Effect of intensity of defoliation on regrowth of pasture

1956 ◽  
Vol 7 (5) ◽  
pp. 377 ◽  
Author(s):  
RW Brougham
Keyword(s):  
Leaf Area ◽  
Dry Matter ◽  
Unit Area ◽  
Incident Light ◽  
Ground Surface ◽  
Maximum Level ◽  
Maximum Growth ◽  
Light Interception ◽  
Maximum Efficiency ◽  
Rate Of Increase

A pasture association comprising short-rotation ryegrass, red clover, and white clover was subjected to three different intensities of defoliation by cutting down to 1, 3, and 5 in. At 4-day intervals over a period of 32 days, measurements were taken of herbage dry matter yield, the leaf area per unit area of ground, and the percentage of light penetrating to a level 1 in. above the ground surface. Where pasture was defoliated to 1 in., light interception was almost complete (95 per cent. or over) approximately 24 days after cutting, whereas pastures defoliated to 3 in. and 5 in. intercepted almost all the incident light 16 and 4 days after cutting respectively. At these stages of growth the leaf area was approximately 5 sq. ft per sq. ft of ground and the herbage yield approximately 1450 lb dry matter per acre, regardless of treatment. The rate of pasture growth increased until complete light interception was approached, and thereafter an almost constant maximum rate was sustained. Leaf efficiency (the rate of increase of herbage dry weight per unit area of leaf) was greatly influenced by intensity of defoliation. Efficiency was initially lower following severe defoliation than following less severe treatment. It increased rapidly to a maximum and thereafter declined gradually. Maximum efficiency in the 3 in. and 5 in. cutting treatments was attained when maximum growth rate was first reached. For pasture defoliated to 1 in., it reached a maximum level during the phase of accelerating growth.

scholarly journals Cluster and Principle Component Analysis of Soybean Grown at Various Row Spacings, Planting Dates and Plant Populations

2018 ◽  
Vol 3 (1) ◽  
pp. 110-121 ◽  
Author(s):  
Charanjit Singh Kahlon ◽  
Bin Li ◽  
James Board ◽  
Mahendra Dia ◽  
Parmodh Sharma ◽  
...  
Keyword(s):  
Cluster Analysis ◽  
Leaf Area Index ◽  
Leaf Area ◽  
Dry Matter ◽  
Light Interception ◽  
Plant Population ◽  
Large Set ◽  
Planting Dates ◽  
Area Index ◽  
Principle Components Analysis

Abstract Increased light interception (LI), along with concomitant increases in crop growth rate (CGR), is the main factor explaining how cultural factors such as row spacing, plant population, and planting date affect soybean yield. Leaf area index (LAI), LI, and CGR are interrelated in a “virtuous spiral” where increased LAI leads to greater LI resulting in a higher CGR and more total dry matter per area (TDM). This increases LAI, thus accelerating the entire physiological process to a higher level. A greater understanding of this complex growth dynamic process could be achieved through use of cluster analysis and principle components analysis (PCA). Cluster analysis involves grouping of similar objects in such way that objects in same cluster are similar to each other and dissimilar to objects in other cluster. PCA is a technique used to reduce a large set of variables to a few meaningful ones. Seasonal relative leaf area index (RLAI), relative light interception (RLI), and relative total dry matter (RTDM) response curves were determined from the data by a stepwise regression analysis in which these parameters were regressed against relative days after emergence (RDAE). Greatest levels of RLAI, RLI and RTDM were observed in soybean planted early on narrow row spacings and recorded greater plant population. In contrast, lower levels of these parameters occurred on plants with wide row spacings at late planting dates. For farmers, these results are useful in terms of adopting certain cultural practices which can help in the management of stress in soybean.

Potential production of grass and clover monocultures in a mediterranean-type environment — an experimental approach

1974 ◽  
Vol 25 (6) ◽  
pp. 835 ◽  
Author(s):  
PS Cocks
Keyword(s):  
Dry Matter ◽  
Experimental Approach ◽  
Incident Light ◽  
Trifolium Subterraneum ◽  
Maximum Growth ◽  
Nutrient Deficiencies ◽  
Potential Production ◽  
Area Index ◽  
Before And After ◽  
Differential Ability

