Intense Growth Phase Research Articles

The influence of exogenous phytohormones and zinc sulfate on the morphophysiological characteristics of Salvinia natans (Salviniaceae)

Hydrophytic ferns of the family Salviniaceae, such as those of the genus Salvinia, hold promise for application in water purification and bioassessment. The Salvinia species are known for their rapid growth, adaptability, resistance to adverse environmental conditions, and also their ability to adsorb pollutants. The manipulation of plant growth and development through the application of exogenous phytohormones is an effective technique. In laboratory settings, we investigated the impact of exogenous phytohormones and zinc sulfate on the morphophysiological characteristics of young sporophytes of Salvinia natans. During the phase of intensive growth, the addition of exogenous abscisic acid (ABA) at a concentration of 10−5 M to the growth medium inhibited the accumulation of biomass in S. natans sporophytes. However, gibberellic acid (GA3) and cytokinins (kinetin or zeatin) at a concentration of 10−6 M, along with indole-3-acetic acid (IAA) at a concentration of 10−5 M, induced a slight increase in biomass. In sporophytes of S. natans grown in a medium containing varying concentration of zinc sulfate (228, 114, 57, 28.5, and 14.25 mg of zinc per liter of water), sings of chlorosis in floating fronds were observed as early as the second day of cultivation, followed by symptoms of necrosis. There was a decrease in the content of photosynthetic pigments. Sporophyte biomass decreased, as zinc concentration increased, ranging from 9.6% to 51%. Simultaneous application of phytohormones with the highest concentration of zinc sulfate partially mitigated the adverse effects of the metal, reducing biomass degradation and sustaining sporophyte viability. Qualitative alterations in the fern phenotype were observed, highlighting the phytotoxicity of excessive zinc concentrations. This underscores the potential use of S. natans as a bioindicator for water pollution.

Long-term day-by-day tracking of microvascular networks sprouting in fibrin gels: From detailed morphological analyses to general growth rules.

Understanding and controlling of the evolution of sprouting vascular networks remains one of the basic challenges in tissue engineering. Previous studies on the vascularization dynamics have typically focused only on the phase of intense growth and often lacked spatial control over the initial cell arrangement. Here, we perform long-term day-by-day analysis of tens of isolated microvasculatures sprouting from endothelial cell-coated spherical beads embedded in an external fibrin gel. We systematically study the topological evolution of the sprouting networks over their whole lifespan, i.e., for at least 14 days. We develop a custom image analysis toolkit and quantify (i) the overall length and area of the sprouts, (ii) the distributions of segment lengths and branching angles, and (iii) the average number of branch generations-a measure of network complexity. We show that higher concentrations of vascular endothelial growth factor (VEGF) lead to earlier sprouting and more branched networks, yet without significantly affecting the speed of growth of individual sprouts. We find that the mean branching angle is weakly dependent on VEGF and typically in the range of 60°-75°, suggesting that, by comparison with the available diffusion-limited growth models, the bifurcating tips tend to follow local VEGF gradients. At high VEGF concentrations, we observe exponential distributions of segment lengths, which signify purely stochastic branching. Our results-due to their high statistical relevance-may serve as a benchmark for predictive models, while our new image analysis toolkit, offering unique features and high speed of operation, could be exploited in future angiogenic drug tests.

Basic Composition, Antioxidative Properties, and Selected Mineral Content of the Young Shoots of Nigella (Nigella sativa L.), Safflower (Carthamus tinctorius L.), and Camelina (Camelina sativa L.) at Different Stages of Vegetation

Young shoots are a completely new and rapidly growing group of foodstuffs. Also known as “vegetable confetti”, they are a useful addition to commonly consumed meals and often serve a decorative purpose, especially when paired with traditional dishes. Most users are unaware of their invaluable properties as a source of bioactive compounds and add them simply as a dish garnish. Hence, the aim of this study is to evaluate and compare selected health quality parameters of the young shoots of rare oilseed plants (Nigella sativa L., Carthamus tinctorius L., and Camelina sativa L.), which have not been studied in the literature. They are examined for proximate composition (dry matter, total protein, crude fat, ash, digestible carbohydrates, dietary fiber), antioxidative properties (vitamin C, total carotenoids, and total polyphenol content), the content of sixteen selected minerals (calcium, potassium, magnesium, sodium, phosphorus, sulphur, selenium, barium, iron, lithium, beryllium, nickel, gallium, indium, bismuth, silver) as well as antioxidant activity at two harvest dates. The ready-to-eat young shoots in the phase of intensive growth are characterized by a very high content of the examined components and antioxidant properties, which differ depending on the harvest date and plant species. Significantly higher contents of protein, fat, and some minerals have been found in the young shoots from the first harvest compared to those from the second harvest. The antioxidant properties of the young shoots generally increase with maturity. It was not possible, however, to conclusively assess which species of young shoots show the highest health quality.

