| Estimation of thrips (Fulmekiola serrata Kobus) density in sugarcane using leaf-level hyperspectral data | Abdel-Rahman, Elfatih M | 2013 |
Keywordsdensity, Fulmekiola serrata, hyperspectral data, sugarcane, thrips AbstractThe aim of this study was to investigate the potential use of leaf-level hyperspectral data to predict the density of sugarcane thrips Fulmekiola serrata (Kobus). A hand-held spectroradiometer was used to make the spectral measurements on spindle leaves of 4- to 5-month-old plants of sugarcane cv. N19 growing in commercial fields near Umfolozi, South Africa. A random forest algorithm followed by partial least squares regression was used for the analysis. Developed models were adequate to predict nymph numbers in December and adult numbers in March, but different models were needed for the thrips life stage assessed and the season when the estimation took place. AuthorsAbdel-Rahman, Elfatih M, Way, Mike, Ahmed, Fethi, Ismail, Riyad and Adam, Elhadi Year Published2013 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.2013.803616 This article contributed by:
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| Weed survey in cotton (Gossypium hirsutum L.) and sunflower (Helianthus annuus L.) fields in the Pandamatenga plains of northeastern Botswana | Abdullahi, A. E. | 2004 |
KeywordsBotswana, cotton, sunflower, weed survey AbstractSunflower and cotton fields in the Pandamatenga plains of northeastern Botswana were surveyed in 1998 and 1999 for weed infestations. Twenty-seven and 24 species were identified from the fields in 1998 and 1999, respectively. Nineteen and 17 species were found to be annuals in 1998 and 1999, respectively, with Amaranthus hybridus L. as the most abundant species. In 1998, Ipomoea coscinosperma Hochst., Phyllanthus maderaspatensis L., Trichodesma zylanicum (Burm. f.) R. Br. and Acalypha crenata L., all broadleaved species, were the most abundant after A. hybridus in that order; whereas in 1999 the most abundant species after A. hybridus were A. crenata, P. maderaspatensis, Euphorbia hirta L., and T. zylanicum. Setaria verticillata (L.)P. Beauv., which was the most abundant grass weed in 1998, declined in abundance in the following year and in 1999 Brachiaria eruciformis (Sm.) Griseb appeared in larger numbers than S. verticillata. Two grass weeds, Sorghum verticilliflorum (Steud)Stapf and Rottboellia exaitata L., which were present in small numbers in both crops during this survey, can pose a serious challenge to crop production in the area if not adequately controlled. AuthorsAbdullahi, A. E. Year Published2004 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.2004.10635017 This article contributed by:
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| Pruimonderstamme: Verdere evaluaste van plaaslik-geteelde klone | Acker, J. H. | 1988 |
KeywordsPlum rootstocks, trunk circumference, yield efficiency AbstractDrie-en-twintig plaaslik-geteelde pruimonderstamseleksies is met virusvrye, klonale Marianna, virusbesmette Marianna en perskesaailing vergelyk. In teenstelling met perskesaailing wat oorwegend Kakamas en Du Plessis is, word hierdie seleksies vegetatief vermeerder. Kumulatiewe opbrengs, stamomtrek en opbrengsdoeltreffendheid is as maatstawwe vir vergelyking gebruik. Siegs 16-4, 13-61 en 16-13 hou belofte in en is geselekteer vir verdere evaluasie teen variërende plantdigthede met verskillende bostamkultivars. Seleksie 16-4 is 'n groeikragtige onderstam met 'n hoër kumulatiewe opbrengs as Marianna en perskesaailing. Dit is ten opsigte van opbrengsdoeltreffendheid vergelykbaar met die kontroles. Die twee groeikragtige seleksies 13-61 en 16-13 se opbrengsdoeltreffendheid is net so goed soos dié van virusvrye Marianna en perskesaailing. Nie een van die verdwergende en semi-verdwergende onderstamme wat getoets is se prestasie was van so 'n aard dat hui vir verdere evaluasie geselekteer kan word nie. AuthorsAcker, J. H. and Calitz, F. J. Year Published1988 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.1988.10634275 This article contributed by:
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| The optimal rooting medium for minisetts of potato (Solanum tuberosum L.) | Addae-Kagyah, K. A. | 1994 |
