Skip to main content

Albert Modi

Followers

0

Following

0

Mentions

1

Public Views

Interests

Uploads

Papers by Albert Modi

Relationship between laboratory and field assessments of common bean (Phaseolus vulgaris L.) seed quality indicators

Acta agriculturae Slovenica

The objective of this study was to extend the measure of seed quality beyond seed germination usi... more The objective of this study was to extend the measure of seed quality beyond seed germination using three common bean (Phaseolus vulgaris. L) cultivars. Under laboratory conditions, total seed germination was included in calculation of other seed performance measures, mean germination rate and germination vigour index. These parameters were used to produce a new parameter, total potential value for germination. The laboratory measures were duplicated under field conditions over two seasons to produce comparable data for seedling emergence, mean emergence rate and emergence vigour index. Consequently, total potential value for emergence was derived. The crop was grown under field conditions at three seeding rates (177 000 plants ha-1, 150 000 plants ha-1 and 115 000 plants ha-1). Prediction of seed performance under field conditions was extended by measuring plant size from the first trifoliate to initiation of reproductive stage. During this period, new measures comparable to those ...

Potential role for wild vegetables in household food security: a preliminary case study in Kwazulu-Natal, South Africa

African Journal of Food, Agriculture, Nutrition and Development, May 26, 2006

The value of wild edible vegetables in food security has not been given sufficient attention in S... more The value of wild edible vegetables in food security has not been given sufficient attention in South Africa. Consequently, there are no formal interventions that seek to encourage people to use traditional vegetables as sources of essential nutrients. Studies on the role of wild leafy vegetables in food security could provide important information for development of policies on careful exploitation of natural resources for human sustenance. The objective of this study was to provide a rapid assessment of general knowledge about wild leafy vegetables among subsistence farmers from Ezigeni, a rural location in South Africa, and to determine the availability of wild leafy vegetables from cropping fields during spring-before the cropping season started. A focus group discussion and transect walk were used to collect qualitative data on knowledge of traditional vegetables. Availability of wild leafy vegetables was quantified using one-square-meter plots, randomly located in a cropping field and in an area that has never been cultivated (veld). Results showed that knowledge of wild leafy vegetables among the participants was positively correlated with age. Education status improved knowledge of wild vegetables for middle-aged participants, but not for the youth (35 years or younger). Availability of wild edible leafy vegetables (plant numbers and yield) increased from August to October, but there was a significant difference between species. Data from a focus group discussion showed that wild leafy vegetable availability occurred early in spring, when traditional crops were less abundant. It is concluded that knowledge of wild leafy vegetables may be lost in the near future, unless efforts are made to educate younger generations about their importance. They could be used as an important source of nutrients during the pre-cropping season, before traditional crops are available for human consumption. It is recommended that agronomic investigations into cultivation of wild leafy vegetables that are adapted to rural areas where exotic leafy vegetables are not widely available be undertaken. Those studies could contribute significantly in government policies to improve food security in rural areas, and in the improvement of wild vegetable status, whose potential as sources of nutrition is currently undervalued.

Effect of plant population and mulching on wild watermelon growth and yield

A field study of wild watermelon (Citrullus lanatus) establishment and yield using seed to compar... more A field study of wild watermelon (Citrullus lanatus) establishment and yield using seed to compare the effects of different population densities (3,000, 6,000, 9,000 and 12,000 plants ha−1) and mulching rates (0, 2.5 and 5 t ha−1) with grass mulch on soil water, temperature, vine length, number of branches and leaves per plant, fruit number per plant and per hectare, total yield, fresh and dry fruit mass was conducted. The fruit per hectare and total yields increased as the plant population increased resulting in high yields in the range from 6,00012,000 plants per hectare. Yield was more influenced by plant population than by mulching. Mulching did not affect growth and yield of wild watermelon but it affected soil temperature and soil moisture. More water was conserved, while soil temperature was reduced upon increased mulching. This was shown by 31 and 12.6% increase in volumetric water content when the amount of mulch was increased by 2.5 and 5 t/ha, respectively. However, this ...

Marginal areas and indigenous people – Priorities for research and action

Context Business-as-usual is not working. Marginal environments and the indigenous people who cul... more Context Business-as-usual is not working. Marginal environments and the indigenous people who cultivate them have one thing in common – they are forgotten. Their soils and climates, crops and livestock, beliefs and knowledge systems rarely attract academic interest, policy studies or investment. Marginal environments refer to Less-Favourable Agricultural Areas (LFAAs) characterized by constrained agricultural potential and resource degradation attributable to biophysical and politico-socio-economic factors.1 Their low production potential is driven by rugged terrains, extreme weather conditions, poor soil and water quality, lack of socio-economic connectivity and limited exposure to agricultural intensification opportunities. In such regions, drought and erratic rainfall, salinization, and other factors present significant constraints for intensive agriculture. Marginal environments encompass all LFAAs and any favourable agricultural areas (e.g., areas not constrained by biophysical...

Photoinhibition influences protein utilisation during seed germination in Cleome gynandra L

African Journal of Biotechnology, 2008

Seed storage proteins are mobilised during germination, especially at radicle protrusion. The obj... more Seed storage proteins are mobilised during germination, especially at radicle protrusion. The objective of this study was to examine changes in protein expression during germination of Cleome gynandra in the presence or absence of light and at constant or alternating temperatures. Seeds were germinated at alternating 30/20 or 20oC in darkness and in continuous white light. Four prominent proteins of 28 - 32 kDa and 18 - 20 kDa, and a fifth low molecular weight protein of 13 kDa were observed in seeds harvested at brown pod maturity. These proteins remained unchanged during photoinhibition as shown on SDS-PAGE gels. Photoinhibition is a pseudodormancy condition during which seed storage proteins are not utilised.

