scholarly journals Morphogenetic and structural comparative characterization of tropical forage grass cultivars under free growth

2010 ◽  
Vol 67 (2) ◽  
pp. 136-142 ◽  
Author(s):  
Márcia Cristina Teixeira da Silveira ◽  
Domicio do Nascimento Júnior ◽  
Sila Carneiro da Silva ◽  
Valéria Pacheco Batista Euclides ◽  
Denise Bataglin Montagner ◽  
...  
Keyword(s):  
Structural Characteristics ◽  
Stem Elongation ◽  
Survival Rates ◽  
Group Analysis ◽  
Leaf Length ◽  
Leaf Life Span ◽  
Large Variability ◽  
Tropical Forage ◽  
Structural Variables ◽  
Free Growth

Understanding of the morphogenetic characteristics allows comprehension of aspects related to the form and function of forage plants, providing opportunities to identify potentially high productive plants and distinct defoliation management requirements. The objective of this experiment was to carry out a comparative study of ten tropical forage grasses using morphogenetic and structural variables. Treatments corresponded to grasses of the Panicum genus (P. maximum cultivars Tanzânia and Mombaça) and the Brachiaria genus (B. brizantha cultivars Piatã, Marandu, Xaraés, Capiporã and Arapoty; B. decumbens cultivar Basilisk; B. humidicola cultivars Comum and Tupi), evaluated under free growth conditions.. Response variables were leaf appearance and elongation rates, phyllochron, stem elongation rate, final leaf length, number of live leaves per tiller, leaf life span and tiller appearance, death and survival rates. There was difference between cultivars for these variables, indicating a large variability within plants. Considering the morphogenetic and structural variables of leaves and tillers, B. brizantha had a similar pattern of variation to those of P. maximum, and B. Decumbens, similar to those of B. humidicola. Tiller appearance was large at the onset of the experiment and second and third generations comprised the large majority of tiller population for the cultivars Mombaça, Tanzânia, Xaraés and Capiporã. Group analysis based on plant morphogenetic and structural characteristics of leaves and tillers was an interesting way of grouping cultivars, indicating the importance and the potential of using morphogenesis in plant selection and evaluation programmes.

scholarly journals Effects of postgrazing residue on morphogenetic and structural characteristics of Tifton 85 pastures

2016 ◽  
Vol 37 (4) ◽  
pp. 2043
Author(s):  
Wilton Ladeira Silva ◽  
Ana Cláudia Ruggieri ◽  
Ricardo Andrade Reis ◽  
Américo Garcia Silva Sobrinho ◽  
Euclides Braga Malheiros
Keyword(s):  
Structural Characteristics ◽  
Stem Elongation ◽  
Light Interception ◽  
Climatic Conditions ◽  
Leaf Length ◽  
Elongation Rate ◽  
Area Index ◽  
Structural Variables ◽  
Senescence Rate ◽  
Leaf Appearance

The ideal time to start grazing is when pastures reach 95% light interception. The use of residual leaf area index (rLAI) to time the interruption of grazing under intermittent grazing has recently been studied in forage species in different climatic conditions in Brazil. However, studies evaluating the formation and development of leaves and tillers through morphogenetic and structural variables in functional rLAI are still lacking for Tifton 85 pastures. Therefore, the objective of this study was to evaluate the effects of varying rLAI in successive grazing cycles on morphogenetic and structural characteristics of Tifton 85 pasture grazed intermittently by sheep. Morphogenetic and structural characteristics were evaluated in three grazing cycles under three rLAI conditions (0.8, 1.6, and 2.4). The regrowth interval (time taken to return to 95% light interception) of pastures increased from 21.33 to 29.66 days with decreasing rLAI. The leaf appearance rate increased at a rate of 0.02 leaves tiller-1 day-1 and the number of live leaves per tiller increased by 0.41 with decreasing rLAI. Phyllochron, leaf elongation rate, final leaf length, leaf senescence rate, and stem elongation rate decreased linearly with decreasing rLAI. The number of live leaves per tiller was lower (7.97) in the third grazing cycle, probably owing to the higher senescence rate observed that same cycle, while the other variables had higher values. The 2.4 rLAI condition promotes excessive stem elongation, reduced leaf appearance, lower number of live leaves per tiller, and increased senescence of leaves, while the 0.8 and 1.6 rLAI conditions promote desirable morphogenetic and structural characteristics, which correlate directly with forage quality. In order to avoid excessive forage losses, grazing must occur preferentially by the end of March, when climatic conditions still support the appropriate development of the plants.

