scholarly journals Angular Leaf Spot of Phaseolus Beans: Relationships Between Disease, Healthy Leaf Area, and Yield

1997 ◽  
Vol 87 (5) ◽  
pp. 506-515 ◽  
Author(s):  
A. Bergamin Filho ◽  
S. M. T. P. G. Carneiro ◽  
C. V. Godoy ◽  
L. Amorim ◽  
R. D. Berger ◽  
...  
Keyword(s):  
Leaf Area ◽  
Field Experiments ◽  
Explanatory Variable ◽  
Phaeoisariopsis Griseola ◽  
Crop Season ◽  
Area Index ◽  
Healthy Leaf ◽  
Progress Curve ◽  
Leaf Area Duration ◽  
The Relationship

Five field experiments were conducted to investigate the relationship between the severity of visible disease (X), area under the disease progress curve (AUDPC), healthy leaf area index on any given day (HLAI), radiation intercepted by healthy leaf area on any given day (HRI), healthy leaf area duration (HAD), total healthy leaf area absorption (HAA), and yield of Phaseolus beans, cultivars Rosinha and Carioca, inoculated with Phaeoisariopsis griseola at several doses. In general, yield was not related to disease severity (X) or AUDPC. In contrast, the highest yields were always related to the highest values of HAD and HAA. The relationship between yield and HAD was linear in each of five trials (29.9 < R2 < 70.2%, P < 0.001). The relationship between yield and HAA was linear in four of the trials (52.3 < R2 < 70.3%, P < 0.001) and exponential in one of them (in which the plant canopy was the largest). Singlepoint models using HRI to estimate yield at various times during the crop season were developed. The slope of the yield-HRI relationship proved to be stable (26.8 ±2.4 g MJ-1), regardless of cultivar, locale, planting date, and bean growth stage (from R5 to R8). The yield-HLAI relationship proved to be less consistent. HRI is proposed as a key explanatory variable for a transportable system of disease management; it may be useful in producing precise recommendations at the farm level.

Quality and yield response to the control of Mycosphaerella graminicola in wheat as affected by nitrogen rate and cultivar bread-making characteristics

2017 ◽  
Vol 68 (4) ◽  
pp. 317 ◽  
Author(s):  
María Constanza Fleitas ◽  
Ana Carolina Castro ◽  
María Rosa Simón
Keyword(s):  
Leaf Area ◽  
Field Experiments ◽  
Mycosphaerella Graminicola ◽  
Green Leaf ◽  
Yield Response ◽  
Bread Making ◽  
Progress Curve ◽  
Leaf Area Duration ◽  
Strobilurin Fungicide ◽  
Green Leaf Area

Septoria leaf blotch (SLB), caused by Mycosphaerella graminicola, reduces yield and grain quality of wheat (Triticum aestivum L.) by affecting the photosynthetically active area of the crop. This might influence grain protein concentration (GPC) and affect bread-making parameters. Nitrogen (N) fertilisation is required to achieve high yields in wheat; however, it may enhance the development of foliar diseases such as SLB. The aim of this study was to evaluate the effect of fungicide and N rate on SLB severity, green-leaf-area duration, grain yield and bread-making parameters in three wheat cultivars differing in bread-making characteristics. Two field experiments were conducted during 2009 and 2010 in a split-split-plot design with three fungicide treatments (triazole, triazole–strobilurin, nil) as main plots, three N fertiliser rates as subplots and three cultivars as sub-subplots. Fungicides significantly reduced the area under disease-progress curve (AUDPC) and this was associated with increased yield, which varied among cultivars. The AUDPC was lower in the higher N-rate treatments. Fungicide applications and increasing N rates extended green-leaf-area duration. GPC increased in untreated plots and it was reduced with applications of triazole–strobilurin fungicide. GPC reduction caused by this type of fungicide tended to be lower when the rate of N increased. The two cultivars with low bread-making characteristics showed a tendency to greater reductions in GPC with both fungicide types. Regarding quality variables, only tenacity and dough strength were reduced by the triazole-strobilurin fungicide. On average, for all treatments, tenacity, water absorption and dough development time were higher in the best quality group cultivars.

scholarly journals Effects of Angular Leaf Spot and Rust on Yield Loss of Phaseolus vulgaris

