Effect of defoliation frequency on an irrigated perennial pasture in northern Victoria 2*Part 1, Aust. J. Agric. Res., 1997, 48, 811 - 17.. Individual plant morphology

1997 ◽  
Vol 48 (6) ◽  
pp. 819 ◽  
Author(s):  
A. R. Lawson ◽  
P. W. G. Sale ◽  
K. B. Kelly
Keyword(s):  
Perennial Ryegrass ◽  
White Clover ◽  
High Rate ◽  
Axillary Bud ◽  
Late Winter ◽  
Individual Plant ◽  
Appearance Rate ◽  
Leaf Appearance Rate ◽  
Defoliation Frequency ◽  
Leaf Appearance

The effect of 5 winter and 2 post-winter defoliation frequencies on the morphology of medium-leafed and large-leafed white clover and perennial ryegrass plants in an irrigated perennial pasture in northern Victoria was investigated. Measurements included leaf appearance rates, axillary bud development and survival, stolon elongation and survival, and tiller production and survival. White clover leaf appearance rate was affected little by either defoliation frequency or cultivar, ranging from 0·4 leaves/week in July to 1·1 leaves/week in February. In contrast, perennial ryegrass leaf appearance rate in the same period ranged from 0·35 to 0·7 leaves/week. Axillary bud production on clover stolons was highest in winter and spring and lowest through summer, and was usually greater in the medium-leafed than in the large-leafed cultivars. When the swards were not defoliated through winter, the rate of bud production was reduced in late winter; this was followed by a high rate of bud production in early spring, resulting in little treatment difference in the number of buds per stolon by mid spring. Bud survival was greater when initiated in winter than in summer. The rate of stolon death in spring was higher in the swards not defoliated during winter and higher in the large-leafed than in the medium-leafed cultivar. These effects were associated with the stolon elongation rate in late winter; the medium-leafed cultivar was unaffected by defoliation frequency, whereas in the large-leafed cultivars the rate of stolon elongation increased as the defoliation interval lengthened and canopy shading increased. Perennial ryegrass tiller production was greater with frequent than infrequent winter or post-winter defoliation, but never exceeded 1·2 daughter tillers/tiller, with 44% of the reproductive tillers failing to replace themselves. The low leaf appearance rate and tiller production of the perennial ryegrass may contribute to its poor competitiveness and persistence in this environment.

Leaf tissue remaining after cutting and regrowth in perennial ryegrass

1974 ◽  
Vol 82 (1) ◽  
pp. 165-172 ◽  
Author(s):  
Alison Davies
Keyword(s):  
Growth Rate ◽  
Perennial Ryegrass ◽  
Plant Material ◽  
Shoot Growth ◽  
Leaf Tissue ◽  
Relative Growth ◽  
Appearance Rate ◽  
Leaf Appearance Rate ◽  
Leaf Appearance ◽  
Increased Activity

SUMMARYWhen one or two leaves were removed out of the three or sometimes four present on each tiller of five genotypes of perennial ryegrass grown in nutrient solution, it was found that the relative growth rate (RGR) was not much less than that of untreated plants. The removal of lower leaves had no effect on RGR. Removal of all leaf blades depressed RGR. It is suggested that the results obtained indicate that the plant has the capacity to compensate for loss of leaf tissue by increased activity in the remaining leaves. Leaf appearance rate and tiller production were found to be the attributes most sensitive to the defoliation treatments imposed, and the degree to which leaf appearance rates were affected by defoliation was found to be a good indicator of the regrowth capacity of the different genotypes. Evidence was obtained linking high regrowth potential with high relative increases in the proportion of plant material allocated to new shoot growth.