Influence of organic-mineral and biological fertilizers on the yield of winter garlic (Allium sativum) under the conditions of their application by drip irrigation

The article presents the results of three-year studies of the impact of the biological preparation Organic-Balance and organo-mineral fertilizer Helprost with Liposam adhesive on the sowing area of garlic of the winter variety Prometheus. It was established that under the conditions of drip irrigation and fertilization with the biological preparation Organic-Balance, organo-mineral fertilizer Helprost and adhesive Liposam with the rate of 2/2/1 l/ha in the phase of intensive growth and development of winter garlic plants were higher than the control variant by 39.4% and 37.3%, the area of the leaf blade is 280.5 cm2 and 252.7 cm2. In the first version, where the plants were watered only with water, the height was 57.4 cm, the area of the assimilation surface was 183.5 cm2. After fertilizing with organo-mineral fertilizer Helprost and adhesive Liposam at the rate of 2/1 and 1/1 l/ha, garlic plants were higher than the control variant by 37.9% and 36.4%, the leaf surface area was 224.0 cm2 and 199.6 cm2 respectively. When fed with the biological preparation Organic-balance and Liposam adhesive with a rate of 2/1 l/ha, the increase in plant height compared to the control was higher by 38.2%, the area of the leaves was 236.5 cm2. The conducted studies show a significant effect of feeding with biopreparations and organic-mineral fertilizers on crop formation. Thus, the best indicator was noted in the case of simultaneous treatment of single-toothed crops with the biological preparation Organic-Balance and organo-mineral fertilizer Helprost with the adhesive Liposam with the rate of 2/2/1 l/ha and with the rate of 2/1/1 l/ha, the yield was the highest 18, 7 and 18.3 t/ha, the yield premium was 6.5 and 6.1 t/ha, respectively. Somewhat lower indicators were obtained for feeding with the biological preparation Organic-balance, but it exceeded the control variant by 5.2 t/ha. When fertilizing with organo-mineral fertilizer Helprost with Lyposam adhesive, higher productivity indicators were obtained in the version with the rate of its application of 2/1 l/ha and prevailed over the control by 2.6%, while when fertilizing with the rate of 1/1 l/ha l/ha supplement to the harvest was 1.9%.

Marketing communications, sustainable development during the promotion of home appliances in online stores under wartime conditions

Methods. The following methods and tools of scientific research are used in the article: induction and deduction – when analyzing data from a survey of respondents; description and generalization – during the analysis of theoretical and methodological components of product promotion; statistical analysis – during the processing of annual financial reports of company; Google ADS analytics methods – during the analysis of the advertising office, sales funnel of the online store and user interaction; competitive analysis, comparison – when researching products promotion on the market. Results. The sale by categories is characterized. The dynamics are evaluated. The organization of the marketing management system of the enterprise thanks to the CRM system of the European platform Bitrix24 is described taking into account sustainable development principles. The management and marketing problem of the enterprise is defined. Internet marketing management at the enterprise was studied, advertising communication flows through Google ADS through responsible consumption were analyzed. It is established that three types of advertising campaigns are used in the communication policy, such as: search, shopping and video campaigns. Types of Miele brand-architecture, Advertising workspace with sustainability are given. It has been established that the online store is currently in a market period in a phase of intensive growth. This is a period of sharp increase in sales volumes. Novelty. According to the results of the analysis, the increase in sales volumes was determined; the functioning of the CRM system at the enterprise of PE RC «Climat system» in 2023 was simulated; types of Miele brand architecture are outlined. The advertising office and sales funnel of the online store were also analyzed taking into account sustainable development. Practical value. The performed analysis allows to improve the planning and organization of Internet marketing communications of economic agents in the markets of household appliances of Ukraine taking into account sustainable development.