scholarly journals Morphogenetic and structural characteristics of clones of elephant grass managed under intermittent stocking

2016 ◽  
Vol 37 (4) ◽  
pp. 2099
Author(s):  
Priscila Beligoli Fernandes ◽  
Carlos Augusto Brandão de Carvalho ◽  
Domingos Sávio Campos Paciullo ◽  
Carlos Augusto De Miranda Gomide ◽  
Mirton José Frota Morenz ◽  
...  
Keyword(s):  
Structural Characteristics ◽  
Stem Elongation ◽  
Elongation Rate ◽  
Leaf Life Span ◽  
Elephant Grass ◽  
Leaf Elongation ◽  
Appearance Rate ◽  
Randomized Experimental Design ◽  
Leaf Appearance Rate ◽  
Leaf Appearance

This work was carried out to evaluate the morphogenetic and structural characteristics of basal and aerial tillers of two dwarf elephant grass clones (BRS Kurumi and CNPGL 00-1-3) managed under intermittent stocking in six grazing cycles. A completely randomized experimental design with three replications (paddocks) in split-split-plot arrangements was used. The clones were allocated to the plots, tiller classes were assigned to the subplots and grazing cycles to sub subplots. Higher values for basal tillers than aerial tillers were seen for the following characteristics: leaf elongation rate (12.8 and 5.1 cm/tiller/day), leaf appearance rate (0.26 and 0.19 leaves/tiller/day), stem elongation rate (0.38 and 0.16 cm/tiller/day), senescence rate (0.98 and 0.47 cm/tiller/day), total number of leaves (9.3 and 7.1 leaves/ tiller), number of live leaves (7.7 and 5.8 leaves/tiller) and final length of leaf blades (33.5 and 20.0 cm). Phyllochron was lower for basal (4.0 days/leaf) than aerial tillers (5.5 days/leaf). The leaf life span increased with the advance of the grazing cycles, averaging 31.2 days. The tiller density increased with the advance of the grazing cycles showing an average increase of 167% of aerial tillers and 62% of basal tillers for both clones. The morphogenetic and structural characteristics of dwarf clones were influenced jointly by the clones and the availability of the environmental factors of growth during the spring and summer. The high leaf elongation rates, associated with high leaf appearance rate, reveal the potential of high production dry matter of leaves and restoration of leaf area after grazing.

scholarly journals Morphogenesis and biomass production of 'BRS Tamani' guinea grass under increasing nitrogen doses

2020 ◽  
Vol 55 ◽  
Author(s):  
Elayne Cristina Gadelha Vasconcelos ◽  
Magno José Duarte Cândido ◽  
Roberto Cláudio Fernandes Franco Pompeu ◽  
Ana Clara Rodrigues Cavalcante ◽  
Marcos Neves Lopes
Keyword(s):  
Structural Characteristics ◽  
Stem Elongation ◽  
Block Design ◽  
Rest Period ◽  
Leaf Biomass ◽  
Leaf Life Span ◽  
Dose Equivalent ◽  
Area Index ◽  
Guinea Grass ◽  
Positive Effect

