It is imperative to possess a comprehensive understanding of the water consumption patterns of sw... more It is imperative to possess a comprehensive understanding of the water consumption patterns of sweet cherry trees under rainfed conditions. This study investigates the water use of sweet cherry using the heat pulse velocity sap flow method. Tree response to drying soil conditions over two consecutive measurement periods (September 2017 to December 2018) in the eastern Free State, South Africa, is also evaluated. During the post-harvest period (December), there was a continuous increase in daily water consumption by trees, in conjunction with an increase in canopy cover, even though the crop load was reduced. Measured sap flow was positively correlated to net radiation, air temperature, and water vapour pressure deficit. The transpiration rates ranged from 1.2 to 3.5 L d-1 during the flowering stage (day of year, DOY, 244 – 270) and showed an increasing trend as the days progressed. During the ripening stage (DOY 271 – 292), transpiration rates decreased from 4.5 to 1.1 L d-1 over th...
Opuntia ficus-indica (L.) Mill. is one of the most recognisable agricultural crops that can withs... more Opuntia ficus-indica (L.) Mill. is one of the most recognisable agricultural crops that can withstand harsh environmental conditions. South Africa is one of the few countries that hosts a large germplasm of Opuntia cultivars that represent an ex-situ conservation population. However, little is known about the genetic diversity in this population. Additionally, some genotypes are morphologically indistinct, and therefore, making it a challenge for novice farmers and researchers to recognise specimens in the germplasm. The current study aimed to differentiate and measure the genetic diversity in 44 cultivars that represent the South African Opuntia germplasm using eight SSR markers. Evidently, the cultivars comprised moderate levels of diversity (average polymorphic information content, PIC = 0.37, Nei’s unbiased gene diversity = 0.42) that discriminated 90% of the cultivars. Analysis of the cultivars with the unweighted pair-group method using arithmetic averages (UPGMA) method revea...
Climate is an essential part of crop production, determining the suitability of a given region fo... more Climate is an essential part of crop production, determining the suitability of a given region for deciduous fruit products such as apples (Malus domestica). It influences the yield and quality of fruits. There is strong evidence of global and regional-scale climate change since the advent of the industrial era. In South Africa, mean surface temperatures have revealed a warming trend over the last century. This study aimed to assess the impact of climate change on temperature and chill unit trends for apple production in Ceres, South Africa. The daily positive Utah chill units (DPCU) model was used as frequent high temperatures can lead to a high negation volume. Historically observed (1981–2010) and future projected (2011–2100) temperatures were obtained from the South African Weather Service (SAWS) and three ensemble members of the Cubic-Conformal Atmospheric Model (CCAM), respectively. The latter employed the RCP8.5 pathway. Linear trends were calculated for temperature and accum...
The Pecan (Carya illinoensis) is the most important species that belongs to the Carya genus. It i... more The Pecan (Carya illinoensis) is the most important species that belongs to the Carya genus. It is cultivated mainly for its nut, which is rich in oils and proteins, and for its good quality wood. Pecan is conventionally propagated by budding or grafting onto rootstocks obtained by open pollination. However, these techniques are not very efficient due to low propagation rates, poor survival and difficult establishment. Therefore, in vitro propagation of pecan can play a very important role in rapid multiplication of cultivars with desirable traits and production of healthy and disease-free plants in a short time. In the present review, the improvements over the years in the propagation of pecans, the refinements of protocols for obtaining high shoot multiplication and regeneration through organogenesis and/or somatic embryogenesis is discussed. Some basics of genetic transformation and its possible benefits are also discussed.
Cactus pears are nutritious, drought-tolerant plants that flourish in hot and arid regions. All i... more Cactus pears are nutritious, drought-tolerant plants that flourish in hot and arid regions. All its plant parts can be consumed by humans and animals. Fruit seed oil production is an important emerging industry in South Africa. As part of an initiative to promote cactus pears as multi-functional crops, dual-purpose cultivars should be identified, and their production increased. The aim of this study was to investigate the role of nitrogen (N) fertilizer on the seed oil yield and quality of Opuntia ficus-indica. The project encompassed a trial using N fertilization from three N sources (limestone ammonium nitrate, ammonium sulfate, urea) and four N application levels (0, 60, 120, 240 kg ha−1). Oil was quantitatively extracted from the seed using the Folch method; fatty acids were quantified using a Varian 430-GC. Seed oil content significantly increased (p = 0.035) with increased N fertilization rates; the oil yield ranged between 7.96 and 9.54%. The composition of the main fatty aci...