2001 ◽  
Vol 91 (11) ◽  
pp. 1045-1053 ◽  
Author(s):  
W. C. de Jesus ◽  
F. X. R. do Vale ◽  
R. R. Coelho ◽  
B. Hau ◽  
L. Zambolim ◽  
...  
Keyword(s):  
Phaseolus Vulgaris ◽  
Leaf Area ◽  
Leaf Spot ◽  
Field Experiments ◽  
Angular Leaf Spot ◽  
Growth And Yield ◽  
Control Treatment ◽  
Healthy Leaf ◽  
Progress Curve ◽  
Host Growth

Three field experiments were conducted in 1997, 1998, and 1999 to investigate the effects of angular leaf spot and rust, separately or combined, on host growth and yield of individual bean plants (Phaseolus vulgaris). In each experiment, three treatments were established by inoculating cv. Carioca with Phaeoisariopsis griseola, Uromyces appendiculatus, or with both pathogens. An additional control treatment was not inoculated, but was sprayed with a fungicide. In the 1997 and 1999 experiments, angular leaf spot reached higher disease levels than rust, whereas in 1998, rust was more severe than angular leaf spot. Host growth, expressed as healthy leaf area duration (HAD), and yield were the highest in 1997 and lowest in 1998. In each experiment, the treatments did not differ significantly to the area under leaf area progress curve, HAD, and healthy leaf area absorption (HAA). All inoculated treatments had significantly more severe disease and less yield than the control treatment. Based on the analysis of 60 plants in each experiment, yield was not related to the areas under disease progress curve for either or both diseases. In 1997 and 1999, yield was related to HAD (R2 = 0.57 and 0.43) and HAA(R2 = 0.60 and 0.55). Based on the combined analysis of all 36 plots, angular leaf spot reduced the leaf area because of defoliation, whereas rust did not affect the leaf area. Rust reduced yield more than four times that of angular leaf spot, although the decrease in photosynthesis to angular leaf spot was twice that of rust.

Leaf area and transpiration efficiency during different growth stages in oats

1991 ◽  
Vol 116 (2) ◽  
pp. 183-190 ◽  
Author(s):  
W. Ehlers
Keyword(s):  
Leaf Area ◽  
Dry Matter ◽  
Field Experiments ◽  
Potential Evapotranspiration ◽  
Rain Water ◽  
Growth Stages ◽  
Transpiration Efficiency ◽  
Area Index ◽  
Leaf Area Duration ◽  
It Efficiency

SUMMARYDry matter production, transpiration and transpiration efficiency (DM production: transpiration) were studied during vegetative growth of oats over 4 years (1976–77 and 1982–83) in field experiments on loess-derived soils near Gottingen, Germany, under different weather conditions. Shoot and root dry matter and leaf area were measured or estimated regularly during the season. The rate of evapotranspiration including intercepted rain water by leaves (ET) was determined during five consecutive growth stages from the water balance in the 2 m soil profile. The rate of soil evaporation (E) and the rate at which rain water was intercepted by leaves (I) were estimated separately in order to attain T, the transpiration rate (T = ET–E–I), or IT, the rate of interception of rain water by leaves plus transpiration (IT = ET–E). The potential evapotranspiration rate (ETp) was derived from meteorological parameters.During the early stages of oat development (seedling growth and tillering), T and IT, related to ETp, were higher than expected from crop growth rate (CGR), calculated for shoot and total dry matter including roots, respectively. It was concluded that, at a leaf area index (LAI) of < 3·4, part of the solar radiation was converted to sensible heat between plant rows, increasing ETp near the ground and hence T, but not CGR. Because of this, LAI influenced IT efficiency and the crop-specific constant m of de Wit's formula. IT efficiency was not only dependent on LAI but also on ETp. Grain yield was related to both cumulative IT (ITC), normalized by ET, and leaf area duration during the period from anthesis to harvest. Increased leaf area duration after anthesis may partly explain the higher yields obtained with modern high-yielding varieties of small-grained cereals.

On the relationship of NDVI with leaf area index in a deciduous forest site

2005 ◽  
Vol 94 (2) ◽  
pp. 244-255 ◽  
Author(s):  
Quan Wang ◽  
Samuel Adiku ◽  
John Tenhunen ◽  
André Granier
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Deciduous Forest ◽  
Forest Site ◽  
Area Index ◽  
Relationship Of ◽  
The Relationship

scholarly journals Effect of nitrogen addition on the comparative productivity of corn and velvetleaf (Abutilon theophrasti)

