| Effect of irrigation scheduling on leaf yield of non-heading Chinese cabbage (Brassica rapa L. subsp. chinensis) | Averbeke, W.
van | 2010 |
KeywordsCanal irrigation, consumptive water use, leafy vegetable, smallholder schemes, South Africa AbstractA field experiment conducted on the Dzindi canal irrigation scheme in the north of South Africa demonstrated that non-heading Chinese cabbage (Brassica rapa L. subsp. chinensis) needed to be irrigated at least twice per week to maintain the water content of the rooting zone close to field capacity and achieve maximum leaf yield. Irrigation scheduling practice affected both total consumptive water use and leaf yield of the crop and the latter two variables were strongly correlated (r = 0.91). Single applications of 20 mm per week, commonly practiced by smallholders on canal irrigation schemes in the region, limited yield to about two-thirds of the maximum achieved when the soil was irrigated to field capacity every other day. Pre-charging the upper 800 mm of the soil profile to field capacity followed by single applications of 20 mm per week increased yield, but only to 80% of the maximum, suggesting that the scope for improving water use efficiency in non-heading Chinese cabbage through the use of deficit irrigation was limited. AuthorsAverbeke, W.
van and Netshithuthuni, C. Year Published2010 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.2010.10640001 This article contributed by:
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| Response of local mustard germplasm to water stress | Modi, A.T. | 2010 |
KeywordsGermination, seed, seedling, wild mustard AbstractA preliminary study was conducted to compare three wild mustard (Brassica species) landraces with respect to germination capacity and seedling emergence under two water regimes. Seeds of three landraces [Isaha, Masihlal-isane (both Brassica juncea (L.) Czern & Coss) and Kway-imba (Brassica nigra (L.) W.D.J. Koch)] were characterised according to seed colour: black, brown, grey, greyish-black and reddish-brown. Seed quality was determined by germination test and seedling establishment in response to two water regimes [25% and 75% field capacity (FC)]. There were highly significant (P < 0.001) effects of landrace and seed colour with respect to germination capacity. Masihlalisane showed 99–100% germination for brown, grey and black seeds. For Isaha brown seeds displayed 85% germination, grayish-black seeds showed 95% germination and reddish-brown seeds showed 82% germination. Kwayimba showed the least germination capacity, and black seeds were the most dormant (close to 0% germination). Brown seeds of Kwayimba had 14% germination and reddish-brown seeds showed 22% germination. There was no significant effect of seed colour on seedling establishment. Seedling establishment under 25% FC was ˜45% for Isaha and Masihlalisane, and Kwayimba did not emerge. At 75% FC, there was ˜80% emergence for all landraces. However, by the end of the experiment (21 days after emergence) only seedlings grown under 75% FC were harvestable and the darker the seeds the better was the biomass (P < 0.01). It is concluded that water stress tolerance in wild mustard maybe associated with the trait of seed colour. AuthorsModi, A.T. and Mbatha, T.P. Year Published2010 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.2010.10640002 This article contributed by:
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| Are ‘ancient wheat species’ more adapted to hostile environments than modern bread wheat? | Sparkes, D.L. | 2010 |
KeywordsBiomass, einkorn, emmer, spelt AbstractThis preliminary study investigated whether three ‘ancient wheat species’, spelt (Triticum spelta L.), emmer (Triticum dicoccum) and einkorn (Triticum monococcum L.) are more adapted to hostile environments than modern bread wheat (Triticum aestivum L.) based on their physiological characteristics and comparative water use efficiencies. Spelt was found to have higher radiation use efficiency (RUE) than the other species and produced a similar amount of above ground biomass. However, bread wheat produced the highest yield, mainly due to a superior harvest index. Emmer had the lowest carbon isotope discrimination (Δ13C) which is expected to translate to the highest water use efficiency (WUE). AuthorsSparkes, D.L. Year Published2010 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.2010.10640003 This article contributed by:
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| A preliminary study to determine water stress tolerance in wild melon (Citrullus Lanatus L.) | Modi, A.T. | 2010 |