African Journal of Agricultural Research, Jan 22, 2015
The response of onion cv. Jaquar (Allium cepa L.) to sowing date and plant population was investi... more The response of onion cv. Jaquar (Allium cepa L.) to sowing date and plant population was investigated in Bloemfontein (Free State Province, South Africa) during the year 2010. Jaquar seeds were sown on 11 and 25 May; and 8 June at five different populations (95, 83, 74, 67 and 61 plants m -2 ) in a randomized complete block design with each treatment combination replicated three times. Plant height and leaf number were measured 18 weeks after emergence. Bulb yield and quality (bulb mass, diameter, firmness and neck diameter) were recorded at harvesting. Significantly taller plants were obtained with the early sowing date (11 May) and a population between 61 and 74 plants m -2 . Leaf production was not significantly influenced by any treatment. Bulb mass, yield and firmness were significantly higher with early sowing dates (11 or 25 May). Plant population significantly influenced bulb mass, but not yield. Bulb diameter increased as population decreased, irrespective of planting date. The three lowest populations (74, 67 and 61 plants m -2 ) yielded significantly harder bulbs than denser plants (83 and 95 plants m -2 ). The best sowing date for Jaquar in Bloemfontein was from 11 to 25 May at a population of between 61 and 74 plants m -2 .
African Journal of Agricultural Research, Jun 13, 2013
Onion are the third most important vegetable crop sold in South Africa. Optimum sowing dates for ... more Onion are the third most important vegetable crop sold in South Africa. Optimum sowing dates for new cultivars was determined in Bloemfontein (South Africa) during 2009 and 2010. Cultivars planted in 2009 and 2010 were 'Charlize', 'Jaquar', 'Python', (South Wester, 2009; Ceres Gold, 2010). Unavailability of 'South Wester' seed resulted in replacement with 'Ceres Gold'. In 2009 onion seeds were sown on 30 April, 7 and 21 May and in 2010 on 11, 25 May and 8 June. Trials were laid out as a randomized complete block design with each treatment combination replicated 3 times. Plant height and leaf number were measured 18 weeks after emergence. At harvest, bulb yield and quality were recorded. Cultivars differed with respect to growth habit, bulb size, neck diameter and bolting, but not bulb fresh mass and yield. Sowing date did not influence plant height and leaf number significantly, except in 2010 where the early sowing dates resulted in taller plants. The respective delayed sowing dates in 2010 (11 May, 25 May, 8 June) significantly decreased average bulb fresh mass (71.48, 49.42, 49.21 g bulb -1 ) and yield (40.96, 34.05, 28.20 t ha -1
A field study was conducted at Umsunduze Training Centre, KwaZulu-Natal, for two seasons to deter... more A field study was conducted at Umsunduze Training Centre, KwaZulu-Natal, for two seasons to determine the response of carrot (Daucus carota cv. Kuroda) to organic fertiliser. Three different organic fertilisers were applied at four rates (chicken manure: 0, 6.25, 12.5 and 25 kg 10 m −2 ; kraal manure: 0, 12.5, 25 and 50 kg 10 m −2 ; and compost: 0, 25, 50 and 100 kg 10 m −2 ). The experiment was laid out as a complete randomised block design with four replications. Leaf number and length, root fresh and dry mass, root length, shoulder diameter, root total soluble solids (TSS) and grade were recorded. Chicken manure-treated plants produced more leaves than compost (2005) and longer leaves than kraal manure (2006) treated plants. The TSS of roots treated with chicken manure or compost was lower than that of roots not receiving fertiliser (2005). Poorer quality roots were harvested from compost than chicken or kraal manure-treated plants. As organic fertiliser rate increased, leaf number, length, root fresh mass and shoulder diameter increased. Root TSS and dry mass decreased as organic fertiliser rate increased and roots were of a lower grade. Organic fertiliser can be beneficial to carrot yield and quality within specific application levels .