Weed Science ◽  
2006 ◽  
Vol 54 (02) ◽  
pp. 354-363 ◽  
Author(s):  
Darren C. Barker ◽  
Stevan Z. Knezevic ◽  
Alex R. Martin ◽  
Daniel T. Walters ◽  
John L. Lindquist
Keyword(s):  
Leaf Area ◽  
Field Experiments ◽  
Yield Loss ◽  
Biomass Accumulation ◽  
Nitrogen Addition ◽  
Corn Yield ◽  
N Addition ◽  
Area Index ◽  
Nitrogen Levels ◽  
Weed Growth

Weeds that respond more to nitrogen fertilizer than crops may be more competitive under high nitrogen (N) conditions. Therefore, understanding the effects of nitrogen on crop and weed growth and competition is critical. Field experiments were conducted at two locations in 1999 and 2000 to determine the influence of varying levels of N addition on corn and velvetleaf height, leaf area, biomass accumulation, and yield. Nitrogen addition increased corn and velvetleaf height by a maximum of 15 and 68%, respectively. N addition increased corn and velvetleaf maximum leaf area index (LAI) by up to 51 and 90%. Corn and velvetleaf maximum biomass increased by up to 68 and 89% with N addition. Competition from corn had the greatest effect on velvetleaf growth, reducing its biomass by up to 90% compared with monoculture velvetleaf. Corn response to N addition was less than that of velvetleaf, indicating that velvetleaf may be most competitive at high levels of nitrogen and least competitive when nitrogen levels are low. Corn yield declined with increasing velvetleaf interference at all levels of N addition. However, corn yield loss due to velvetleaf interference was similar across N treatments except in one site–year, where yield loss increased with increasing N addition. Corn yield loss due to velvetleaf interference may increase with increasing N supply when velvetleaf emergence and early season growth are similar to that of corn.

scholarly journals Leaf Removal Affects Maize Morphology and Grain Yield

Agronomy ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 269 ◽  
Author(s):  
Guangzhou Liu ◽  
Yunshan Yang ◽  
Wanmao Liu ◽  
Xiaoxia Guo ◽  
Jun Xue ◽  
...  
Keyword(s):  
Grain Yield ◽  
Leaf Area ◽  
Field Experiments ◽  
Photosynthetic Capacity ◽  
Maize Yield ◽  
Light Distribution ◽  
Planting Density ◽  
Leaf Removal ◽  
Area Index ◽  
Source Sink

Increasing planting density is an important practice associated with increases in maize yield, but densely planted maize can suffer from poor light conditions. In our two-year field experiments, two morphologically different cultivars, ZD958 (less compact) and DH618 (more compact), were planted at 120,000 plants ha−1 and 135,000 plants ha−1, respectively. We established different leaf area index (LAI) treatments by removing leaves three days after silking: (1) control, no leaves removed (D0); (2) the two uppermost leaves removed (D1); (3) the four uppermost leaves removed (D2); (4) the leaves below the third leaf below the ear removed (D3); (5) the leaves of D1 and D3 removed (D4); (6) the leaves of D2 and D3 removed (D5). Optimal leaf removal improved light distribution, increased photosynthetic capacity and the post-silking source-sink ratio, and thus the grain yield, with an average LAI of 5.9 (5.6 and 6.2 for ZD958 and DH618, respectively) for the highest yields in each year. Therefore, less-compact cultivars should have smaller or fewer topmost leaves or leaves below the ear that quickly senesce post-silking, so as to decrease leaf area and thus improve light distribution and photosynthetic capacity in the canopy under dense planting conditions. However, for more compact cultivars, leaves below the ear should senesce quickly after silking to reduce leaf respiration and improve the photosynthetic capacity of the remaining top residual leaves. In future maize cultivation, compact cultivars with optimal post-silking LAI should be adopted when planting densely.

scholarly journals Estimation of Peanut Leaf Area Index from Unmanned Aerial Vehicle Multispectral Images

Sensors ◽  
2020 ◽  
Vol 20 (23) ◽  
pp. 6732
Author(s):  
Haixia Qi ◽  
Bingyu Zhu ◽  
Zeyu Wu ◽  
Yu Liang ◽  
Jianwen Li ◽  
...  
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Vegetation Index ◽  
Field Experiments ◽  
Predictive Accuracy ◽  
Vegetation Indices ◽  
Planting Density ◽  
Coefficient Of Determination ◽  
Multispectral Images ◽  
Area Index