Association of seed coat colour with germination of three wild mustard species with agronomic potential

Seed dormancy and germination present significant challenges when wild species are domesticated f... more Seed dormancy and germination present significant challenges when wild species are domesticated for cultivation and economic exploitation. Wild plant species are generally characterized by dormant seeds with variable germination widely spread over time. The objective of this study was to evaluate the influence of colour selection on seed germination of wild mustard (Brassicaceae) species that have been identified as wild edible leafy vegetable in South Africa. Seed lots were separated by colour and germinated in a completely randomized design (CRD) after chilling and after-ripening for 6 months. The light seed lot of cultivar Kwayimba (K) showed higher germination percentage than the dark seed lot of the same cultivar but colour selection did not improve the germination in cultivars Isaha (I) and Maslahlisane (M). The dark seed lot of K recorded the lowest germination percentage and the slowest germination rate. Chilling improved the speed of germination in wild mustards, but after-...

Correction: Multi-criteria suitability analysis for neglected and underutilised crop species in South Africa

PLOS ONE, 2021

Evaluating nutritional content among Bambara groundnut lines

Journal of Food Composition and Analysis, 2021

Abstract Bambara groundnut (Vigna subterranea (L.) Verdc) has the potential to address food insec... more Abstract Bambara groundnut (Vigna subterranea (L.) Verdc) has the potential to address food insecurity in sub-Saharan Africa. However, a lack of cultivars with improved nutritional quality hinders its potential. This study evaluated nutritional content in the grain of 19 Bambara groundnut lines. The nutritional content of the lines varied significantly (p

Assessing progress towards sustainable development over space and time

Nature, 2020

To address global challenges 1-4 , 193 countries have committed to the 17 United Nations Sustaina... more To address global challenges 1-4 , 193 countries have committed to the 17 United Nations Sustainable Development Goals (SDGs) 5. Quantifying progress towards achieving the SDGs is essential to track global efforts towards sustainable development and guide policy development and implementation. However, systematic methods for assessing spatio-temporal progress towards achieving the SDGs are lacking. Here we develop and test systematic methods to quantify progress towards the 17 SDGs at national and subnational levels in China. Our analyses indicate that China's SDG Index score (an aggregate score representing the overall performance towards achieving all 17 SDGs) increased at the national level from 2000 to 2015. Every province also increased its SDG Index score over this period. There were large spatio-temporal variations across regions. For example, eastern China had a higher SDG Index score than western China in the 2000s, and southern China had a higher SDG Index score than northern China in 2015. At the national level, the scores of 13 of the 17 SDGs improved over time, but the scores of four SDGs declined. This study suggests the need to track the spatio-temporal dynamics of progress towards SDGs at the global level and in other nations.

Soil fertility assessment and management from the perspective of farmers in four villages of eastern South Africa

Soil Use and Management, 2019

Understanding farmer perceptions of soil fertility is necessary for the development of appropriat... more Understanding farmer perceptions of soil fertility is necessary for the development of appropriate assessment methods for sustainable agro‐ecosystems. This study investigated farmer perceptions of soil fertility and management in four villages of eastern South Africa. A questionnaire was administered to 50 farmers from each village to obtain a general overview of local soil knowledge as well as soil fertility perceptions and assessment. Ten farmers were then chosen from each village for in‐field walks and to gather in‐depth knowledge of local soil fertility concepts, soil‐crop associations and soil management. During in‐field walks, farmers were asked to identify fertile, moderately fertile and low soil fertility plots in their fields from which topsoil samples were taken for laboratory fertility analysis. Local soil fertility descriptors included crop performance and yield, soil texture, stoniness and consistence. Using these descriptors, farmers have developed specific soil use an...

Watermelon landrace seedling establishment and field performance in response to differing water regimes

African Journal of Agricultural Research, 2012

Wild watermelon (Citrullus lanatus) is an indigenous crop whose agronomic potential has not been ... more Wild watermelon (Citrullus lanatus) is an indigenous crop whose agronomic potential has not been well investigated in South Africa. However, the country has a significant amount of the crop's germplasm in the form of landraces. Three local landraces of watermelon were compared for seedling establishment and production under controlled and dry land field conditions. The objective of the study was to determine watermelon landrace seedling establishment, plant growth and fruit production under controlled environment using different growth media (pine bark, sand and a mixture of pine bark and sand (1: 1 (v/v) and dry land field conditions in response to planting dates from September, 2008 to January, 2009. Results showed that seedling establishment was significantly affected by growth medium. Pine bark produced significantly at (P < 0.05) larger seedlings than the mixture or sand alone due to its capacity to hold water better than the other two media. Seedling production of wild watermelon did not improve significantly when the field capacity of the growing medium was increased above 50% suggesting potential drought tolerance for the crop. Early field planting was found to be associated with larger fruit size in spite of low soil water availability early in the season, another evidence for potential drought tolerance.