Abstract: The objective of this work was to evaluate the morphogenic and structural characteristics of Megathyrsus maximus 'BRS Tamani', subjected to increasing nitrogen doses, as well as the components of its biomass. The experiment was carried out in a randomized complete block design with four treatments (0, 300, 600, and 1,200 kg ha-1 N per year) and three replicates, in 12 experimental units of 12.5 m² each. The evaluations were performed in the rest period of the pasture, after defoliation to a residual leaf area index of 1.0, until the pasture reached the number 3.0 of new leaves produced per tiller. Leaf and stem elongation rates increased with the increment in N doses up to 1,200 kg ha-1 N per year. There was a decreasing linear response for phyllochron and leaf life span. Increases of 704% were observed for the harvestable green leaf biomass, at the dose equivalent to 1,200 kg ha-1 N per year. The biomasses of dead forage and harvestable stem were not affected by the N doses. Nitrogen fertilization shows a positive effect on the morphogenic, structural, and productive characteristics of 'BRS Tamani' guinea grass up to the dose equivalent to 1,200 kg ha-1 N per year.

scholarly journals Morphogenic and structural characteristics of tropical forage grasses managed under different regrowth periods in the Brazilian semi-arid region

2019 ◽  
Vol 40 (1) ◽  
pp. 283
Author(s):  
Genildo Fonseca Pereira ◽  
João Virgínio Emerenciano Neto ◽  
Gelson Dos Santos Difante ◽  
Liz Carolina da Silva Lagos Cortes Assis ◽  
Patrícia De Oliveira Lima
Keyword(s):  
Accumulation Rate ◽  
Structural Characteristics ◽  
Stem Elongation ◽  
Buffel Grass ◽  
Science And Technology Education ◽  
Federal Institute ◽  
Tropical Forage ◽  
Blade Width ◽  
Semi Arid Region ◽  
Leaf Appearance

The objective of this study was to evaluate the morphogenetic and structural characteristics of tropical grasses managed under different regrowth periods. The experiment was conducted at the Federal Institute of Science and Technology Education of Rio Grande do Norte, located in the municipality of Apodi-RN, Brazil. The study design was in randomized blocks and the treatments were allocated in a 3x4 factorial arrangement, with three cultivars (Andropogon, Buffel and Massai) in four regrowth periods (21, 35, 49 and 63 days). The interaction between cultivar and age was significant for all studied variables, with the exception of leaf blade width and accumulation rate. The highest leaf appearance rates were observed in Buffel grass, regardless of the regrowth age. This characteristic was not influenced by age only in Andropogon grass. Higher stem elongation rates were observed in Buffel grass, while the lowest were observed in Massai grass until 35 days of regrowth, attributed to the presence of inflorescences. Canopy heights in Massai and Andropogon grass were greater than Buffel grass until 35 days of regrowth, Andropogon grass had higher height from 35 days of regrowth than the others. Andropogon grass showed higher rates of accumulation than Massai grass only at 21 days of regrowth, and no effects of regrowth age were observed for this variable. Buffel grass should be defoliated at 21 days, while Andropogon and Massai grass can be managed without losses between 21 and 63 days of regrowth.

scholarly journals Establishment of Brachiaria cultivars in the soil-climatic conditions of the Brazilian semi-arid region

2020 ◽  
Vol 43 ◽  
pp. e51802
Author(s):  
Jéssica Gomes Rodrigues ◽  
Gelson dos Santos Difante ◽  
Antonio Leandro Chaves Gurgel ◽  
Emmanuel Lievio de Lima Veras ◽  
Ana Beatriz Graciano da Costa ◽  
...  
Keyword(s):  
Arid Region ◽  
Structural Characteristics ◽  
Stem Elongation ◽  
Climatic Conditions ◽  
Leaf Length ◽  
Elongation Rate ◽  
Appearance Rate ◽  
Leaf Appearance Rate ◽  
Semi Arid Region ◽  
Semi Arid

