Soybean (Glycine max) Interference on Common Cocklebur (Xanthium strumarium) and Entireleaf Morningglory (Ipomoea hederaceavar.integriuscula)

Weed Science ◽  
1995 ◽  
Vol 43 (3) ◽  
pp. 402-409 ◽  
Author(s):  
Dwight G. Mosier ◽  
Lawrence R. Oliver

Field experiments were conducted to evaluate soybean interference on common cocklebur and entireleaf morningglory under irrigated and nonirrigated conditions. Interference from the mixture of soybean and entireleaf morningglory, and soybean alone reduced the total leaf area index (LAI), LAI within the common cocklebur canopy, and growth rate of common cocklebur more than did entireleaf morningglory; more reduction occurred without irrigation than with irrigation. Irrigated common cocklebur produced 687 burs per plant, while nonirrigated produced 359. Irrigated and nonirrigated soybeans and the mixture of soybeans and entireleaf morningglory reduced common cocklebur bur production 43 to 47%. Irrigated entireleaf morningglory reduced common cocklebur bur production 42%, while nonirrigated reduced bur production 28%. Interference from the mixture of irrigated soybeans and common cocklebur reduced the total leaf area index (LAI), LAI within the entireleaf morningglory canopy, and growth rate of entireleaf morningglory more than did soybean or common cocklebur alone. Irrigated entireleaf morningglory produced 542 and 1107 seeds per plant in 1982 and 1983, respectively. The mixture of irrigated soybeans and common cocklebur reduced entireleaf morningglory seed production 84 to 90%. Nonirrigated entireleaf morningglory was not competitive in any treatment combination either year due to lack of sufficient LAI.

1989 ◽  
Vol 19 (9) ◽  
pp. 1131-1136 ◽  
Author(s):  
William R. Bidlake ◽  
R. Alan Black

Total leaf-area index and the vertical distribution of leaf-area index were described for an unthinned stand (density 11 250 stems/ha) and a thinned stand (density 1660 stems/ha) of 30-year-old Larixoccidentalis Nutt. Two independent methods were used to estimate leaf-area index in each of the two stands. The first method is based on allometric relationships that are applied to stem measurements, and the second method is based on gap-fraction analysis of fisheye photographs. Leaf-area index estimates obtained by the two methods were not significantly different. The gap-fraction method provides a desirable alternative because much less fieldwork is required, however, use of this method is limited to canopies where the light-blocking elements are randomly displayed. Total leaf-area index values for the unthinned and thinned stands were 5.0 and 3.6, respectively. The vertical distribution of leaf-area index in the unthinned stand resembled a normal distribution. The vertical distribution of leaf-area index in the thinned stand would have resembled a normal distribution, except that thinning operations resulted in a truncated distribution of leaf-area index at the canopy base.


1988 ◽  
Vol 18 (8) ◽  
pp. 1090-1093 ◽  
Author(s):  
Craig Wallace Hedman ◽  
Dan Binkley

Relationships between canopy profiles and site quality were examined in 11 old, uneven-aged (>180 years) hardwood forests in the Piedmont of eastern North Carolina. Site fertility was indexed by extractable soil calcium and phosphorus, by the content of calcium, phosphorus and nitrogen in litter fall, and by the aboveground net primary productivity of each stand. Canopy profiles were indexed by the leaf area index for each 3.3-m height interval. Total leaf area index correlated highly with most measures of site fertility, but we found no clear patterns between canopy profiles and any measure of site fertility. We conclude that site fertility is reflected in broad ecosystem-level variables such as total leaf area index and stand productivity, but that detailed patterns such as canopy profiles relate strongly to specific stand composition, age structure, and history.


2012 ◽  
Vol 5 (1) ◽  
pp. 309-318 ◽  
Author(s):  
MI Kabir ◽  
MG Mortuza ◽  
MO Islam

The experiment was conducted to see the effect of nutrient spray on morphophysiological feature and growth of three orchid varieties namely Dendrobium Red Bull, D. Kasim Gold and D White 5 N. Results revealed that the morphophysiological and growth attributes significantly varied among the cultivars. D Red Bull showed the highest plant height, leaf length, leaf area and stem diameter among the varieties. D. White 5 N was superior in leaf number and total leaf area and D. Kasim Gold was superior in leaf area index and leaf width to the other varieties. On the other hand, the trend of increasing in leaf length, leaf width, leaf area index, leaf number, leaf area and total leaf area was the highest for N:P:K as 10:25:30. Plant height and stem diameter was maximum for N:P:K as 15:20:20. In conclusion, low level of nitrogen and high level of phosphorus and potassium was suitable for leaf length, leaf width, leaf area index, leaf number, leaf area and total leaf area while high level of nitrogen and low level of potassium was suitable for plant height and stem diameter. DOI: http://dx.doi.org/10.3329/jesnr.v5i1.11598 J. Environ. Sci. & Natural Resources, 5(1): 309-318, 2012


Weed Science ◽  
1995 ◽  
Vol 43 (2) ◽  
pp. 239-246 ◽  
Author(s):  
Dwight G. Mosier ◽  
Lawrence R. Oliver

Field experiments were conducted to evaluate common cocklebur and entireleaf morningglory interference on soybean under irrigated and nonirrigated conditions. Total leaf area index (LAI), LAI within the soybean canopy, crop growth rate, and seed yield of soybean were decreased more by common cocklebur than by entireleaf morningglory. Interference from entireleaf morningglory, common cocklebur, or both species reduced soybean yields 21, 57, and 64%, respectively, with irrigation and 12, 60, and 76%, respectively, without irrigation. Soybean yield reduction from interference with entireleaf morningglory, common cocklebur, or both species was not influenced by soybean date of planting. Soil water was extracted from greater soil depths by soybean growing with the weeds than by soybean alone. High WUE without irrigation suggests that soybean uses water more efficiently when soil moisture is limiting than when soil moisture is available under irrigated conditions.