KeywordsCitrullus Lanatus, drought tolerance, indigenous crop, pot trial AbstractCommon wild melon (Citrullus Lanatus L.) is an indigenous crop that can contribute to the alleviation of food insecurity as it is an easy-to-grow food source with the potential for processing. The objective of this study was to test the potential of three landraces of common wild melon (‘Brown’, ‘Dark-Brown’ and ‘Very Dark-Brown’, respectively named for seed colour) for drought tolerance under controlled conditions in a glasshouse. Three media (sand, pine bark and a 1:1 mixture of sand and pine bark) were used to grow plants under three water regimes [75%, 50% and 25% Field Capacity (FC)]. Plant growth (height) was determined until plants reached approximately 50% flowering, at which stage biomass was determined. There were significant differences (P < 0.01) between landraces with respect to drought tolerance, as determined by plant growth and biomass. The mixture of sand and pine bark provided the best opportunity (P < 0.05) to grow wild melon under controlled environment conditions compared to sand or pine bark alone. The results of this study will be used as indicator for treatments to be used in a follow-up field experiment where wild melon will be grown during different seasons of the year in Pietermaritzburg, South Africa. AuthorsModi, A.T. and Zulu, N.S. Year Published2010 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.2010.10640004 This article contributed by:
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| An overview of indigenous crop development by the Mpumalanga Department of Agriculture and Land Administration (DALA) | Mathews, C. | 2010 |
KeywordsBambara, cassava, cowpea, food security, pigeonpea AbstractIndigenous as well as indigenized crops form part of the daily diet of the smallholder and developing farmers in the Mpumalanga province. Developmental efforts by national research institutes on these crops under smallholder environments have been negligible in the past due to the subsistence nature of these crops. The Mpu-malanga provincial department of agriculture, therefore, initiated programmes to improve productivity of these crops with the objectives of enhancing household food security and sustainability. This paper provides an overview on the potential, production constraints and the efforts taken by DALA to improve productivity of a few popular crops. Identification of improved varieties was given priority so as to minimize financial burden in terms of input costs to farmers in adopting improved technologies. Although several improved varieties have been identified by DALA in the past, these are not widely used by farmers due to the absence of institutionalized arrangement to produce and distribute seeds. Crop failure, coupled with nutritional inadequacies of the maize-based diet, lead to about 50% of the smallholder farming households living in conditions of severe poverty and malnutrition. Almost all of these households collect and utilize a number of wild plants or leafy vegetables to enhance food security. There is a great need to identify diversity of indigenous crops in terms of species, economic importance and consumption patterns as such studies have not been carried out in Mpumalanga so far. Furthermore, efforts need to be made to develop improved production packages for economically important species and to provide appropriate support facilities in terms of inputs, marketing and value adding. AuthorsMathews, C. Year Published2010 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.2010.10640005 This article contributed by:
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| Grain yield, nitrogen uptake and use efficiency components of South African irrigation wheat cultivars under different nitrogen management strategies | Otto, W.M. | 2010 |
KeywordsNUE, Triticum aestivum, nitrogen, yield AbstractThe effect of different N management strategies on the grain yield, N uptake and use efficiency components of five commercial wheat cultivars were investigated for two consecutive years at Riet River and Loskop irrigation schemes. The cultivars ranged ingrowth period to initial flowering, from 95, 102, 106, 108 and 109 days for SST 822, Steenbras, SST 876, Olifants and Baviaans. Management strategies consisted of zero (NO) and recommended Napplication split-applied at different growth stages (N1 = 100% at planting; N2 = 54% at planting, 23% at stem elongation and 23% at flag leaf; N3 = 38% at planting, 44% at stem elongation and 18% at flag leaf; N4 = 100% at stem elongation in the first year, and 37% at planting and 63% at stem elongation in the second year). The lowest grain yield and N uptake resulted for N0, followed by N4 and then either N1, N2 and N3. The longer-growing Baviaans, Olifants and SST 876 (more than 106 days to flowering) responded more to N fertilization than the shorter growing Steenbras and SST 822 (less than 102 days to flowering). This also applied to grain yield, N uptake and N harvest index. The cultivars SST 822 and Steenbras had the lowest and SST 876 the highest N physiological efficiency (NPE). Application of N had limited effect on the agronomic (NAE) and recoveryefficiency (NRE) of the element. The results of this study showed that several factors must be considered in the selection of N efficient wheat cultivars. AuthorsOtto, W.M. and du Preez, C.C. Year Published2010 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.2010.10639987 This article contributed by:
