Growth Of Young Plants Research Articles

The roleS of ABA, reactive oxygen species and Nitric Oxide in root growth during osmotic stress in wheat: comparison of a tolerant and a sensitive variety

The effects of PEG 6000-induced osmotic stress (-0.976 MPa) on the root growth of young plants, and the changes in abscisic acid (ABA), reactive oxygen species (ROS) and NO contents were investigated in the root tips of a drought-tolerant and a drought-sensitive wheat cultivar (Triticum aestivum L. cvs. MV Emese and GK Élet, respectively). The root length of cv. MV Emese was more effectively reduced than that of GK Élet by osmotic stress. Concomitantly, the ABA content of the 15-mm apical zone of the roots remained at the control level in GK Élet cultivar, but in MV Emese it decreased significantly after the early phase of the experiment, indicating that the accumulation of ABA is necessary for the maintenance of root growth under osmotic stress. The extent of ROS accumulation relative to the respective control was more pronounced in the elongation zone of roots in MV Emese in the later stages of the experiment, while NO concentrations increased significantly early after PEG exposure, suggesting that high concentrations of ROS and NO were unfavourable for root expansion. In contrast, in cv. Élet, the high NO content in the elongation zone declined to the control level under osmotic stress within 4 days. The changes in root growth due to osmotic stress did not exhibit a correlation with the drought tolerance of the genotypes defined on the basis of the crop yield.

Growth of young plants of four Sargassum species in Ichiri-zaki, Miyazaki Prefecture, under various irradiance levels

Growth of young plants of four <i>Sargassum</i> species in Ichiri-zaki, Miyazaki Prefecture, under various irradiance levels

Diel changes in nitrogen and carbon resource status and use for growth in young plants of tomato (Solanum lycopersicum).

Modellers often define growth as the development of plant structures from endogenous resources, thus making a distinction between structural (W(S)) and total (W) dry biomass, the latter being the sum of W(S) and the weight of storage compounds. In this study, short-term C and N reserves were characterized experimentally (forms, organ distribution, time changes) in relation to light and nutrition signals, and organ structural growth in response to reserve levels was evaluated. Tomato plants (Solanum lycopersicum) were grown hydroponically in a growth room with a 12-h photoperiod and an adequate supply of NO(3)(-) (3 mol m(-3)). Three experiments were carried out 18 d after sowing: [NO(3)(-)] was either maintained at 3 mol m(-3), changed to 0.02 mol m(-3) or to 0 mol m(-3). Plants were sampled periodically throughout the light/dark cycles over 24-48 h. Organ W(S) was calculated from W together with the amount of different compounds that act as C and N resources, i.e. non-structural carbohydrates and carboxylates, nitrate and free amino acids. With adequate nutrition, carbohydrates accumulated in leaves during light periods, when photosynthesis exceeded growth needs, but decreased at night when these sugars are the main source of C for growth. At the end of the night, carbohydrates were still high enough to fuel full-rate growth, as W(S) increased at a near constant rate throughout the light/dark cycle. When nitrate levels were restricted, C reserves increased, but [NO(3)(-)] decreased progressively in stems, which contain most of the plant N reserves, and rapidly in leaves and roots. This resulted in a rapid restriction of structural growth. Periodic darkness did not restrict growth because sufficient carbohydrate reserves accumulated during the light period. Structural growth, however, was very responsive to NO(3)(-) nutrition, because N reserves were mostly located in stems, which have limited nitrate reduction capacity.

Response of transgenic poplar overexpressing cytosolic glutamine synthetase to phosphinothricin