Impact of Agricultural Land Use Types on Soil Moisture Retention of Loamy Soils

Increasingly severe hydrological extremes are predicted for the Pannonian Basin as one of the consequences of climate change. The challenges of extreme droughts require the adaptation of agriculture especially during the intense growth phase of crops. For dryland farming, the selections of the optimal land use type and sustainable agricultural land management are potential adaptation tools for facing the challenges posed by increased aridity. To this end, it is indispensable to understand soil moisture (SM) dynamics under different land use types over drought-affected periods. Within the framework of a Slovenian–Hungarian project, soil moisture, matric potential and rainfall time series have been collected at three pilot sites of different land use types (pasture, orchards and a ploughland) in SW Hungary since September 2018. Experiments were carried out in soils of silt, silt loam and clay loam texture. In the summers (June 1 to August 31) of 2019 and 2022, we identified normal and dry conditions, respectively, with regard to differences in water balance. Our results demonstrated that soil moisture is closely controlled by land use. Marked differences of the moisture regime were revealed among the three land use types based on statistical analyses. Soils under pasture had the most balanced regime, whereas ploughland soils indicated the highest amplitude of moisture dynamics. The orchard, however, showed responses to weather conditions in sharp contrast with the other two sites. Our results are applicable for loamy soils under humid and subhumid temperate climates and for periods of extreme droughts, a condition which is expected to be the norm for the future.

ОСОБЛИВОСТІ РОСТУ ТА РОЗВИТКУ СОРТІВ НУТУ ЗВИЧАЙНОГО ЗАЛЕЖНО ВІД ВНЕСЕННЯ МАКРО- Й МІКРОДОБРИВ

Встановлено, що за проведення позакореневого підживлення мікродобривами у фазі інтенсивного росту й розвитку рослин та, можливо, на початку бутонізації на тлі передпосівного внесення мінеральних добрив тривалість міжфазного періоду нуту від повних сходів до повної стиглості зерна коливалася в межах 89–95 діб, або збільшилася на 4–6 діб порівняно з контролем за нерівномірного вологозабезпечення та зміни температурного режиму в період вегетації. Таким чином, позакореневе внесення бору та молібдену підвищувало енергію проростання насіння нуту і його схожість, а також сприяло збереженню рослин у комплексі з позакореневим підживленням упродовж усього періоду вегетації порівняно з контролем без передпосівного внесення мінеральних добрив.

ENERGY EFFICIENCY OF TECHNOLOGICAL METHODS OF CHICKPEA GROWING IN CONDITIONS OF CLIMATE CHANGE

In the context of climate change in the right-bank Forest-Steppe of Ukraine, as well as temperature fluctuations over the years, an important direction in increasing the productivity of arable land is the cultivation of drought-resistant leguminous crops and the improvement of technological methods of cultivation aimed at creating highly productive agrocenoses. It has been studied that chickpeas are among the drought-resistant leguminous crops, which can withstand high temperatures and prolonged droughts; a detailed analysis of the features of energy-efficient technological aspects of growing chickpeas has been carried out. It was revealed that the factors that have a direct impact on energy efficiency indicators in the context of climate change include pre-sowing seed treatment and foliar top dressing. The calculations proved the absence of a negative energy balance when growing chickpeas. Consequently, the sum of the total energy costs and calculations of the developed technology amounted to 17,611.2 MJ. In Pegasus chickpea plants, the energy consumption control was 14.85 GJ / ha and the gross energy yield was 34.26 GJ / ha, while the net energy profit was 19.46 GJ / ha and the energy efficiency ratio was 2.31. The highest energy efficiency coefficient (3.20) was recorded for the technology of growing chickpeas, which provides for a combination of pre-sowing treatment of seeds to the bioenoculant Rizoline in combination with Risosave and two-time foliar top dressing of microfertilizers Harvest legumes in the phase of intensive growth. It is thanks to the optimal combination and development of new adaptive technological methods in the varietal technology of growing chickpeas for the conditions of the right-bank Forest-Steppe of Ukraine that it is possible to obtain competitive products with high-quality energy valuable seeds.

Modulation of Hepatic Insulin and Glucagon Signaling by Nutritional Factors in Broiler Chicken.

