scholarly journals Effects of Fall Applications of Chemical Defoliants, Urea, and Gibberellic Acid on Defoliation in the Fall and Performance of Hydrangeas During Forcing

HortScience ◽  
2009 ◽  
Vol 44 (6) ◽  
pp. 1604-1607
Author(s):  
Guihong Bi ◽  
Carolyn F. Scagel

In two separate experiments, Hydrangea macrophylla (Thunb.) Ser. ‘Merritt's Supreme’ plants were used to study the effects of foliar sprays of Def 6 (tributyl phosphorotrithioate, 2500, 5000, 7500, and 10,000 mg·L−1), gibberellic acid (GA, 50 mg·L−1), copper–EDTA (CuEDTA, 0.5% and 1.0%), Florel (2000 mg·L−1), and urea (3%) on defoliation in the fall and growth and flowering performance during forcing. Compared with controls (plants sprayed with water only), spraying plants with urea or GA alone had no influence on defoliation or plant performance during forcing, and spraying plants with Florel alone had no influence on defoliation but decreased total flower dry weight during forcing. Combining urea with Florel sprays decreased the adverse effects of Florel on plant quality and combining GA with Florel improved defoliation. Increasing concentrations of Def 6 and CuEDTA increased defoliation. Compared with controls, plants sprayed with CuEDTA exhibited more defoliation, showed bud and leaf necrosis, and produced lower flower dry weight during forcing. Combining urea with CuEDTA sprays decreased the adverse effects of CuEDTA on plant quality. Compared with controls, spraying plants with Def 6 increased defoliation, caused no visible damage to plants, and had no adverse effects on plant quality during forcing. Adding urea to sprays containing Def 6 decreased or had no influence on the efficiency of defoliation and increased total flower dry weight during forcing compared with Def 6 alone. Adding GA to sprays containing lower concentrations of Def 6 (2500 and 5000 mg·L−1) increased the efficiency of defoliation without adversely influencing plant quality.

2012 ◽  
Vol 21 (8) ◽  
pp. 992 ◽  
Author(s):  
Tom Lewis ◽  
Joanne De Faveri

Wildfire represents a major risk to pine plantations. This risk is particularly great for young plantations (generally less than 10 m in height) where prescribed fire cannot be used to manipulate fuel biomass, and where flammable grasses are abundant in the understorey. We report results from a replicated field experiment designed to determine the effects of two rates of glyphosate (450 g L–1) application, two extents of application (inter-row only and inter-row and row) with applications being applied once or twice, on understorey fine fuel biomass, fuel structure and composition in south-east Queensland, Australia. Two herbicide applications (~9 months apart) were more effective than a once-off treatment for reducing standing biomass, grass continuity, grass height, percentage grass dry weight and the density of shrubs. In addition, the 6-L ha–1 rate of application was more effective than the 3-L ha–1 rate of application in periodically reducing grass continuity and shrub density in the inter-rows and in reducing standing biomass in the tree rows, and application in the inter-rows and rows significantly reduced shrub density relative to the inter-row-only application. Herbicide treatment in the inter-rows and rows is likely to be useful for managing fuels before prescribed fire in young pine plantations because such treatment minimised tree scorch height during prescribed burns. Further, herbicide treatments had no adverse effects on plantation trees, and in some cases tree growth was enhanced by treatments. However, the effectiveness of herbicide treatments in reducing the risk of tree damage or mortality under wildfire conditions remains untested.


2020 ◽  
Vol 18 (1) ◽  
pp. 1093-1104
Author(s):  
Grzegorz Kulczycki ◽  
Elżbieta Sacała

AbstractThis study aimed to examine the influence of increasing doses of chromium (Cr) (26, 39, and 52 mg kg−1 soil) and elemental sulfur (S) (60 mg kg−1 soil) on growth, yield, and mineral nutrition in wheat and maize. Macro- and micronutrients and Cr concentrations were determined in the aboveground parts of plants. All examined doses of Cr caused a marked decrease in the fresh and dry weight of maize. Wheat was more tolerant than maize, and lower Cr doses caused a small but statistically significant increase in the total yield. Wheat accumulated more than twofold Cr than maize, and the concentrations increased with higher Cr concentrations in the soil. The application of S significantly improved the total biomass production and lowered the Cr content in both plants. Cr changed the mineral nutrition in both cereals, but the pattern of changes observed was not the same. Applying S alleviated some adverse effects caused by the Cr. Hence, it is concluded that the application of elemental S may be an effective strategy to reduce adverse effects in plants grown on soil contaminated by heavy metals, especially Cr.


