scholarly journals (80) Calculating Base Temperature and Leaf Appearance Rate for Sweet Viburnum

HortScience ◽  
2005 ◽  
Vol 40 (4) ◽  
pp. 1040D-1041
Author(s):  
Gisele Schoene ◽  
Thomas Yeager ◽  
Joe Ritchie
Keyword(s):  
Linear Regression ◽  
Leaf Area ◽  
Minimum Temperature ◽  
Thermal Time ◽  
Base Temperature ◽  
Regression Equations ◽  
Appearance Rate ◽  
Leaf Appearance Rate ◽  
Leaf Appearance ◽  
Sweet Viburnum

In crop models, it is important to determine the leaf area, because the amount of light interception by leaves influences two very important processes in the plant: photosynthesis and evaporation. Leaf area is dependent on leaf appearance and expansion rates. Leaf appearance rate is driven mainly by temperature. Although the influence of temperature on leaf area development is well known for several agronomic crops, there is no information for woody ornamentals. An experiment was conducted to study the relationship between temperature and leaf appearance of container-grown sweet viburnum. Plants were grown in field conditions in Gainesville, Fla., during two growing periods (Apr. to Aug. 2004 and Aug. 2004 to Jan. 2005). Daily maximum and minimum temperature and leaf appearance were recorded. Linear regression equations were fitted to data and maximum and minimum temperature and leaf appearance were recorded. Linear regression equations were fitted to data and base temperature was assumed to be 8 °C. Thermal time (°C d) was calculated as daily average maximum and minimum air temperature minus the base temperature and was regressed against leaf number. The sum of accumulated thermal time was found to be linearly correlated with leaf number. Phyllochron, which is the thermal time between the appearances of successive leaves, was estimated 51 °C per day. The information presented in this study will be useful in modeling water use of sweet viburnum in response to environmental conditions.

scholarly journals Leaf Appearance Rate of Summer Squash as a Function of Thermal Time

HortScience ◽  
1995 ◽  
Vol 30 (4) ◽  
pp. 810B-810
Author(s):  
D. Scott NeSmith
Keyword(s):  
Linear Functions ◽  
Thermal Time ◽  
Leaf Number ◽  
Base Temperature ◽  
Planting Dates ◽  
Data Set ◽  
Appearance Rate ◽  
Summer Squash ◽  
Leaf Appearance Rate ◽  
Leaf Appearance

Different planting dates were used to study the influence of thermal time on leaf appearance rate of four summer squash (Cucurbita pepo L.) cultivars. During the first year (1991), thermal time or growing degree days (GDD) were calculated using a base temperature of 8C and a ceiling temperature of 32C for several planting dates. Leaf numbers per plant were determined every 2 to 3 days. Leaves that were beginning to unfold with a width of 2 cm or greater were included in the counts. The relationship between leaf number and GDD was established from the initial data set, and data from subsequent years were used for model validation. Results indicated that single equation could be used to predict leaf appearance of all four cultivars in response to thermal time. The response of leaf appearance to GDD was curvilinear, with a lag over the first five leaves. After five leaves, the increase in leaf number per plant was linear with increased GDD. Segmented regression with two linear functions also fit the data well. With this approach, leaf 5 was the node, and a separate linear function was used to predict the leaf number below five leaves and above five leaves. The results of this model should prove to be useful in developing a model of leaf area development, and eventually a crop growth model, for summer squash.

scholarly journals Estimating leaf appearance rate and phyllochron in safflower (Carthamus tinctorius L.)

2005 ◽  
Vol 35 (6) ◽  
pp. 1448-1450 ◽  
Author(s):  
Nereu Augusto Streck ◽  
Rogério Antonio Bellé ◽  
Edileusa Kersting da Rocha ◽  
Mariângela Schuh
Keyword(s):  
Linear Regression ◽  
Block Design ◽  
Carthamus Tinctorius ◽  
Time Interval ◽  
Angular Coefficient ◽  
Base Temperature ◽  
Appearance Rate ◽  
Leaf Appearance Rate ◽  
Leaf Appearance ◽  
Santa Maria

