| Die invloed van swartpunt by gars (Hordeum distichon) op ontkieming en α-amilase-aktiwiteit | Maree, P.
C.J. | 1985 |
Keywordsα-Amylase, barley, black-end, germination capacity, germination energy, Hordeum distichon AbstractGesonde garssaad en swartpuntgarssaad vanaf verskillende lokaliteite is vergelyk. Die ontkiemingsenergie van gesonde saad was na een maand beduidend beter as die van swartpuntsaad. Na 'n opbergingperiode van twee tot drie maande het geen verskille in ontkiemingsenergie en -kapasiteit meer voorgekom nie. Die a-amilase-aktiwiteit was laer in swart- puntsaad as in gesonde saad. Ontkiemingsenergie en a- amilase-aktiwiteit het verskil tussen monsters vanaf verskillende lokaliteite. Ontkiemingskapasiteit is nie benadeel deur die voorkoms van swartpunt nie. Die resultate dui daarop dat swartpuntsaad wel geskik is vir gebruik as moutgars. S.-Afr. Tydskr. Plant Grond 1985, 2: 35–37 AuthorsMaree, P.
C.J. and Caims, A.
L.P. Year Published1985 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.1985.10634136 This article contributed by:
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| The origin of textural lamellae in Quaternary coast sands of Natal | van Reeuwijk, L. P. | 1985 |
KeywordsClay-size particles, coast sands, micromorphology, origin, textural lamellae AbstractA new concept of the formation of textural subsoil lamellae has been developed on the basis of their morphology in aeolian coastal deposits in Natal. It has been concluded that they are initiated somewhere at depth in the profile by a single, partial impediment to the downward movement of clay-size materials. The impediment may or may not be readily observable. Because clay is accumulated at the upper surface of a lamella and lost at the lower surface, the lamella will migrate upwards through the profile although the net movement of day ts downward. After a lamella has departed from the initiating plane, a new lamella will start forming at this level and the process will be repeated. Movement of a lamella upwards will eventually lead to its disappearance at shallow depth in the profile by wasting as the diminishing supply of clay no longer balances the loss Micromorphological data have indicated that large amounts of clay in lamellae occur in a non-oriented fashion. The largest porpor of this clay is illuvial, whereas some may have formed neogenetically S Ah J Plant Soil 1985. 2: 38–44 Authorsvan Reeuwijk, L. P. and de Villiers, J. M. Year Published1985 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.1985.10634137 This article contributed by:
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| Screening for DIMBOA (benzoxazinone) concentration among South African inbred maize lines and sorghum cultivars | Malan, C. | 1984 |
KeywordsBenzoxazinone, DIMBOA, maize cultivars, sorghum cultivars AbstractTwenty-seven popular South African inbred maize lines, four commercial maize cultivars, two sweet corn cultivars and two grain sorghum cultivars were screened by means of a rapid, semi-quantitative method to determine DIMBOA concentration. Significant differences were found between inbred lines. Sweet corn cultivars exhibited a relatively high concentration of DIMBOA, while grain sorghum contained a very low concentration. Although differences in concentration between plants cultivated from different seed sizes were found, no definite trend could be established. S. Air. J. Plant Soil 1984, 1: 99–102 AuthorsMalan, C., Visser, J. H. and van de Venter, H. A. Year Published1984 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.1984.10634120 This article contributed by:
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| Growth responses of inbred maize lines with high and low DIMBOA (benzoxazinone) contents to atrazine | Malan, C. | 1984 |
KeywordsAtrazine, benzoxazinone, DIMBOA, maize AbstractThe growth response of five inbred maize lines with high and low DIMBOA content were compared in the presence of 3 and 12 ppm atrazine. A growth-promoting effect of atrazine on roots, mesocotyls and coleoptiles was observed in dark-grown seedlings of the low DIMBOA concentration lines, whereas virtually no effect could be detected in high DIMBOA concentration lines. S. Afr. J. Plant Soil 1984, 1: 103–105 AuthorsMalan, C., Visser, J. H. and van de Venter, H. A. Year Published1984 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.1984.10634121 This article contributed by:
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| Fisiologiese blaarabnormaliteite en bolopbrengs by katoen (Gossypium hirsutum L.) soos deur kalium-, kalsium- en boorvoeding beïnvloed | Combrink, N.
