The influence of defoliation on vegetation growth in swards of three strains of subterranean clover

1976 ◽  
Vol 27 (2) ◽  
pp. 197 ◽  
Author(s):  
RC Rossiter
Keyword(s):  
Solar Radiation ◽  
Leaf Area ◽  
Plant Density ◽  
Subterranean Clover ◽  
Experimental Period ◽  
Daily Maximum ◽  
Area Index ◽  
Vegetation Growth ◽  
Original Plant ◽  
Dead Material

Three defoliation regimes—uncut, defoliated every 14 days at 1.5 cm, and defoliated every three or four days (alternately) at 1.5 cm—were imposed on dense swards of Blackwood, Dwalganup and Daliak subterranean clover. The swards were grown in boxes, out of doors, at Perth from 1 June to 29 August. Mean daily solar radiation ranged from c. 1050 to 1450 J/cm2/day, and the average daily maximum and minimum temperatures were about 17° and 8.5°C respectively. The main finding was that defoliated swards yielded considerably less than uncut swards; averaging strains (and the two defoliated treatments) the decrease was c. 20% at day 33 and more than 40% at day 89. The lower yields of defoliated swards were associated with lower leaf area indices. During the first half of the experimental period, defoliation depressed growth in Blackwood more than in Dwalganup and Daliak. Uncut swards maintained the original plant density (28 plants/dm2), though some dead material was recorded in harvests at day 61 and (more particularly) day 89. Leaf area index exceeded 9 at day 89, with no clear optimum. Defoliated swards—especially those cut every three or four days—had more but smaller leaves, and higher branch numbers than uncut swards. In some respects these results conflict with those of previous reports, and explanations are proposed for apparent inconsistencies, mainly in terms of the temperature conditions.

The interrelationship of solar radiation and leaf area index in determining the rate of dry matter production of swards of subterranean clover (Trifolium subterraneum L.)

1963 ◽  
Vol 14 (1) ◽  
pp. 20 ◽  
Author(s):  
JN Black
Keyword(s):  
Growth Rate ◽  
Solar Radiation ◽  
Leaf Area Index ◽  
Leaf Area ◽  
Growth Rates ◽  
Subterranean Clover ◽  
Crop Growth ◽  
Area Index ◽  
Specific Level ◽  
Crop Growth Rate

The relationship of crop growth rate, leaf area index, and solar radiation has been examined for swards of subterranean clover, of the variety Bacchus Marsh. Leaf area index was varied by growing swards at eight densities of sowing, and radiation varied by two levels of shading, in addition to full daylight; the whole experiment was done three times—in summer, early winter, and spring—at the Waite Agricultural Research Institute, Adelaide. Crop growth rate was measured as the difference between the dry weights of the swards on two harvest occasions, and was calculated from smoothed values obtained by fitting an appropriate equation to the yield : density relationship. Thus a set of nine curves were available, each showing the response of growth rate to varying leaf area index at a specific level of radiation. These nine curves formed a consistent series, the growth rate rising with leaf area index until a maximal value was reached at the "optimum leaf area index", thereafter falling. At low levels of radiation, growth rate fell to zero at high leaf area indices. Both the maximal growth rate and the optimum leaf area index increased with radiation, and an analysis of the data indicated that these growth indices were dependent on radiation, the effect of temperature being negligible. A generalized series of curves was calculated by extrapolation, so that crop growth rates can be derived for any combination of leaf area index and radiation. A comparison of maximal crop growth rates and percentage utilization of light energy of subterranean clover and other crops suggests that this clover is relatively inefficient in integrating its environment.

scholarly journals The impact of location, row direction, plant density and rootstock on the sunburn damage of apple cultivars

2005 ◽  
Vol 11 (1) ◽  
Author(s):  
J. Racskó ◽  
J. Nagy ◽  
Z. Szabó ◽  
M. Major ◽  
J. Nyéki
Keyword(s):  
Solar Radiation ◽  
Leaf Area ◽  
Fruit Quality ◽  
Plant Density ◽  
Fruit Size ◽  
Quality Parameters ◽  
Apple Seedling ◽  
Apple Cultivars ◽  
The Impact ◽  
Crab Apple