This study aimed was the establishment of the genus Brachiaria in the Brazilian semi-arid region. The experiment was conducted from April to June 2016, as a randomized-block experimental design with five treatments and four replicates. Treatments were represented by five Brachiaria cultivars, namely, Marandu, Paiaguás, Piatã, Xaraés and Basilisk. Morphogenetic (leaf appearance rate, leaf elongation rate e stem elongation rate) and structural characteristics (final leaf length, tiller population density e number of leaves per tiller, forage mass, leaf blade mass, stem mass, senescent material mass and leaf:stem ratio) of the forage cultivars were evaluated. Canopy height fitted a linear regression model (P<0,05), with estimated daily increases of 0.50, 0.53, 0.53, 0.54 and 0.56 cm for cvs Basilisk, Marandu, Paiaguás, Piatã and Xaraés, respectively. The number of live leaves in cvs Basilisk and Paiaguás increased linearly (p < 0.05), by 4.3 and 2.8 leaves per tiller, respectively, during the 60-day period. The recommended height at which the growth of Brachiaria cultivars should be interrupted is upon reaching 25 to 35 cm. In the soil-climatic conditions of the Brazilian semi-arid region, the Brachiaria cultivars Basilisk, Marandu, Paiaguás, Piatã and Xaraés are established at 75 days after sowing, which is the recommended time for performing the first harvest or lenient grazing to stimulate tillering.

scholarly journals Morphogenesis and tiller density of Aruana grass managed at different heights under sheep grazing

2019 ◽  
Vol 40 (5Supl1) ◽  
pp. 2341
Author(s):  
Renata Negri ◽  
Guilherme Batista dos Santos ◽  
Vicente de Paulo Macedo ◽  
Magali Floriano da Silveira ◽  
Leticia Wlodarski ◽  
...  
Keyword(s):  
Stem Elongation ◽  
Block Design ◽  
Leaf Length ◽  
Elongation Rate ◽  
Leaf Life Span ◽  
Sheep Grazing ◽  
Randomized Block Design ◽  
Leaf Appearance Rate ◽  
Representative Area ◽  
Tiller Density

This study aimed to assess the morphogenic characteristics and tiller density of Aruana grass managed at different heights under sheep grazing. Aruana grass was managed at four mean heights (12, 15, 20, and 25 cm) distributed in a randomized block design with three replications, totaling 12 paddocks of 250 m² each. Twenty-four crossbred Dorper x Santa Inês lambs, with mean age and weight of 60 ± 15 days and 16.69 ± 2.70 kg, respectively, were randomly distributed in the treatments. Five tillers were demarcated per paddock for measuring morphogenic variables. A representative area in the paddock was used for counting the number of tillers. No differences (P > 0.05) were observed for leaf appearance rate, leaf elongation rate, stem elongation rate, leaf senescence rate, final leaf length, and leaf life span between the assessed heights. Phyllochron was longer at the height of 25 cm when compared to 15 and 20 cm (19.35, 12.11, and 12.75 days, respectively). The number of live leaves was higher at heights of 12, 15, and 20 cm when compared to 25 cm (3.99, 4.35, 4.15, and 2.86, respectively). The number of basal and aerial tillers presented no variation (P > 0.05) between canopy heights. Management heights from 15 to 20 cm allowed a higher number of live leaves and a shorter phyllochron in Aruana grass pastures managed for sheep. Canopy height management did not influence other morphogenic characteristics and tiller density.

scholarly journals Morphogenic and structural characteristics of Marandu grass cultivated under grazing management and nitrogen fertilization

2019 ◽  
Vol 40 (5Supl1) ◽  
pp. 2331 ◽  
Author(s):  
Luan Fernandes Rodrigues ◽  
Antonio Clementino dos Santos ◽  
Otacílio Silveira Junior ◽  
José Geraldo Donizetti dos Santos ◽  
Ana Flávia Gouveia de Faria ◽  
...  
Keyword(s):  
Nitrogen Fertilization ◽  
Structural Characteristics ◽  
Stem Elongation ◽  
Rest Period ◽  
Elongation Rate ◽  
Grazing Management ◽  
Quadratic Model ◽  
Leaf Life Span ◽  
Rest Periods ◽  
Quadratic Relationship