Selection of Superior Genotypes in 37 Clones of Camu-Camu by Repetitivity Analysis

Journal of Agricultural Science, 2017

In order to select camu-camu superior genotypes, a comparative of clones from natural populations... more In order to select camu-camu superior genotypes, a comparative of clones from natural populations, farmer plantations and an experimental field of the National Institute of Agrarian Innovation (INIA), was established in 2004 in varzea, at the Peruvian Amazon Research Institute (IIAP). Nine harvests between 2006 and 2016 have been evaluated, including variables in vegetative and reproductive development states. Statistical analysis was performed using the SPSS program for analysis of variance and SELEGEN REML/BLUP for repetitivity analysis of “fruit yield” (FY) and “fruit weight” (FW) with 5 and 4 measurements (years) respectively. For FY, a repetitivity index r = 0.117±0.07 was obtained with a selective precision of 0.63 and efficiency of 1.84 where clones 69, 48, 58, 50, 61, 13, 18, 29, 49 and 32, were selected in descending order of merit. For FW, r = 0.690±0.294 was obtained with selective precision of 0.948, efficiency of 1.14 and selection of clones 44, 13, 26, 23, 69, 64 22, 5...

Revitalising Agricultural Education and Training in South Africa

Envisioning AET in the Future 131 key finding 1: Continued Challenges Facing AET 131 key finding ... more Envisioning AET in the Future 131 key finding 1: Continued Challenges Facing AET 131 key finding 2: The (Dis-)Enabling Environment 132 Governance and Coordination (CS1&2) 132 The Case of the Agricultural Colleges (CS3) 132 key finding 3: Relevant Institutions and Adequate Resources 133 Articulation and Integration (CS3-7) 133 Reversing the Inverted Pyramid 134 Funding and Resource Allocation (CS 3-7) 135 key finding 4: An Adequate Number of Appropriately Trained Graduates 135 Relevance and Responsiveness of Curricula 135 The AET System is in Dire Need of Quality,

A Comparative Study on Antioxidant Potential of Selected African and Exotic Leafy Vegetables

HortScience, 2016

African leafy vegetables (ALVs) are thought to contain an immense variety of antioxidants, which ... more African leafy vegetables (ALVs) are thought to contain an immense variety of antioxidants, which may provide nutritional and health benefits. However, there is limited, robust, and comparable information describing their nutritional composition. The aim of this study is to determine the antioxidant potential of selected ALVs [black jack (Bidens pilosa L.) and amaranth (Amaranthus hybridus L.)] in comparison with exotic leafy vegetables (ELVs) [lettuce (Lactuca sativa L.), green cabbage (Brassica oleracea), red cabbage (B. oleracea var. capitata)]. Different nonenzymatic and enzymatic antioxidant assays were used to determine plant carbohydrates (CHOs) using high-performance liquid chromatography (HPLC), phenols (Folin–Ciocalteu), ascorbic acid, carotenoids, total antioxidant capacity (TAOC) using reducing ferric ion antioxidant potential (FRAP) and 1,1-diphenyl-2-picrylhydrazyl free radical (DPPH) assays, super oxide dismutase (SOD), catalase (CAT), and peroxidase (POD). Both amaran...

Transitioning toward Sustainable Development Goals: The Role of Household Environment in Influencing Child Health in Sub-Saharan Africa and South Asia Using Recent Demographic Health Surveys

Frontiers in public health, 2016

The Millennium Development Goals are now replaced by 17 sustainable development goals. The emphas... more The Millennium Development Goals are now replaced by 17 sustainable development goals. The emphasis of old goals was on improving water, sanitation, and child mortality conditions in developing countries. The study explored the major question about the association between different household environment conditions with child survival and health in Sub-Saharan African and South Asian countries in the current scenario. This paper estimated the risk of death, morbidity, and undernutrition among children living in households with the improved sources of water, sanitation, and non-solid cooking fuel. Two sources of information are explored in this study. First, data from World Health Statistics (WHS)-2014 for all of the Sub-Saharan African and South Asian countries were used. Second, available standard Demographic and Health Survey (DHS) performed in the countries of Sub-Saharan Africa and South Asia after 2010 was included in the study. It resulted in the inclusion of 15 countries which...

Comparing Extraction and Quantity/Intensity Based Recommendations for Nitrogen, Phosphorus and Potassium Recommendation

Journal of Agricultural Science, 2015

Conventional, extraction based fertilizer recommendations for phosphorus and potassium have been ... more Conventional, extraction based fertilizer recommendations for phosphorus and potassium have been shown to lack mechanistic basis, thus unreliable. This has led to an urgent need for the development and evaluation of accurate and consistent phosphorus and potassium recommendations approaches with mechanistic basis. Also it has been shown that integrating nitrogen mineralization on nitrogen recommendations, has a potential of improving nitrogen recommendations. We established two parallel pot trial studies with the objective of comparing between extraction based fertilizer recommendations with alternative strategies. The first study was to compare the effect of integrating nitrogen mineralization on N recommendations. Second pot experiment in addition to N being recommended after integrating N mineralization; P and K were also recommended with an alternative strategy, which was derived from quantity/intensity relations. No negative impacts were observed on crop growth and nutrient uptake due to the integration of mineralizable nitrogen, despite nitrogen amounts being lower compared to treatments where N was applied without adjusting for mineralizable N. The same was true for the second pot trial, P and N recommended by conventional approach were higher, yet the crop response was not concurrently improved by higher rates. Potassium rates recommended by alternative strategy were higher and this was concurrent with potassium uptake. We therefore concluded, that this NPK recommendation experimental approach (N e P e K e) is superior to its conventional counterpart (N c P c K c). Hence, more reliable recommendations can be developed using this approach and this might reduce environmental footprint of agro-ecosystems, and reduce input cost for farmers where warranted.