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| Targeting of early to intermediate maize hybrids for yield performanceand yield stability using SREG model | Setimela, P.S. | 2010 |
KeywordsGenotype x environment interactions, GGE biplots, maize hybrids, site regression model (SREG) AbstractThe effectiveness of targeting and predicting maize (Zea mays.L) hybrid performance is difficult when the magnitude of genotype x environment (GE) interaction and yield prediction cannot be interpreted and is only based on genotypes (G) and GE means. The traditional analysis of variance (ANOVA) is not sufficient in predicting and giving information into the patterns of genotypes and environments that give rise to GE interaction. The objectives of this study were to show the usefulness of G plus GE interaction (GGE) using the properties of GGE biplot based on the site regression (SREG) model analysis of a biplot in predicting yield performance and stability of early to intermediate maturing hybrids (EIHYB) grown in southern Africa. The SREG analysis model was based on regional trial data of EIHYB from three seasons (2005 - 2007) across 30 environments under four different management practices: well fertilized/rain fed conditions, managed nitrogen stress, managed drought stress, and managed low pH stress. GGE biplots were constructed using the first two principal components (PC1 and PC2) derived from singular value decomposition of environment-centered multi-environmental trials. The PC1 scores of the hybrids and the environments were plotted against their respective PC2 scores to effectively show mean performance and stability for grain yield across years and environments; discriminativeness vs. representativeness of test locations across the years and which-won-where. The SREG model showed that maize hybrids were under major environmental and GE interactions. In spite of large variation from year to year maize hybrids responded positively to better environmental conditions relative to grain yield performance and key environmental patterns could be established. AuthorsSetimela, P.S., Crossa, J. and Bänziger, M. Year Published2010 PublicationSouth African Journal of Plant and Soil Locations- Chitedze, Central Region, Malawi (-13.9815, 33.6372)
- Tsangano, Ntcheu, Central Region, Malawi (-15.15, 34.5833)
- Angonia, Tete, Mozambique (-14.6721, 34.2422)
- Chokwe, Gaza Province, Mozambique (-24.5323, 32.9832)
- Nampula, Mozambique (-14.7605, 39.3206)
- Sussundenga, Manica, Mozambique (-19.7103, 33.2588)
- Arusha, Tanzania (-3.3658, 36.6744)
- Ilonga, Tanzania (-9.0342, 36.8452)
- Tumbi, Tabora, Tanzania (-5.0732, 32.6913)
- Kasama, Northern, Zambia (-10.2084, 31.1825)
- Nanga, Sesheke, Western, Zambia (-16.6853, 25.025)
- Harare, Zimbabwe (-17.8292, 31.054)
- Chiredzi, Masvingo, Zimbabwe (-21.05, 31.6667)
- Gwebi Road, Harare, Zimbabwe (-17.9019, 30.9724)
- Kadoma, Mashonaland West, Zimbabwe (-18.3369, 29.9142)
- Harare, Zimbabwe (-17.8292, 31.054)
- Savé Valley Conservancy, Chiredzi, Masvingo, Zimbabwe (-20.5422, 32.0837)
DOI10.1080/02571862.2010.10639988 This article contributed by:
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| Phytophtho citophthro trunk and branch canker on Clementine mandarins in the Western Cape province of South Africa | Schutte, G.C. | 2010 |
KeywordsClementine mandarin, gumming, P. citrophthora, scion, soil AbstractBark and soil samples collected from trunks of Clementine mandarin cv. `Nules’ orchards in the Knysna area of South Africa were used for isolations to determine the cause of a canker on tree trunks. Phytophthora citrophthora was the predominant species isolated from trunks and was identified by its cultural, morphological, physiological and molecular profiles. A PCR study confirmed that the isolates were P. citrophthora. Using the BLASTn algorithm, all strains showed a high percentage sequence similarity (>98%) with significant alignments of E values = 0.0 and bit scores, aligning all South African strains with P. citrophthora ITS sequence data accessiblefrom Genbank and the Phytophthora database. P. citrophthora isolates showed that colonies on PDA had a petaloid growth habit. P. citrophthora was isolated from the bark and soil and was used in stem-inoculation studies. Under cool greenhouse conditions (<25°C), nursery trees inoculated with P. citrophthora, resulted in extensive gumming and eventual death of the nursery trees within two weeks whilst the rootstocks were not affected. P. citrophthora was also successfully re-isolated from the inoculated nursery trees, thereby confirming Koch’s postulates that P. citrophthora is the cause of trunk and branch cankers on Clementine mandarins in South Africa. AuthorsSchutte, G.C. and Botha, W.J. Year Published2010 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.2010.10639989 This article contributed by:
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| Response of Lachenalia growing in soil to interactions between nitrogen and phosphorus fertilisation in the nursery phase | Preez, C.c.