Influencing the endocrine metabolic regulation of chickens by nutritional factors might provide novel possibilities for improving animal health and productivity. This study was designed to evaluate the impact of dietary cereal type (wheat-based (WB) vs. maize-based (MB) diets), crude protein level (normal (NP) vs. lowered (LP)), and sodium (n-)butyrate (1.5 g/kg diet) supplementation (vs. no butyrate) on the responsiveness of hepatic glucagon receptor (GCGR), insulin receptor beta (IRβ) and mammalian target of rapamycin (mTOR) in the phase of intensive growth of chickens. Liver samples of Ross 308 broiler chickens (Gallus gallus domesticus) were collected on day 21 for quantitative real-time polymerase chain reaction and Western blot analyses. Hepatic GCGR and mTOR gene expressions were up-regulated by WB and LP diet. GCGR and IRβ protein level decreased in groups with butyrate supplementation; however, the quantity of IRβ and mTOR protein increased in WB groups. Based on these data, the applied dietary strategies may be useful tools to modulate hepatic insulin and glucagon signaling of chickens in the period of intensive growth. The obtained results might contribute to the better understanding of glycemic control of birds and increase the opportunity of ameliorating insulin sensitivity, hence, improving the production parameters and the welfare of broilers.

Seasonal antimicrobial activity of volatile substances emitted by the representatives of <i>Begonia</i> L. genus (Begoniaceae)

The paper continues multi-year integrated studies of the numerous taxons of tropical Begonia genus, which allowed us to evaluate the adaptive capacity of the representatives of this genus relying on the revealed morphological, rhythmological and biochemical features. The investigation of antimicrobial activity of intact plants and different fractions of plant extracts allowed us to distinguish several promising representatives of this genus exhibiting activity against a broad range of test microorganisms. The involvement of these plants within phytomodules in child care centers caused a substantial decrease in total microbial contamination of the air. The paper contains results of the experimental investigation of seasonal antimicrobial activity of 13 species, 8 hybrids. The phytoncide activity was measured by exposing the streak cultures of microbial test species bacteria Staphylococcus epidermidis, Esсherichia coli and yeast-like fungi Candida albicans to the volatile emissions of plants. It has been established that 95% of begonias are distinguished by the pronounced activity against S. epidermidis bacteria, 48% against E. coli bacteria and 43% against fungi Candida albicans. The seasonal specificity of the antimicrobial action of begonias was detected: the growth of the colonies of S. epidermidis bacteria is inhibited to the highest extent during spring and summer, at the phase of intense growth, while the activity against E. coli is the highest during autumn and winter at the phase of moderate growth. The taxons with clearly pronounced, long-term and universal antimicrobial action to the studied test objects were revealed and recommended for practical planting in various types of indoor environments. The data obtained in the study may serve as the basis for further investigation of the chemical composition of volatile exometabolites by the example of the representatives of Gireoudia and Coelocentrum sections that have exhibited high antimicrobial activity against S. epidermidis and E. coli.

Morphotechnological parameters and analysis of microplants of potato varieties with accelerated reproduction (in vitro) in a selection nursery

The studies were carried out with in vitro test-tube micro plants at the Smolensk State Agricultural Academy in a research laboratory and in protected ground (frame greenhouses) under standard conditions and protection measures during the period of their cultivation. The article analyzes and presents data on the growth and development of potato varieties during their growing season. The object of research was micro plants of potato varieties Fritella, Grand, Mayak, Violet, Vympel, Vasilek, Meteor and Gulliver. The data obtained showed that test-tube micro plants of potato varieties by the end of the phase of intensive growth - the beginning of the phase of slow growth had a well-developed root system, 4-5 internodes, a plant height of 9.5-13.1 cm, a green color, a sufficiently developed leaf apparatus and planting them in flowerpots, survival rate was 100%. The duration of the growing season depended on the variety of micro plants and ranged from 82 to 107 days, height from 46.8 to 66.8 cm, the number of tubers from 3.5 pcs. up to 8.26 pieces, the yield of the seed fraction is from 44 to 92%. In terms of yield, the following potato varieties were distinguished: Gulliver (10.5 t / ha); Lighthouse (10.0 t / ha); Grand (9.24 t / ha); Meteor (9.20 t / ha); Purple (8.16 t / ha). The rest of the studied varieties had a lower yield level (5.5-7.35 t / ha), which is associated with both the high presence of fine-fraction tubers and the number of tubers in the nest. These circumstances necessitate additional seed reproduction of micro tubers (<15-20g) in the autumn-winter period in greenhouse conditions. In terms of morphobiological characteristics, the nature of setting, the formation of tubers, the structure of the clone, each variety, even one ripeness group, had its own varietal specificity, which should be taken into account when cultivating them in nurseries of original and elite seed production.

