Estimating the risk associated with drying-off strategies for irrigated sugarcane before harvest

1999 ◽  
Vol 50 (1) ◽  
pp. 65 ◽  
Author(s):  
M. J. Robertson ◽  
R. C. Muchow ◽  
R. A. Donaldson ◽  
N. G. Inman-Bamber ◽  
A. W. Wood
Keyword(s):  
South Africa ◽  
Systems Approach ◽  
Sucrose Concentration ◽  
Climatic Variability ◽  
Dry Weight ◽  
Field Studies ◽  
Cane Yield ◽  
Climate Data ◽  
Soil Model ◽  
Harvest Dates

The development of recommendations for drying-off management in sugarcane is difficult due to climatic variability and lack of knowledge of the sensitivity of changes in sucrose content and cane yield to severity of water deficit. Relative cane biomass targets were developed for drying-off irrigated sugarcane before harvest based on derived relationships between cane yield, cane dry weight, and sucrose concentration, using pooled data from previous field studies. These targets were then linked to a crop–soil model and long-term climate data to determine the economically optimum duration of drying-off, and its variability from season to season for 2 locations in Australia and one location in South Africa, for a range of harvest dates and soil types. The crop–soil model was validated on yields measured in 37 drying-off treatments conducted in South Africa and Australia. The simulation results show that the required drying-off duration can be highly variable, although the level of variability is not necessarily correlated with rainfall per se. There were interactions between soil type and harvest date, but not at every location. The systems approach outlined here can be useful in developing recommendations for drying-off where experience is limited, such as in expanding areas of sugar industries, for districts in which the practice of irrigation is increasing, or for harvest dates outside the current harvesting season.

Systems view of integrated water quality monitoring within the requirements of the new national water policy in South Africa

1998 ◽  
Vol 38 (11) ◽  
pp. 141-148 ◽  
Author(s):  
P. Marjanovic ◽  
M. Miloradov
Keyword(s):  
South Africa ◽  
Water Quality ◽  
Water Policy ◽  
Systems Approach ◽  
Water Quality Management ◽  
Water Quality Monitoring ◽  
Point Sources ◽  
Quality Monitoring ◽  
Efficient Manner ◽  
National Water

The new National water policy will change the way water quality is managed in South Africa. The paper considers the water policy and the repercussions it will have for water quality monitoring in South Africa. Using the systems approach the paper discusses an integrated water quality monitoring system for ambient water quality and point and non point sources of aquatic pollution. The proposed methodology makes possible continuos assessment of water quality in an efficient manner so as to support water quality management in South Africa.

scholarly journals Rust and leaf spot diseases on American elderberry plants

2017 ◽  
Author(s):  
◽  
Kaley Hensel
Keyword(s):  
Leaf Spot ◽  
Dry Weight ◽  
Growing Season ◽  
Significant Loss ◽  
Leaf Wetness ◽  
Conservative Estimate ◽  
Sambucus Nigra ◽  
Shoot Dry Weight ◽  
Harvest Dates ◽  
High Level

Elderberry rust (Puccinia sambuci Schewin.) Arthur (=P. bolleyana) and leaf spot diseases are frequently found in commercial American elderberry (Sambucus nigra L. subsp. canadensis L.) plantings throughout the growing season in Missouri. Thus, studies were conducted to ascertain if rust infections affect plant growth, fruiting, or berry puree quality. Rust symptoms were observed in early April at 9 to 18[degrees] C, [greater than or equal to] 3 h leaf wetness, and [greater than or equal to] 85% relative humidity. When young, potted elderberry plants averaged 3 to 6 rust pustules/plant, vegetative growth was not adversely affected. However, field-grown elderberry plants heavily infected with rust (137 pustules/cane) lost nearly twice as many leaves as controls during the growing season, indicating rust-induced defoliation. Shoot dry weight of these heavily infected canes was also 32% less than that of controls. First and last harvest dates were advanced by the high level of rust infection on 'Wyldewood' elderberry canes, but not by low pustules numbers ([less than] 6 pustules/plant) on 'Bob Gordon' or 'Ozark' plants. Similarly, berry yields were not significantly different at low infection levels, even though rust-infected 'Bob Gordon' plants had a 31% reduction in yield with an estimated $440/ha loss of income. Heavily-infected 'Wyldewood' canes had a significant loss in berry yield (47%) and potential income ($2,295/ha), assuming a conservative estimate of five canes/plan. In another study, Colletotrichum was isolated from elderberry leaf spot lesions and identified before subsequent re-inoculation of elderberry plants with this pathogen. Three species of Colletotrichum (C. salicis Funkel, C. kahawae subsp. ciggaro Wollenw., and C. aenigma C.M. Tian and Z. Li) were putatively identified as being casual agents of leaf spot indicating the diversity of species within this genus on elderberry plants.