scholarly journals Attributes related to seasonal herbage growth in white clover

2009 ◽  
Vol 66 (1) ◽  
pp. 20-27 ◽  
Author(s):  
Omar Scheneiter ◽  
Beatriz Rosso ◽  
Mauro Corletto
Keyword(s):  
White Clover ◽  
Dry Matter ◽  
Leaf Size ◽  
Growth Patterns ◽  
Dry Matter Accumulation ◽  
Seasonal Growth ◽  
Local Populations ◽  
Appearance Rate ◽  
Leaf Appearance Rate ◽  
Leaf Appearance

When breeding temperate forage species is investigated, some attributes such as herbage accumulation and seasonal growth patterns have to be considered. To modify some of these traits, knowledge of the detailed process might be useful. In order to evaluate seasonal growth of contrasting white clover populations an experiment was carried out. Treatments were five cultivars and three local populations collected in Argentina. Weekly measures were taken during each season to calculate leaf appearance and flower appearance rates, stolon growing rate and dry matter (DM) net accumulation. Different germplasm of this species have different mechanisms for DM accumulation. Leaf size, more than leaf appearance rate, was the variable with most differences among germplasm and mostly related to dry matter accumulation. During spring and summer, inflorescences production had important effects on growing stolon rate, and differences among germplasm were evident. Some local populations showed favourable attributes that could be useful for breeding.

scholarly journals Effect of summer moisture deficit on growth of five white clover cultivars

1995 ◽  
pp. 73-76
Author(s):  
X. Wang ◽  
J.R. Caradus ◽  
A.C.P. Chu
Keyword(s):  
Drought Tolerance ◽  
Soil Water ◽  
Water Deficit ◽  
White Clover ◽  
Growth Parameters ◽  
Water Deficit Stress ◽  
Appearance Rate ◽  
Leaf Appearance Rate ◽  
Leaf Appearance ◽  
Response To Water

Growth of five New Zealand white clover cultivars, Grasslands Kopu, Grasslands Pitau, Grasslands Huia, Grasslands Tahora and Prop, was quantified at differing soil moistures in both the field and the glasshouse. The first trial employed a rain-out shelter to impose two soil water treatments. While there were no differences among the cultivars for leaf water status, there were differences in plant growth parameters in response to water deficit. Water deficit did not significantly affect leaf appearance rate of Prop, although there was a 2- fold difference. There was, however, a 3.5- to 6-fold decrease in leaf appearance rate due to water deficit for the other cultivars. Water deficit did not significantly reduce leaf size for the medium- and small-leaved cultivars Huia, Tahora and Prop; but was halved for Kopu and Pitau. Prop had the lowest stolon growing point survival under water deficit and Pitau the highest. Leaf longevity was greatest for Prop and least for Pitau when grown under optimum water supply, but this pattern was reversed under water deficit stress. The second trial, a pot trial, investigated the response of the same five cultivars to three different soil water regimes (control, mild and severe stress). The growth parameters of smaller-leaved cultivars, particularly Prop, were less affected than the large-leaved cultivars in their response to water deficit. These short-term trials showed that some small-leaved cultivars of white clover have an ability to adjust their growth and habit in response to water deficit more effectively than large-leaved cultivars. Prop was able to maintain a higher leaf appearance rate than other cultivars when grown under water deficit. However, while exhibiting this drought tolerance adaptation the low stolon growing point survival of Prop could result in a poor recovery from drought. Small-leaved cultivars are rarely taprooted, a characteristic of plants adapted to more prolonged drought conditions. The probability of combining these characteristics and improving summer production of white clover through identification of drought tolerance is discussed. Keywords: cultivars, drought, Trifolium repens, variation, water deficit

Defoliation frequency and cultivar effects on the storage and utilisation of stolon and root reserves in white clover

2000 ◽  
Vol 51 (8) ◽  
pp. 1039 ◽  
Author(s):  
A. R. Lawson ◽  
K. B. Kelly ◽  
P. W. G. Sale
Keyword(s):  
White Clover ◽  
Plant Size ◽  
Water Soluble ◽  
Cultivar Differences ◽  
Soluble Carbohydrate ◽  
Leaf Production ◽  
Plant Weight ◽  
Stolon Length ◽  
Defoliation Frequency ◽  
Leaf Appearance

