CCC, urea and Aminex. The effect of the treatment on dry weight of overground parts of wheat, number of bacteria, production of carbon dioxide, urease activity and content of ammonium in the rhizosphere soil was investigated. In all cases evolution of carbon dioxide in the rhizosphere soil was higher than that in the control soil. Highest numbers of bacteria were found in the rhizosphere soil of plants treated with urea, the herbicide and their mixtures. Content of ammonium was higher in the control soil than in the rhizosphere soils, the urease activity was highest in the rhizosphere soil of plants treated with the solution of the herbicide and with the combination of the herbicide with urea.     

Effect of trophic conditions on asparagine transamination in wheat plants

In dialyzed extracts from winter wheat plants transamination reactions occurred between asparagine and α-ketoglutaric acid (L-asparagine+2-oxoacid=2-oxosuccinamate+ +amino acid; 2. 6. 1. 14). Reactions with pyruvate exhibited a very low activity. Besides transamination products,i. e. glutamate and alanine, aspartic acid was formed in both reactions. Deamidation was more intensive in the weak reaction asparagine-alanine and less intensive in the asparagine-glutamate reaction. When calculated per dry weight unit the activity was the same in plants of all variants (three experimental variants—Knop, potassium humate, water). A higher, activity was found in root dialysates; however, a highly significant difference could be observed only between shoots and roots of Knop variant. When evaluating results in terms of protein content we found a significant difference between mineral variant (Knop—the lowest activity) and both deficient variants (potassium humate, water—the highest activity). Thus the highest growth activity was in connection with the lowest transamination activity and vice versa, which was the same as in transaminations of aspartic acid. In the case of asparagine, too, one can consider the possibility of its utilization via transamination for biosynthesis of glutamic acid in plants which have, for reasons of nutrition, a low level of this metabolically important amino acid.     

Abscisic acid accumulation in the roots of nutrient-limited plants: its impact on the differential growth of roots and shoots

We describe the involvement of abscisic acid (ABA) in the control of differential growth of roots and shoots of nutrient limited durum wheat plants. A ten-fold dilution of the optimal concentration of nutrient solution inhibited shoot growth, while root growth remained unchanged, resulting in a decreased shoot/root ratio. Addition of fluridone (inhibitor of ABA synthesis) prevented growth allocation in favour of the roots. This suggests the involvement of ABA in the redirecting of growth in favour of roots under limited nutrient supply. The ABA content was greater in shoots and growing apical root parts of starved plants than in nutrient sufficient plants. Accumulation of ABA in shoots of nutrient deficient plants was linked to a decrease in leaf turgor. Increased flow of ABA in the phloem apparently contributed to the accumulation of ABA in the apical part of the roots. Thus, partitioning of growth between roots and shoots of wheat plants limited in mineral nutrients appears to be modulated by accumulation of ABA in roots. This ABA may originate in the shoots, where its synthesis is stimulated by the loss of leaf turgor.     

Action of volatile substances liberated from couch grass

A study was made of the action of volatile substances liberated from the rhizome of couch grass on wheat seedlings. The experiments were made in a closed atmosphere in glass vessels with continual removal of expired CO₂ and the addition of O₂. Volatile substances liberated from couch grass produced numerous morphological and physiological changes in wheat seedlings. They caused retarding of the growth of overground parts and roots, the excessive formation of root hairs, curling of the roots and bending of the coleoptiles. The respiratory rate was higher in the leaves and roots of the experimental wheat seedlings than in the controls. The changes observed were similar to those produced by hydrocarbons of the ethylene series, which are well documented in the literature.     

Dependence of radiostrontium uptake by pea and lupin on the content of calcium in the nutrient solution

In lupin (Lupinus albus L.) and pea (Pisum sativum L., cv. Raman) it was shown that the uptake of⁸⁹Sr from Knop's nutrient solution is significantly increased from a solution with decreased calcium content (one tenth of the normal content) and is slightly decreased from a solution with higher calcium content (150% of the normal content). The calciphile pea absorbs approximately 50% more calcium than the calciphobe lupin, and accordingly 50% radiostrontium less. The pea plant more strongly blocks the translocation of radiostrontium from roots to overground parts, as is proved by the higher discrimination factor of pea (i.e. by the ratio of specific activities of mCi⁸⁹ Sr/g Ca of roots to overground parts). The presence of chlorine in the nutrient solution decreases the content of radiostrontium per gram of dry matter, both in pea and lupin. Radiostrontium is absorbed quickly by both species of plants and is autoradiographically detectable as early as 2 hours after the introduction of radiostrontium to the nutrient solution. *** DIRECT SUPPORT *** A01GP049 00004     