The goal of this study was to evaluate the morphogenic and structural characteristics of Marandu grass cultivated under grazing management and nitrogen fertilization. The experimental design was a completely randomized 4 × 2 split-plot design with four blocks. The treatments consisted of combinations of two rest periods (28 days - RPFixed - and height of 40 cm - RPVar) and four nitrogen doses (0, 150, 300, and 450 kg N ha-1 year-1) applied as ammonium sulfate. The following variables were analyzed: leaf appearance rate (LAR), phyllochron, leaf elongation rate (LER), stem elongation rate (SER), leaf senescence rate (LSR), leaf life span (LLS), average length of leaf blade (ALLB), sheath length (SL), number of live and dead leaves (NLL and NDL), and tiller population density (TPD). The variables LAR, LER, SER, ALLB and SL presented positive linear relationships with RPFixed and a quadratic relationship with RPVar, considering the application of the N doses. As for phyllochron and LLS, a negative linear relationship was observed with RPFixed and a quadratic relationship with RPVar. The N doses caused an effect on LSR, following the quadratic model for both rest periods studied. NLL and NDL exhibited linear effects on RPVar. The best indexes for the rest period variable were obtained when nitrogen was applied in the range of 280 to 333 kg ha-1, whereas the dose of 450 kg ha-1 of N provided desired results when using a fixed rest period. The rest period alleviated the process of senescence, especially given the application of higher nitrogen doses.

scholarly journals Plasma concentration guided dosing of drugs used for the treatment of childhood leukaemias: protocol for a systematic review

BMJ Open ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. e053308
Author(s):  
Madelé van Dyk ◽  
Chelsea Boylan ◽  
Robin Michelet ◽  
Anna M Mc Laughlin ◽  
Ganessan Kichenadasse ◽  
...  
Keyword(s):  
Systematic Review ◽  
Plasma Concentration ◽  
Clinical Outcomes ◽  
Survival Rates ◽  
Cytogenetic Response ◽  
Small Sample ◽  
Childhood Leukaemia ◽  
Molecular Response ◽  
Large Variability ◽  
Dose Individualisation

IntroductionChildhood leukaemia is the most common type of cancer in children and represents among 25% of the diagnoses in children <15 years old. Childhood survival rates have significantly improved within the last 40 years due to a rapid advancement in therapeutic interventions. However, in high-risk groups, survival rates remain poor. Pharmacokinetic (PK) data of cancer medications in children are limited and thus current dosing regimens are based on studies with small sample sizes. In adults, large variability in PK is observed and dose individualisation (plasma concentration guided dosing) has been associated with improved clinical outcomes; whether this is true for children is still unknown. This provides an opportunity to explore this strategy in children to potentially reduce toxicities and ensure optimal dosing. This paper will provide a protocol to systematically review studies that have used dose individualisation of drugs used in the treatment of childhood leukaemias.Methods and analysisSystematic review methodology will be applied to identify, select and extract data from published plasma guided dosing studies conducted in a paediatric leukaemia cohort. Databases (eg, Ovid Embase, Ovid MEDLINE, Ovid Cochrane) and clinical trial registries (CENTRAL, ClinicalTrials.gov and ISRCTN) will be used to perform the systematic literature search (up until February 2021). Only full empirical studies will be included, with primary clinical outcomes (progression-free survival, toxicities, minimal residual disease status, complete cytogenetic response, partial cytogenetic response and major molecular response) being used to decide whether the study will be included. The quality of included studies will be undertaken, with a subgroup analysis where appropriate.Ethics and disseminationThis systematic review will not require ethics approval as there will not be collection of primary data. Findings of this review will be made available through publications in peer-reviewed journals and conference presentations. Gaps will be identified in current literature to inform future-related research.PROSPERO registration numberCRD42021225045.

scholarly journals Catheter ablation or surgical therapy in moderate-severe tricuspid regurgitation caused by long-standing persistent atrial fibrillation. Propensity score analysis