The WISSH quasars project

Context. Sources at the brightest end of the quasi-stellar object (QSO) luminosity function, during the peak epoch in the history of star formation and black hole accretion (z ∼ 2−4, often referred to as “Cosmic noon”) are privileged sites to study the cycle of feeding &amp; feedback processes in massive galaxies. Aims. We aim to perform the first systematic study of cold gas properties in the most luminous QSOs, by characterising their host-galaxies and environment. These targets exhibit indeed widespread evidence of outflows at nuclear and galactic scales. Methods. We analyse ALMA, NOEMA and JVLA observations of the far-infrared continuum, CO and [CII] emission lines in eight QSOs (bolometric luminosity LBol ≳ 3 × 1047 erg s−1) from the WISE-SDSS selected hyper-luminous (WISSH) QSOs sample at z ∼ 2.4−4.7. Results. We report a 100% emission line detection rate and a 80% detection rate in continuum emission, and we find CO emission to be consistent with the steepest CO ladders observed so far. Sub-millimetre data reveal presence of (one or more) bright companion galaxies around ∼80% of WISSH QSOs, at projected distances of ∼6−130 kpc. We observe a variety of sizes for the molecular gas reservoirs (∼1.7−10 kpc), mostly associated with rotating disks with disturbed kinematics. WISSH QSOs typically show lower CO luminosity and higher star formation efficiency than infrared matched, z ∼ 0−3 main-sequence galaxies, implying that, given the observed SFR ∼170−1100 M⊙ yr−1, molecular gas is converted into stars in ≲50 Myr. Most targets show extreme dynamical to black-hole mass ratios Mdyn/MBH ∼ 3−10, two orders of magnitude smaller than local relations. The molecular gas fraction in the host-galaxies of WISSH is lower by a factor of ∼10−100 than in star forming galaxies with similar M*. Conclusions. Our analysis reveals that hyper-luminous QSOs at Cosmic noon undergo an intense growth phase of both the central super-massive black hole and of the host-galaxy. These systems pinpoint the high-density sites where giant galaxies assemble, where we show that mergers play a major role in the build-up of the final host-galaxy mass. We suggest that the observed low molecular gas fraction and short depletion timescale are due to AGN feedback, whose presence is indicated by fast AGN-driven ionised outflows in all our targets.

Young shoots of red cabbage are a better source of selected nutrients and glucosinolates in comparison to the vegetable at full maturity

Cruciferous vegetables are a valuable source of ingredients with health benefits. The most characteristic compounds of cruciferous vegetables with identified anticancer properties are glucosinolates. Young shoots and sprouts of red cabbage are becoming a popular fresh food rich in nutrients and bioactive compounds. The objective of this research was to determine, for the first time in a comprehensive approach, whether young shoots of red headed cabbage are a better source of selected nutrients and glucosinolates in the human diet in comparison to the vegetable at full maturity. The proximate composition (protein, fat, digestible carbohydrates, fiber), fatty acids profile, minerals (calcium, magnesium, potassium, sodium, iron, zinc, manganese, copper), as well as glucosinolates were examined. The red headed cabbage was characterized by a significantly larger amount of dry matter, and total and digestible carbohydrates in comparison to young shoots. The ready-to-eat young shoots, which are in the phase of intensive growth, are a better source of protein, selected minerals, and especially glucosinolates. The level of some nutrients can be enhanced and the intake of pro-healthy glucosinolates can be significantly increased by including young shoots of red cabbage into the diet.

ДИНАМИКА СОДЕРЖАНИЯ АЗОТИСТЫХ ВЕЩЕСТВ И ЛИПИДОВ В ХВОЕ ИНТРОДУЦИРОВАННЫХ ВИДОВ PICEA А. DIETR. В ТАЕЖНОЙ ЗОНЕ (КАРЕЛИЯ)

