Lower Growth Response Research Articles

Response of Douglas-fir stem profile to operational nitrogen fertilization in western Oregon

Nitrogen (N) fertilizer is a commonly applied silvicultural treatment intended to promote growth of intensively managed coast Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco var. menziesii] plantations in the Pacific Northwest region of the US (PNW) and adjacent areas of Canada. Because responses have been geographically variable, fertilization trials were established in the Coast Range of northwestern Oregon to enhance general understanding of Douglas-fir growth response and test the economic viability of operational N applications in this subregion. Twenty-three operational stands comprising the trials were dominated by Douglas-fir, had an initial total age of 16–24 years, had been pre-commercially thinned 7–10 years prior to establishment of the fertilization trials, and started with 387–1260 trees ha−1. Nitrogen fertilizer was applied aerially as pelletized urea (46% N) at a rate of 224 kg N ha−1 to half of each stand during the dormant season of 2009–2010. In the dormant season of 2016–2017, seven growing seasons following fertilizer application, forty sample trees were felled in ten randomly selected stands to assess the influence of N-fertilization on stem form. A variable exponent taper model was developed using a nonlinear mixed-effects modelling approach. A tree-level random effect and a first-order continuous autoregressive [CAR(1)] error process were incorporated into the model to facilitate accurate tests of significance on model parameter estimates. The variable exponent taper model captured significant variation in stem form resulting from fertilization based on interaction with a crown variable, suggesting that the N-fertilization influence on stem form was mediated by initial crown length of trees with given diameter and height. Volume predictions from the resulting taper model were compared to those from the regional growth model ORGANON, which assumes no influence of fertilization on stem form. The regional growth model ORGANON significantly (p < 0.01) under-predicted fertilized tree volume by 3.6%. Results are being incorporated into individual-tree growth models to improve site-specific predictions of growth response. Improved understanding and modeling of mechanistic responses of foliage, growth, and stem form to fertilization may help discriminate between sites with high and low growth response potential. Mechanistic insights coupled with better site characterization should help improve the understanding of economic and environmental performance of fertilized Douglas-fir stands.

GROWTH RESPONSE OF YANKASA SHEEP TO DIFFERENT LEVELS OF CONCENTRATE SUPPLEMENTATION

In a study that lasted for 120 days, 20 weaned Yankasa ram lambs aged 6 months and weighing between 10.5 and 14.5kg with an average of 12.75kg were offered a basal Digitaria smutsii hay diet at 2% of body weight. This was supplemented with a concentrate mixture made to supply 14.6% crude protein and 2.6 Mcal ME per kg and offered to treatment groups A, B, C and D at 1, 2, 3, and 4% of body weight respectively. There were five replicates and the animals were fed individually. Results indicated that the differences in Average Daily Gain was significant (P&lt;0.05) between all the treatments; the value increased with increased level of feeding. The cost of effecting one unit of live weight increase was not significantly different (P&lt;0.05) between treatments, A, B, and C, but it was significantly lower (P&lt;0.05) than for treatment D. The low growth response of lambs fed the concentrate at 1% of body weight and the higher cost per unit gain of lambs offered the supplement at 4% of body weight suggested that concentrate supplementation at 2 and 3% of body weight was adequate for optimum liveweight gains in the Yankasa sheep breed.

The interplay between light, plant growth regulators and elicitors on growth and secondary metabolism in cell cultures of Fagonia indica

Manipulation in the light regimes combined with the effects of plant growth regulators (PGRs) and elicitors through plant cell culture technology is a promising strategy for enhancing the yield of medicinally important secondary metabolites. In this study, the effects of interplay between PGRs, elicitors and light regimes on cell cultures of F. indica have been investigated. The results showed that callus cultures resulted in maximum biomass formation (13.2 g/L) when incubated on solid MS (Murashige and Skoog) medium containing 1.0 mg/L BA under continuous light for 4 weeks. Among the other PGRs, compared with the auxins such as 2,4-D, and IBA, TDZ resulted in higher biomass accumulation (12.1 g/L). Elicitors (Me-J and PAA) resulted in a lower growth response, when compared with cytokinins and a higher response than auxins under all the light regimes on solid MS media. However, in liquid media, no significant increase in biomass was observed in response to the combined effects of PGRs and photoperiod regimes. Further, the highest phenolic content (TPC = 6.8 mg) and flavonoid content (TFC = 5.2 mg) were detected in the dark-grown cell cultures raised in vitro at 0.5 mg/L Me-J. The highest antioxidant activity (88%) was recorded in the dark-grown cell cultures harvested from LOG phase of the growth cycle supplemented with 0.5 mg/L Me-J. Furthermore, BA resulted in considerable flavonoids production (TFC = 4.7 mg) in the cell cultures grown under continuous light. However, overall dark treatment and elicitation with Me-J resulted in the optimal metabolic response in terms of secondary metabolites accumulation in cell suspension cultures of F. indica.