Glutamine synthetase (GS) is the main enzyme involved in ammonia assimilation in plants and is the target of phosphinothricin (PPT), an herbicide commonly used for weed control in agriculture. As a result of the inhibition of GS, PPT also blocks photorespiration, resulting in the depletion of leaf amino acid pools leading to the plant death. Hybrid transgenic poplar ( Populus tremula × P. alba INRA clone 7171-B4) overexpressing cytosolic GS is characterized by enhanced vegetative growth [Gallardo, F., Fu, J., Cantón, F.R., García-Gutiérrez, A., Cánovas, F.M., Kirby, E.G., 1999. Expression of a conifer glutamine synthetase gene in transgenic poplar. Planta 210, 19–26; Fu, J., Sampalo, R., Gallardo, F., Cánovas, F.M., Kirby, E.G., 2003. Assembly of a cytosolic pine glutamine synthetase holoenzyme in leaves of transgenic poplar leads to enhanced vegetative growth in young plants. Plant Cell Environ. 26, 411–418; Jing, Z.P., Gallardo, F., Pascual, M.B., Sampalo, R., Romero, J., Torres de Navarra, A., Cánovas, F.M., 2004. Improved growth in a field trial of transgenic hybrid poplar overexpressing glutamine synthetase. New Phytol. 164, 137–145], increased photosynthetic and photorespiratory capacities [El-Khatib, R.T., Hamerlynck, E.P., Gallardo, F., Kirby, E.G., 2004. Transgenic poplar characterized by ectopic expression of a pine cytosolic glutamine syntetase gene exhibits enhanced tolerance to water stress. Tree Physiol. 24, 729–736], enhanced tolerance to water stress (El-Khatib et al., 2004), and enhanced nitrogen use efficiency [Man, H.-M., Boriel, R., El-Khatib, R.T., Kirby, E.G., 2005. Characterization of transgenic poplar with ectopic expression of pine cytosolic glutamine synthetase under conditions of varying nitrogen availability. New Phytol. 167, 31–39]. In vitro plantlets of GS transgenic poplar exhibited enhanced resistance to PPT when compared with non-transgenic controls. After 30 days exposure to PPT at an equivalent dose of 275 g ha −1, growth of GS transgenic poplar plantlets was 5-fold greater than controls. The response of young leaves to PPT treatment depends on physiological state as indicated by GS and Rubisco (LSU) levels. Young leaves from control plants, typically in a low differentiation state, respond to the herbicide showing up-regulation of GS and LSU. In contrast, young leaves from transgenic lines, with higher initial GS and LSU levels compared to control, display up-regulation of NADP +-isocitrate dehydrogenase. Differences between control and GS transgenics in their response to PPT are discussed in relation to their differences in photosynthetic and photorespiratory capacities ( El-Khatib et al., 2004).

Exigências nutricionais da grápia em Argissolo Vermelho distrófico arênico: efeito da adubação NPK no teor de nutrientes nos tecidos

A grápia (Apuleia leiocarpa (Vog.) Macbride) é uma espécie florestal nativa de ampla utilidade na indústria madeireira, motivo pelo qual, atualmente, encontra-se em processo de extinção. Em trabalho prévio, utilizando-se um Argissolo Vermelho distrófico arênico, foi demonstrado que o crescimento de plantas jovens de grápia respondeu à adubação de N, P e K com dose de máxima eficiência técnica estimada em, respectivamente, 70, 80 e 80mg kg-1. No presente trabalho, objetivou-se caracterizar o efeito da adubação NPK nos teores de macronutrientes e micronutrientes dos tecidos de plantas de grápia. Em condições de casa de vegetação, foram realizados 27 tratamentos de adubação em esquema trifatorial completo (3x3x3), representados por três níveis (0, 40 e 80mg kg-1) de N, de P e de K. A parcela experimental foi constituída de um vaso com 3,5kg de Argissolo Vermelho distrófico arênico e duas plantas. Aos 140 dias após a emergência das plantas, avaliou-se o crescimento e os teores de N, P, K, Ca, Mg, Cu, Zn, Fe e Mn nas folhas, no caule e nas raízes da grápia. Os resultados sugerem que os teores adequados de nutrientes nas folhas de plantas jovens de grápia, para se obter de 80 a 100% da produção de biomassa, sejam: N=2,5 a 3,0%; P=0,1 a 0,18%, K=1,6 a 2,1%, Ca=0,60 a 0,75%, Mg=0,2 a 0,3%; Cu=1,5 a 2,5mg kg-1, Zn=50 a 85mg kg-1, Fe=100 a 150mg kg-1 e Mn=250 a 400mg kg-1.