Safflower may be an interesting option for the flower market, either as fresh or dried cut flower. Estimating the leaf appearance rate and the phyllochron (the time interval between the appearance of successive leaves) is important for calculating the number of emerged leaves (NL) on the plant, which is an excellent measure of plant development. The objective of this study was to estimate the leaf appearance rate and the phyllochron in safflower (Carthamus tinctorius L.). An experiment was conducted in Santa Maria, RS, Brazil, inside an 8 x 15m plastic greenhouse. Sowing was on 03 October 2003 and emergence was on 08 October 2003. The experimental design was a randomized complete block design with three replications. The main stem NL was measured twice a week from 24 October 2003 to 15 November 2003 in four plants per replication. Daily growing degree days above a base temperature (5°C) and accumulated thermal time (TT) were calculated. The NL was linearly regressed against TT. The angular coefficient of the linear regression is the LAR (leaves/ °C day) and the phyllochron (°C days/leaf) was estimated by the inverse of the angular coefficient of the linear regression. The LAR was 0.0467 ± 0.0203 leaves/ °C day and the phyllochron was 25.5 ± 14.6°C days/leaf.

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

scholarly journals 591 MelonMan: A Simple Phenology Model of Muskmelon Development

HortScience ◽  
2000 ◽  
Vol 35 (3) ◽  
pp. 498D-498
Author(s):  
J.T. Baker ◽  
D.I. Leskovar ◽  
V.R. Reddy ◽  
F.J. Dainello
Keyword(s):  
Threshold Temperature ◽  
Time Interval ◽  
Base Temperature ◽  
Node Number ◽  
Appearance Rate ◽  
Leaf Appearance Rate ◽  
Final Yield ◽  
Phenology Model ◽  
Leaf Appearance ◽  
Cardinal Temperatures

A temperature experiment with two cultivars of muskmelon (`Gold Rush' and `Mission') was conducted in growth chambers to determine how main vine leaf appearance rates responded to temperature. We identified three cardinal temperatures for leaf appearance rate: the base temperature (10 °C) at which leaf appearance rate was zero, an optimum temperature where leaf appearance rate was at a maximum (34 °C) and an upper threshold temperature (45 °C) where leaf appearance rate returned to zero. Using these three cardinal temperatures, we constructed a simplified thermal unit accumulator for hourly measurements of air temperature. Main vine plastochron interval (PI), thermal time to harvest and final yield was determined for three cultivars of muskmelon (`Explorer', `Goldrush', and `Mission') grown in the field over six transplanting dates. The PI was calculated for each cultivar-transplanting date combination as the reciprocal of the slope of main vine node number vs. accumulated hourly thermal units (Tu). The PI was significantly affected by both cultivar and transplanting date. Final yield was sharply reduced in the last two planting dates, presumably due to high temperature stresses impacting reproductive development. As air temperatures warmed during the field experiment, the time interval from transplanting to 10% final harvest were reduced by between 21 to 28 days among the three cultivars and the first four transplanting dates. Our goal was to construct a simple muskmelon phenology model that could be run with easily obtainable weather station data and used by growers to quantify phenological development and aid in projecting harvest dates. We also wanted to test whether main vine node number was a useful description of vegetative development for muskmelon.

Temperature response function for leaf appearance rate in wheat and corn

1999 ◽  
Vol 79 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Y. W. Jame ◽  
H. W. Cutforth ◽  
J. T. Ritchie
Keyword(s):  
Response Function ◽  
Plant Development ◽  
Full Range ◽  
Beta Function ◽  
Temperature Response ◽  
Base Temperature ◽  
Appearance Rate ◽  
Leaf Appearance Rate ◽  
Leaf Appearance ◽  
Rate Of Leaf Appearance

The ability to predict leaf appearance would enhance our capability of modeling plant development and the rate of leaf area expansion. Many crop models use the constant thermal time for successive leaf tip appearance (which is often termed a phyllochron) as one model parameter to predict total number of leaves and date of anthesis. However, many researchers have found that phyllochron is not constant, but is dependent upon environment. The problem could be related to the simplified assumption that the daily leaf appearance rate is linearly related to temperature (and hence, phyllochron is constant, independent of temperature). In reality, the temperature response function for the development of a biological system is nonlinear. Thus, we fitted daily leaf appearance rate–temperature relationships obtained from growth room studies for both wheat (Triticum aestivum) and corn (Zea mays L.) to a nonlinear beta function with 0 °C as the base temperature and 42 °C as the upper critical temperature. The function described the relationships very well over the full range of temperatures for plant development. Other variables that are used to describe the duration and rate of leaf appearance, such as calendar days, phyllochron, and thermal rate of leaf appearance, are related to the daily leaf appearance rate, eliminating the need to develop various mathematical functions to independently describe the response of these variables to temperature. Because of the nonlinear nature of the temperature response function, we demonstrated that more accurate determinations of daily leaf appearance rates can be achieved by calculating rates over relatively short periods (i.e., hourly) and summing these to get the mean daily rate. Many environmental factors other than temperature also affect leaf appearance rate. However, once the proper temperature response function for leaf appearance rate is determined, it is much easier to determine when and how other factors are involved to modify the leaf appearance rate under a given environment.Key words: Temperature, leaf appearance rate, phyllochron, wheat, corn, beta function

