The release for semi-commercial evaluation of the first new rootstock from the ITSC rootstock bre... more The release for semi-commercial evaluation of the first new rootstock from the ITSC rootstock breeding programme is discussed. Building of the Phytophthora unit was completed during July 1998 and 5000 seedlings have been screened but clonal propagation of selections will only commence in the new unit during 1999. Results and techniques, used by the ITSC and Californian breeding programmes up to the present, are discussed. New techniques and exciting developments for 1999 are highlighted.
Development and selection of Phytophthora-tolerant avocado rootstocks is the major objective of A... more Development and selection of Phytophthora-tolerant avocado rootstocks is the major objective of ARC-ITSC's avocado rootstock breeding programme. This paper reports on new approaches that will improve efficiency of the rootstock breeding programme. These include the establishment of a polycross nursery and the use of large bins for the transplantation of selected seedlings to facilitate multiplication.
The purpose of a rootstock evaluation trial is to collect information on the performance of impor... more The purpose of a rootstock evaluation trial is to collect information on the performance of important avocado cultivars in combination with various rootstock cultivars. The first ARC-ITSC trials were established with five rootstock cultivars, namely Duke 7, Thomas, G6 combination with the commercial scions Fuerte, Hass, Pinkerton and Ryan. These trials were planted at Levubu and Burgerst however, lost during 1996 as a result of the excessive rains of that season. With Fuerte the best yield per tree came from scions grafted on the Thomas rootstock, at 40.6 kg fruit per tree. This rootstock was also the best performer based on tree size. Hass also had the best per tree yield also on Thomas, but based on tree size, performed better on Duke 7. Pinkerton produced an average of 64.5 kg fruit/tree on Duke 7, with this rootstock also being the best on a tree volume basis. Ryan production was very poor with G6 being the better rootstock at 16.2 kg fruit/tree. However, based on tree volume th...
During the 1996 season 3323 seedlings yielded the high number of 190 selections. During 1997 thes... more During the 1996 season 3323 seedlings yielded the high number of 190 selections. During 1997 these were reduced to 10 selections and have been transplanted to be multiplied for the statistical screening phase. Another 3646 seedlings have been screened during 1997, and 20 were selected. The polycross unit that was finalized during I996/97 produced its first seeds as predicted. However, larger numbers are needed from this facility. Due to the genetic make-up of each seedling being different, difficulty was experienced in multiplying these seedlings and little results were obtained. It was thus decided that the ease with which a seedling can be multiplied should also be a selection criterion. With this in mind the facilities were further upgraded with the building of a Phytophthora unit which will house both the screening phases as well as the multiplication of selections. While awaiting completion of this unit, the facility of the pathology department was utilised as an interim measur...
The purpose of a Phase II evaluation programme is to gather information on current commercial cul... more The purpose of a Phase II evaluation programme is to gather information on current commercial cultivars, as well as on new imported and local selections with regard to their horticultural performance and scion/rootstock interactions. Data from orchards established at Levubu and Burgershall are reported on. In the commercial cultivar evaluation trial at Levubu, the Pinkerton was overall the best producer with nearly 50 kg fruit per tree on average. Gwen on Duke 7 was found to be a solid performer with a cumulative yield over three years of 58.3 kg/tree. This cultivar could fill a local late season market niche. Of the new imported selections at both Levubu and Burgershall, I 373, #86, BL 135 and TX 531 performed very well and should be further evaluated, with OA 184 and H 222 as strong contenders for a place in the market. Only one local selection, namely Eksteen, has possibilities.
XXVIII International Horticultural Congress on Science and Horticulture for People (IHC2010): International Symposium on Environmental, Edaphic, and Genetic Factors Affecting Plants, Seeds and Turfgrass, 2012
The breeder can supply specific strategies to achieve the aims of a breeding programme. Some of t... more The breeder can supply specific strategies to achieve the aims of a breeding programme. Some of these, such as, general combining ability, specific combining ability, cumulative effect of favourable genes, corrective mating, and repeated back crossing are briefly described. The phenomena of the interaction of genotype and environment and its implication are also discussed.