Du | 2010 |
KeywordsBulb quality, carbohydrates, leaf area, nutrients AbstractThe interactions between nutrients required by plants play an important role in sustainable crop production. Both nitrogen and phosphorus are involved in a number of important functions in the plant such as carbohydrate and protein formation. The need to investigate either the antagonistic or synergistic effects of nitrogen and phosphorus originated after studying the role of nitrogen fertilisation in Lachenalia bulb production. A pot trial with two Lachenalia cultivars (Ronina and Rupert), five nitrogen (0, 70, 180, 330 and 520 kg ha-~) and five phosphorus levels (0, 10, 30, 50 and 80 kg ha-~) was conducted in a glasshouse. The applications of both nitrogen and phosphoruswere split into a third at planting and two thirds 10 weeks after planting. Neither the interactions between nitrogen and phosphorus, nor the phosphorus level significantly influenced the leaf area of Lachenalia plants. Phosphorus significantly influenced bulb firmness. The firmness of Rupert bulbs increased and Ronina bulbs decreased with an increase in phosphorus. The interactions between nitrogen and phosphorus did not influence the fresh mass, circumference or firmness of Lachenalia bulbs. Neither the interactions between nitrogen and phosphorus, nor the phosphorus level significantly influenced the nutrient content of Lachenalia bulbs. The sucrose content of Lachenalia bulbs increased and the starch content decreased with an increase in phosphorus. Phosphorus had in comparison with nitrogen little influence on the growth and development of Lachenalia, probably due to sufficient residual soil phosphorus. A proper study to establish optimum soil phosphorus concentrations for Lachenalia is warranted. AuthorsPreez, C.c.
Du, Engelbrecht, G.M. and Spies, J.J. Year Published2010 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.2010.10639990 This article contributed by:
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| Effect of nitrogen levels and sources on production of Swiss Chard (Beta vulgaris var. Cicla) | Engelbrecht, G.M. | 2010 |
Keywordsleaf growth, fertilisation, nitrate content, vegetable nutrition AbstractTo optimise the production of Swiss chard, high levels of nitrogen fertiliser are often applied. This may have adverse effects on both the economy of fertilisation and the nutritional value of the human diet. Very little is known about both the optimum levels and influence of different sources of nitrogen on this crop under South African conditions. Glasshouse experiments were therefore conducted to determine the integrated effects of nitrogen level and source on the yield and quality of Swiss chard. Three Swiss chard seedlings were planted in each 4 L pot and later thinned to one plant per pot. Nine nitrogen levels (0, 100, 200, 300, 400, 500, 600, 700 and 800 kg ha-~ N) and six nitrogen sources (ammonium nitrate, calcium nitrate, potassium nitrate, ammonium sulphate, urea ammonium nitrate and urea) were combined in a factorial arrangement with four replications. The number of leaves harvested, leaf area, fresh and dry leaf mass, and leaf nitrogen content increased with increasing nitrogen levels up to 800 kg ha-~ N. Dry leaf mass was significantly higher where urea was applied compared to calcium nitrate. Although the different nitrogen sources did not differ significantly at the corresponding application levels, the nitrate accumulation within Swiss chard leaves was significantly increased with the use of ammonium nitrate. AuthorsEngelbrecht, G.M., Ceronio, G.M. and Motseki, P.C. Year Published2010 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.2010.10639991 This article contributed by:
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