KeywordsSubstrate, minisett propagation, Solanum tuberosum L. AbstractThree different rooting media, namely, river sand, sawdust and wood shavings, were used for rooting various sizes of minisetts of potato (Solanum tuberosum L.), uniformly pre-treated with wood ash, indolebutyric acid (IBA), Captan and Lindane. The best substrate was found to be pure river sand, followed by wood shavings and lastly, sawdust. Four sizes of minisetts were used in the experiment, i.e. 5 g, 10 g, 20 g and 40 g. It was apparent from the results that the 10-g minisetts rooted better (P > 0.05) than the others. AuthorsAddae-Kagyah, K. A. Year Published1994 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.1994.10634323 This article contributed by:
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| Rate and timing of nitrogen fertilizer applications on wheat grown under dryland and supplementary irrigation | Adjetey, J. A. | 2001 |
Keywordsirrigated and dryland wheat, nitrogen uptake AbstractField experiments were carried out at the University of Sydney Farm, to examine nitrogen fertilizer application strategies for increasing N uptake and productivity of wheat (Triticum aestivum L.) grown on a red-brown earth (Natrixeralf) in Australia, under dryland and supplementary irrigation. Increasing N rate increased shoot dry matter and N uptake consistently but grain yield response was greatly dependent on soil moisture or rainfall in the post-heading period. Water availability at this time determined kernel weight and hence grain yield, even when sufficient grain number had been established. Split application of N increased N uptake most, when the second dose was applied at tillering. On the other hand, delayed applications to the time of heading or anthesis resulted in a relatively lower uptake of N even with supplementary irrigation. The effect of a single pre-sowing application was similar to that applied at sowing or early tillering. We conclude that a split application of N is important for increasing N uptake when the second dose is applied during tillering rather than at heading or anthesis. AuthorsAdjetey, J. A., Searle, P.
G.E. and Campbell, L. C. Year Published2001 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.2001.10634394 This article contributed by:
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| Invloed van nitraat:ammoniumverhoudings op die ontwikkeling van Zea mays L. | Adriaanse, F. G. | 1988 |
KeywordsNitrate:ammonium ratio, plant characteristics, Zea mays L. AbstractDie invloed van drie nitraat:ammoniumverhoudings by twee stikstofkonsentrasies op planteienskappe is met blomtyd en na fisiologiese volwassenheid vir suiwerlyne gemeet. 'n Kwartssandkultuur is as groeimedium in 'n glashuis gebruik. Toenemende NH4 +-verhoudings het planthoogtes, blaaroppervlaktes en droëmateriaalproduksie van verskillende plantkomponente verminder. Die akkumulasie van totale N in die stamme tydens die graanvul- periode is verhoog deur hoër NH4 +-verhoudings by albei N-konsentrasies. Die translokasieverlies van totale N uit die blare tydens die graanvulperiode was minder met toenemende NH4 +-verhoudings by 100 en 400 mg N −1. Die 3:1 nitraat:ammoniumverhouding wat die hoogste translokasieverlies vanuit die blare gehad het, was egter 'n uitsondering op hierdie reël. AuthorsAdriaanse, F. G. and Human, J. J. Year Published1988 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.1988.10634268 This article contributed by:
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| Die relatiewe belang van die vorm en konsentrasie van stikstof in die wortelsone op die ontwikkeling van Zea mays L. | Adriaanse, F. G. | 1988 |
KeywordsNitrate:ammonium ratio, nitrogen uptake, Zea mays L. AbstractDie invloed van ses nitraat:ammoniumverhoudings by 200 mg N l1 in een proef en twee ander verhoudings by 50, 100 en 200 mg N l1 in 'n tweede proef is op droëmateriaalproduksie en stikstofinhoud ondersoek. Die algehele beste behandeling was 'n 3:1 nitraat:ammoniumverhouding by 100 mg N l1. Hierdie behandeling was betekenisvol beter as 'n 3:1-verhouding by 200 mg N l1 en 'n 1:0-verhouding by 100 of 200 mg N l1 vir droëmassaproduksie en stikstofopname. Nitraat:ammoniumverhoudings van 2:3,3:2,1:4,4:1 en 3:1 by 200 mg N l1 het betekenisvol hoër N% in die bogrondse plantdele bo 'n 1:0-verhouding by dieselfde N-konsentrasie gegee. Vyf basters het betekenisvol van mekaar verskil in hul vermoë om stikstof op te neem. Hierdie verskille het verskil vir die twee proewe. AuthorsAdriaanse, F. G. and Human, J. J. Year Published1988 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.1988.10634269 This article contributed by:
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| Die rol wat nitraat: ammoniumverhoudings speel in die effektiewe benutting van stikstof by Zea mays L. | Adriaanse, F. G. | 1986 |