2010 ◽  
pp. 132-140 ◽  
Author(s):  
MA Islam ◽  
MH Reza ◽  
SMAHM Kamal ◽  
MA Wazed ◽  
KM Islam

An experiment was conducted with a local cultivar of garlic to study the effects of planting date and gibberellic acid on the growth and yield of garlic at the field laboratory of the Department of Crop Botany, Bangladesh Agricultural University, Mymensingh during November 2001 to April 2002. Early planting influenced the plant height, leaf number, bulb diameter and total dry matter. With the delay in planting time starting from November 7, the yield was chronologically reduced in later plantings. Significantly the highest bulb yield (2.67 t/ha) was recorded when planting was done on November 7 and lowest yield (0.92 t/ha) was obtained from December 22 planted crop. Bulb yield was higher in control plants than those of GA3 treated plants. The interaction effects of planting date and different concentrations of GA3 differed significantly in respect of plant height, number of leaves, bulb diameter and dry weight of roots, leaves and bulbs and yield of garlic.


1981 ◽  
Vol 38 (1) ◽  
pp. 127-138 ◽  
Author(s):  
Paulo R.C. Castro ◽  
Roberto S. Moraes

This research deals with the effects of exogenous growth regulators on production of soybean plant (Glycine max cv.. Davis) under greenhouse conditions, At the flower anthesis, 2,3,5-triiodobenzoic acid (TIBA) 20 ppm was applied. Other two applications with TiBA, with intervals of four days, were realized. Before flowering, Agrostemin (1 g/10 ml/3 1), gibberellic acid (GA) 100 ppm, and (2-chloroethyl) trimethylammonium chloride (CCC) 2,000 ppm were applied. It was observed that CCC and TIBA reduced stem dry weight. Soybean plants treated with TIBA reduced weight of pods without seeds , seed number and seed weight.


1996 ◽  
Vol 121 (3) ◽  
pp. 414-418 ◽  
Author(s):  
Brian A. Kahn ◽  
Peter J. Stoffella

Seeds of `Rutgers California Supreme' tomato (Lycopersicon esculentum Mill.) were exposed to outer space conditions aboard the long duration exposure facility (LDEF) satellite in the space exposed experiment developed for students (SEEDS) project of the National Aeronautics and Space Administration (NASA). Seeds aboard the LDEF were packed in dacron bags forming four layers per sealed canister. Some of these seeds were used in Oklahoma and Florida for studies of germination, emergence, and fruit yield. Among all measured variables in three experiments, there was only one significant main effect of canister 2 versus canister 7 (for mean time to germination) and only one main effect of layer (for seedling shoot dry weight). There also were only two inconsistent canister x layer interactions in the germination tests. The contrast of Earth-based control seed versus space-exposed seed was significant four times: in Oklahoma in 1991 the mean time to germination of space-exposed seeds and the days to 50% of final germination were 0.7 days less than for Earth-based seeds, and in Florida in 1992 seedling percent emergence and shoot dry weight were increased by space exposure. Fruit yield and marketability were unaffected in plants grown from space-exposed seeds. These results support student findings from the SEEDS project, and provide evidence that tomato seeds can survive in space for several years without adverse effects on germination, emergence, and fruit yield.


2013 ◽  
Vol 31 (4) ◽  
pp. 259-266 ◽  
Author(s):  
Arjina Shrestha ◽  
Janet C. Cole

Water use, growth, and leaf necrosis of Burkwood viburnum, Korean spice viburnum, and leatherleaf viburnum were evaluated on plants grown in 0 (full sun), 30, or 60% shade during 2010 and 2011. In both years, total water use of Burkwood viburnum decreased with increased shade intensity. Water use of leatherleaf viburnum was lowest in 0% and highest in 30% shade. Daily water use was lower in 0% than in 30 or 60% shade for leatherleaf viburnum plants in August of both years and September of 2010 due to greater leaf necrosis, leaf abscission, and less growth in height and width. In both years, growth in height and width, and leaf number at harvest generally increased in all three species with increased shade intensity. All species had a larger leaf area, stem dry weight, and root dry weight in 30 and 60% than in 0% shade. Shade intensity did not influence root to shoot (R/S) ratio in Burkwood viburnum in 2010, but in 2011, a curvilinear relationship occurred between R/S ratio and shade intensity. Root to shoot ratio of Korean spice and leatherleaf viburnum decreased linearly in 2010 but curvilinearly in 2011 with increasing shade. Leaf necrosis ratings were lower in shaded plants of all three species in both years. Results indicate that greater plant growth, quality, and water use efficiency occurs when these three viburnum species are grown in shade than when they are grown in full sun.


