Rainfall and the prediction of sorghum yield in South Africa

Wenzel, W. G.

doi:10.1080/02571862.2003.10634902

Cited by 6 publications

(7 citation statements)

References 7 publications

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“…This view agrees with Brush's theory (Brush, 1991) that farmers maintain a significant degree of crop diversity even as they adopt modern varieties in Vavilov centers. Similar farmer behavior has been reported from South Africa and Zimbabwe (Wenzel, 2003; Tongoona, 2003). Gao also reports that, due to the increase in the Chinese population and particularly the rapid growth of a market economy since the 1980s, most of the localities of wild rice (CWR) have been turned into cultivated rice fields, fish ponds, residences, factories, and highways.…”

Section: Introductionsupporting

confidence: 83%

Loss of Agro‐Biodiversity, Uncertainty, and Perceived Control: A Comparative Risk Perception Study in Austria and China

Schmidt

Wei

2006

Risk Analysis

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The biogeographical centers of origin of important food crops-called Vavilov centers-are considered to be crucial sources of genetic diversity for present and future crop-breeding programs and thus for human food safety worldwide. Global environmental change and more intensified modes of crop production may cause genetic erosion (loss of traditional crop varieties and loss of crop wild relatives), especially in Vavilov centers. The present study focused on how the risk of genetic erosion (or loss of agro-biodiversity) is perceived in comparison to 16 other risk topics by experts and lay people in Austria and China. The most striking result was that genetic erosion was perceived to be an exceptionally unknown and uncertain risk topic, given that only genetically modified organisms (GMOs) were perceived as being even more uncertain. As a consequence of the high uncertainty, the idea of applying the precautionary principle to further prevent genetic erosion is discussed. An unprecedented finding-one that differs from Austrian participants-is that the Chinese have a higher perceived control over all risk topics. The increased perception of controllability in China is discussed in light of the theory of reflexive modernization. This theory strives to explain the increased critical attitude in Western countries such as Austria toward scientific innovations and toward the idea that everything can be calculated and mastered at will. By revealing different notions of risk perception, this research also provides additional scientific input to risk communication efforts for public education.

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Section: Introductionsupporting

confidence: 83%

Loss of Agro‐Biodiversity, Uncertainty, and Perceived Control: A Comparative Risk Perception Study in Austria and China

Schmidt

Wei

2006

Risk Analysis

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“…Under field conditions, many factors will affect gene flow, i.e., the particular cultivar, field size (especially of the pollen donor), or planting density. The weather conditions (temperature, humidity and strength and direction of the wind and rainfall) during the growing period and especially during pollination will also affect the quantity and quality of the pollen available to the receptor (Arriola, 1995; Wenzel, 2003; Song et al, 2004). This is obviously the case for all field studies.…”

Section: Discussionmentioning

confidence: 99%

“…In terms of plant‐derived energy uptake, only rice, wheat ( Triticum aestivum L.), maize, and potatoes ( Solanum tuberosum L.) surpass sorghum in feeding humans worldwide. Sorghums are remarkably drought‐resistant and vitally important where the climate is too dry for maize, i.e., at annual rainfalls ranging from 350 to 750 mm (FAO, 2003; Wenzel, 2003), and it tolerates an astounding array of soils. These characteristics make sorghum an ideal food crop in semiarid areas of Africa (and elsewhere) where other crops, such as maize, would fail.…”

mentioning

confidence: 99%

Risk Assessment for Transgenic Sorghum in Africa: Crop‐to‐Crop Gene Flow in Sorghum bicolor (L.) Moench

Schmidt

Bothma

2006

Crop Science

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A crop‐to‐crop gene flow risk assessment study was conducted with Sorghum bicolor subsp. bicolor to estimate the impact of transgenic sorghum in (South) Africa. The trial was conducted with a central sorghum field (30 × 30 m) with male fertile donor plants that was surrounded by eight arms planted with male sterile recipient plants at a distance of 13 to 158 m from the central field. Gene flow was relatively high within the first 40 m and relatively low beyond that distance, but gene flow was detected even at the greatest distance investigated (158 m). The average hybridization or outcrossing rate for male sterile plants was 2.54% at 13 m, below 1% at a distance of 26 m or greater, and eventually dropping to 0.06% at 158 m. Outcrossing rates are expected to be even lower for male fertile plants, which were not investigated in this study. Mathematical models were used to estimate the maximum gene flow distance that is expected to be between approximately 200 and 700 m. These values are in line with observational data from sorghum plant breeders, who use an isolation distance of 100 m to achieve less than 1% genetic pollution. On the basis of the presence of fully fertile crop wild relatives and the weedy relative johnsongrass [S. halepense (L.) Pers.], which may form hybrids with crop sorghum, and on the fact that gene flow takes place, there is strong evidence that introgression of genetically modified‐ (GM)‐sorghum into crops and crop wild relatives will take place once GM‐sorghum is deployed.

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“…This was achieved by carrying out extensive surveys on apple trees cultivated under a wide range of conditions. Maximum grain yield in relation to total rainfall during the growing season was quantified in a similar way (Wentzel, 2003).…”

Section: Methodsmentioning

confidence: 99%

Use of Boundary Lines to Determine Effects of Some Salinity-associated Soil Variables on Grapevines in the Breede River Valley

Myburgh

Howell

2016

SAJEV

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The boundary line concept was used to assess grapevine responses to salinity-associated soil variables. Soil chemical status and grapevine responses were measured in 13 vineyards in the Breede River Valley during the 2001/2002 season. Chardonnay grafted onto 110R and 101-14 Mgt, as well as Ruby Cabernet on the same two rootstocks, was included. The selected vineyards were representative of the variation in salinityassociated soil variables, as well as of leaf and juice element contents previously reported for South African vineyards. Under the prevailing conditions, the four scion-rootstock combinations responded similarly to the salinity-associated variables. The results confirm that soil pH (KCl) should be at least 6.0 for grapevines. The salinity threshold for vineyards in the Breede River Valley should be between 0.7 dS/m and 1.5 dS/m to avoid growth and yield reductions. To reduce the risk of Na toxicity, the SAR should be below 3, and the soluble Na content in the soil should not exceed 5 mg/kg. If gypsum is used to reduce soil Na, it should be applied judiciously to avoid soil SO 4 accumulation, thereby reducing the risk of K and Mg deficiencies. Under the prevailing conditions, B and Cl toxicity apparently contributed to reduced vegetative growth. Therefore, soil Cl and B should be kept as low as possible, but care should be taken that B is not reduced to deficient levels. The boundary line concept proved to be useful for determining the effect of a single salinity-associated soil variable on grapevine response.

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Rainfall and the prediction of sorghum yield in South Africa

Cited by 6 publications

References 7 publications

Loss of Agro‐Biodiversity, Uncertainty, and Perceived Control: A Comparative Risk Perception Study in Austria and China

Loss of Agro‐Biodiversity, Uncertainty, and Perceived Control: A Comparative Risk Perception Study in Austria and China

Risk Assessment for Transgenic Sorghum in Africa: Crop‐to‐Crop Gene Flow in Sorghum bicolor (L.) Moench

Use of Boundary Lines to Determine Effects of Some Salinity-associated Soil Variables on Grapevines in the Breede River Valley

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