The effect of row direction (N-S, E-W), plant density (conventional and intensive) and rootstock (M9, MM106 and crab apple) on the sensitivity of 41 apple cultivars to sunburn injury was studied at 6 locations (Derecske, Kálmánáaza, Nagykutas, Nagylapos, Siófok, Tornyospálca). During the observations the cultivars had rootstock-specific properties in respect of sunburn-susceptibility. Accordingly, the injury was decreased in the order: M9, MM106 and seedling rootstocks. The differences in sensitivity depend on the canopy of trees, caused finally by the growing vigour of rootstocks. Accordingly, the highest value of sunburn injury was observed on M9 rootstock, because this rootstock has a dwarfing effect upon the scion cultivars. Thus, vegetative area of these trees grow very slowly and the foliage is not enough compact to protect the fruit from solar radiation. The size and density of the foliage increased in the order: M9, MM 106 and crab apple seedling as rootstock. Moreover, relationships were demonstrated between the diameter of upper part of the crown, the leaf area, the number of fruits per tree and the injury of sunburn. Authors categorized the cultivars in respect of values of sunburn incidence: 1. „Not sensitive", II. „Moderately sensitive" and HI. „Strongly sensitive" categories were constituted. Generally, Topaz and Gala cultivars showed low damage (or were free from symptoms), in contrast to this, Golden mutants suffered relatively much. The most sensitive cultivar was Jonica on all the three rootstocks. We searched for relationship between the fruit quality parameters and the frequency of sunburn. Significant correlation was found in the cases of fruit size and the extent of cover-colour. The latter is interpreted with the fact that the best coloured fruits are found on the periphery of crown as a consequence of more intense irradiation.

scholarly journals A Plant Process Economic Model for Weed Management Decisions in Irrigated Onion

1999 ◽  
Vol 124 (1) ◽  
pp. 99-105 ◽  
Author(s):  
Claudio M. Dunan ◽  
Philip Westra ◽  
Frank D. Moore
Keyword(s):  
Leaf Area ◽  
Plant Density ◽  
Light Extinction ◽  
Species Number ◽  
Yield Reduction ◽  
Weed Species ◽  
Early Application ◽  
Area Index ◽  
Variable Approach ◽  
Number Of Leaves

A simulation model was built as a decision aid for management of five weed species in direct seeded irrigated onion (Allium cepa L.). The model uses the state variable approach and simulations are driven by temperature and sunlight as photosynthetically active radiation (PAR). It predicts yield reduction caused by competition for PAR according to the ratio of crop leaf area index (LAI) to weed LAI and respective light extinction coefficients (k). Input variables are plant density by species and average number of leaves by species. Number of leaves per plant is used by the model to provide an estimate of initial leaf area per plant. The model calculates initial species LAIs by multiplying species density times average leaf area per plant. The model accurately describes competitive interactions, taking into account respective plant densities, time of emergence, and time of weed removal. It permits economic evaluation of management factors such as handweeding, chemical weed control, herbicide phytotoxicity due to early application, and control of weed flushes during the season. The model is also used to evaluate mechanisms of plant competition for sunlight. In a sensitivity analysis, onion yield loss was more sensitive to weed PAR interception than to PAR use efficiency, the latter a species-dependent constant in the model.

scholarly journals AVALIAÇÃO DE TRÊS MÉTODOS DE OBTENÇÃO DO ÍNDICE DE ÁREA FOLIAR PARA CULTURA DA SOJA

Nativa ◽  
2019 ◽  
Vol 7 (3) ◽  
pp. 284
Author(s):  
Ana Laura Pereira Souza ◽  
Marcelo Marques Costa ◽  
Darly Geraldo de Sena Junior ◽  
Rogério Borges de Oliveria Paz
Keyword(s):  
Leaf Area ◽  
Plant Density ◽  
Digital Images ◽  
Block Design ◽  
Linear Equations ◽  
Density Variation ◽  
Imaging Method ◽  
Area Index ◽  
Soybean Crop ◽  
Randomized Block Design