The effects of defoliation frequency (2 or 6 defoliations over a 91-day period) on the reserve status and growth rate of 2 white clover cultivars, cvv. Irrigation (medium-leafed) and Haifa (large-leafed), were examined over the final 42 days of the defoliation treatments. The clover plants consisted of single stolons growing in a sand/scoria mix in an unheated glasshouse, and were fertilised weekly with a solution containing essential nutrients excluding nitrogen. More frequent defoliation reduced the leaf appearance rate, stolon elongation rate, and plant size, and increased stolon death, with all of these effects being less pronounced in Irrigation than in Haifa (18% v. 30%, 60% v. 80%, and 23% v 34%, respectively, for leaf appearance rates, stolon elongation rates, and the proportion of stolon length that died). With infrequent defoliation, the combined utilisation of starch and water-soluble carbohydrate (WSC) reserves in the first 14 days after defoliation was equivalent to 15% of the plant weight at defoliation, and to 95% of the new leaf produced during that period. Frequent defoliation reduced the reserve content and remobilisation less in Irrigation than in Haifa, with the combined mass of remobilised starch and WSC over the first 14 days after defoliation being 2.9% and 2.0% of the plant weight at defoliation, and 29% and 19% of leaf production over that period, for Irrigation and Haifa, respectively. The greater reserve mobilisation in Irrigation than in Haifa plants under frequent defoliation probably contributed to their higher growth rates and reduced stolon death. These cultivar differences with frequent defoliation suggest that Irrigation is more suited to frequent defoliation than Haifa.

scholarly journals Morphogenetic characteristics of three Brachiaria brizantha cultivars submitted to nitrogen fertilization

2013 ◽  
Vol 85 (1) ◽  
pp. 371-377 ◽  
Author(s):  
Marcos F Silva ◽  
Edson M. V Porto ◽  
Dorismar D Alves ◽  
Cláudio M.T Vitor ◽  
Ignacio Aspiazú
Keyword(s):  
Nitrogen Fertilization ◽  
Leaf Blade ◽  
Elongation Rate ◽  
Leaf Elongation ◽  
Brachiaria Brizantha ◽  
Nitrogen Levels ◽  
Appearance Rate ◽  
Leaf Elongation Rate ◽  
Leaf Appearance Rate ◽  
Leaf Appearance

This study aims to evaluate the morphogenetic characteristics of three cultivars of Brachiaria brizantha subjected to nitrogen fertilization. The design was a randomized block in factorial arrangement 4x3; three cultivars of B. brizantha - Marandu, Piatã, Xaraés and four nitrogen levels - 0, 80, 160 and 240 kg/ha, with three replications. The experimental units consisted of plastic pots filled with 5 dm3 of soil. Thereupon the establishment fertilization, varieties were sowed directly in the pots, leaving, after thinning, five plants per pot. Forty-five days after planting, it was done a standardization cut at 10 cm tall. Nitrogen levels were distributed according to the treatments, divided in three applications. The morphogenetic characteristics were evaluated in three tillers per sampling unit and data were submitted to analysis of variance and regression. For all evaluated characteristics there was no interaction between factors cultivar and nitrogen levels, verifying only the effects of nitrogen on the variables leaf appearance rate and phyllochron. The dose 240 kg/ha of N corresponds to the greater leaf appearance rate. Cultivar Marandu shows the higher leaf blade: pseudostem and ratio of leaf elongation rate and elongation pseudostem, which favors higher forage quality.

scholarly journals Contrasting phenotypes emerging from stable rules: A model based on self-regulated control loops captures the dynamics of shoot extension in contrasting maize phenotypes