Author(s):  
Y.T.M. Astuti ◽  
Adi Prawoto ◽  
Kumala Dewi

This experiment was carried out to study the photosynthate allocation between flush and young pods, and the effect of (naphthalene acetic acid) and (gibberellic acid) application to sink strength. Two cocoa clones KW 163 and KW 165 located in Kaliwining Experimental Station of Indonesian Coffea and Cocoa Research Institut were used on this experiment. Each clone was treated with flushes and without flush. Beside that, the young pods sprayed with NAA 250 mg L-1, GA 250 mg L-1, NAA 250 mg L-1 dan GA 250 mg L-1 and control (K = without NAA and GA). There were 2 x 4 treatment combinations for each clone, and replicated three trees for each combination. The parameter were cherelle wilt percentage, sucrose content, fresh and dry weight, long and diameter of healthy and wilting pods.The result showed that sink strength of young pods was lower than that of flushes, which caused application photosynthate translocation to the young pods was lower. NAA and GA application to the pods could improve sucrose allocation, increased pod weight and cherelle wilt was suppressed. The lack of photosynthate on young pod cause metabolism change, so pod became cherelle wilt. But, there was still not known the optimum concentration and method of application of those growth regulators to obtained minimum cherelle wilt.Key words: Cocoa, flush, pod, naphthylacatic acid, gibberellic acid, cherelle wilt.


2006 ◽  
Vol 41 (2) ◽  
pp. 251-255
Author(s):  
Luís Fernando Guedes Pinto ◽  
Marcos Silveira Bernardes ◽  
Antônio Roberto Pereira

Agroforestry systems are indicated as an alternative for sugarcane (Saccharum officinarum) cultivation in Piracicaba, SP, Brazil, however there are not many field experiments on plant performance under these conditions in the world. The objective of this work was to assess crop yield and partitioning in a sugarcane-rubber (Hevea brasiliensis) interface in on-farm conditions. The availability of irradiance for the crop along the interface was simulated and its effe ct over sugarcane dry matter production was tested. Crop yield was negatively affected by distance of the trees, but development and sucrose were not affected. Above ground dry matter increased from 16.6 to 51.5 t ha-1 from trees. Partitioning did not have a defined standard, as harvest index increased from 0.85 to 0.93, but specific leaf area was not significant along the transect, ranging from 13.48 to 15.73 m² kg-1. Light is the main factor of competition between the trees and the crop, but the relative importance of below ground interactions increases closer to the trees. Feasibility of the system depends on maturity of the trees and management strategies.


2014 ◽  
Vol 22 (2) ◽  
pp. 167-174 ◽  
Author(s):  
Omid Younesi ◽  
Ali Moradi

AbstractThe experiment was conducted in order to study effects of seeds priming with gibberellic acid (GA3) at 0, 3, 5 and 8 mM on germination, growth and antioxidant enzymes activity in alfalfa seedlings under salinity stress (200 mM NaCl). All control seeds germinated. The rate of germinated seeds was reduced to 48% in the presence of NaCl, and increased to 76% after seeds priming with 5 mM GA3. Priming with 5 mM GA3 was also correlated with an increase of dry weight of seedlings derived from both stressed and non-stressed seeds as well as with the reduction of electrolyte leakage (EL) and malondialdehyde (MDA) level in salt stressed seedlings. The activity of superoxide dismutase, catalase, guaiacol peroxidase and ascorbate peroxidase in primed and non-primed seeds increased in the presence of NaCl and after priming of seeds with 5 mM GA3, whereas only small effect on glutathione reductase activity in both primed and non-primed seeds was observed. The total ascorbate level was higher in both stressed and non-stressed seedlings from primed seeds. These results suggest that GA3 priming might increase the salt tolerance of alfalfa seedlings through enhancing the activities of antioxidant enzymes and reducing the membrane damage as estimated using biomarkers, EL index and MDA content.


1989 ◽  
Vol 16 (3) ◽  
pp. 265 ◽  
Author(s):  
TL Setter ◽  
H Greenway ◽  
T Kupkanchanakul

Submergence of rice in water at low CO2 concentrations was studied in phytotron experiments using plants in the 3rd to 4th leaf stage. Cultivars known to differ in tolerance to complete submergence were adversely affected by the same mechanisms but to a different degree. Submergence for 4-12 days either reduced dry weight production of the whole plant by 6 to 10 fold or even resulted in a loss of dry weight. Nevertheless, the emerging leaf elongated, and both ethanol insoluble material and protein content increased with time. These increases were associated with translocation of dry matter and nitrogen from expanded to expanding leaves. Submergence also reduced concentrations of soluble sugars and starch in all plant parts by 4 to 12 fold. In contrast, concentrations of potassium and free amino acids in shoots were either the same or, in the case of the emerging leaf, higher than in plants which were not submerged. These results indicate (i) these solutes were not limiting growth and (ii) the tissues retained their semipermeability to these solutes during submergence. Insufficient capacity of root metabolism in submerged plants was indicated by low rates of respiration, which persisted in the presence of glucose, and by a low ability to consume ethanol. A model is presented on the adverse effects of submergence of rice which considers possible interactions between CO2, low O2 and high ethylene concentrations.


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