The aim of Phase II evaluations is to assess various rootstock/scion combinations in different pr... more The aim of Phase II evaluations is to assess various rootstock/scion combinations in different production areas to select the best producing and quality combinations for a given area. The ITSC Phase II scion program involves planting the promising selections from the breeding and selection program, and imported cultivars at different sites on three different rootstocks, namely Duke 7, Thomas and Barr-Duke. The rootstock evaluation program consists of grafting new rootstock cultivars and promising selections from the rootstock breeding program with Fuerte, Hass, Pinkerton and Ryan scions. This program is currently progressing smoothly with 92 different scion combinations and 20 different rootstock combinations planted at two different locations.
Development and selection of Phytophthora tolerant avocado rootstocks is one of the major researc... more Development and selection of Phytophthora tolerant avocado rootstocks is one of the major research objectives of the avocado breeding program of the ITSC. During 1992 and 1993, a total of 27 Phytophthora cinnamomi tolerant avocado rootstocks were selected in primary screening trials, Phytophthora tolerance of these selected rootstocks will be verified in second phase laboratory tests.
The new breeding programme was initiated in 1991 after a visit of Dr Du Plooy to California. This... more The new breeding programme was initiated in 1991 after a visit of Dr Du Plooy to California. This new breeding programme consists of two parts namely rootstock breeding and scion breeding. Both of these programmes are based on the establishment of a genesource, introduction of promising overseas materials, self-pollination, cross pollination and poly-cross nurseries. Satisfactory progress was made since the strategy for the new breeding programme was announced. This progress is discussed in the various sections that were mentioned.
The new breeding programme was initiated in 1991 after a visit of Dr Du Plooy to California. This... more The new breeding programme was initiated in 1991 after a visit of Dr Du Plooy to California. This new breeding programme consists of two parts namely rootstock breeding and scion breeding. Both of these programmes are based on the establishment of a genesource, introduction of promising overseas materials, selfpollination, cross pollination and poly-cross nurseries. Satisfactory progress was made since the strategy for the new breeding programme was announced. This progress is discussed in the various sections that were mentioned.
The aim of Phase II evaluations is to assess various rootstock/scion combinations in different pr... more The aim of Phase II evaluations is to assess various rootstock/scion combinations in different production areas to select the best producing and quality combinations for a given area. The ITSC Phase II scion program involves planting the promising selections from the breeding and selection program, and imported cultivars at different sites on three different rootstocks, namely Duke 7, Thomas and Barr-Duke. The rootstock evaluation program consists of grafting new rootstock cultivars and promising selections from the rootstock breeding program with Fuerte, Hass, Pinkerton and Ryan scions. This program is currently progressing smoothly with 92 different scion combinations and 20 different rootstock combinations planted at two different locations.
Development and selection of Phytophthora tolerant avocado rootstocks is one of the major researc... more Development and selection of Phytophthora tolerant avocado rootstocks is one of the major research objectives of the avocado breeding program of the ITSC. During 1992 and 1993, a total of 27 Phytophthora cinnamomi tolerant avocado rootstocks were selected in primary screening trials, Phytophthora tolerance of these selected rootstocks will be verified in second phase laboratory tests.
An avocado breeding programme was initiated in 1991 by the Institute for Tropical and Subtropical... more An avocado breeding programme was initiated in 1991 by the Institute for Tropical and Subtropical Crops (ITSC) in order to develop superior cultivars for Southern Africa. The programme consists of two main parts, namely rootstock and scion breeding, followed by extensive Phase II evaluation. The breeding programmes were founded on the establishment of a gene source, continued introduction of improved overseas material, controlled self- and cross pollinations and evaluations in Phase I orchards. Since the inception of the scion breeding programme, 5,240 seedlings have been established. Eleven local seedlings were selected for Phase II evaluation. The rootstock breeding programme is devoted exclusively to the selection of Phytophthora tolerant types. Over the past three seasons 25,000 seedlings were grown under conditions of severe artificial infection with Phytophthora. Thirty three seedlings were selected for further screening. The breeding and selection programmes are followed by P...