2020 ◽  
Vol 15 (1) ◽  
Author(s):  
Jiangang Wang ◽  
Songnan Li ◽  
Qing Ye ◽  
Xiaolong Ma ◽  
Yichen Zhao ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Catheter Ablation ◽  
Tricuspid Regurgitation ◽  
Propensity Score Analysis ◽  
Survival Rates ◽  
Group Analysis ◽  
Tricuspid Valve Repair ◽  
Surgical Ablation ◽  
Severe Tricuspid Regurgitation ◽  
Recurrent Atrial Fibrillation

Abstract Background This study aimed to describe the mid-term outcomes of different treatments in patients with atrial fibrillation caused tricuspid regurgitation. Methods A retrospective study of patients diagnosed as atrial fibrillation caused moderate-severe tricuspid regurgitation undergoing ablation (n = 411) were reviewed. The surgical cohort (n = 114) underwent surgical ablation and tricuspid valve repair; the catheter cohort (n = 279) was selected from those patients who had catheter ablation. Results The estimated actuarial 5-year survival rates were 96.8% (95% CI: 92.95–97.78) and 92.0% (95% CI: 85.26–95.78) in the catheter and surgical cohort, respectively. Tethering height was showed as independent risk factors for recurrent atrial fibrillation and tricuspid regurgitation in both cohorts. A matched group analysis using propensity-matched was conducted after categorizing total patients by tethering height < 6 mm and ≥ 6 mm. Kaplan–Meier analysis showed in patients with tethering height < 6 mm, there were no differences in survival from mortality, stroke, recurrent atrial fibrillation and tricuspid regurgitation between two groups. In patients with tethering height ≥ 6 mm, there were significantly higher cumulative incidence of stroke (95% CI, 0.047–0.849; P = 0.029), recurrent atrial fibrillation (95% CI, 0.357–09738; P = 0.039) and tricuspid regurgitation (95% CI, 0.359–0.981; P = 0.042) in catheter group. Conclusions Atrial fibrillation caused tricuspid regurgitation resulted in less leaflets coaptation, which risk the recurrence of atrial fibrillation and tricuspid regurgitation. Patients whose tethering height was less than 6 mm showed satisfying improvement in tricuspid regurgitation with the restoration of sinus rhythm after catheter ablation. However, in patients with severe leaflets tethering, the results favored surgical over catheter.

Juvenile lodging in barley: a yield-depressing phenomenon

1975 ◽  
Vol 26 (2) ◽  
pp. 231 ◽  
Author(s):  
CJ Gardener ◽  
AJ Rathjen
Keyword(s):  
Yield Components ◽  
Stem Elongation ◽  
South Australia ◽  
Leaf Length ◽  
High Fertility ◽  
Nitrogen Application ◽  
Area Index ◽  
Wire Grid ◽  
Plant Densities ◽  
The Relationship

A field experiment was conducted in South Australia to examine the relationship between juvenile lodging (lodging prior to stem elongation) and ear production in barley. Two levels of nitrogen application and six treatments were used either to prevent or increase juvenile lodging in two cultivars. Applications of 2-chloroethyltrimethylammonium chloride (CCC) at the fourth and sixth leaf stages shortened both pseudostems and leaves, prevented juvenile lodging, and increased the number of ears and the grain yield. CCC did not reduce the mature plant height, but did increase the incidence of Rhynchosporium secalis in one cultivar. Ear numbers were marginally increased by supporting the crop with a wire grid or by defoliating the crop to 20 cm at the fifth leaf stage, but this advantage was nullified by a compensating decrease in the other yield components. Removing up to 4 units of leaf area index at this stage did not reduce the yield. Deliberately lodging the crop before stem elongation had little effect since most of the controls lodged naturally. All treatments became erect during stem elongation, and the plants did not lodge again before maturity. It is concluded that short pseudostems, a maximum leaf length under 30 cm, fewer leaves per culm and a shorter period prior to stem elongation are characters which will reduce the juvenile lodging in barley which occurs when the crop is sown early at high plant densities or is grown at high fertility levels.

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