O Índice de área foliar (IAF) representa a eficiência na interceptação e utilização da radiação solar pelas plantas. O IAF pode ser obtido de forma direta, determinando-se a área foliar e área ocupada pela planta. Entretanto, métodos indiretos são comumente utilizados para sua estimativa devido a necessidade de praticidade. O objetivo deste trabalho foi avaliar a equivalência das estimativas do IAF obtidas por meio de um ceptômetro, pelo método de discos e utilizando imagens digitais. Para tanto, foi conduzido um experimento com a cultura da soja, no delineamento em blocos casualizados, com variação da densidade de plantas, para comparar os valores de IAF obtidos pelos diferentes métodos aos 34 dias após a semeadura (DAS). A comparação foi feita por meio dos coeficientes de equações lineares ajustadas entre os resultados obtidos. O método do disco e do ceptômetro, apresentaram uma boa equivalência entre seus valores. Entretanto, o método que utiliza imagens superestimou o IAF, não apresentando uma boa equivalência de seus valores aos do método de discos e ao ceptômetro.Palavras-chave: ceptômetro, discos foliares, imagens digitais. EVALUATION OF THREE OBTAINMENT METHODS OF FOLIAR AREA INDEX FOR SOYBEAN CROP ABSTRACT:The leaf area index (LAI) represents the interception efficiency and use of solar radiation by plants. IAF can be obtained directly, determining the leaf area and area occupied by the plant. However, indirect methods are commonly used for their estimation because for practicality. The objective of this work was to evaluate the equivalence of the LAI estimates obtained with a ceptometer, using the disc method and digital images. A experiment was conducted with soybean crop, in a randomized block design with plant density variation to compare the LAI values obtained by the different methods at 34 days after sowing (DAS). The comparison was made through the coefficients of linear equations adjusted between the results obtained. The disc and the ceptometer method presented a good equivalence between their values. However, the imaging method overestimated the LAI, not presenting a good equivalence of its values to those of the disc method and the ceptometer.Keywords: ceptometer, leaf discs, digital images.

scholarly journals Solar radiation use efficiency by soybean under field conditions in the Amazon region

2009 ◽  
Vol 44 (10) ◽  
pp. 1211-1218 ◽  
Author(s):  
Paulo Jorge de Oliveira Ponte de Souza ◽  
Aristides Ribeiro ◽  
Edson José Paulino da Rocha ◽  
José Renato Bouça Farias ◽  
Renata Silva Loureiro ◽  
...  
Keyword(s):  
Solar Radiation ◽  
Leaf Area ◽  
Biomass Production ◽  
Amazon Region ◽  
Field Conditions ◽  
Radiation Use Efficiency ◽  
Area Index ◽  
Natural Field ◽  
Use Efficiency ◽  
Radiation Use

The objective of this work was to evaluate the efficiency of soybean (Glycine max) in intercepting and using solar radiation under natural field conditions, in the Amazon region, Brazil. The meteorological data and the values of soybean growth and leaf area were obtained from an agrometeorological experiment carried out in Paragominas, Pará state, during 2007 and 2008. The radiation use efficiency (RUE) was obtained from the ratio between the above-ground biomass production and the intercepted photosynthetically active radiation (PAR) accumulated to 99 and 95 days after sowing, in 2007 and 2008, respectively. Climatic conditions during the experiment were very distinct, with reduction in rainfall in 2007, which began during the soybean mid-cycle, due to the El Niño phenomenon. An important reduction in the leaf area index and biomass production was observed during 2007. Under natural field conditions in the Amazon region, the values of RUE were 1.46 and 1.99 g MJ-1 PAR in the 2007 and 2008 experiments, respectively. The probable reason for the differences found between these years might be associated to the water restriction in 2007 coupled with the higher air temperature and vapor pressure deficit, and also to the increase in the fraction of diffuse radiation that reached the land surface in 2008.