2019 ◽  
Vol 126 (4) ◽  
pp. 615-633 ◽  
Author(s):  
T Vidal ◽  
B Andrieu
Keyword(s):  
Initial Conditions ◽  
Growth Conditions ◽  
Internal Variables ◽  
Model Parameters ◽  
Crop Models ◽  
Control Loops ◽  
Modelling Framework ◽  
Appearance Rate ◽  
Leaf Appearance Rate ◽  
Leaf Appearance

Abstract Background and Aims The dynamics of plant architecture is a central aspect of plant and crop models. Most models assume that whole shoot development is orchestrated by the leaf appearance rate, which follows a thermal time schedule. However, leaf appearance actually results from leaf extension and taking it as an input hampers our ability to understand shoot construction. The objective of the present study was to assess a modelling framework for grasses, in which the emergence of leaves and other organs is explicitly calculated as a result of their extension. Methods The approach builds on a previous model, which uses a set of rules co-ordinating the timing of development within and between phytomers. We first assessed rule validity for four experimental datasets, including different cultivars, planting densities and environments, and accordingly revised the equations driving the extension of the upper leaves and of internodes. We then fitted model parameters for each dataset and evaluated the ability to simulate the measured phenotypes across time. Finally, we carried out a sensitivity analysis to identify the parameters that had the greatest impact and to investigate model behaviour. Key Results The modified version of the model simulated correctly the contrasting maize phenotypes. Co-ordination rules accounted for the observations in all studied cultivars. Factors with major impact on model output included extension rates, the time of tassel initiation and initial conditions. A large diversity of phenotypes could be simulated. Conclusions This work provides direct experimental evidence for co-ordination rules and illustrates the capacity of the model to represent contrasting phenotypes. These rules play an important role in patterning shoot architecture and some of them need to be assessed further, considering contrasting growth conditions. To make the model more predictive, several parameters could be considered in the future as internal variables driven by plant status.

The effect of grazing severity and fertiliser application during winter on herbage regrowth and quality of perennial ryegrass (Lolium perenne L.)

2007 ◽  
Vol 47 (7) ◽  
pp. 825 ◽  
Author(s):  
J. M. Lee ◽  
D. J. Donaghy ◽  
J. R. Roche
Keyword(s):  
Water Soluble ◽  
Soluble Carbohydrate ◽  
Initial Water ◽  
The Third ◽  
Appearance Rate ◽  
Leaf Appearance Rate ◽  
N Treatment ◽  
Fertiliser Application ◽  
Tiller Density ◽  
Leaf Appearance

The objective of the current study was to quantify the effects of greater herbage residuals in winter on leaf appearance rate, herbage accumulation and quality, and plant energy reserves, as well as quantifying the effects nitrogen (N), or phosphorus (P) and sulfur (S) fertilisers had on the above measures. Ten pasture areas were grazed to different residual masses (1260 ± 101 and 1868 ± 139 kg DM/ha, Severe and Lax, respectively) over five consecutive days by dry dairy cows. Two randomly located subplots within each grazing area were fertilised with either 50 kg N/ha (N treatment) or 50 kg N/ha, 31 kg S/ha plus 26 kg P/ha (N + S + P treatment) on the day immediately following defoliation (day 1), and were compared with a control subplot. Neither growth rate (15.1 ± 8.1 kg DM/ha.day), nor leaf appearance rate (15.1 ± 0.3 days per new leaf) differed between treatments. As a result, herbage accumulated over the 49 days of regrowth was similar across grazing treatments and averaged 726 kg DM/ha. Application of N + S + P tended to increase total herbage accumulated during regrowth compared with either the control or N treatment subplots (860 v. 675 and 643 kg DM/ha, respectively), likely a result of increased tiller density. Swards defoliated more severely had lower initial water-soluble carbohydrate (WSC) concentrations compared with swards laxly defoliated, but this difference had disappeared before appearance of the third new leaf. Herbage quality improved in the Severe treatment subplots after emergence of the third new leaf, with higher digestibility, greater WSC and metabolisable energy, and lower fibre content than in laxly grazed subplots.