Studies were conducted in the Botanical Garden of Petrozavodsk State University, located in the taiga zone. The objects were 1 aboriginal (Рicea fennica (Regel) Кom.) аnd 5 introduced (P. pungens Engelm. f. glauca Regel and f. viridis Regel, P. obovata Ledeb., P. glauca (Mill.) Britt., P. omorica (Pane) Purk., P. mariana Britt.). It is established that in the process of adaptation of introduced species Picea to low winter tempera-tures most of the involved proteins. Their number increases significantly during the transition from the period of active shoot growth to a period of deep rest have all studied species of Picea. The accumulation of proteins causes a decrease in the level of total free amino acids of most types of exotic species, while the local form of the amino acid content is maintained at a high level. In the needles of most of the studied species of Picea to the period of deep rest, the fraction of glutamic acid and albanina and increases the proportion of arginine and ethanolamine in the total amount of amino acids. The increase in the content of total lipids and phospholipids in the needles during the transition to a period of deep rest less significant than proteins. In the needles of na-tive species in comparison with the needles of exotic species total lipids actively used in the phase of inten-sive growth of shoots. Despite some differences, the introduced species Picea adapted to endure low tempera-tures using the same biochemical mechanisms as a local view. This indicates successful adaptation of the studied introduced species Picea to new conditions of existence.

Water Relations and Osmolite Accumulation Related to Sugarcane Yield Under Drought Stress in a Tropical Climate

The number of areas subject to drought is likely to increase in response to climate change and will affect the yields of globally important crops such as sugarcane. In this respect, the aim of the present study was to assess the drought tolerance of sugarcane varieties in different phenophases and identify the physiological and biochemical characteristics associated with the lowest yield loss under drought conditions. Six of the most widely cultivated varieties in the region were studied, namely SP79-1011, RB855113, RB92579, RB867515, RB72454 and RB855536. Plant physiological characteristics were assessed during the dry season in the tillering, intense growth and ripening stages, and yield was quantified after 12 months of cultivation. This study shows that different sugarcane varieties are more affected by drought in the intense growth phenophase, since plants showed a greater decline in water and osmotic potential at midday during this period. The varieties most affected by drought in this phenophase were RB855536 and RB855113, which exhibited greater reductions in water and osmotic potential. They also had larger osmoregulator accumulation as a response to drought, but not enough to prevent dehydration, which likely contributed to the lower yield. The RB867515 and RB92579 varieties underwent no significant change in osmotic potential at midday during drought stress in the intense growth phase, despite of low leaf water potential, and little variation in the osmoregulators contents. For these reasons, these two varieties showed greater drought acclimation potentials and were more productive as submitted to drought conditions.

Exploring financial sustainability of SMEs during periods of production growth: A simulation study

The purpose of this paper is to understand the impact of financial key performance indicators (KPIs)—namely customer accounts receivable flow time and credit limit allowed by financial partners—on the financial sustainability of small and medium sized enterprises (SMEs) during business growth trajectories from an operations management perspective. This study explores the impact of a financing scheme on company performance during business growth, since new banking constraints for credit risk reduction have been introduced (such as BASEL III regulations). Based on qualitative and quantitative data from a longitudinal empirical case study of a Swiss family-owned SME during a phase of intense growth, we have built a simulation model by combining agent-based with system dynamics modelling that comprehensively represents the growing firm, its decision-making, and enables the impact evaluation of relevant financial KPIs on financial sustainability. Our analysis shows that the baseline scenario entails 80% risk of bankruptcy for high-growth SMEs; featuring 30 days customer accounts receivable flow time target and a credit limit allowed by the financial partner of 25% of last period turnover. However, if customer accounts receivable flow time is reduced to ten days, and credit limit increased to 65% of last turnover, the risk of bankruptcy drops to 30%. Our findings point to the detrimental unanticipated side effects of macro-level banking regulation on micro-level firm performance, and hence have implications for policy-making. Moreover, our study guides managers and financial service providers in anticipating risky situations, and in taking corrective actions by effectively managing financial KPIs.

Morphological changes recorded in different phenophases of sugarcane plants subjected to water stress in tropical field conditions