Synergistic effect between phosphate solubilizing bacteria and vesicular-arbuscular mycorrhizal fungi on growth and p uptake in Cajanus cajana L. (Pigeon pea)

The influence of phosphate solubilizing bacterium (Bacillus polymyxa) and arbuscular mycorrhizal fungi (Rhizophagus fasciculatus) on growth and phosphorus uptake in Cajanus cajana were studied, in green house conditions. Experiments were carried out by using both sterilized and unsterilized garden soil (sandy loam). Mycorrhiza with P-solubilizing bacteria inoculated with sterilized soil produced significantly higher growth, dry matter and increase in nodule number and P uptake in shoot. Moderate or lower growth response was observed among the plants grown in unsterilized soil either PSB or AMF inoculation. On the contrary non-inoculated plants in sterilized garden soil did not showed meager growth and higher total P uptake. A synergistic effect was recorded with increased plant dry matter, nodule number and P uptake in the plants treated with both the inoculum and in sterilized soil.

Experimental drought and heat can delay phenological development and reduce foliar and shoot growth in semiarid trees.

Higher temperatures associated with climate change are anticipated to trigger an earlier start to the growing season, which could increase the terrestrial C sink strength. Greater variability in the amount and timing of precipitation is also expected with higher temperatures, bringing increased drought stress to many ecosystems. We experimentally assessed the effects of higher temperature and drought on the foliar phenology and shoot growth of mature trees of two semiarid conifer species. We exposed field-grown trees to a ~45% reduction in precipitation with a rain-out structure ('drought'), a ~4.8°C temperature increase with open-top chambers ('heat'), and a combination of both simultaneously ('drought+heat'). Over the 2013 growing season, drought, heat, and drought+heat treatments reduced shoot and needle growth in piñon pine (Pinus edulis) by ≥39%, while juniper (Juniperus monosperma) had low growth and little response to these treatments. Needle emergence on primary axis branches of piñon pine was delayed in heat, drought, and drought+heat treatments by 19-57days, while secondary axis branches were less likely to produce needles in the heat treatment, and produced no needles at all in the drought+heat treatment. Growth of shoots and needles, and the timing of needle emergence correlated inversely with xylem water tension and positively with nonstructural carbohydrate concentrations. Our findings demonstrate the potential for delayed phenological development and reduced growth with higher temperatures and drought in tree species that are vulnerable to drought and reveal potential mechanistic links to physiological stress responses. Climate change projections of an earlier and longer growing season with higher temperatures, and consequent increases in terrestrial C sink strength, may be incorrect for regions where plants will face increased drought stress with climate change.

Inter‐rotational Effects of Fertilization and Weed Control on Juvenile Loblolly Pine Productivity and Nutrient Dynamics

The inter‐rotational effects of fertilization and weed control treatments on the productivity and soil nutrient availability of loblolly pine (Pinus taeda L.) stands growing on a North Florida Spodosol were investigated using two replicated, randomized complete block design experiments. The first rotation treatments were: control (C), fertilizer only (F), weed control only (W), and fertilizer + weed control (FW). One experiment was actively retreated as in the previous rotation, while the second was left untreated (CC, CF, CW, and CFW). A common full‐sib loblolly pine family was planted in both experiments. After three growing seasons, the second‐rotation pine growth consistently outperformed the first rotation. The actively retreated FW treatment had fourfold higher aboveground pine biomass than the C treatment (7.7 Mg ha−1); the untreated CF (17.9 Mg ha−1) treatment had 1.5‐fold higher pine biomass than the CFW treatment. While a suite of improved cultural practices (e.g., advanced genetics and site preparation) and environmental factors may be responsible for higher growth responses in the second rotation than the first in both experiments, lower growth response in the CFW treatment compared with the CF treatment was associated with lower soil P availability (r = 0.8, p &lt; 0.01) and historical P movement from the E to Bh and Bt horizons. These results suggest that the understory vegetation and forest floor from the first rotation served as an important nutrient sink, especially for P, which then subsequently became a nutrient source (through mineralization) in the second rotation. Historical P fertilization on flatwoods Spodosols may thus alleviate the need for P fertilization during stand establishment when an intact understory was present in the previous stand.