Seedling Establishment of Selected Wild Watermelon Landraces in Response to Varying Water Regimes

II International Symposium on Underutilized Plant Species: Crops for the Future - Beyond Food Security, 2013

The challenge of food security requires that agricultural production is no longer based on the na... more The challenge of food security requires that agricultural production is no longer based on the narrow genetic material present in conventional crops. Whereas conventional crops have been genetically improved to suit management practices of the modern farmer, the future farmer requires that there be access to a wide variety of genetic material for economic exploitation and to respond to the challenges of climate change in a sustainable fashion. This study was designed to determine seed quality and seedling establishment of wild watermelon (Citrullus lanatus (Thunb.) Matsumura and Nakai) landraces found in two provinces of South Africa, KwaZulu-Natal (sub-tropical) and Eastern Cape (semi-arid). In addition to provenance, seed colour was used to separate the germplasm into three seedlots: B, DB and VDB. Following one season of seed production at a research farm in Pietermaritzburg, KwaZulu-Natal, seeds were tested for germination capacity, before seed lot response to water stress was determined in three substrates made of pine bark, a 1:1 mixture of fine sand and pine bark and fine sand only. The substrates were kept at 75% F.C. (Field Capacity), 50% F.C. and 25% F.C., to create varying levels of water regimes during 12 weeks of seedling growth in a glasshouse (16/21°C (day/night) and 60% RH). Leaf proline content was determined at seedling harvest. There were significant differences (P<0.05) between seed lots with respect to seed quality and seedling yield, which consistently showed that 'Brown'>'Very Dark Brown'>'Dark Brown'. Wild watermelon was responsive to water stress during seedling growth, but high water regimes compromised water use efficiency. Proline accumulation correlated with water stress.

Contribution of the seed to fruit development: A tool to understand avocado tree management and fruit maturity parameters

Mesocarp percentage moisture of 'Fuerte' and 'Hass' avocado (Persea Americana Mil... more Mesocarp percentage moisture of 'Fuerte' and 'Hass' avocado (Persea Americana Mill.) fruits harvested during 1999-2000 and 2001-2002 growing seasons was determined at different stages of development and correlated to seed water potential. The two relations declined with increasing fruit ontogeny, and were linearly and signifi cantly infl uenced by the number of days after full bloom (stage of development) and the cultivar (P< 0.001). Immature 'Fuerte' fruit had lower seed water potential than 'Hass' (- 0.86 ± 0.09 MPa and - 1.18 ± 0.11 MPa respectively). At maturity, the early harvested 'Fuerte' had higher seed water poten- tial (- 2.13 ± 0.13) than the late harvested 'Hass' (- 1.35 ± 0.06 MPa). Seed water potential of developing 'Fuerte' and 'Hass', for which a stochiometric relationship change to the cell sap content was observed, was measured to negatively correlate with mesocarp percentage moisture (r 2 = 0.991)....

Hydro-Priming in Dry Bean (Phaseolus vulgaris L.)

Research Journal of Seed Science, 2009

Growth temperature and plant age influence on nutritional quality of <i>Amaranthus</i> leaves and seed germination capacity<sup>#</sup>

Water SA, 2009

As a leafy vegetable, Amaranthus can be harvested at different stages of plant growth, ranging fr... more As a leafy vegetable, Amaranthus can be harvested at different stages of plant growth, ranging from young seedlings to the late juvenile stage, but data on the changes in leaf nutritional value with plant age are scanty. The objective of this study was to determine the effect of growth temperature on Amaranthus leaf yield and nutritional quality at different stages of plant growth. Five species, A. hybridus var. cruentus, A. hypochondriacus, A. tricolor, A. thunbergii and A. hybridus were compared for their response to hot (33/27 o C), warm (27/21 o C) and cool (21/15 o C) temperature regimes (day/night) in separate glasshouses. Plants were harvested at 20, 40 and 60 d after sowing and leaf yield, minerals (Ca, P and Fe), total protein content, amino acid (methionine and lysine) content and antioxidant activity (inhibition of linoleic acid oxidation) were determined. Seed yield and germination capacity, during two years of after-ripening, were also determined. Results showed that leaf protein content differed significantly (P < 0.01) between species. It was also significantly (P < 0.01) influenced by the growth temperature and stage of plant growth. The pattern of changes in the amounts of lysine and methionine was comparable to that of protein content, but A. thunbergii showed significantly higher amino acid content than the other species. Amaranthus leaves also contained significantly (P < 0.01) more lysine than methionine, regardless of the species and growth temperature. The phosphorus content of leaves was not significantly affected by temperature and stage of plant development, and there were also no significant differences between species. However, the amounts of both calcium and iron changed significantly (P < 0.05) with stages of plant development and with increasing temperatures for all species. The antioxidant activity of Amaranthus leaves increased consistently with plant age and there were significant (P < 0.01) differences between stages of plant development and growth temperature. Warm temperature regimes were most favourable (P < 0.01) for biomass accumulation in all species. Seed production under cool and hot temperatures significantly (P < 0.01) decreased seed germination capacity for all species, but germination improved in response to after-ripening. It is recommended that for greater nutritional benefit, Amaranthus should be grown under warm conditions and younger leaves are preferable.