Nowadays, water deficit is one of the major environmental stress issues affecting sugarcane crops around the world. It has been causing significant production decrease due to the increased mortality rates generated by water stress in sugarcane plantations. The aim of the current study is to assess sugarcane morphological and yield responses during different phenophases of sugarcane varieties when plants are subjected to drought stress in the fields of a tropical region. Six sugarcane varieties, namely: SP79-1011, RB855113, RB92579, RB867515, RB72454, and RB855536, were subjected to water stress. The herein adopted water regimes were (i) irrigated crop and (ii) crop subjected to natural drought in the field. Plants were cultivated under water stress imposition throughout three phenological stages (i) tillering, three months after planting; (ii) intense growth, seven months after planting; and (iii) ripening, eleven months after planting. The irrigation treatment consisted of supplementing the crop with 50 mm of water per month during the dry season, whereas non-irrigated plants were naturally grown under water stress conditions throughout the experiment. Water stress mostly affected the sugarcane crop during the intense growth phase. Varieties RB72454 and RB855536 presented smaller green-leaf number, as well as narrower leaf width and smaller leaf area under water stress; besides, they showed low productive potential and high stress susceptibility index (SSI). Stalk height maintenance and the larger number of tillers in RB92579 plants subjected to water stress helped balancing yield rates. This variety also showed the best drought tolerance (DTI) and yield/tolerance indices (YTI); moreover, the principal component analysis evidenced that leaf area, plant height and yield were important factors to distinguish the most tolerant varieties. Such results show that RB92579 is more drought tolerant and has better physiological acclimation potential than the other five varieties; therefore, it can be recommended for crops subjected to drought periods.

Changes in humus forms, soil invertebrate communities and soil functioning with forest dynamics

Three field studies have been performed, in order to assess changes in the composition of soil animal communities, soil physical and chemical features and mineralization processes with Norway spruce (Picea abies, L.) phases of the forest cycle. These field studies were conducted in three sites that differed in the acidity level of their bedrock (acidic, sub-acidic, and basic). The influence of exposure, through modifying microclimatic conditions, was also taken in consideration by comparing north and south exposures at each site. The data issued from each of these studies have already been published separately, and the aim of the present paper is to confront the three series of data in order to assess: 1) The general trend of changes in soil invertebrate communities, humus forms and mineralization processes with the age of spruce; 2) The impact of the type of bedrock and exposure on these changes.The results indicate that deep modifications occurred in animal communities, humus forms and soil functioning among clearing, regeneration and mature tree stands. The changes consist in an increase of Humus Index and the density of mites, especially oribatids, with a decrease in mineralization rate and animal diversity, from clearing to mature stands.Regeneration stands occupy an intermediate level as regards soil features but cumulates highest densities of most groups, highest levels of zoological diversity and mineralization activity. This higher level of richness and functional activity in regeneration stands could be explained by a more heterogeneous habitat in this phase of the forest cycle. Our results thus support the hypothesis that forest dynamics drives soil functioning and diversity, at least during the phase of intense growth of trees.The evolution of humus forms and animal communities along the developmental phases of forest stands were considerably more pronounced in south-facing sites than in north-facing sites. Unexpectedly, no increase in animal diversity was observed from the more to the less acidic bedrock. Suggestions for forest management are proposed.

Changes in protein content and activity of proteases and acid phosphatases in needles of Norway spruce (Picea abies L. Karst) seedlings treated with 2,4,5-T

Effect of 2, 4, 5-T in different concentrations and time of herbicide applications on protein biosynthesis and enzymatic activity of proteases and acid phosphatases in needles of spruce seedlings was investigated. 2, 4, 5-T in all concentrations tested and applied on the seedlings during phase of intensive growth caused significant increase in soluble protein content. After spraying the seedlings with 100 and 300 mg ·l&lt;sup&gt;-1&lt;/sup&gt; of 2, 4, 5-T before bud development a small decrease in soluble protein level was noted. The herbicide caused marked disturbances in the activity of enzymatic systems of proteases and acid phosphatases. No effect of 2, 4, 5-T on dry matter accumulation was observed.

Dynamics of indole-3-acetic acid oxidase activity in suspension culture of sunflower crown-gall

IAA oxidase activity was determined in several growth phases of a suspension culture of sunflower crown-gall. During the short phase of intensive growth (zero passage - PO) a negative correlation was noted between enzymatic activity and the rate of growth. IAA oxidase activity increased to a certain level is not a factor limiting cell division. For protraction of the phase of intensive growth (first passage - P1), however, a decrease in the activity of this enzyme seems indispensable. IAA oxidase activity in the tested culture is under the control of inhibitors present in the cells and medium. High enzyme inhibition was observed in PO cells during the phase, of intensive growth and in P1 at the beginning and in the middle part of this phase. These results suggest' that the -auxin level determined in earlier studies in sunflower crown-gall culture is controlled by the IAA oxidase set. During the long phase of intensive growth (P1) this control is of negative feedback type.