Measurements of enzyme response with hulless barley-based diets full-fed to Leghorn and broiler chicks or restricted-fed broiler chicks

Broiler chicks fed diets high in soluble non-starch polysaccharides (NSP; e.g., wheat- and/or barley-based diets) have a higher capacity to ingest, digest and absorb nutrients when diets are supplemented with appropriate NSP enzymes. However, this same enzyme response is typically reduced or non-significant in older birds, Leghorn chicks and turkey poults. We hypothesise that the enzyme response in the latter classes of poultry is reduced because feed intake is lower in comparison to feed intake by broilers. In the present study, the hypothesis that restricted feeding of broilers would reduce the enzyme response typically observed in full-fed broilers was tested. Two experiments were conducted to determine the feeding value of hulless barley supplemented or not supplemented with enzyme (Avizyme 1100, Finnfeeds Int, UK). In Study 1, eight sources of hulless barley were included at 80% in each diet and fed to four groups of six male broilers or Leghorn chicks from 4 to 17 d of age. The response to enzyme in hulless barley-based diets by broilers was approximately twofold that of Leghorns for growth and feed intake. The Leghorns had higher digesta viscosity than broilers, although the relative drop in digesta viscosity with enzyme supplementation was equal. In a second study (Study 2) broiler chicks were fed one of four diets (two hulless barley cultivars with or without enzyme) at three feed allotment levels (ad libitum, R1 and R2) from 4 to 21 d of age. The R1 and R2 feed allotments were pre-determined fixed daily feed amounts. Actual feed restriction in the R1 group was only achieved for diets with, but not without, an enzyme. At the lowest feed allotment (R2) actual feed intake of diets with or without enzyme were lower than that recorded for ad libitum fed birds. Study 2 demonstrated that restricted-fed broilers had a lower growth response to enzyme supplementation compared to birds allowed ad libitum intake, in part due to improved retention of energy, either directly in response to feed restriction or because digesta viscosity in diets without enzyme was lowered. Although digesta viscosity of restricted-fed birds was lower, it is still high enough to be considered problematic. In determining feeding value of cereal grains or supplements such as enzymes, especially those directed for use with broilers, it is imperative that a broiler chick bioassay be used and that they have ad libitum access to the diets. Key words: Enzyme, hulless barley, viscosity, feed intake

Influence of extraction on the determination of vitamin B 6 in food by HPLC

The effect of the extraction procedure on the total vitamin B6 content in different food matrices is presented. The use of hydrochloric acid, sulphuric acid and trichloroacetic acid, combined with enzymatic hydrolysis using several commercial enzyme preparations, was tested. The results of two liquid chromatographic methods (isocratic and gradient elution) and those of microbiological assay were compared. Reproducible results were achieved using a mineral acid followed by β-glucosidase/acid phosphatase hydrolysis for extraction of the same sample and only a few unknown compounds caused interference in the reversed-phase chromatogram. However, the conversion efficiency of the enzyme preparation should always be checked. The liquid chromatographic method indicated that there was a higher vitamin content compared with the microbiological assay. This is probably due to a lower growth response of Saccharomyces with pyridoxamine and pyridoxal rather than pyridoxine.

Glucose tolerance in Atlantic salmon, Salmo salar L., dependence on adaption to dietary starch and water temperature

Individually tagged Atlantic salmon, Salmo salar L., were fed three different adaptation diets containing low, medium or high levels of extruded starch, before intraperitoneal injection of glucose. The injections were done at winter and at summer temperatures. This was to investigate whether the tolerance for glucose varied according to adaption diet and/or according to season. The results showed a temperature-dependent response. At winter temperatures (2°C) the Atlantic salmon had problems adapting to both medium and high levels of dietary starch. This was indicated by lower growth response in the adaptation period, as well as by delayed glucose regulation. At summer temperatures (12.5°C) the Atlantic salmon could tolerate and utilize both medium and high levels of dietary starch. In summer also all groups responded evenly to the tolerance tests with respect to blood glucose regulation. Incorporation of liver glycogen was higher at summer than at winter temperatures in the high- carbohydrate group. No effect was found on haematocrit values as a response to diet or season.