It is imperative to possess a comprehensive understanding of the water consumption patterns of sw... more It is imperative to possess a comprehensive understanding of the water consumption patterns of sweet cherry trees under rainfed conditions. This study investigates the water use of sweet cherry using the heat pulse velocity sap flow method. Tree response to drying soil conditions over two consecutive measurement periods (September 2017 to December 2018) in the eastern Free State, South Africa, is also evaluated. During the post-harvest period (December), there was a continuous increase in daily water consumption by trees, in conjunction with an increase in canopy cover, even though the crop load was reduced. Measured sap flow was positively correlated to net radiation, air temperature, and water vapour pressure deficit. The transpiration rates ranged from 1.2 to 3.5 L d-1 during the flowering stage (day of year, DOY, 244 – 270) and showed an increasing trend as the days progressed. During the ripening stage (DOY 271 – 292), transpiration rates decreased from 4.5 to 1.1 L d-1 over th...
Opuntia ficus-indica (L.) Mill. is one of the most recognisable agricultural crops that can withs... more Opuntia ficus-indica (L.) Mill. is one of the most recognisable agricultural crops that can withstand harsh environmental conditions. South Africa is one of the few countries that hosts a large germplasm of Opuntia cultivars that represent an ex-situ conservation population. However, little is known about the genetic diversity in this population. Additionally, some genotypes are morphologically indistinct, and therefore, making it a challenge for novice farmers and researchers to recognise specimens in the germplasm. The current study aimed to differentiate and measure the genetic diversity in 44 cultivars that represent the South African Opuntia germplasm using eight SSR markers. Evidently, the cultivars comprised moderate levels of diversity (average polymorphic information content, PIC = 0.37, Nei’s unbiased gene diversity = 0.42) that discriminated 90% of the cultivars. Analysis of the cultivars with the unweighted pair-group method using arithmetic averages (UPGMA) method revea...
Climate is an essential part of crop production, determining the suitability of a given region fo... more Climate is an essential part of crop production, determining the suitability of a given region for deciduous fruit products such as apples (Malus domestica). It influences the yield and quality of fruits. There is strong evidence of global and regional-scale climate change since the advent of the industrial era. In South Africa, mean surface temperatures have revealed a warming trend over the last century. This study aimed to assess the impact of climate change on temperature and chill unit trends for apple production in Ceres, South Africa. The daily positive Utah chill units (DPCU) model was used as frequent high temperatures can lead to a high negation volume. Historically observed (1981–2010) and future projected (2011–2100) temperatures were obtained from the South African Weather Service (SAWS) and three ensemble members of the Cubic-Conformal Atmospheric Model (CCAM), respectively. The latter employed the RCP8.5 pathway. Linear trends were calculated for temperature and accum...
The Pecan (Carya illinoensis) is the most important species that belongs to the Carya genus. It i... more The Pecan (Carya illinoensis) is the most important species that belongs to the Carya genus. It is cultivated mainly for its nut, which is rich in oils and proteins, and for its good quality wood. Pecan is conventionally propagated by budding or grafting onto rootstocks obtained by open pollination. However, these techniques are not very efficient due to low propagation rates, poor survival and difficult establishment. Therefore, in vitro propagation of pecan can play a very important role in rapid multiplication of cultivars with desirable traits and production of healthy and disease-free plants in a short time. In the present review, the improvements over the years in the propagation of pecans, the refinements of protocols for obtaining high shoot multiplication and regeneration through organogenesis and/or somatic embryogenesis is discussed. Some basics of genetic transformation and its possible benefits are also discussed.
Cactus pears are nutritious, drought-tolerant plants that flourish in hot and arid regions. All i... more Cactus pears are nutritious, drought-tolerant plants that flourish in hot and arid regions. All its plant parts can be consumed by humans and animals. Fruit seed oil production is an important emerging industry in South Africa. As part of an initiative to promote cactus pears as multi-functional crops, dual-purpose cultivars should be identified, and their production increased. The aim of this study was to investigate the role of nitrogen (N) fertilizer on the seed oil yield and quality of Opuntia ficus-indica. The project encompassed a trial using N fertilization from three N sources (limestone ammonium nitrate, ammonium sulfate, urea) and four N application levels (0, 60, 120, 240 kg ha−1). Oil was quantitatively extracted from the seed using the Folch method; fatty acids were quantified using a Varian 430-GC. Seed oil content significantly increased (p = 0.035) with increased N fertilization rates; the oil yield ranged between 7.96 and 9.54%. The composition of the main fatty aci...