Rate of leaf appearance in sugarcane, including a comparison of a range of varieties

1998 ◽  
Vol 25 (7) ◽  
pp. 829 ◽  
Author(s):  
G. D. Bonnett
Keyword(s):  
Power Law ◽  
Large Change ◽  
Thermal Time ◽  
Linear Polynomial ◽  
Appearance Rate ◽  
Biological Explanation ◽  
Leaf Appearance Rate ◽  
Number Of Leaves ◽  
Leaf Appearance ◽  
Rate Of Leaf Appearance

Leaf appearance rate is a major determinant of canopy establishment, radiation interception and therefore yield. The effect of genotype on leaf appearance rate in sugarcane is largely unknown. Leaf appearance rate was recorded for the mainstems of pot grown sugarcane plants of nine commercial varieties, over 10 months in Townsville, Australia. Bi-phasic linear, polynomial and power-law models were fitted to data describing leaf appearance with thermal time. The bi-phasic model (previously used for sugarcane) had a single large change in phyllochron for which no biological explanation is apparent. Polynomials were less likely to predict leaf appearance accurately outside the range of fitted data. The power-law model gave a continuously increasing thermal time between the appearance of successive leaves (phyllochron) and was used to compare the varieties. An increasing phyllochron for the first 15 leaves could be explained, in part, by the increasing length of lamina each successive leaf had to grow through. However, an explanation for an increasing phyllochron throughout ontogeny has yet to be found. The rate of leaf appearance was significantly different between the varieties. After 5000˚Cd the number of leaves predicted to have appeared ranged from 35 to 46. These variety specific parameters make an important contribution to describing how different varieties produce leaf area.

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.

Temperature and leaf area expansion of sugarcane: integration of controlled-environment, field and model studies

1998 ◽  
Vol 25 (7) ◽  
pp. 819 ◽  
Author(s):  
Michael J. Robertson ◽  
Graham D. Bonnett ◽  
R. Michael Hughes ◽  
Russell C. Muchow ◽  
James A. Campbell
Keyword(s):  
Leaf Area ◽  
Leaf Senescence ◽  
Leaf Size ◽  
Field Studies ◽  
Growth Conditions ◽  
Thermal Time ◽  
Leaf Position ◽  
Potential Growth ◽  
Leaf Stage ◽  
Leaf Appearance

Canopy development is an important determinant of crop radiation interception, and in the absence of stress is mainly driven by temperature. The responses to temperature of the component processes of canopy dynamics in sugarcane: leaf appearance, leaf size, tillering, and leaf senescence, were analysed for the commercial Australian cultivar, Q117. Data were derived under optimal growth conditions from controlled environments, and from irrigated field studies in subtropical and tropical locations. Regression of number of fully-expanded leaves in field-grown plants against cumulative thermal time revealed that the thermal time between the appearance of successive leaves increased as a function of leaf number, such that leaf 1 required 86˚Cd and leaf 40 required 160˚Cd. At any moment, on average there were 3.7 leaves still expanding on the stalks. Functions describing leaf appearance gave acceptable prediction of the time course of leaf appearance taken from independent datasets of field-grown plant and ratoon crops. Leaf size increased with leaf position, with the largest leaves observed at approximately leaf 17 and above. Combining functions describing leaf appearance and leaf size as a function of leaf position allowed estimation of leaf area index (LAI) of main stems in plant and ratoon crops in subtropical and tropical environments. Tiller LAI, derived by difference, accounted for 60–90% of total LAI at the 5- leaf stage, declining to 20–50% at the 15-leaf stage. Plant and ratoon crops were similar in terms of the amount and proportion of tiller LAI. Combining data from all field studies indicated under potential growth conditions, leaf senescence was closely related to leaf production. The functions derived in this study give a basis for simulating canopy dynamics under potential growth conditions in sugarcane, though the extent of genotypic variation for the key parameters and their modification by stress remains to be assessed.

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.

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.

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