Growth of Austrian pine (Pinus nigra Arnold) treated with soil conditioners on Loket spoil bank

The effects of soil conditioners Frisol, TerraCottem, Bi-algeen, and fertilisers Silvamix Forte and Cererit on the welfare of Austrian pine were observed in a seven-year experiment on Loket spoil bank. Simultaneously the economic aspects of growing the Austrian pine until the stage of established plantation were examined. The application of products one year and a half after planting did not cause seedling mortality. The elongation growth of young plants conditioned by the application of Silvamix Forte and Frisol was statistically significant whereas these effects manifested themselves in the second year: they persisted till the end of the experiment for Silvamix Forte, and for three years in total for Frisol. The other products &amp;ndash; TerraCottem, Bi-algeen and Cererit &amp;ndash; also showed generally better, though statistically insignificant results as compared to those of the control plants. The elongation growth for all products culminated in the fifth year and then declined. The stem diameter growth for the best products reached its maximum in the second year. Regarding the overall height growth after seven years, the average number of the highest plants on the experiment location was on plots treated with Silvamix Forte; these plants exceeded the control plants by 46.2 cm. Pines treated with Frisol were higher by 23.4&amp;nbsp;cm. However, the application of soil conditioners and fertilisers to the given location proved economically ineffective because there was no need to improve the soil at the location, the same applies to mowing and hoeing since almost no forest weed grew there and the substrate surface remained well-aerated and porous.

Transcriptional profiling of summer wheat, grown under different realistic UV-B irradiation regimes

There is limited information on the impact of present-day ultraviolet-B (UV-B) radiation on a reprogramming of gene expression in crops. Summer wheat was cultivated in controlled environmental facilities under simulated realistic climatic conditions. We investigated the effect of different regimes of UV-B radiation on summer wheat (Triticum aestivum L.) cultivars Nandu, Star and Turbo. Until recently, these were most important in Bavaria. Different cultivars of crops often show great differences in their sensitivity towards UV-B radiation. To identify genes that might be involved in UV-B defence mechanisms, we first analyzed selected genes known to be involved in plant defence mechanisms. RNA gel blot analysis of RNA isolated from the flag leaf of 84-day-old plants showed differences in transcript levels among the cultivars. Flag leaves are known to be important for grain development, which was completed at 84 days post-anthesis. Catalase 2 (Cat2) transcripts were elevated by increased UV irradiation in all cultivars with highest levels in cv. Nandu. Pathogenesis-related protein 1 (PR1) transcripts were elevated only in cv. Star. A minor influence on transcripts for phenylalanine ammonia-lyase (PAL) was observed in all three cultivars. This indicates different levels of acclimation to UV-B radiation in the wheat cultivars studied. To analyze these responses in more detail, UV-B-exposed flag leaves of 84-day-old wheat (cv. Nandu) were pooled to isolate cDNAs of induced genes by suppression-subtractive hybridization (SSH). Among the initially isolated cDNA clones, 13 were verified by RNA gel blot analysis showing an up-regulation at elevated levels of UV-B radiation. Functional classification revealed genes encoding proteins associated with protein assembly, chaperonins, programmed cell death and signal transduction. We also studied growth, flowering time, ear development and yield as more typical agricultural parameters. Plant growth of young plants was reduced at increased UV-B radiation. Flowering and ear development were delayed concomitantly, whereas total grain weight was not influenced at any of the UV-B irradiation regimes.

Summer dormancy in Dactylis glomerata L.: the influence of season of sowing and a simulated mid-summer storm on two contrasting cultivars

A series of trials to increase understanding of the summer dormancy trait in Dactylis glomerata was conducted. Autumn-sown reproductive and younger, spring-sown plants of 2 drought-resistant cultivars, contrasting for summer dormancy, were established and then tested in summer 2002 under long drought, drought + mid-summer storm, or full irrigation. The autumn-sown reproductive plants of cv. Kasbah were summer dormant under all moisture regimes and exhibited the characteristic traits including growth cessation, rapid herbage senescence, and dehydration of surviving organs (–6.7 MPa). Cultivar Kasbah used 8% less soil water over the summer and also began to rehydrate its leaf bases from conserved soil water before the drought broke. The non-dormant cv. Medly grew for 10 days longer under drought and whenever moisture was applied; Medly also responded to the storm with a decline in dehydrin expression in leaf bases, whereas no decline occurred in Kasbah, presumably because it remained dormant and therefore much drier. The irrigated, younger, spring-sown swards of cv. Kasbah had restrained growth and produced only about 25% of the herbage of cv. Medly. Drought reduced activity and growth of young plants of both cultivars, but whereas Medly regrew in response to the storm, cv. Kasbah did not, indicating that dormancy, although only partially expressed after spring sowing, was reinforced by summer drought. A longer drought in 2003 caused a 22% loss of the basal cover in cv. Medly, whereas Kasbah fully maintained its sward and therefore produced a higher post-drought autumn yield. This work confirms summer dormancy as a powerful trait for improving persistence over long, dry summers.