Relationship between laboratory and field assessments of common bean (Phaseolus vulgaris L.) seed quality indicators

Acta agriculturae Slovenica

The objective of this study was to extend the measure of seed quality beyond seed germination usi... more The objective of this study was to extend the measure of seed quality beyond seed germination using three common bean (Phaseolus vulgaris. L) cultivars. Under laboratory conditions, total seed germination was included in calculation of other seed performance measures, mean germination rate and germination vigour index. These parameters were used to produce a new parameter, total potential value for germination. The laboratory measures were duplicated under field conditions over two seasons to produce comparable data for seedling emergence, mean emergence rate and emergence vigour index. Consequently, total potential value for emergence was derived. The crop was grown under field conditions at three seeding rates (177 000 plants ha-1, 150 000 plants ha-1 and 115 000 plants ha-1). Prediction of seed performance under field conditions was extended by measuring plant size from the first trifoliate to initiation of reproductive stage. During this period, new measures comparable to those ...

Potential role for wild vegetables in household food security: a preliminary case study in Kwazulu-Natal, South Africa

African Journal of Food, Agriculture, Nutrition and Development, May 26, 2006

The value of wild edible vegetables in food security has not been given sufficient attention in S... more The value of wild edible vegetables in food security has not been given sufficient attention in South Africa. Consequently, there are no formal interventions that seek to encourage people to use traditional vegetables as sources of essential nutrients. Studies on the role of wild leafy vegetables in food security could provide important information for development of policies on careful exploitation of natural resources for human sustenance. The objective of this study was to provide a rapid assessment of general knowledge about wild leafy vegetables among subsistence farmers from Ezigeni, a rural location in South Africa, and to determine the availability of wild leafy vegetables from cropping fields during spring-before the cropping season started. A focus group discussion and transect walk were used to collect qualitative data on knowledge of traditional vegetables. Availability of wild leafy vegetables was quantified using one-square-meter plots, randomly located in a cropping field and in an area that has never been cultivated (veld). Results showed that knowledge of wild leafy vegetables among the participants was positively correlated with age. Education status improved knowledge of wild vegetables for middle-aged participants, but not for the youth (35 years or younger). Availability of wild edible leafy vegetables (plant numbers and yield) increased from August to October, but there was a significant difference between species. Data from a focus group discussion showed that wild leafy vegetable availability occurred early in spring, when traditional crops were less abundant. It is concluded that knowledge of wild leafy vegetables may be lost in the near future, unless efforts are made to educate younger generations about their importance. They could be used as an important source of nutrients during the pre-cropping season, before traditional crops are available for human consumption. It is recommended that agronomic investigations into cultivation of wild leafy vegetables that are adapted to rural areas where exotic leafy vegetables are not widely available be undertaken. Those studies could contribute significantly in government policies to improve food security in rural areas, and in the improvement of wild vegetable status, whose potential as sources of nutrition is currently undervalued.

Effect of plant population and mulching on wild watermelon growth and yield

A field study of wild watermelon (Citrullus lanatus) establishment and yield using seed to compar... more A field study of wild watermelon (Citrullus lanatus) establishment and yield using seed to compare the effects of different population densities (3,000, 6,000, 9,000 and 12,000 plants ha−1) and mulching rates (0, 2.5 and 5 t ha−1) with grass mulch on soil water, temperature, vine length, number of branches and leaves per plant, fruit number per plant and per hectare, total yield, fresh and dry fruit mass was conducted. The fruit per hectare and total yields increased as the plant population increased resulting in high yields in the range from 6,00012,000 plants per hectare. Yield was more influenced by plant population than by mulching. Mulching did not affect growth and yield of wild watermelon but it affected soil temperature and soil moisture. More water was conserved, while soil temperature was reduced upon increased mulching. This was shown by 31 and 12.6% increase in volumetric water content when the amount of mulch was increased by 2.5 and 5 t/ha, respectively. However, this ...

Marginal areas and indigenous people – Priorities for research and action

Context Business-as-usual is not working. Marginal environments and the indigenous people who cul... more Context Business-as-usual is not working. Marginal environments and the indigenous people who cultivate them have one thing in common – they are forgotten. Their soils and climates, crops and livestock, beliefs and knowledge systems rarely attract academic interest, policy studies or investment. Marginal environments refer to Less-Favourable Agricultural Areas (LFAAs) characterized by constrained agricultural potential and resource degradation attributable to biophysical and politico-socio-economic factors.1 Their low production potential is driven by rugged terrains, extreme weather conditions, poor soil and water quality, lack of socio-economic connectivity and limited exposure to agricultural intensification opportunities. In such regions, drought and erratic rainfall, salinization, and other factors present significant constraints for intensive agriculture. Marginal environments encompass all LFAAs and any favourable agricultural areas (e.g., areas not constrained by biophysical...

Photoinhibition influences protein utilisation during seed germination in Cleome gynandra L

African Journal of Biotechnology, 2008

Seed storage proteins are mobilised during germination, especially at radicle protrusion. The obj... more Seed storage proteins are mobilised during germination, especially at radicle protrusion. The objective of this study was to examine changes in protein expression during germination of Cleome gynandra in the presence or absence of light and at constant or alternating temperatures. Seeds were germinated at alternating 30/20 or 20oC in darkness and in continuous white light. Four prominent proteins of 28 - 32 kDa and 18 - 20 kDa, and a fifth low molecular weight protein of 13 kDa were observed in seeds harvested at brown pod maturity. These proteins remained unchanged during photoinhibition as shown on SDS-PAGE gels. Photoinhibition is a pseudodormancy condition during which seed storage proteins are not utilised.