Degradation of Algal Exudates by Mixed Bacterial Biocenoses

In the frame of a research project concerning regrowth problems a water utility at Lake Constance is involved. For this plant it was interesting to find out which effect is exerted by organic products released from algae living in the lake water. Therefore model experiments were carried out using two different algal cultures in the stationary phase, where the algae were carefully separated by filtration. From these extracellular organic carbon solutions (exudates) dilutions were prepared using highly purified deionized water. These were tested for their ability to support bacterial growth by adding a mixed bacterial biocenosis after sterile filtration and monitoring growth curves by turbidity measurements, a method developed at the DVGW-Research-Center in Karlsruhe to judge drinking water with respect to its regrowth potential. It was shown that the exudate from a Haematococcus culture is very growth stimulating, though the substrate concentration analyzed as ∆DOC was very low. In contrast the exudate from a Stephanodiscus culture gave a very low growth response. The effect of the Stephanodiscus culture for the drinking water plant at Lake Constance is much more important because Stephanodiscus is a species common in Lake Constance whereas Haematococcus is not.

Methionyl human growth hormone in Turner's syndrome.

Sixteen girls with Turner's syndrome aged 7.9-15.2 years (bone ages 7.0-11.8 years) were given methionyl growth hormone (somatrem) 4 IU/m2 body surface daily, corresponding to 0.9 IU/kg/week. During one year of treatment their mean (SD) height velocity increased from 3.4 (0.9) to 7.2 (1.7) cm/year and height prediction from 148.2 (4.4) to 150.0 (4.4) cm. All the girls except one had a height velocity increment of more than 2 cm/year and these velocities are above the age references for girls with Turner's syndrome. The girl with a low growth response had antibodies against growth hormone with high binding capacity (3.7 U/l). The height velocity increment was inversely correlated with age and bone age, but this might be partly due to the somewhat higher dosage/m2 body surface and kg body weight that the younger patients were given because of the rounding off of the dose. The better results of our study compared with those of other workers who used similar dosages but did not give the drug as often suggest that giving it daily might have increased the growth response as it does in children deficient in growth hormone.

Pathogenesis of heterogeneity in human multinodular goiter. A study on growth and function of thyroid tissue transplanted onto nude mice.

Functional and morphologic heterogeneity of human multinodular goiters was investigated in 300 samples from "cold" and "hot" regions of 20 goiters transplanted onto nude mice. Transplants were labeled with [3H]thymidine and radioiodine, while the host's thyroid-stimulating hormone (TSH) secretion was either stimulated or suppressed. Proliferation and function of follicular cells were assessed in whole follicles reconstructed from autoradiographs of serial sections. Hot transplants had a higher autonomous iodine uptake than those of cold tissue in TSH-suppressed hosts. Functional autonomy widely varied among the follicles, but even more so among individual cells. Hot grafts differed from cold ones only by a comparatively larger fraction of autonomous cells. Intercellular differences of iodinating activity were not abolished by TSH. Grafts faithfully reproduced the individual growth pattern of the original tissue. Between 0.5% and 7% of all follicular cells replicated despite suppression of TSH. Up to 70% of these cells were clustered, forming scattered foci of autonomously growing tissue. Other cells only started replicating after long-term TSH stimulation. Thus, goiters contained subsets of cells with high and others with low growth response. Progenies of replicating cells remained clustered, sometimes budding outwards to form new follicles. Autonomy of growth and autonomy of function are independent traits of epithelial cells. Epithelial cells have their individual growth pattern, replication rate, and functional capacity. These traits are passed on from a mother cell to its progeny during follicle neogenesis. To this main mechanism accounting for the morphologic and functional heterogeneity of human goiters, inheritable modifications of gene expression must probably be added.

Effects of cytochalasins on Neurospora crassa. I. Growth and ultrastructure.

Growth of various strains ofNeurospora crassa in the continued presence of cytochalasins A and B results in the following pattern. At low concentration the drugs cause an increase in branching which, depending on the strain, may also reveal an increase in dry weight. Increasing the concentration results in abnormal hyphae (swollen, irregular) and eventually in inhibition of growth. Most strains are inhibited at 10–20 Μg/ml cytochalasin A. Ultrastructure of hyphae grown in the presence of cytochalasin A reveals the presence of abnormal wall deposits. These deposits are not observed in cultures grown with cytochalasin B which generally causes a lower growth response also.