Leaf area index (LAI) is used to predict crop yield, and unmanned aerial vehicles (UAVs) provide new ways to monitor LAI. In this study, we used a fixed-wing UAV with multispectral cameras for remote sensing monitoring. We conducted field experiments with two peanut varieties at different planting densities to estimate LAI from multispectral images and establish a high-precision LAI prediction model. We used eight vegetation indices (VIs) and developed simple regression and artificial neural network (BPN) models for LAI and spectral VIs. The empirical model was calibrated to estimate peanut LAI, and the best model was selected from the coefficient of determination and root mean square error. The red (660 nm) and near-infrared (790 nm) bands effectively predicted peanut LAI, and LAI increased with planting density. The predictive accuracy of the multiple regression model was higher than that of the single linear regression models, and the correlations between Modified Red-Edge Simple Ratio Index (MSR), Ratio Vegetation Index (RVI), Normalized Difference Vegetation Index (NDVI), and LAI were higher than the other indices. The combined VI BPN model was more accurate than the single VI BPN model, and the BPN model accuracy was higher. Planting density affects peanut LAI, and reflectance-based vegetation indices can help predict LAI.

Relationship between tillering and leaf area index: quantifying critical leaf area index for tillering in rice

2002 ◽  
Vol 138 (3) ◽  
pp. 269-279 ◽  
Author(s):  
X. ZHONG ◽  
S. PENG ◽  
J. E. SHEEHY ◽  
R. M. VISPERAS ◽  
H. LIU
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Planting Density ◽  
Coefficient Of Determination ◽  
Area Index ◽  
N Input ◽  
Major Factors ◽  
The Relationship ◽  
Changing Light ◽  
Input Level

A field study was conducted at the International Rice Research Institute (IRRI), Philippines during the dry seasons of 1997 and 1998 under irrigated conditions. The objectives of this study were to quantify the critical leaf area index (LAIc) at which tillering stops based on the relationship between tillering rate and LAI, and to determine the effect of nitrogen (N) on LAIc in irrigated rice (Oryza sativa L.) crop. Results showed that the relative tillering rate (RTR) decreased exponentially as LAI increased at a given N input level. The coefficient of determination for the equation quantifying the RTR-LAI relationship ranged from 0·87 to 0·99. The relationship between RTR and LAI was affected by N input level, but not by planting density. The N input level had a significant effect on LAIc with a high N input level causing an increase in LAIc. Tillering stopped at LAI of 3·36 to 4·11 when N was not limiting. Under N limited conditions LAIc reduced to as low as 0·98. Transplanting spacing and number of seedlings per hill had little effect on LAIc. Results from this study suggest that LAI and plant N status are two major factors that influence tiller production in rice crops. The possibility that LAI influences tillering by changing light intensity and/or light quality at the base of the canopy where tiller buds and young tillers are located is discussed.

The effect on yield and leaf area of wheat of applying nitrogen as a top-dressing in April or in sprays at ear emergence

1955 ◽  
Vol 46 (4) ◽  
pp. 449-456 ◽  
Author(s):  
Gillian N. Thorne ◽  
D. J. Watson
Keyword(s):  
Winter Wheat ◽  
Nitrogen Content ◽  
Leaf Area ◽  
The Other ◽  
Nitrogen Application ◽  
Area Index ◽  
Rapid Fall ◽  
Shoot Number ◽  
Leaf Area Duration ◽  
Effect On Yield

Nitrogen, at the rate of 0.5 cwt./acre, was applied to winter wheat as an April dressing of nitrochalk, or as eight sprayings of 2% NH4NO3 solution applied either to the soil or to the leaves at about the period of maximum leaf area, before and during ear emergence. All three methods of nitrogen application caused similar increases in yield and nitrogen content of grain. April nitrogen gave a greater yield of straw than the later dressings.Late nitrogen application caused a small increase in leaf area index, first noticeable one week after ear emergence and persisting for another four weeks. L.A.I. of plots that received nitrogen in April was much larger than that of the other plots at the period of maximum leaf area, but by four weeks after ear emergence it was less than that of plots receiving the late nitrogen. Shoot number per metre and leaf area per shoot were increased by early nitrogen, but only the latter was increased by nitrogen applied at ear emergence.Leaf area duration after ear emergence was the same on all nitrogen-treated plots and the yield of grain divided by L.A.D. was nearly constant for all plots.Applying nitrogen late, after an April dressing, did not prevent the rapid fall in L.A.I. from the high value reached at the period of maximum leaf area and caused no greater increase in yield than when applied in the absence of an April top-dressing. A single urea spray applied in early June increased yield to the same extent as the ammonium nitrate sprays.

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