Association of seed coat colour with germination of three wild mustard species with agronomic potential

Seed dormancy and germination present significant challenges when wild species are domesticated f... more Seed dormancy and germination present significant challenges when wild species are domesticated for cultivation and economic exploitation. Wild plant species are generally characterized by dormant seeds with variable germination widely spread over time. The objective of this study was to evaluate the influence of colour selection on seed germination of wild mustard (Brassicaceae) species that have been identified as wild edible leafy vegetable in South Africa. Seed lots were separated by colour and germinated in a completely randomized design (CRD) after chilling and after-ripening for 6 months. The light seed lot of cultivar Kwayimba (K) showed higher germination percentage than the dark seed lot of the same cultivar but colour selection did not improve the germination in cultivars Isaha (I) and Maslahlisane (M). The dark seed lot of K recorded the lowest germination percentage and the slowest germination rate. Chilling improved the speed of germination in wild mustards, but after-...

Correction: Multi-criteria suitability analysis for neglected and underutilised crop species in South Africa

PLOS ONE, 2021

Evaluating nutritional content among Bambara groundnut lines

Journal of Food Composition and Analysis, 2021

Abstract Bambara groundnut (Vigna subterranea (L.) Verdc) has the potential to address food insec... more Abstract Bambara groundnut (Vigna subterranea (L.) Verdc) has the potential to address food insecurity in sub-Saharan Africa. However, a lack of cultivars with improved nutritional quality hinders its potential. This study evaluated nutritional content in the grain of 19 Bambara groundnut lines. The nutritional content of the lines varied significantly (p

Assessing progress towards sustainable development over space and time

Nature, 2020

To address global challenges 1-4 , 193 countries have committed to the 17 United Nations Sustaina... more To address global challenges 1-4 , 193 countries have committed to the 17 United Nations Sustainable Development Goals (SDGs) 5. Quantifying progress towards achieving the SDGs is essential to track global efforts towards sustainable development and guide policy development and implementation. However, systematic methods for assessing spatio-temporal progress towards achieving the SDGs are lacking. Here we develop and test systematic methods to quantify progress towards the 17 SDGs at national and subnational levels in China. Our analyses indicate that China's SDG Index score (an aggregate score representing the overall performance towards achieving all 17 SDGs) increased at the national level from 2000 to 2015. Every province also increased its SDG Index score over this period. There were large spatio-temporal variations across regions. For example, eastern China had a higher SDG Index score than western China in the 2000s, and southern China had a higher SDG Index score than northern China in 2015. At the national level, the scores of 13 of the 17 SDGs improved over time, but the scores of four SDGs declined. This study suggests the need to track the spatio-temporal dynamics of progress towards SDGs at the global level and in other nations.

Soil fertility assessment and management from the perspective of farmers in four villages of eastern South Africa

Soil Use and Management, 2019

Understanding farmer perceptions of soil fertility is necessary for the development of appropriat... more Understanding farmer perceptions of soil fertility is necessary for the development of appropriate assessment methods for sustainable agro‐ecosystems. This study investigated farmer perceptions of soil fertility and management in four villages of eastern South Africa. A questionnaire was administered to 50 farmers from each village to obtain a general overview of local soil knowledge as well as soil fertility perceptions and assessment. Ten farmers were then chosen from each village for in‐field walks and to gather in‐depth knowledge of local soil fertility concepts, soil‐crop associations and soil management. During in‐field walks, farmers were asked to identify fertile, moderately fertile and low soil fertility plots in their fields from which topsoil samples were taken for laboratory fertility analysis. Local soil fertility descriptors included crop performance and yield, soil texture, stoniness and consistence. Using these descriptors, farmers have developed specific soil use an...

Watermelon landrace seedling establishment and field performance in response to differing water regimes

African Journal of Agricultural Research, 2012

Wild watermelon (Citrullus lanatus) is an indigenous crop whose agronomic potential has not been ... more Wild watermelon (Citrullus lanatus) is an indigenous crop whose agronomic potential has not been well investigated in South Africa. However, the country has a significant amount of the crop's germplasm in the form of landraces. Three local landraces of watermelon were compared for seedling establishment and production under controlled and dry land field conditions. The objective of the study was to determine watermelon landrace seedling establishment, plant growth and fruit production under controlled environment using different growth media (pine bark, sand and a mixture of pine bark and sand (1: 1 (v/v) and dry land field conditions in response to planting dates from September, 2008 to January, 2009. Results showed that seedling establishment was significantly affected by growth medium. Pine bark produced significantly at (P < 0.05) larger seedlings than the mixture or sand alone due to its capacity to hold water better than the other two media. Seedling production of wild watermelon did not improve significantly when the field capacity of the growing medium was increased above 50% suggesting potential drought tolerance for the crop. Early field planting was found to be associated with larger fruit size in spite of low soil water availability early in the season, another evidence for potential drought tolerance.