scholarly journals Pengaruh Sitokinin Eksogen dan Sukrosa terhadap Produksi Biomassa dan Alkaloid Canthinone di dalam Kultur Suspensi Sel Pasak Bumi (Eurycoma longifolia Jack.)

2012 ◽  
Vol 12 (2) ◽  
pp. 143
Author(s):  
Luthfi Aziz Mahmud Siregar
Keyword(s):  
Cell Suspension ◽  
Sucrose Concentration ◽  
Cell Suspension Cultures ◽  
Dry Weight ◽  
Suspension Cultures ◽  
Eurycoma Longifolia ◽  
Eurycoma Longifolia Jack

The effect of addition cytokinins and modification of sucrose concentration on growth and alkaloid canthinoneproduction in cell suspension cultures of Eurycoma longifilia Jack were studied. The additions of cytokines, BAand kinetin, show effect on the production of biomass and alkaloid in cell suspension of E. longifilia Jack. Theoptimum totals of two-alkaloids were obtained on addition 4.44 μM BAP and without kinetin, respectively. Theaddition of 4.44 μM BA (6-benzyladenine) into TAM medium stimulated increased total of 9-hydroxycanthine-6-one,but decreased total of 9-methoxycanthin-6-one. While the addition of 2.32 - 9.29 μM kinetin (6-furfurylaminopurine)into TAM medium decreased total of two alkaloids (from 0.582 mg to 0.461 - 0.257 mg per 25 ml medium). Whensucrose concentration in TAM medium was increased from 3% to 5%, production of biomass would increase from0.374 g to 0.585 g dry weight per 25 ml medium. While total of two-alkaloids increase from 0.328 mg to 0.441 mgper 25 ml medium when concentration of sucrose in TAM medium was increased from 3% to 4% sucrose.

Sethoxydim and Crop Oil Concentrate Increase Pyridate Phytotoxicity in Transplanted Cabbage (Brassica oleracea)

1997 ◽  
Vol 11 (1) ◽  
pp. 81-87 ◽  
Author(s):  
Robin R. Bellinder ◽  
Jonathan Kirkwyland ◽  
Russell W. Wallace ◽  
Marija Arsenovic
Keyword(s):  
Brassica Oleracea ◽  
Dry Weight ◽  
Field Studies ◽  
Crop Injury ◽  
Before And After

Greenhouse and field studies were conducted in 1991 and 1992 to determine the potential for interaction among pyridate (0.5, 1.0 kg ai/ha), sethoxydim (0.22 kg ai/ha), and crop oil concentrate (COC) (1.25% v/v) applied alone or in two- and three-way combinations to transplanted cabbage. Additionally, the effect of applying sethoxydim and COC 1 and 2 d before and after application of pyridate was investigated. In greenhouse-grown cabbage, injury increased twofold and dry weight was reduced 15% when pyridate dose was doubled. Sethoxydim increased pyridate injury significantly, reducing dry weight 31%. When COC was applied with pyridate, injury increased and dry weight decreased linearly. Despite substantial crop injury 7 d after treatment with pyridate alone, pyridate + sethoxydim, and pyridate + COC, yields of field-grown cabbage were reduced significantly in 1 yr only when the three materials were combined. Pyridate injury decreased as time between sethoxydim + COC applications, before and after pyridate was applied, increased.