Monocultures of Lolium rigidum cv. Wimmera and Trifolium subterraneum cv. Woogenellup were established at four densities and mown at three contrasting heights over a 5 month period. Heavy applications of fertilizer were applied to eliminate nutrient deficiencies. Dry matter yields and leaf areas were measured before and after the 3-weekly defoliations, and shoot numbers before the defoliations. Growth rate was related to leaf area index (LAI) in all but one of the sampling periods. Maximum growth rates were proportional to light energy, and the average efficiency of conversion was 4.5% for the clover and 5.5% for the grass. Total herbage yields as high as 17.3 t ha-1 were obtained from the grass, and up to 16.4 t ha-1 from the clover. The results are discussed in relation to the differential ability of grass and clover to exploit the environment. The grass was leafier and had more shoots, but it is thought that clover intercepted more of the incident light at low LAI. The results indicate that potential yields would be reduced at the low LAI values associated with an efficiently utilized pasture.

The growth of swards of subterranean clover with particular reference to leaf area

1958 ◽  
Vol 9 (1) ◽  
pp. 53 ◽  
Author(s):  
JL Davidson ◽  
CM Donald
Keyword(s):  
Leaf Area ◽  
Dry Matter ◽  
Substantial Reduction ◽  
Ground Surface ◽  
Subterranean Clover ◽  
Climatic Conditions ◽  
Dry Matter Production ◽  
Leaf Production ◽  
Area Index ◽  
Matter Production

An experiment was conducted to study the growth of subterranean clover (Trifolium subterraneum L.) sown at different densities; the control swards were not defoliated while others were subjected to a single defoliation at various dates. During the final month the rate of dry matter production (tops only) increased to a maximum when the leaf area index (the ratio of the area of the leaves to the area of the ground surface — L.A.I.) was about 4-5, falling by about 30 per cent. as the L.A.I. increased to 8.7. The rate of leaf production was greatest at about L.A.I. 4-5, falling to zero at L.A.I. 8.7. Climatic conditions during the growing season influenced the relationship of L.A.I. to growth; as conditions became more favorable the values of the optimum LA.1. for growth and of the ceiling L.,4.1. progressively rose. Irrespective of the density, all swards tended towards a common ceiling L.A.I. and yield by the end of the season. The effect of defoliation depended on the L.A.I. at which defoliation occurred, on the value to which the L.A.I. was reduced, and on current climatic conditions. If swards near the ceiling L.A.I. were defoliated, total dry matter production was slightly increased and there was a great increase in leaf production. On the other hand, defoliation of swards from about the optimum L.A.I. to very low L.A.I. values led to a substantial reduction in both dry matter and leaf production. It is suggested that all these effects depend on the light relationships within the sward and their influence on the balance of photosynthesis and respiration. Pasture at the optimum L.A.I. will give greater production than swards of lower or higher L.A.I.; defoliation can give greatly increased leaf production, unless L.A.I. is reduced to very low values.

scholarly journals Differential Influences of Leaf Tip Trimming on Light Interception and Dry Matter Production in Tomato Dutch Cultivar Gourmet and Japanese Cultivar Momotaro York

HortScience ◽  
2017 ◽  
Vol 52 (5) ◽  
pp. 686-691 ◽  
Author(s):  
Tadahisa Higashide ◽  
Yuya Mochizuki ◽  
Takeshi Saito ◽  
Yasushi Kawasaki ◽  
Dong-Hyuk Ahn ◽  
...  
Keyword(s):  
Leaf Area ◽  
Dry Matter ◽  
Leaf Shape ◽  
Light Interception ◽  
Light Extinction ◽  
Area Index ◽  
Mature Leaves ◽  
Significant Difference ◽  
Young Leaves ◽  
Japanese Cultivar

To investigate the influence of morphological changes in individual leaves of tomato on light interception and dry matter (DM) production, we altered leaf shape by trimming leaflets of young or mature leaves of the Dutch cultivar Gourmet and the Japanese cultivar Momotaro York. Young leaves 5-cm long were trimmed of their first and second leaflets from the leaf apex. Mature leaves were similarly trimmed at ≥71 days after transplanting (DAT). The individual leaf area (LA) of intact ‘Momotaro York’ leaves was significantly larger than that of ‘Gourmet’. Light–photosynthesis curves of the cultivars were almost identical. Mature-trimmed plants of both cultivars had a smaller individual LA and a smaller leaf area index (LAI), and a greater light-extinction coefficient (LEC). Although there was no significant difference in light-use efficiency (LUE) (i.e., DM production per unit intercepted solar radiation) in ‘Gourmet’ between trimming stages, LUE of ‘Momotaro York’ was decreased significantly by young-leaf trimming. Trimming of young leaves significantly decreased the LEC in ‘Gourmet’ but increased it in ‘Momotaro York’. Although leaf trimming would be impractical for commercial cultivation, these results may provide with a clue for breeding for yield improvement.