Responses of Subterranean Clover Communities to Temperature. I. Dry Matter Production and Plant Morphogenesis

1976 ◽  
Vol 3 (4) ◽  
pp. 527 ◽  
Author(s):  
S Fukai ◽  
JH Silsbury
Keyword(s):  
Leaf Area ◽  
Growth Curve ◽  
Dry Matter ◽  
Subterranean Clover ◽  
Experimental Period ◽  
Main Stem ◽  
Logistic Growth ◽  
Similar Time ◽  
Plant Parts ◽  
Leaf Appearance

Subterranean clover communities were grown in temperature-controlled naturally lit glasshouses at 15, 20, 25 and 30�C. Dry matter yield, leaf area and the distribution of dry matter between plant parts were determined at about 14-day intervals for up to 130 days from planting. Leaf appearance, leaf death, leaf number and growth of laterals were observed for individual plants in the community over a similar time period. A logistic growth curve was found for each temperature and crop growth rate calculated from the equation fitted for each growth curve. The optimum temperature for growth was relatively high (20-25°C) when plants were young, but decreased during growth so that after 100 days total dry matter was inversely related to temperature over the range 15-30°C. Both the rate of leaf appearance and the rate of leaf death on the main stem were constant at each temperature during the experimental period and were directly related to temperature. The number of leaves per unit ground area was determined mainly by the rates of leaf appearance and leaf death on the main stem, since the contribution of laterals was small. The proportion of stem and petiole to total dry matter increased, and that of green leaf lamina decreased, with increase in total dry matter. Neither was markedly affected by temperature. An inverse relationship between specific leaf area and temperature resulted in a lower ratio of leaf area to total dry matter at 15°C compared with that at 20, 25 or 30°C.

scholarly journals The effect of light availability on leaf area index, biomass production and plant species composition of park grasslands in Warsaw  

2013 ◽  
Vol 59 (No. 12) ◽  
pp. 543-548 ◽  
Author(s):  
P. Dąbrowski ◽  
B. Pawluśkiewicz ◽  
Kalaji HM ◽  
Baczewska AH
Keyword(s):  
Solar Radiation ◽  
Leaf Area Index ◽  
Leaf Area ◽  
Light Availability ◽  
Vegetation Coverage ◽  
Light Conditions ◽  
Area Index ◽  
Sward Height ◽  
Poa Trivialis ◽  
Leaf Density

How light conditions affect development of park grasslands is a question that has not been satisfactory addressed. The aim of this study was therefore determination of the level to which unfavorable light conditions influence grassy parks area and relationships between parameters which determine state of turf grasses. Researches were conducted in two parks in Warsaw, in various light conditions and included measurement of: leaf density, sward height, leaf area index (LAI), and botanical composition of the communities. The leaf density of shaded areas did not exceed 70%. LAI value varied from 0.5 to 0.9-fold lower than in the areas in half-shade and in sun. The participation of basic lawn species at Skaryszewski Park was higher under shade, while at Łazienki Królewskie was higher in full-sunlight areas. The state of tested grassy areas in limited solar radiation does not satisfy the requirements of recreational and representational functions. The development processes of vegetation coverage were inhibited at the sites of lower solar radiation. LAI was influenced by both leaf coverage and sward height. Agrostis stolonifera and Poa trivialis may be recommended to create grass areas under limited solar radiation.

scholarly journals Comparative Yield, Fiber Quality and Dry Matter Production of Cotton Planted at Various Densities under Equidistant Row Arrangement

Agronomy ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 232
Author(s):  
Nangial Khan ◽  
Fangfang Xing ◽  
Lu Feng ◽  
Zhanbiao Wang ◽  
Minghua Xin ◽  
...  
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Dry Matter ◽  
Plant Density ◽  
Fiber Quality ◽  
Biomass Accumulation ◽  
Lint Yield ◽  
Planting Density ◽  
Area Index ◽  
High Plant Density

The number of cotton plants grown per unit area has recently gained attention due to technology expense, high input, and seed cost. Yield consistency across a series of plant populations is an attractive cost-saving option. Field experiments were conducted to compare biomass accumulation, fiber quality, leaf area index, yield and yield components of cotton planted at various densities (D1, 1.5; D2, 3.3; D3, 5.1; D4, 6.9; D5, 8.7; and D6, 10.5 plants m−2). High planting density (D5) produced 21% and 28% more lint yield as compared to low planting density (D1) during both years, respectively. The highest seed cotton yield (4662 kg/ha) and lint yield (1763 kg/ha) were produced by high plant density (D5) while the further increase in the plant population (D6) decreased the yield. The increase in yield of D5 was due to more biomass accumulation in reproductive organs as compared to other treatments. The highest average (19.2 VA gm m−2 d−1) and maximum (21.8 VM gm m−2 d−1) rates of biomass were accumulated in reproductive structures. High boll load per leaf area and leaf area index were observed in high planting density as compared to low, while high dry matter partitioning was recorded in the lowest planting density as compared to other treatments. Plants with low density had 5% greater fiber length as compared to the highest plant density, while the fiber strength and micronaire value were 10% and 15% greater than the lowest plant density. Conclusively, plant density of 8.7 plants m−2 is a promising option for enhanced yield, biomass, and uniform fiber quality of cotton.