Row Spacing and Seeding Rate Effects on Eastern Black Nightshade (Solanum Ptycanthum) and Soybean

2007 ◽  
Vol 21 (1) ◽  
pp. 124-130 ◽  
Author(s):  
Adrienne M. Rich ◽  
Karen A. Renner
Keyword(s):  
Dry Weight ◽  
Field Studies ◽  
Production Costs ◽  
Row Spacing ◽  
Seeding Rate ◽  
Soybean Yield ◽  
Eastern Black Nightshade ◽  
Solanum Ptycanthum ◽  
Black Nightshade ◽  
Rate Effects

Reducing seeding rates in 19- or 76-cm row soybean below the optimum rate may reduce soybean competitiveness with weeds, and indirectly increase production costs to the grower. Field studies in 2001 and 2002 evaluated the effect of soybean seeding rate and row spacing on the emergence, growth, and competitiveness of eastern black nightshade (EBN) in soybean. EBN emergence ceased within 45 d after planting (DAP), and was similar across soybean seeding rates and row spacing. EBN control by glyphosate was not affected by soybean population or row spacing. Soybean planted in 19-cm rows was more competitive with EBN, regardless of seeding rate. Increasing the soybean seeding rate in 76-cm rows from 185,000 seeds/ha to 432,000 seeds/ha reduced EBN dry weight threefold at East Lansing and nearly twofold at Clarksville in 2002. There was no increase in EBN density or dry weight in 19-cm row soybean planted at 308,000 seeds/ha compared with 556,000 seeds/ha, whereas a seeding rate of 432,000 seeds/ha in 76-cm row soybean did not suppress EBN dry weight or increase soybean yield in the presence of EBN compared with a seeding rate of 308,000 seeds/ha.

Notes on the systematics and nomenclature of Tritonia (Iridaceae: Crocoideae)

Bothalia ◽  
2006 ◽  
Vol 36 (1) ◽  
pp. 57-61
Author(s):  
P. Goldblatt ◽  
J. C. Manning
Keyword(s):  
South Africa ◽  
Field Studies ◽  
Type Specimen ◽  
New Combination ◽  
Western Cape ◽  
Tropical Africa ◽  
Western Half

Study of some early types of species now known to belong to the genus  Tritonia Ker Gaw l.. a member of Iridaceae. sub­family Crocoideae, comprising some 28 species of southern and south tropical Africa, has shown the need for some nomen- clatural adjustments. Ixia undulata Burm.f. (1768) is an earlier name for T. crispa (L.f.) Ker Gawl. based on Gladiolus crispus L.f. (1782) and the combination  T. undulata (Burm.f.) Baker must be used for the species, which is native to the western half of Western Cape, South Africa. The variety  T. crispa var. parx iflora is also reduced to synonymy. The type specimen of Ixia gladiolaris Lam. (1789), currently considered a synonym of Tritonia securigera (Aiton) Ker Gawl.. has flowers that lack the characteristic tooth-like ridges on the lower tepals of the latter, and corresponds closely to the eastern southern African  T.  lineata (Salisb.) Ker Gawl., based on Gladiolus lineatus Salisb. (1796). The new combination  T. gladiolaris (Lam.) Goldblatt J.C. Manning is made and  T. lineata is reduced to synonymy.  Montbretia lacerata and  Tritonia lacerata. erroneously regarded as synonyms of T. crispa, are combinations based on Gladiolus laceratus Burm.f., a species that remains unidenti­fied because no type is known and the description is too vague to permit its identification. Lastly, field studies have shown that the cnsped-leaved T. watermeveri is connected by a series of morphological intermediates to typical  T. securigera. which has straight leaves and identical flowers. The new combination  T. securigera subsp. watermeveri (L.Bolus) J.C.Manning Goldblatt is proposed for this taxon.

Economic and interference threshold densities of quackgrass (Elytrigia repens) in potato (Solanum tuberosum)

Weed Science ◽  
1998 ◽  
Vol 46 (2) ◽  
pp. 176-180 ◽  
Author(s):  
Régis Baziramakenga ◽  
Gilles D. Leroux
Keyword(s):  
Yield Loss ◽  
Dry Weight ◽  
Field Studies ◽  
Potato Yield ◽  
Hyperbolic Function ◽  
Yield Losses ◽  
Economic Threshold ◽  
Elytrigia Repens ◽  
Shoot Number ◽  
Dry Biomass

Field studies were conducted in 1989 and 1990 at St-Augustin, Quebec, Canada, to determine the economic threshold density of quackgrass in potato. Potato yield losses due to quackgrass interference increased with quackgrass population density. Potato yield ranged from 33 to 73% in 1989, and from 19 to 44% in 1990. The relationship between potato yield losses and quackgrass densities was described by a rectangular hyperbolic function. Dry weight of quackgrass proved to be the best predictor of potato yield loss compared to shoot number. The interference thresholds for 10% potato yield loss amounted to 25 shoots m−2or 20 g total dry biomass m−2. The economic threshold varied between 0.04 and 2 shoots m−2or 0.0165 and 1.5 g total dry biomass m−2, depending on the variables considered.