2017 ◽  
Vol 14 (2) ◽  
pp. 147-154 ◽  
Author(s):  
MM Kamrozzaman ◽  
MAH Khan ◽  
S Ahmed ◽  
N Sultana

An experiment was conducted at Sadipur charland under Farming System Research and Development Site, Hatgobindapur, Faridpur, during rabi season of 2012-13 and 2013-14 to study the growth and yield performance of cv. BARI Gom-24 as affected by different dates of sowing under Agro-ecological Zone-12 (AEZ-12) of Bangladesh. The experiment was laid out in randomized complete block design with six replications, comprising five different dates of sowing viz. November 5, November 15, November 25, December 5 and December 15. Results reveal that the tallest plant, leaf area index, total dry matter, and crop growth rate were observed in November 25 sown crop and leaf area index, total dry matter and crop growth rate were higher at booting, grain filling, and tillering stages of the crop. Maximum effective tillers hill-1 (3.49), spikes m-2, (311), number of grains spike-1 (42.20) and 1000-grain weight (52.10 g) were produced by November 25 sown crop exhibited the highest grain (4.30 t ha-1) and straw yield (4.94 t ha-1) as well as harvest index (46.88%) of the crop. Lowest performance was observed both in early (November 5) and late sown crop (December 15). The overall results indicated that November 25 sown crop showed better performance in respect of growth and yield of wheat under charland ecosystem of Bangladesh.J. Bangladesh Agril. Univ. 14(2): 147-154, December 2016


Sensors ◽  
2020 ◽  
Vol 20 (23) ◽  
pp. 6732
Author(s):  
Haixia Qi ◽  
Bingyu Zhu ◽  
Zeyu Wu ◽  
Yu Liang ◽  
Jianwen Li ◽  
...  

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.


2017 ◽  
Vol 5 (4) ◽  
pp. 423-429 ◽  
Author(s):  
Mohan Mahato ◽  
Bishnu Bilas Adhikari

A field experiment was conducted under humid subtropical agro-climatic condition of Nepal during rainy season of 2014. The experiment was laid out in to two factor Randomized Complete Block Design with  three replications consisting three drought tolerant rice varieties (Sukhadhan-4, Sukhadhan-5 and Radha-4) and four planting geometry (15 cm × 10 cm, 15 cm × 15 cm, 20 cm × 15 cm and 20 cm × 20 cm). The results revealed that the highest plant height and maximum leaf area index was recorded in planting geometry 15 cm × 10 cm in all growth stages. Whereas, planting geometry 20 cm × 15 cm produced the maximum number of tiller m-2 in all growth stage.  While planting geometry 20 cm × 15 cm and 20 cm × 20 cm produced statistically similar crop growth rate and dry matter accumulation in all stage of growth. Regarding the varieties, Sukhadhan- 4 showed highest plant height up to 75 DAT and plant height was statistically similar to Radha - 4 in 60 and 75 DAT. But maximum number of tiller m-2, leaf area index, crop growth rate and dry matter accumulation were recorded in Sukhadhan – 5 varieties. Int. J. Appl. Sci. Biotechnol. Vol 5(4): 423-429


2017 ◽  
Vol 35 (2) ◽  
pp. 216-222 ◽  
Author(s):  
Rafael David Fraile-Robayo ◽  
Javier Giovanni Álvarez-Herrera ◽  
Andrea Johana Reyes M. ◽  
Omar Ferney Álvarez-Herrera ◽  
Ana Lucía Fraile-Robayo

The production of lettuce in hydroponic systems with a recirculating nutrient solution has been growing, so it is necessary to evaluate the growth and quality of production under this system. Two harvest cycles were evaluated, comparing the behavior of physiological variables and growth rates on lettuce plants in a hydroponic system with a plastic cover. Lettuce plants were planted at 30 days after germination in an NFT hydroponic system. Nutrient solutions were prepared with sources of potassium nitrate, calcium nitrate, urea phosphate, magnesium sulfate and a source of minor nutrifeed. The second cycle had the highest total dry mass and leaf area index (LAI) at 43 days after transplant (dat). The relative growth rate (RGR) declined over time. The absolute growth rate (AGR) presented a sigmoid behavior as a gaussian bell shape; the leaf area index (LAI) increased until 43 dat, with the second cycle presenting the highest value; the net assimilation rate (NAR) decreased over time, with the second cycle having the highest value at 22 dat. The chlorophyll content for this variety was low, with a yellow pigmentation in the plant. The stomatal conductance (SC) in the two cycles at transplant time presented low values caused by the stress leaded by an imbalance in the pH of the solution, when the plants adapted to the system, this value increased.


1962 ◽  
Vol 13 (4) ◽  
pp. 615 ◽  
Author(s):  
WR Stern ◽  
CM Donald

A study was made of the light regime and the growth of clover: (a) in mixed swards with varying proportions of grass; (b) in specially designed cultures in which grass and clover competed for light alone. The growth of the clover showed direct dependence on the level of radiation at the surface of the clover leaf canopy; it was positive when radiation values were above about 60–80 cal/cm²/day but fell to zero or negative rates at lower radiation levels. A relationship is presented between the level of radiation, the leaf area index, and the crop growth rate. It is shown that the optimum leaf area index increases with increasing levels of radiation; and further that as the leaf area index increases, the level of radiation required for maximum growth rate also rises. The implications in agricultural practice are discussed briefly.


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