Distúrbios nutricionais induzidos pela adubação de fósforo e ferro em plantas jovens de grápia (&lt;i&gt;Apuleia leiocarpa&lt;/i&gt;).

A grápia (Apuleia leiocarpa Vog. Macbride) é uma espécie florestal nativa de grande interesse madeireiro, encontrando-se, atualmente, bastante dizimada. Em trabalhos anteriores, foi observado que as folhas novas de plantas jovens de grápia apresentaram sintomas visuais indicativos de deficiência de Fe na presença de doses crescentes de P. O presente trabalho teve como objetivo caracterizar os efeitos da interação da adubação de P e Fe no balanço nutricional e no crescimento de plantas jovens de grápia cultivadas num ARGISSOLO VERMELHO Distrófico arênico, sob condições de casa de vegetação. Os tratamentos consistiram de uma combinação bifatorial (2x3) completa, com dois níveis de adubação de fósforo (60 e 180 mg kg-1) e três níveis de ferro (0, 6 e 12 mg kg-1); além disso, realizou-se adubação complementar de N, K, Ca e Mg em todos tratamentos. A análise de crescimento das plantas foi realizada mensalmente, considerando a altura de planta, diâmetro do caule e número de folhas por planta. Aos 150 dias após a emergência das plantas, avaliaram-se ainda a massa seca de raízes, do caule, das folhas e total da planta, comprimento das raízes, comprimento radicular específico, número de folhas caídas, relação entre a massa seca de raízes e da parte aérea e a concentração de P, Fe, Cu e Zn nos tecidos da planta. A relação de concentração entre o P e os micronutrientes Fe, Cu e Zn é mais apropriada na avaliação do estado nutricional da grápia que a análise da concentração absoluta desses elementos nos tecidos. A alta disponibilidade de P no solo causou deficiência de Fe, Cu e Zn nas plantas de grápia. O aumento da disponibilidade de Fe, ocasionado pela adubação desse elemento, ou pela diminuição do pH do solo, induzida pela adubação com outros nutrientes, provocou decréscimo nas concentrações de Cu e Zn nas raízes. Na presença de 180 mg de P kg-1 de solo, a aplicação de 12 mg de Fe kg-1 de solo, na forma de Fe-EDTA, diminuiu a clorose foliar e aumentou o crescimento de plantas jovens de grápia.

Trocas gasosas, características das folhas e crescimento de plantas jovens de Cupania vernalis Camb. submetidas a diferentes níveis de sombreamento

Cupania vernalis Camb. é uma espécie arbórea pertencente à família sapindaceae, conhecida popularmente como camboatá, camboatã. É uma espécie de grande importância pelo seu uso em plantios mistos destinados à recuperação de áreas degradadas e preservação permanente. Este estudo teve como objetivo básico caracterizar o desempenho ecofisiológico desta espécie sob condições de viveiro. Avaliou-se o efeito de quatro níveis de irradiância (Pleno sol, 30%, 50% e 70% de sombreamento) sobre as trocas gasosas, concentração de nitrogênio, clorofilas foliares e crescimento de plantas jovens de Cupania vernalis. As plantas submetidas a 50% de sombreamento acumularam maior massa seca de folha, caule e massa seca total em comparação com as cultivadas a pleno sol, não sendo observada diferença quanto à massa seca de raízes. A maior taxa fotossintética e condutância estomática foram observadas em folhas de plantas crescidas sob pleno sol e 30% de sombreamento. Plantas sob condições mais sombreadas apresentaram teores mais elevados tanto de clorofilas quanto de nitrogênio nas folhas. Fato semelhante ocorreu com outras características como altura, diâmetro de caule e área foliar. Essas últimas características constituem fatores determinantes da qualidade de mudas. Os resultados possibilitaram concluir que as mudas desta espécie devem ser formadas sob condições de viveiro com sombreamento de 50% ou 70% para que se obtenham mudas de melhor qualidade.