Selection of Superior Genotypes in 37 Clones of Camu-Camu by Repetitivity Analysis

Journal of Agricultural Science, 2017

In order to select camu-camu superior genotypes, a comparative of clones from natural populations... more In order to select camu-camu superior genotypes, a comparative of clones from natural populations, farmer plantations and an experimental field of the National Institute of Agrarian Innovation (INIA), was established in 2004 in varzea, at the Peruvian Amazon Research Institute (IIAP). Nine harvests between 2006 and 2016 have been evaluated, including variables in vegetative and reproductive development states. Statistical analysis was performed using the SPSS program for analysis of variance and SELEGEN REML/BLUP for repetitivity analysis of “fruit yield” (FY) and “fruit weight” (FW) with 5 and 4 measurements (years) respectively. For FY, a repetitivity index r = 0.117±0.07 was obtained with a selective precision of 0.63 and efficiency of 1.84 where clones 69, 48, 58, 50, 61, 13, 18, 29, 49 and 32, were selected in descending order of merit. For FW, r = 0.690±0.294 was obtained with selective precision of 0.948, efficiency of 1.14 and selection of clones 44, 13, 26, 23, 69, 64 22, 5...

Revitalising Agricultural Education and Training in South Africa

Envisioning AET in the Future 131 key finding 1: Continued Challenges Facing AET 131 key finding ... more Envisioning AET in the Future 131 key finding 1: Continued Challenges Facing AET 131 key finding 2: The (Dis-)Enabling Environment 132 Governance and Coordination (CS1&2) 132 The Case of the Agricultural Colleges (CS3) 132 key finding 3: Relevant Institutions and Adequate Resources 133 Articulation and Integration (CS3-7) 133 Reversing the Inverted Pyramid 134 Funding and Resource Allocation (CS 3-7) 135 key finding 4: An Adequate Number of Appropriately Trained Graduates 135 Relevance and Responsiveness of Curricula 135 The AET System is in Dire Need of Quality,

A Comparative Study on Antioxidant Potential of Selected African and Exotic Leafy Vegetables

HortScience, 2016

African leafy vegetables (ALVs) are thought to contain an immense variety of antioxidants, which ... more African leafy vegetables (ALVs) are thought to contain an immense variety of antioxidants, which may provide nutritional and health benefits. However, there is limited, robust, and comparable information describing their nutritional composition. The aim of this study is to determine the antioxidant potential of selected ALVs [black jack (Bidens pilosa L.) and amaranth (Amaranthus hybridus L.)] in comparison with exotic leafy vegetables (ELVs) [lettuce (Lactuca sativa L.), green cabbage (Brassica oleracea), red cabbage (B. oleracea var. capitata)]. Different nonenzymatic and enzymatic antioxidant assays were used to determine plant carbohydrates (CHOs) using high-performance liquid chromatography (HPLC), phenols (Folin–Ciocalteu), ascorbic acid, carotenoids, total antioxidant capacity (TAOC) using reducing ferric ion antioxidant potential (FRAP) and 1,1-diphenyl-2-picrylhydrazyl free radical (DPPH) assays, super oxide dismutase (SOD), catalase (CAT), and peroxidase (POD). Both amaran...

Transitioning toward Sustainable Development Goals: The Role of Household Environment in Influencing Child Health in Sub-Saharan Africa and South Asia Using Recent Demographic Health Surveys

Frontiers in public health, 2016

The Millennium Development Goals are now replaced by 17 sustainable development goals. The emphas... more The Millennium Development Goals are now replaced by 17 sustainable development goals. The emphasis of old goals was on improving water, sanitation, and child mortality conditions in developing countries. The study explored the major question about the association between different household environment conditions with child survival and health in Sub-Saharan African and South Asian countries in the current scenario. This paper estimated the risk of death, morbidity, and undernutrition among children living in households with the improved sources of water, sanitation, and non-solid cooking fuel. Two sources of information are explored in this study. First, data from World Health Statistics (WHS)-2014 for all of the Sub-Saharan African and South Asian countries were used. Second, available standard Demographic and Health Survey (DHS) performed in the countries of Sub-Saharan Africa and South Asia after 2010 was included in the study. It resulted in the inclusion of 15 countries which...

Comparing Extraction and Quantity/Intensity Based Recommendations for Nitrogen, Phosphorus and Potassium Recommendation

Journal of Agricultural Science, 2015

Conventional, extraction based fertilizer recommendations for phosphorus and potassium have been ... more Conventional, extraction based fertilizer recommendations for phosphorus and potassium have been shown to lack mechanistic basis, thus unreliable. This has led to an urgent need for the development and evaluation of accurate and consistent phosphorus and potassium recommendations approaches with mechanistic basis. Also it has been shown that integrating nitrogen mineralization on nitrogen recommendations, has a potential of improving nitrogen recommendations. We established two parallel pot trial studies with the objective of comparing between extraction based fertilizer recommendations with alternative strategies. The first study was to compare the effect of integrating nitrogen mineralization on N recommendations. Second pot experiment in addition to N being recommended after integrating N mineralization; P and K were also recommended with an alternative strategy, which was derived from quantity/intensity relations. No negative impacts were observed on crop growth and nutrient uptake due to the integration of mineralizable nitrogen, despite nitrogen amounts being lower compared to treatments where N was applied without adjusting for mineralizable N. The same was true for the second pot trial, P and N recommended by conventional approach were higher, yet the crop response was not concurrently improved by higher rates. Potassium rates recommended by alternative strategy were higher and this was concurrent with potassium uptake. We therefore concluded, that this NPK recommendation experimental approach (N e P e K e) is superior to its conventional counterpart (N c P c K c). Hence, more reliable recommendations can be developed using this approach and this might reduce environmental footprint of agro-ecosystems, and reduce input cost for farmers where warranted.