无菌条件下小麦氨基酸态氮及铵态氮营养效应研究

对铵态氮(硫酸铵)、氨基酸态氮(甘氨酸,谷氨酸及赖氨酸)和缺氮无菌砂培条件下小麦单株干物重、全氮量及根、叶谷草转氨酶和谷丙转氨酶活性作了研究．结果表明,铵态氮和氨基酸态氮均可被小麦吸收,且吸收量相当．培养30d后,甘氨酸和谷氨酸处理的小麦干物重显著高于缺氮及铵态氮处理,而铵态氮、赖氨酸及缺氮处理的干物重相近．低浓度铵态氮(0．7mmol·L^1)培养15d的小麦仅根的GPT活性显著高于缺氮处理,而高浓度(35．7mmol·L^1)处理6h对这两种转氨酶活性影响不大.不同种类、不同浓度的氨基酸态氮培养15d或处理6h后,小麦植株根、叶的GOT或GPT活性变化趋势有较大差异,这反映出小麦外源氨基酸主要同化部位及同化量,与氨基酸种类及浓度有较大关系．     

Phytoprotective Effect of Ammonium Humate at High Copper Concentrations in the Environment

The influence of ammonium humate obtained from peat on the tolerance of wheat plants to high CuSO₄ concentrations (100, 250, 500, and 1000 μM/L) has been studied. Seeds were germinated on a copper sulfate solution with and without the humate. Then the plants were grown on Hoagland’s solution in an artificial climate chamber. The coefficient of protective action by humate was estimated in the following two ways: by dry weight changes and by the copper ion content in comparison with the plants grown without humate. The protective role of the humate at 100 and 250 μM has been established, which is due to reduction of copper accumulation in the plants. It has been found that the humate at higher concentrations enhances the toxic effect of copper.     

Effect of heterogeneous distribution of nutrients on root growth, ABA content and drought resistance of wheat plants

Heterogeneous distribution of nutrients influenced morphology of wheat roots; they were shorter and had more laterals at the site of high nutrient content. The roots outside the nutrient-rich patch were longer and penetrated deeper in the soil than those of the plants supplied with the same quantity of nutrients but having them homogeneously distributed. The ABA content of roots sampled from the site of high nutrient content was greater than in those elsewhere. It is suggested that this might be important for inhibition of their extension growth and stimulation of laterals in the nutrient rich patch. Heterogeneously distributed nutrients beneficially influenced accumulation of ¹⁵N and assimilation of CO₂ by the plants, enabling an increased supply of nutrients to the parts of the root system beyond the nutrient rich patch and sustained their rapid extension. Enhanced penetration of roots into the deeper soil layers could contribute to the observed increase in drought resistance of plants grown with localised placement of fertilisers under field conditions.     

Allelopathic effects of ragweed (Ambrosia artemisiifolia L.) on cultivated plants

During the past years ragweed has been coming to the forefront of interest in Hungary and in other European countries as well because its serious health risk. Results of the 5th National Weed Survey has proven that ragweed is the most important weed species on Hungarian field lands, its coverage shows a rising tendency in cereals moreover it not only occurs in cultivated plants. Allelopathic effects of aqueous extracts derived from different parts of ragweed plants (air dried leafy stems, seeds) on the germination and growth of other cultivated plants [maize (Zea mays L.), winter wheat (Triticum aestivum L.), rye (Secale cereale L.), oat (Avena sativa L.)] were studied. The extracts made for the trials were prepared with distilled water. Petri dishes were used for the germination experiments and distilled water was used as a control treatment. The seven days long experiment was carried out within a Binder-type thermostat under dark conditions. The germination percentage was checked in every two days and the growth of sprouts was evaluated after a week counting the germinated seeds and measuring the length of the radicle and plumule. The measured data were statistically analysed and the effect of extracts on germinating and length of sprouts were assessed.