J.J. | 1984 |
KeywordsBoron, calcium, cotton, physiological leaf abnormalities, potassium AbstractPhysiological leaf abnormalities and boll yield of cotton (Gossypium hirsutum L.) as affected by potassium, calcium and boron nutrition. A pot trial with a sand medium and two levels each of K, Ca and B nutrition, factorially arranged, was carried out with cotton over a period of 13 weeks. A low level of B nutrition resulted in stunted plants. The high K level suppressed Ca uptake, resulting in a K X Ca interaction. A low boll yield and distorted leaves in the growing point were associated with deficient Ca nutrition. A high K level had a detrimental effect only at the low Ca level. Necrotic lesions, that may be confused with infection by Xanthomonas malvacearum (E.F. Smith) Dowson, occurred on leaves at the low Ca and B levels. Damage to cell walls in the spongy parenchyma or to phloem cells of the leaf veins preceded the development of necrotic lesions. Transparent spots were the result of a group of enlarged cells containing almost no chloroplasts, which developed between the two epidermal layers. S. Afr. J. Plant Soil 1984, 1: 106–110 AuthorsCombrink, N.
J.J. Year Published1984 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.1984.10634122 This article contributed by:
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| Potato irrigation scheduling and straw mulching | Burgers, M. S. | 1984 |
KeywordsIrrigation scheduling, mulch, potatoes, soil temperature AbstractThe effect of mulching and irrigation frequency on tuber yield was investigated during three seasons at the Glen Agricultural Research Institute The soil on the experimental site consisted of a loamy sand topsoil and sandy clay subsoil with 94 mm total available water in the top 775 mm of the soil profile. A wheal straw mulch of 14 t ha−1 reduced soil temperature and increased tuber yield consistently (averaged over all irrigation treatments in all three seasons, mulched plots produced 30% more tubers than bare plots). Tuber yield also responded well to increased irrigation frequencies it was concluded that the cooling effect ot frequent irrigation could be obtained much cheaper by mulching It is recommended that from commencement of stolonization, potatoes should be irrigated with 50 mm of water as soon as 50 mm of water has evaporated from a Class A pan for an unmulched crop and 65 mm for a mulched crop. S Afr J. Plant Soil 1984. 1: 111–116 AuthorsBurgers, M. S. and Nel, P. C. Year Published1984 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.1984.10634123 This article contributed by:
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| Practical means of scheduling irrigation of maize using a programmable pocket calculator | Mottram, R. | 1984 |
KeywordsIrrigation scheduling, maize AbstractThe irrigation scheduling model IRRISCHED-4, here described, enables the irrigator to choose one of four techniques for estimating crop water use, depending upon data available. Daily inputs include maximum and minimum temperatures, sunshine hours, leaf area index, crop factor, rain, and irrigation. The model is run on a programmable pocket calculator. The techniques used in determining daily soil-water status depend on Class A pan evaporation, the Linacre and Blaney & Criddle equations, and a modified version of the Priestley & Taylor equation. These four techniques were tested over two seasons at Cedara and compared to lysimeter-determined values of evapotranspiration. All methods perform satisfactorily but the modified Priestley & Taylor method provided the most reliable evapotranspiration estimates, owing to the utilization of leaf area index data. S. Afr. J. Plant. Soil 1984, 1: 117–121 AuthorsMottram, R. and Clemence, R.