Seedling Establishment of Selected Wild Watermelon Landraces in Response to Varying Water Regimes

II International Symposium on Underutilized Plant Species: Crops for the Future - Beyond Food Security, 2013

The challenge of food security requires that agricultural production is no longer based on the na... more The challenge of food security requires that agricultural production is no longer based on the narrow genetic material present in conventional crops. Whereas conventional crops have been genetically improved to suit management practices of the modern farmer, the future farmer requires that there be access to a wide variety of genetic material for economic exploitation and to respond to the challenges of climate change in a sustainable fashion. This study was designed to determine seed quality and seedling establishment of wild watermelon (Citrullus lanatus (Thunb.) Matsumura and Nakai) landraces found in two provinces of South Africa, KwaZulu-Natal (sub-tropical) and Eastern Cape (semi-arid). In addition to provenance, seed colour was used to separate the germplasm into three seedlots: B, DB and VDB. Following one season of seed production at a research farm in Pietermaritzburg, KwaZulu-Natal, seeds were tested for germination capacity, before seed lot response to water stress was determined in three substrates made of pine bark, a 1:1 mixture of fine sand and pine bark and fine sand only. The substrates were kept at 75% F.C. (Field Capacity), 50% F.C. and 25% F.C., to create varying levels of water regimes during 12 weeks of seedling growth in a glasshouse (16/21°C (day/night) and 60% RH). Leaf proline content was determined at seedling harvest. There were significant differences (P<0.05) between seed lots with respect to seed quality and seedling yield, which consistently showed that 'Brown'>'Very Dark Brown'>'Dark Brown'. Wild watermelon was responsive to water stress during seedling growth, but high water regimes compromised water use efficiency. Proline accumulation correlated with water stress.

Contribution of the seed to fruit development: A tool to understand avocado tree management and fruit maturity parameters

Mesocarp percentage moisture of 'Fuerte' and 'Hass' avocado (Persea Americana Mil... more Mesocarp percentage moisture of 'Fuerte' and 'Hass' avocado (Persea Americana Mill.) fruits harvested during 1999-2000 and 2001-2002 growing seasons was determined at different stages of development and correlated to seed water potential. The two relations declined with increasing fruit ontogeny, and were linearly and signifi cantly infl uenced by the number of days after full bloom (stage of development) and the cultivar (P< 0.001). Immature 'Fuerte' fruit had lower seed water potential than 'Hass' (- 0.86 ± 0.09 MPa and - 1.18 ± 0.11 MPa respectively). At maturity, the early harvested 'Fuerte' had higher seed water poten- tial (- 2.13 ± 0.13) than the late harvested 'Hass' (- 1.35 ± 0.06 MPa). Seed water potential of developing 'Fuerte' and 'Hass', for which a stochiometric relationship change to the cell sap content was observed, was measured to negatively correlate with mesocarp percentage moisture (r 2 = 0.991)....

Hydro-Priming in Dry Bean (Phaseolus vulgaris L.)

Research Journal of Seed Science, 2009

Growth temperature and plant age influence on nutritional quality of <i>Amaranthus</i> leaves and seed germination capacity<sup>#</sup>

Water SA, 2009

As a leafy vegetable, Amaranthus can be harvested at different stages of plant growth, ranging fr... more As a leafy vegetable, Amaranthus can be harvested at different stages of plant growth, ranging from young seedlings to the late juvenile stage, but data on the changes in leaf nutritional value with plant age are scanty. The objective of this study was to determine the effect of growth temperature on Amaranthus leaf yield and nutritional quality at different stages of plant growth. Five species, A. hybridus var. cruentus, A. hypochondriacus, A. tricolor, A. thunbergii and A. hybridus were compared for their response to hot (33/27 o C), warm (27/21 o C) and cool (21/15 o C) temperature regimes (day/night) in separate glasshouses. Plants were harvested at 20, 40 and 60 d after sowing and leaf yield, minerals (Ca, P and Fe), total protein content, amino acid (methionine and lysine) content and antioxidant activity (inhibition of linoleic acid oxidation) were determined. Seed yield and germination capacity, during two years of after-ripening, were also determined. Results showed that leaf protein content differed significantly (P < 0.01) between species. It was also significantly (P < 0.01) influenced by the growth temperature and stage of plant growth. The pattern of changes in the amounts of lysine and methionine was comparable to that of protein content, but A. thunbergii showed significantly higher amino acid content than the other species. Amaranthus leaves also contained significantly (P < 0.01) more lysine than methionine, regardless of the species and growth temperature. The phosphorus content of leaves was not significantly affected by temperature and stage of plant development, and there were also no significant differences between species. However, the amounts of both calcium and iron changed significantly (P < 0.05) with stages of plant development and with increasing temperatures for all species. The antioxidant activity of Amaranthus leaves increased consistently with plant age and there were significant (P < 0.01) differences between stages of plant development and growth temperature. Warm temperature regimes were most favourable (P < 0.01) for biomass accumulation in all species. Seed production under cool and hot temperatures significantly (P < 0.01) decreased seed germination capacity for all species, but germination improved in response to after-ripening. It is recommended that for greater nutritional benefit, Amaranthus should be grown under warm conditions and younger leaves are preferable.