African Journal of Agricultural Research, Jan 22, 2015
The response of onion cv. Jaquar (Allium cepa L.) to sowing date and plant population was investi... more The response of onion cv. Jaquar (Allium cepa L.) to sowing date and plant population was investigated in Bloemfontein (Free State Province, South Africa) during the year 2010. Jaquar seeds were sown on 11 and 25 May; and 8 June at five different populations (95, 83, 74, 67 and 61 plants m -2 ) in a randomized complete block design with each treatment combination replicated three times. Plant height and leaf number were measured 18 weeks after emergence. Bulb yield and quality (bulb mass, diameter, firmness and neck diameter) were recorded at harvesting. Significantly taller plants were obtained with the early sowing date (11 May) and a population between 61 and 74 plants m -2 . Leaf production was not significantly influenced by any treatment. Bulb mass, yield and firmness were significantly higher with early sowing dates (11 or 25 May). Plant population significantly influenced bulb mass, but not yield. Bulb diameter increased as population decreased, irrespective of planting date. The three lowest populations (74, 67 and 61 plants m -2 ) yielded significantly harder bulbs than denser plants (83 and 95 plants m -2 ). The best sowing date for Jaquar in Bloemfontein was from 11 to 25 May at a population of between 61 and 74 plants m -2 .
African Journal of Agricultural Research, Jun 13, 2013
Onion are the third most important vegetable crop sold in South Africa. Optimum sowing dates for ... more Onion are the third most important vegetable crop sold in South Africa. Optimum sowing dates for new cultivars was determined in Bloemfontein (South Africa) during 2009 and 2010. Cultivars planted in 2009 and 2010 were 'Charlize', 'Jaquar', 'Python', (South Wester, 2009; Ceres Gold, 2010). Unavailability of 'South Wester' seed resulted in replacement with 'Ceres Gold'. In 2009 onion seeds were sown on 30 April, 7 and 21 May and in 2010 on 11, 25 May and 8 June. Trials were laid out as a randomized complete block design with each treatment combination replicated 3 times. Plant height and leaf number were measured 18 weeks after emergence. At harvest, bulb yield and quality were recorded. Cultivars differed with respect to growth habit, bulb size, neck diameter and bolting, but not bulb fresh mass and yield. Sowing date did not influence plant height and leaf number significantly, except in 2010 where the early sowing dates resulted in taller plants. The respective delayed sowing dates in 2010 (11 May, 25 May, 8 June) significantly decreased average bulb fresh mass (71.48, 49.42, 49.21 g bulb -1 ) and yield (40.96, 34.05, 28.20 t ha -1
A field study was conducted at Umsunduze Training Centre, KwaZulu-Natal, for two seasons to deter... more A field study was conducted at Umsunduze Training Centre, KwaZulu-Natal, for two seasons to determine the response of carrot (Daucus carota cv. Kuroda) to organic fertiliser. Three different organic fertilisers were applied at four rates (chicken manure: 0, 6.25, 12.5 and 25 kg 10 m −2 ; kraal manure: 0, 12.5, 25 and 50 kg 10 m −2 ; and compost: 0, 25, 50 and 100 kg 10 m −2 ). The experiment was laid out as a complete randomised block design with four replications. Leaf number and length, root fresh and dry mass, root length, shoulder diameter, root total soluble solids (TSS) and grade were recorded. Chicken manure-treated plants produced more leaves than compost (2005) and longer leaves than kraal manure (2006) treated plants. The TSS of roots treated with chicken manure or compost was lower than that of roots not receiving fertiliser (2005). Poorer quality roots were harvested from compost than chicken or kraal manure-treated plants. As organic fertiliser rate increased, leaf number, length, root fresh mass and shoulder diameter increased. Root TSS and dry mass decreased as organic fertiliser rate increased and roots were of a lower grade. Organic fertiliser can be beneficial to carrot yield and quality within specific application levels .
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