Impact of soil conditioners on the growth of European ash (Fraxinus excelsiorL.) on dumps

The effects of soil conditioners TerraCottem, Frisol, Bio-algeen and fertilisers Silvamix Forte and Cererit on the survival rate and growth of European ash seedlings until the stage called established plantation were observed on two experimental plots with different anthropogenic substrates. Eight-year experiments showed that under the given conditions the tested agents fulfilled the declared effects only partially. The application of TerraCottem was statistically insignificant both in the survival rate and in the growth. In the applied dose, Frisol manifested itself as an agent that may cause problems with the survival of plants, but at the same time also as a preparation improving the overall growth of young plants statistically significantly. Its effective dosage largely depends on the soil character. Bio-algeen had a&amp;nbsp;very good effect on the survival rate of plants, but it did not surpass the control plants in the initial growth of plants. Silvamix Forte did not cause the mortality of seedlings and influenced the growth of plants statistically significantly for 1&amp;ndash;3 years. In the applied dose, Cererit caused a high mortality of seedlings. The application of soil conditioners and Silvamix Forte did not markedly accelerate the growth and development until the stage of the established plantation. Until that time, the costs of the application of conditioners were higher by 4&amp;ndash;13% as compared with the costs in the control plants.

Cultivating the Medicinal Plant Merwilla Natalensis as a Crop

The indigenous South African medicinal plant, Merwilla natalensis, was cultivated in two different geographical regions with different climatic conditions. Bulbs grew exponentially reaching approximately 300 g fresh weight after 24 months in the field. Plants were cultivated under three different treatments. The results suggested that bulb growth was not dependent on additional fertilizer (organic or inorganic) or irrigation, as there were no significant differences (p=0.05) in the average dry weight of the bulbs grown under the three treatments. Irrigation had an effect on the growth of young plants, preventing senescence and causing the plants to grow during the dormancy period. Bulbs started flowering after two years of growing in cultivated fields. Bulbs seemed to flower more when irrigated.

Role of winter-active aphids spreading Barley yellow dwarf virus in decreasing wheat yields in a Mediterranean-type environment

In the grainbelt of south-western Australia, which experiences Mediterranean-type climatic conditions, 3 field experiments with wheat were sown in autumn, 2 at Site A over 2 years and 1 at Site B in the first year only. These experiments related both activity of aphid vectors (migration into and colonisation of wheat) and the spread of infection with Barley yellow dwarf virus (BYDV) serotype PAV to wheat grain yield and quality. Incidences of BYDV serotype RMV and Cereal yellow dwarf (CYDV) were mostly low and BYDV serotype MAV was not distinguished. Rhopalosiphum padi was the predominant vector species but small numbers of R. maidis and Sitobion miscanthi were also present. Repeated insecticide spray applications began at different times in the different experimental treatments. These sprays killed or repelled aphid vectors, thereby preventing further virus spread from the time they were first applied. At both sites, migrant aphids were caught flying into the wheat throughout the winter period. Peak numbers of colonising aphids ranged from 0 to 99/0.5-m transect of crop. BYDV-PAV incidence ranged from 0.1 to 58% of plants and yields ranged from 1.9 to 8.6 t/ha. First aphid arrival was earlier, and virus spread and resulting yield losses greater at Site A. At this site, in treatments where repeated insecticide sprays did not start until 8 weeks after crop emergence (WAE), virus incidence and subsequent yield losses were significantly greater than when the regular applications started at emergence. However, delaying the start of sprays beyond 8 weeks had no further effect on virus spread. Since aphid numbers were very low up to 8–10 WAE, yield losses were due entirely to virus infection of plants during this early growth period. Variation in BYDV-PAV incidence explained 81 or 91% of the variation in yield gaps in the 2 years at Site A where, for each 1% increase in virus incidence, there was a yield decrease of 55 or 72 kg/ha. It also explained the variation in seed weight (88%) and protein content (69%), but not in seed screenings. At Site B, virus spread started too late to cause significant yield or quality losses. These results show that wheat yields are decreased substantially in a Mediterranean-type environment, when aphids immigrate early into wheat crops and remain active throughout the winter-growing period, spreading virus infection at young plant growth stages.