Inhibition of the calcium paradox in isolated rat hearts by high perfusate sucrose concentrations

1994 ◽  
Vol 266 (5) ◽  
pp. H1729-H1737
Author(s):  
A. Omachi ◽  
R. A. Kleps ◽  
T. O. Henderson ◽  
R. J. Labotka
Keyword(s):  
Pressure Gradient ◽  
Sucrose Concentration ◽  
Choline Chloride ◽  
Weight Ratio ◽  
Dry Weight ◽  
Calcium Paradox ◽  
Oncotic Pressure ◽  
Rat Hearts ◽  
The Moment ◽  
Langendorff Hearts

If a colloid osmotic (oncotic) pressure gradient develops across the myocyte membrane during the calcium paradox, adding an oncotic agent to the perfusate should be inhibitory. After 10-min perfusion with Ca(2+)-free Krebs-Henseleit (KH) buffer under constant flow at 34 degrees C, myoglobin release was measured from Langendorff hearts reperfused with Ca(2+)-containing KH buffer. When the Ca(2+)-free medium contained 200 mM sucrose, myoglobin release was reduced to 5% of that observed in the absence of sucrose, a change that was not seen when 200 mosM NaCl, choline chloride, LiCl, or glycerol was added. Replacement of 75 mM NaCl in the perfusate with 150 mM sucrose resulted in myoglobin release values that were 4% of the control. Plots of myoglobin release against sucrose concentration under these hypertonic and isotonic conditions yielded similar though separate curves. Sucrose also inhibited increases in wet weight-to-dry weight ratio and decreases in ATP and phosphocreatine contents. These results support the hypothesis that an oncotic pressure gradient arises during the calcium paradox at the moment of increased membrane permeability and plays a major role in its development.

Spring Wheat (Triticum aestivum)Cultivar Responses to Trifluralin and Postemergence Herbicides

1995 ◽  
Vol 9 (2) ◽  
pp. 352-355 ◽  
Author(s):  
Sharon A. Clay ◽  
Jim F. Gaffney ◽  
Leon J. Wrage
Keyword(s):  
Spring Wheat ◽  
Plant Stress ◽  
Dry Weight ◽  
Field Studies ◽  
Growth And Yield ◽  
Hard Red Spring Wheat ◽  
Wheat Field ◽  
Shoot Dry Weight ◽  
Cultivar Responses ◽  
Postemergence Herbicides

Trifluralin is used for weed control in wheat but may reduce vegetative growth and yield. Postemergence (POST) herbicides may cause additional plant stress to trifluralin-stressed wheat. Field studies at Groton, SD in 1991 and 1992 and at Highmore, SD in 1992 evaluated the effects of 2,4-D-amine, difenzoquat, metsulfuron, and a combination of fenoxaprop-ethyl + 2,4-D-ester + MCPA-ester on hard red spring wheat cultivars ‘2375,’ ‘Prospect,’ and ‘Butte 86’ seeded in areas treated with preplant incorporated trifluralin either in the spring before seeding (0.56 kg ai/ha) or the previous year (1.12 or 2.24 kg ai/ha). Trifluralin applied alone in the spring, and followed by some POST herbicides, reduced shoot dry weight and grain yield. Trifluralin reduced the yield of Prospect the most and the yield of 2375 the least. Yields of trifluralin-treated wheat were reduced 23% by metsulfuron and 14% by fenoxaprop-ethyl + 2,4-D + MCPA compared to yields of wheat treated with only the respective POST herbicide. Yields were not reduced with any trifluralin-POST herbicide combination when trifluralin was applied a year prior to seeding wheat.

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