ON HORMONES AND WEEPING: ASYMMETRIC HORMONE DISTRIBUTION AND THE PENDULOUS GROWTH HABIT OF THE WEEPING MULBERRY, MORUS ALBA VAR. PENDULA

SummaryThe possibility that asymmetric hormone distribution causes downward bending of weeping mulberry (Morus alba var. pendula) twigs was investigated. By extraction, bioassay and gas chromatography it was shown that while upper and lower twig sections had no differences in auxin activity, the two sides differed considerably in content of GA and ABA. The lower side contained high levels of endogenous GA while the upper side had higher concentrations of ABA. The significance of these results and their possible role in the weeping habit of tree growth are discussed. It is suggested that the high GA levels coupled to low ABA content induce greater lignification on the lower side of the twig and that this tissue is less sensitive to auxin and has a lower growth response than the upper side of the twig thus causing a downward inclination of growth.

The Effect of Long Chain Fatty Acid Isomers on Growth, Fatty Acid Composition and Osmotic Fragility of Mycoplasma laidlawii A

SUMMARY: Growth of Mycoplasma laidlawii a in a tryptose medium, with lipid pre-extracted, containing charcoal-treated bovine plasma albumin, occurred only after addition of long-chain fatty acids. Of the long-chain fatty acids tested, positional as well as geometrical isomers of octadecenoic acids were effective in growth promotion; trans isomers were more effective in promoting growth and in lowering osmotic fragility than their corresponding cis isomers. Tetra-decenoic or hexadecenoic acids did not replace the growth requirement for an octadecenoic acid. Although fatty acids containing cyclopropane-rings promoted growth, a greater toxicity and lower growth response was observed. No fatty acid isomerization by this mycoplasma was detected and the octadecenoic acids added to the growth medium were recovered from membrane polar lipids unchanged. Fatty acid analyses revealed that myristic and palmitic acids were the major saturated fatty acid components of the membrane polar lipids. No differences were found in the fatty acid content or composition of membrane polar lipids from mycoplasmas grown at 25° and 37°. Major differences in the fatty acid composition between glycolipids and phospholipids were not apparent.

Low Energy Effects of Light on Growth and Pigment Content in a Yellow-in-the-Dark Mutant of Chlamydomonas reinhardi

The y-2 mutant of Chlamydomonas reinhardi differs from the wild type in being unable to synthesize chlorophyll in the dark and in a requirement for catalytic amounts of light for organotrophic growth. Light-grown y-2 cells given acetate are capable of the equivalent of 9 to 10 divisions when placed in darkness. Cultures adapt gradually to dim white or monochromatic light and after 8 to 10 generations assume a steady state with respect to growth and pigment content.Two energetically distinct light reactions promote the growth of y-2 on acetate. A low energy requirement is satisfied at about 0.1 muw/cm(2) of white light which results in a growth rate of 0.5 log unit per day. A high energy response, which saturates at 2000 muw/cm(2) and a growth rate of 0.9 log unit per day, is probably attributable to net photosynthesis. An action spectrum for the low energy growth response contains a broad major peak in the blue between 462 and 502 nm and a minor peak in the far-red between 700 and 736 nm. All intermediate wavelengths have low but positive activity. The action spectrum was investigated with y-2 cultures that were grown for many generations under steady-state conditions in growth-limiting monochromatic light. Many wavelengths resulted in a selection pressure that strongly favored a strain of green-in-the dark cells that usually appeared after 5 to 8 generations of light-limited growth. Under the low light intensity of these experiments (0.15 +/- 0.05 muw/cm(2)) the green strain was much richer in chlorophyll than y-2 and divided more rapidly with the consequence that y-2 was generally replaced in the course of a few generations. Consideration of the results led to the conclusion that both chlorophyll and carotenoids act as photoreceptors in the low energy growth response of y-2.

Availability of Phosphorus Supplements for Chicks

ABSTRACT The scientific literature dealing with the availability of the phosphorus in various phosphate supplements for chicks was reviewed by Motzok et al. (1956). These workers reported that four colloidal phosphates (soft phosphate with colloidal clay) gave a growth response and percent bone ash, in chicks at 5 weeks of age, below those achieved with tricalcium phosphate. One sample of a fifth colloidal phosphate did not result in inferior growth or bone ash, but another sample resulted in a lower growth response than that with tricalcium phosphate, although the percent bone ash was not significantly different. Samples from ten carload lots from the same producer gave varying growth and bone ash responses, but all were inferior to those resulting from bone meal. However, when half of the supplemental phosphorus supplied by colloidal phosphate was replaced by bone meal there was marked improvement in growth, although the average weight of the chicks . . .