Analysis of the regrowth of a tropical grass/legume sward subjected to different frequencies and intensities of defoliation

1980 ◽  
Vol 31 (4) ◽  
pp. 673 ◽  
Author(s):  
MM Ludlow ◽  
DA Charles-Edwards
Keyword(s):  
Leaf Area ◽  
Dry Matter ◽  
Dry Weight ◽  
Light Interception ◽  
Photosynthetic Characteristics ◽  
Dry Matter Production ◽  
Canopy Photosynthesis ◽  
Area Index ◽  
Matter Production ◽  
Cutting Height

Dry weight, leaf area, light interception and canopy photosynthesis were measured during 3- or 5-week regrowth periods of Setaria anceps/Desmodium intortum swards cut to 7.5 or 15 cm. Dry matter production during the experiment and over the growing season increased with cutting height and with interval between defoliations, but the proportion of grass to legume was unaffected. These effects of defoliation on dry matter production were similar to those estimated for integrated canopy photosynthesis from measured light interception and calculated leaf photosynthetic characteristics. Height and frequency of defoliation had no effect on canopy extinction coefficient for light, nor on the leaf photosynthetic characteristics, except for the first 1-2 weeks after defoliation when leaf photosynthetic rates appeared to be depressed. The main effects of height and frequency of defoliation on dry matter production were through their effects on leaf area index and light interception.

scholarly journals Production and nutritional quality of ryegrass forage grown in different population stands under successive cuts

2020 ◽  
Vol 41 (4) ◽  
pp. 1291
Author(s):  
André Dochwat ◽  
Mikael Neumann ◽  
Edelmir Silvio Stadler Junior ◽  
Bruno José Venancio ◽  
Emylli Pereira e Silva ◽  
...  
Keyword(s):  
Nutritional Quality ◽  
Dry Matter ◽  
Agronomic Traits ◽  
Unit Area ◽  
Block Design ◽  
Maximum Efficiency ◽  
Green Leaves ◽  
Randomized Block Design ◽  
Whole Plant

The Brazilian livestock activity is undergoing constant evolution, and aiming at its maximum efficiency, it is necessary to have available to the animals food in quantity and quality all the year. To this end, the cultivation of winter forage is carried out. The present study aimed to evaluate the productive and qualitative agronomic traits of ryegrass forage. The experiment was a randomized block design in a 3 x 2 factorial arrangement consisting of six treatments, three plant stands (525, 1050 and 2095 plants m-2) associated with two successive cutting times (vegetative and full vegetative), and four repetitions. There was no interaction between population stand and cutting times for the variables studied. The stand of 525 plants m-2 had a higher participation of green leaves (50.52 %), higher digestibility of the whole plant dry matter (84.81 %) compared to the stands of 1.050 and 2.095 plants m-2, and dry biomass production per unit area equivalent to the others (6087, 7243 and 6989 kg ha-1, respectively). The first harvest season presented higher participation of green leaves and better leaf/stem ratio, 58.62 % and 3.41 % respectively, as well as higher digestibility of green leaves (77.26 %) and stem (80.82 %).

scholarly journals Adding Far-Red to Red-Blue Light-Emitting Diode Light Promotes Yield of Lettuce at Different Planting Densities

2021 ◽  
Vol 11 ◽  
Author(s):  
Wenqing Jin ◽  
Jorge Leigh Urbina ◽  
Ep Heuvelink ◽  
Leo F. M. Marcelis
Keyword(s):  
Leaf Area ◽  
Biomass Production ◽  
Plant Biomass ◽  
Stem Elongation ◽  
Incident Light ◽  
Dry Weight ◽  
Light Interception ◽  
Planting Density ◽  
Light Use Efficiency ◽  
Use Efficiency