St. E. Year Published1984 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.1984.10634124 This article contributed by:
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| Potassium effects on stalk strength, premature death and lodging of maize (Zea mays L.) | Melis, Maria | 1984 |
KeywordsLodging, maize, potassium, premature death, stalk strength AbstractIn a field trial with maize, applications of potassium (K) proved to have a highly significant effect on stalk strength, premature death, root lodging and stalk breakage. A week prior to harvest the percentage of lodged plants varied from 77% in plots which received 50 kg K ha−1 to 47% in plots which received 200 kg K ha−1. Although some stalk breakage of green plants and root lodging were evident, premature death was clearly the prime cause of lodging. Significantly, premature death and stalk breakage were lowest in plots which received no K fertilization. The virtual absence of ears precluded the establishment of the carbohydrate sink, considered to play an important role in predisposing plants to invasion by stalk-rot organisms. The marked effects of K observed in this study suggest that K stress could profitably be used as a selection aid in breeding programmes. It seems probable that discrimination in terms of standability will be reduced when crops are adequately fertilized with K. S. Afr. J. Plant Soil 1984, 1: 122–124 AuthorsMelis, Maria and Farina, M.
P.W. Year Published1984 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.1984.10634125 This article contributed by:
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| Invloed van sekere grondeienskappe op matrikspotensiaal by, en tydsverloop tot, veldkapasiteit | Beukes, D. J. | 1984 |
KeywordsField capacity, hydraulic conductivity, matric potential, soil texture AbstractVeldkapasiteit (VK) is bepaal op 5x5 m-persele op verskeie gronde in Wes-Kaapland. Tekstureel het die gronde gewissel van growwe sand tot sandklei. Gronde van die Avalon-, Dundee-, Fernwood-, Hutton-, Oakleafen Westleighvorme is gebruik. Matrikspotensiaal (ψm) is gemonitor met kwiktensiometers, terwyl waterinhoud gravimetries bepaal is. Veldkapasiteit is op vyf gronddieptes bepaal en het gewissel van 4,9% tot 27,2% op massabasis. In totaal is 105 bepalings op 23 persele uitgevoer. Lineêre korrelasiestudies het getoon dat daar 'n swak verwantskap bestaan tussen % klei (r = 0,40), % slik + klei (r = 0,53), % fynsand (r = −0,52) en hidrouliese geleivermoë (K) (r = −0,42), onderskeidelik, en matrikspotensiaal by VK. Hierdie tekstuureienskappe en K is nog swakker gekorreleer met die tydsverloop vanaf versadiging tot VK. Trosontledings het alle waarnemings in 'n aantal goed afgebakende groepe geplaas op basis van die genoemde deeltjiegroottefraksies en grond- watereienskappe. Vyf tekstuurgroepe is geïdentifiseer. Die ontledings het getoon dat (i) daar geen uniekheid is in die groeperings sover dit lokaliteite of grondvorme betref nie; (ii) matrikspotensiaal by VK 'n funksie van hidrouliese geleivermoë is; (iii) daar gevolgllk nie 'n unieke verband bestaan tussen tekstuur en ψ by VK nie; en (iv) daar geen verwantskap bestaan tussen tekstuur of hidrouliese geleivermoë, en die tydsverloop vanaf versadiging tot VK nie. S.-Afr. Tydskr. Plant Grond 1984, 1: 125–131 AuthorsBeukes, D. J. Year Published1984 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.1984.10634126 This article contributed by:
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| Reaction of oriental tobacco to spacing and topping treatments at three levels of nitrogenous fertilizer application | Lamprecht, M. P. | 1984 |
KeywordsNicotiana tabacum, nitrogen, oriental tobacco, spacing, topping AbstractThree levels of nitrogenous fertilizer were applied to oriental tobacco (Nicotiana tabacum L. cv. Elcatra) at different spacings and topped to 14 and 28 leaves per plant respectively. Yield, income, total nitrogen and total alkaloids of the cured leaves increased, and total reducing sugars decreased as nitrogen application was increased. Acceptable levels of quality attributes such as total nitrogen, alkaloids, and reducing sugars, as well as a high income, were obtained when plants were spaced 20 cm from each other in 25 cm twin rows with an interrow space of 50 cm, topped to 28 leaves and fertilized with a high level of N (72 kg N ha−1). S. Afr. J. Plant Soil 1984, 1: 132–134 AuthorsLamprecht, M. P. and van der Merwe, W.
J.C. Year Published1984 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.1984.10634127 This article contributed by:
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