KeywordsNitrate: ammonium ratio, nitrogen utilization, Zea mays L. AbstractDie invloed van verskillende nitraat: ammoniumverhoudings by sub- en supra-optimale stikstofkonsentrasies op die opname en benutting van stikstof is ondersoek. Effektiewe stikstofbenutting is in terme van saadopbrengs per eenheid opgeneemde stikstof gemeet. Die beste nitraat: ammoniumverhouding was 3:1 by 100 mg N l−1. Hierdie verhouding het 'n hoogs betekenisvolle hoër benutting van opgeneemde stikstof bo 'n 1:0- of 1:1-verhouding by 100 mg N l−1 gehad. Nitraat: ammoniumverhoudings van 3:1 en 1:1 by 400 mg N l−1 was erg nadelig ten opsigte van saadproduksie en die effektiewe benutting van stikstof. 'n Hoër ammonium-N-konsentrasie by dieselfde stikstofkonsentrasie in die voedingsoplossing het die stikstofinhoud (%N) in die plantdele betekenisvol verhoog. Hierdie verhoging het egter nie gepaard gegaan met 'n verhoogde stikstofopname nie. S.-Afr. Tydskr. Plant Grond. 1986, 3: 57–60 AuthorsAdriaanse, F. G. and Human, J. J. Year Published1986 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.1986.10634189 This article contributed by:
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| Effect of soil tillage, crop rotation and nitrogen application rates on bread-baking quality of spring wheat (Triticum aestivum L.) in the Swartland wheat producing area of South Africa | Agenbag, G. A. | 2006 |
KeywordsBread-baking quality, crop rotation, nitrogen-fertiliser rates, spring wheat, tillage methods AbstractSpring wheat (Triticum aestivum L.) is produced in the wheat producing areas of the Western Cape Province, Republic of South Africa, primarily for bread-baking purposes. Milling and baking characteristics are therefore of utmost importance. In a long-term tillage and crop rotation experiment in the Swartland, it was found that during the 2000 growing season, flour yield was increased by conventional tillage but hectolitre mass did not respond to tillage during the same season or on average for the period 1992–1998. Although grain protein content and ultimately loaf volume were also higher with conventional tillage when compared to no-tillage, the latter resulted in the highest grain protein yield owing to slightly higher grain yield obtained with no-tillage. The inclusion of a legume crop (lupin) and canola in rotation with wheat had little effect on either milling or baking characteristics, possibly owing to the fact that legumes were only planted once in a four-year cycle. Increased N-fertiliser rates (140 kg N ha−1) resulted in reduced hectolitre mass, but higher grain protein when compared to low N rates of 60 kg N ha−1. This study once more illustrated the complexity of the bread-baking process and the need for good management practices in order to obtain both high yield and good bread-baking quality under Mediterranean climatic conditions. AuthorsAgenbag, G. A. and Maali, S. H. Year Published2006 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.2006.10634749 This article contributed by:
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| Rooting responses of guayule (Parthenium argentatum Gray) cuttings to hormone solutions | Agenbag, G. A. | 2005 |
KeywordsGuayule, Parthenium argentatum, rooting hormones, vegetative propagation AbstractVegetative propagation of selected guayule (Parthenium argentatum Gray), with elite qualities of vigorous growth and high latex yield, was Investigated. Rooting responses of guayule cuttings to treatment solutions of indole butyric acid (IBA), naphthalene acetamide (NA) and naphthalene acetic acid (NAA) were determined. Specific concentrations of hormone solutions were applied to guayule cuttings, cultivar AZ-3, and rooting response was determined in terms of rooting percentage, root length and root dry weight. Naphthalene acetic acid treatment rooted the highest percentage of cuttings (52.38%) at a concentration of 60 mg I−1. Indole butyric acid treatment produced the longest roots (147.83 mm) at a concentration of 120 mg I−1. Naphthalene acetamide contributed the heaviest root dry mass (1.8 g) at a concentration of 120 mg I−1. Results indicated that all three hormones were concentration specific in improving root formation, root length and root weight when compared to the controls. AuthorsAgenbag, G. A., Pieterse, P. J., Reinten, E. Y. and Bekaardt, C. R. Year Published2005 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.2005.10634719 This article contributed by:
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