The economic viability and energy use of vertical farms strongly depend on the efficiency of the use of light. Increasing far-red radiation (FR, 700–800 nm) relative to photosynthetically active radiation (PAR, 400–700 nm) may induce shade avoidance responses including stem elongation and leaf expansion, which would benefit light interception, and FR might even be photosynthetically active when used in combination with PAR. The aims of this study are to investigate the interaction between FR and planting density and to quantify the underlying components of the FR effects on growth. Lettuce (Lactuca sativa cv. Expertise RZ) was grown in a climate chamber under two FR treatments (0 or 52 μmol m–2 s–1) and three planting densities (23, 37, and 51 plants m–2). PAR of 89% red and 11% blue was kept at 218 μmol m–2 s–1. Adding FR increased plant dry weight after 4 weeks by 46–77% (largest effect at lowest planting density) and leaf area by 58–75% (largest effect at middle planting density). Radiation use efficiency (RUE: plant dry weight per unit of incident radiation, 400–800 nm) increased by 17–42% and incident light use efficiency (LUEinc: plant dry weight per unit of incident PAR, 400–700 nm) increased by 46–77% by adding FR; the largest FR effects were observed at the lowest planting density. Intercepted light use efficiency (LUEint: plant dry weight per unit of intercepted PAR) increased by adding FR (8–23%). Neither specific leaf area nor net leaf photosynthetic rate was influenced by FR. We conclude that supplemental FR increased plant biomass production mainly by faster leaf area expansion, which increased light interception. The effects of FR on plant dry weight are stronger at low than at high planting density. Additionally, an increased LUEint may contribute to the increased biomass production.

Estimates of physiological determinants forAmaranthus retroflexus

Weed Science ◽  
1999 ◽  
Vol 47 (3) ◽  
pp. 291-296 ◽  
Author(s):  
Stevan Z. Knezevic ◽  
Michael J. Horak ◽  
Richard L. Vanderlip
Keyword(s):  
Leaf Area ◽  
Specific Leaf Area ◽  
Environmental Conditions ◽  
Dry Matter ◽  
Plant Density ◽  
Light Interception ◽  
Radiation Use Efficiency ◽  
Redroot Pigweed ◽  
Use Efficiency ◽  
Radiation Use

Redroot pigweed is a troublesome weed in the sorghum-growing regions of North America. In 1994 and 1995, field studies were conducted at two locations near Manhattan, KS, to determine the influence of redroot pigweed density and environmental conditions on physiological determinants of redroot pigweed growth: duration of plant growth, light interception, radiation-use efficiency, and dry matter partitioning. In addition, specific leaf area was determined. Redroot pigweed was seeded at monoculture densities of 2, 4, and 12 plants m−1of row each year at each location. Duration of redroot pigweed growth was not influenced by plant density. Light interception was defined as a simple exponential function of leaf area index. Specific leaf area did not change over the season and averaged 135 cm2g−1. Partitioning of redroot pigweed dry matter was not influenced by plant density or environmental conditions but did not change within vegetative and reproductive stages. Radiation-use efficiency was not influenced by redroot pigweed density; the most reliable estimate was 1.74 g dry matter MJ−1of intercepted photosynthetically active radiation. Physiological determinants described were not affected by redroot pigweed density or environmental conditions and therefore provide a starting point for the development of a redroot pigweed growth module. The module could be coupled with available crop growth models (e.g., the sorghum growth model SORKAM) to simulate redroot pigweed–sorghum competition.

The effects of seed size and spacing on growth and yield of lesser yam (Dioscorea esculenta)

1972 ◽  
Vol 78 (2) ◽  
pp. 215-225 ◽  
Author(s):  
B. A. C. Enyi
Keyword(s):  
Leaf Area ◽  
Seed Size ◽  
Dry Matter ◽  
Unit Area ◽  
Tuber Initiation ◽  
Area Index ◽  
Spacing Distance ◽  
Leaf Area Duration ◽  
Growth Development ◽  
Bulking Rate

SUMMARYThe effects of seed size and spacing on growth, development and yield of lesser yam and the relationship between growth, development and yield in this yam variety were investigated in the 1967 and 1968 growing seasons. Larger seeds outyielded smaller ones both in the total and ware tuber yields. The seed size effect was associated with a difference in tuber number, leaf area duration and bulking rate. Mean tuber weight at harvest, decreased with the decrease in seed size. Total and ware tuber yields increased with the decrease in spacing distance. The spacing effect was associated with differences in leaf area duration and bulking rate per unit area. Final total dry matter produced per plant increased with the increase in both seed size and spacing distance but the dry matter produced per unit area decreased with the increase in spacing distance. Leaf area index and leaf area duration increased with an increase in seed size and decreased with increase in spacing distance. There was a greater positive relationship between total tuber yield and leaf area duration between tuber initiation and the final sampling period than that between it and absolute leaf area duration.

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