Effect of residual leaf area index on spatial components of Tifton 85 pastures and ingestive behaviour of sheep

2017 ◽  
Vol 57 (5) ◽  
pp. 903 ◽  
Author(s):  
W. L. Silva ◽  
J. P. R. Costa ◽  
G. P. Caputti ◽  
A. L. S. Valente ◽  
D. Tsuzukibashi ◽  
...  
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Rainy Season ◽  
Structural Characteristics ◽  
Light Interception ◽  
Dry Season ◽  
Area Index ◽  
Dead Material ◽  
Point Quadrat ◽  
Ingestive Behaviour

This study compared the effect of residual leaf area index (rLAI) on the spatial distribution of morphological components of Tifton 85 (Cynodon spp.) pastures and the ingestive behaviour of grazing sheep. Also, it was investigated whether any specific correlation could be found between pasture structural characteristics and sheep ingestive behaviour. Four rLAI treatments (0.8; 1.4; 2.0 and 2.6) with four replications were evaluated per period. Sheep grazed under rotational stocking management and they grazed for 4 days in each pasture while pasture regrowth period was determined by the 95% light interception requirement. Pasture structure was evaluated using inclined point-quadrat, LAI estimates, light interception and leaf : stem ratio. The 2.6 rLAI yielded the highest proportion of dead material in the lower canopy. In the post-grazing period the proportion of leaves increased with increasing rLAI, especially on the canopy surface during the rainy season. In the pre-grazing average pasture height ranged between 19 and 26 cm with dead material and stem observed up to the canopy surface in the dry season. The animals grazed longer on the last day (89.72%) compared with the first day (80.25%) in the dry season. However, they spent less time (11.45%) ruminating in the dry season compared with the rainy season (15.38%), regardless of the grazing day. Grazing time decreased and rumination time increased as rLAI increased. Sheep grazing time correlated negatively with pasture height, before and after grazing. The sheep tend to graze longer on Tifton 85 pastures when rLAI was lower and forage supply was possibly less as on the last grazing day and in the dry season.

Seed size as a factor in the growth of subterranean clover (Trifolium subterraneum L.) under spaced and sward conditions

1957 ◽  
Vol 8 (4) ◽  
pp. 335 ◽  
Author(s):  
JN Black
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Seed Size ◽  
Seed Weight ◽  
Agricultural Research ◽  
Incident Light ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Area Index ◽  
Significant Difference

The significance of seed weight in the growth of subterranean clover (Trifolium subterraneum L) , of the Bacchus Marsh strain, has been assessed under both spaced plant and sward conditions at the Waite Agricultural Research Institute. Under conditions of spacing, plants of three widely separated seed size grades were grown a t a density of 1 per 25 sq. links. The dry weights of the plants were proportional to seed weight from the time of sowing (in May) till the end of October – over almost the entire growing period of the crop. Three sets of swards were grown a t a density of 25 plants per sq. link, each sward being planted with seed of one of the three sizes. Dry weight was proportional to seed weight in the early part of the season but when the swards reached a leaf area index of about 4 (i.e. when there were 4 sq. links of leaf surface on 1 sq. link of ground), a reduction in growth rate occurred. This critical leaf area index was reached first in "large seed" swards, followed later by "medium seed" and finally by "small seed" swards. Thus there was a period in which the swards were growing at different rates, and in which the dry weights came to parity, so that on the final sampling occasion (in December) there was no significant difference between the dry weights of the swards from the three seed sizes. It is concluded that a t a leaf area index of about 4, interception of incident light energy is complete.

Sign in / Sign up

Export Citation Format

Share Document