Synthesis of superabsorbent polymers by irradiation and their applications in agriculture

AbstractThe superabsorbent polymers (SAPs) were synthesized by grafting copolymerization of acrylic acid and acrylamide onto starch by using γ‐ray radiation technique and poly(ethylene glycol) (PEG) as a crosslinker. The samples were characterized by IR spectroscopy. The effect of various synthetic parameters such as irradiation dose, irradiation dose rate, monomer concentration, monomer/starch ratio, and PEG content were studied. The effects of different drying methods on water absorbency of the SAPs were also studied. The experimental results showed that the water absorbency of the SAPs depends largely on the specific conductance of water when the specific conductance is below 500 μs/cm. The water retention of sand and soil was enhanced by using the SAPs. Effects of the SAPs on the germination of seeds and growth of young plants were investigated. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1748–1755, 2004

Crescimento de plantas jovens de Tabebuia aurea (Manso) Benth. &amp; Hook. f. ex S. Moore submetidas a estresse hídrico

Tabebuia aurea (Manso) Benth. &amp; Hook. f. ex S. Moore pertence à família Bignoniaceae e ocorre nas margens dos rios temporários do Nordeste semi-árido. O crescimento das plantas jovens foi acompanhado em casa de vegetação por quatro meses e foi analisado em função do alongamento (cm), massa da matéria seca (g) e densidade estomática (mm²). Trinta dias após a semeadura, as plantas foram submetidas a três tratamentos hídricos: 100, 50 e 25% da capacidade de campo (cc). A densidade estomática foi verificada mensalmente nas regiões apical, mediana e basal da folha. Utilizou-se impressão em esmalte e a contagem foi efetuada em área de 1mm². O tratamento de 25%cc propiciou maior redução do crescimento. Nesse tratamento, a razão de crescimento (cm) parte subterrânea/aérea foi de 2:1 até os 60 dias; o número médio de folhas produzidas reduziu a partir dos 90 dias, e a área foliar média, dos 30 aos 120 dias de experimento. Em todos os tratamentos, evidenciou-se o efeito do estresse na massa da matéria seca (g) a partir dos 90 dias. O maior percentual de biomassa foi alocado para a parte aérea até os 90 dias e aos 120 dias para a parte subterrânea. T. aurea é hipoestomática, com estômatos do tipo anomocítico e densidade estomática variando de 119,63 a 155,19 estômatos por mm².

Assembly of a cytosolic pine glutamine synthetase holoenzyme in leaves of transgenic poplar leads to enhanced vegetative growth in young plants

ABSTRACTOver‐expression of glutamine synthetase (GS, EC 6.3.1.2), a key enzyme in nitrogen assimilation, may be a reasonable approach to enhance plant nitrogen use efficiency. In this work phenotypic and biochemical characterizations of young transgenic poplars showing ectopic expression of a pine cytosolic GS transgene in photosynthetic tissue (Gallardo et al., Planta 210, 19–26, 1999) are presented. Analysis of 22 independent transgenic lines in a 6 month greenhouse study indicated that expression of the pine GS transgene affects early vegetative growth and leaf morphology. In comparison with non‐transgenic controls, transgenic trees exhibited significantly greater numbers of nodes and leaves (12%), and higher average leaf length and width resulting in an increase in leaf area (25%). Leaf shape was not altered. Transgenic poplars also exhibited increased GS activity (66%), chlorophyll content (33%) and protein content (21%). Plant height was correlated with GS content in young leaves, suggesting that GS can be considered a marker for vegetative growth. Molecular and kinetic characterization of GS isoforms in leaves indicated that poplar GS isoforms are similar to their counterparts in herbaceous plants. A new GS isoenzyme that displayed molecular and kinetic characteristics corresponding to the octomeric pine cytosolic GS1 was identified in the photosynthetic tissues of transgenic poplar leaves. These results indicate that enhanced growth and alterations in biochemistry during early growth are the consequence of transgene expression and assembly of pine GS1 subunits into a new functional holoenzyme in the cytosol of photosynthetic cells.