Effects of photoperiod on leaf appearance rate and leaf dimensions in winter and spring wheats

1996 ◽  
Vol 76 (1) ◽  
pp. 43-50 ◽  
Author(s):  
S. Pararajasingham ◽  
L. A. Hunt
Keyword(s):  
Leaf Area ◽  
Leaf Length ◽  
Leaf Number ◽  
Dry Matter Accumulation ◽  
Flag Leaves ◽  
Appearance Rate ◽  
Rate Of Increase ◽  
Leaf Appearance Rate ◽  
Leaf Dimensions ◽  
Leaf Appearance

Research on genotypic variation in the response of leaf-area production and expansion to photoperiod in wheat is limited. Growth-cabinet experiments using four spring and four winter wheat (Triticum aestivum L.) cultivars and four photoperiod (8, 12, 16 and 20 h) treatments were thus conducted with the objective of investigating the effect of photoperiod on leaf appearance rate and leaf dimensions. Winter wheats were grown without vernalization. In the spring wheats, flag leaves and spikes were formed under the longer photoperiod (16 and 20 h) treatments, and leaf number increased linearly with time. At the shorter photoperiods, flag leaves and spikes appeared in some cultivars only, and the rate of increase in leaf number decreased in the later stages. Final leaf number was greater at shorter photoperiods. In the winter cultivars, more leaves appeared than in the spring types under the longer photoperiods. For leaves 3–7, leaf number was a linear function of time, with photoperiod and cultivar effects. For one of four spring cultivars, the rate of leaf appearance was greater at 8 h than at 20 h, whereas for three of the winter cultivars the reverse was true. Leaf length increased with leaf number up to at least nodes 5–6 for both spring and winter types but decreased for the later-formed leaves for the spring but not for the winter types. Leaves of plants grown under photoperiods longer than 8 h were longer and broader than those grown under the short photoperiod, and the effect was more pronounced in winter than in spring cultivars. Such genotypic differences in the direct effects of photoperiod on leaf dimensions, which could influence the rates of leaf-area production and dry-matter accumulation under field conditions, emphasize that future studies should incorporate genotypes from different eco-physiological regions and that simulation models of wheat growth and development may need to account for variability in the control of vegetative growth. Key words: Wheat, photoperiod, leaf appearance rate, leaf length, leaf width

The effect of cutting frequency and root segregation on the yield from perennial ryegrass-white clover associations

1967 ◽  
Vol 69 (3) ◽  
pp. 391-397 ◽  
Author(s):  
B. F. Bland
Keyword(s):  
Perennial Ryegrass ◽  
White Clover ◽  
Dry Matter ◽  
The Third ◽  
Nitrogen Yield ◽  
Cutting Frequency ◽  
Nitrogen Yields ◽  
Below Ground ◽  
The Mean ◽  
Defoliation Frequency

1. Dry-matter and nitrogen yields were recorded from perennial ryegrass-white clover associations which were defoliated 2, 4 or 6 times a year during the period 1963 to 1965.2. The average yearly output of dry matter was approximately 4000, 7000 and 6000 lb/acre for 1963, 1964 and 1965 respectively. Nitrogen harvested amounted to 132, 184 and 179 lb N/acre.3. The mean annual dry-matter yields from 2, 4 and 6 defoliations were 5300, 6100 and 6000 lb/acre and the corresponding figures for nitrogen yields were 112, 166 and 217 lb N/acre.4. Both segregation of the species below ground and increasing the defoliation frequency were responsible for higher contributions towards drymatter and nitrogen yield from the clover component.5. A comparison of the nitrogen yields between the plots with species segregated rather than integrated below ground suggests that the effects of underground nitrogen transference from 30–31 lb N/acre could first be demonstrated in the spring of the third year.

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