Kura clover and birdsfoot trefoil response to soil pH1

Use of the rhizomatous perennial forage legume kura clover (Trifolium ambiguum M. Bieb.) has been limited by slow establishment. Mature kura clover responds to liming on some acid soils, but the soil pH required for vigorous growth of young plants is unknown. A factorial greenhouse experiment was conducted with two kura clover cultivars (Rhizo and Endura) and one cultivar of birdsfoot trefoil (Lotus corniculatus L., Norcen) planted in three soil types (Sartell loamy fine sand, Hubbard loamy sand, and Sanborg clay loam) amended with Ca(OH)2 to obtain six soil pH levels. The experiment was performed twice, once using soil taken directly from the field and once using steamed soil. Response of kura clover and birdsfoot trefoil to soil pH differed. Maximum yield increases in kura clover obtained by adjusting soil pH from 4.9 to 6.5 were about 50% on nonsteamed soil and more than 150% on steamed soil. Birdsfoot trefoil did not respond to liming on nonsteamed soil. On steamed soil birdsfoot trefoil response to liming was inconsistent. Optimal soil pH for growth of kura clover and birdsfoot trefoil was generally between pH 6 and 7. Biomass yield was correlated with nodulation in both kura clover and birdsfoot trefoil, but nodulation was correlated with nitrogen uptake only in kura clover. Increased biomass yield of young kura clover plants in response to liming was best explained by alleviation of aluminum (Al), zinc (Zn), and manganese (Mn) toxicities and increased availability of phosphorus (P) and molybdenum (Mo) at higher soil pH levels. Joint contribution of the Minnesota Agricultural Experiment Station and USDA-ARS.

Production d'une substance rhizogène à effet similaire à celui de l'acide indole acétique par le ver de terreLumbricus terrestris

In vitro biological tests show that excreta or gross total and partial extracts of Lumbricus terrestris stimulate rhizogenesis and enhance root growth in young plants of the bean Phaseolus vulgaris. Similar results were obtained in experiments with worms freshly collected in the field and with worms previously deprived of food for 4 weeks. The rhizogenous substance produced by the worms is therefore not of exogenous origin, coming from the soil via the digestive tract. The similar effects of indol acetic acid at different concentrations and of excreta and gross extracts of worms in various dilutions indicate that the rhizogenous substance is similar to indol acetic acid, a well-known phytohormone in plants. Expressed as indol acetic acid equivalents, the quantity of the rhizogenous substance in worms would be approximately 18 × 103ng/g, of which half (9 × 103ng/g) is released in the excreta alone.[Journal translation]

Microclima y regeneración natural de Raulí, Roble y Coigüe (Nothofagus alpina, N. obliqua y N. dombeyi)

SUMMARY The natural reproduction of Nothofagus alpina, N. dombeyi and N. obliqua was examined at 74 locations in BioBio, Malleco and Cautin provinces (Chile). Relationships between the occurrence and growth of young plants and some microclimatic variables were studied by means of multivariate analyses. N. alpina is restricted to conditions of low light (<27%) and reduced evaporation, as well as to moderate air and soil temperatures. It avoids situations that involve frost hazard during the vegetation period. In comparison, N. obliqua is a typical heliophyte, preferring open sites of intensive light and high evaporation rates, and can even survive night temperatures around the freezing point. The microclimatic requirements of N. dombeyi were generally very similar to those of N. alpina within the investigated region. The ecological classification, particularly of the latter, is discussed in this paper.

Effect of Salts on Germination of Seeds and Growth of Young Plants of Hordeum vulgare, Triticum aestivum, Cicer arietinum and Brassica juncea

A greenhouse experiment was conducted on four crop plants in the western region of Gujarat State, India to assess their responses to increasing levels of soil salinity. Of the four crop plants tested (Hordeum vulgare, barley; Triticum aestivum, wheat; Cicer arietinum, gram and Brassica juncea, mustard), barley appeared to be the most tolerant to salinity with regard to seed germination and early growth of the plants. Wheat, gram and mustard were tolerant only to low soil salinity. However, high salt concentrations in the soil reduced the absorption of nitrogen and phosphorus by the young plants. The imbalance of mineral nutrients resulted in a reduction or an inhibition of plant growth. High salinity also caused burning symptoms on the leaves and shoot apices of barley.