The release for semi-commercial evaluation of the first new rootstock from the ITSC rootstock bre... more The release for semi-commercial evaluation of the first new rootstock from the ITSC rootstock breeding programme is discussed. Building of the Phytophthora unit was completed during July 1998 and 5000 seedlings have been screened but clonal propagation of selections will only commence in the new unit during 1999. Results and techniques, used by the ITSC and Californian breeding programmes up to the present, are discussed. New techniques and exciting developments for 1999 are highlighted.
Development and selection of Phytophthora-tolerant avocado rootstocks is the major objective of A... more Development and selection of Phytophthora-tolerant avocado rootstocks is the major objective of ARC-ITSC's avocado rootstock breeding programme. This paper reports on new approaches that will improve efficiency of the rootstock breeding programme. These include the establishment of a polycross nursery and the use of large bins for the transplantation of selected seedlings to facilitate multiplication.
The purpose of a rootstock evaluation trial is to collect information on the performance of impor... more The purpose of a rootstock evaluation trial is to collect information on the performance of important avocado cultivars in combination with various rootstock cultivars. The first ARC-ITSC trials were established with five rootstock cultivars, namely Duke 7, Thomas, G6 combination with the commercial scions Fuerte, Hass, Pinkerton and Ryan. These trials were planted at Levubu and Burgerst however, lost during 1996 as a result of the excessive rains of that season. With Fuerte the best yield per tree came from scions grafted on the Thomas rootstock, at 40.6 kg fruit per tree. This rootstock was also the best performer based on tree size. Hass also had the best per tree yield also on Thomas, but based on tree size, performed better on Duke 7. Pinkerton produced an average of 64.5 kg fruit/tree on Duke 7, with this rootstock also being the best on a tree volume basis. Ryan production was very poor with G6 being the better rootstock at 16.2 kg fruit/tree. However, based on tree volume th...
During the 1996 season 3323 seedlings yielded the high number of 190 selections. During 1997 thes... more During the 1996 season 3323 seedlings yielded the high number of 190 selections. During 1997 these were reduced to 10 selections and have been transplanted to be multiplied for the statistical screening phase. Another 3646 seedlings have been screened during 1997, and 20 were selected. The polycross unit that was finalized during I996/97 produced its first seeds as predicted. However, larger numbers are needed from this facility. Due to the genetic make-up of each seedling being different, difficulty was experienced in multiplying these seedlings and little results were obtained. It was thus decided that the ease with which a seedling can be multiplied should also be a selection criterion. With this in mind the facilities were further upgraded with the building of a Phytophthora unit which will house both the screening phases as well as the multiplication of selections. While awaiting completion of this unit, the facility of the pathology department was utilised as an interim measur...
The purpose of a Phase II evaluation programme is to gather information on current commercial cul... more The purpose of a Phase II evaluation programme is to gather information on current commercial cultivars, as well as on new imported and local selections with regard to their horticultural performance and scion/rootstock interactions. Data from orchards established at Levubu and Burgershall are reported on. In the commercial cultivar evaluation trial at Levubu, the Pinkerton was overall the best producer with nearly 50 kg fruit per tree on average. Gwen on Duke 7 was found to be a solid performer with a cumulative yield over three years of 58.3 kg/tree. This cultivar could fill a local late season market niche. Of the new imported selections at both Levubu and Burgershall, I 373, #86, BL 135 and TX 531 performed very well and should be further evaluated, with OA 184 and H 222 as strong contenders for a place in the market. Only one local selection, namely Eksteen, has possibilities.
XXVIII International Horticultural Congress on Science and Horticulture for People (IHC2010): International Symposium on Environmental, Edaphic, and Genetic Factors Affecting Plants, Seeds and Turfgrass, 2012
The breeder can supply specific strategies to achieve the aims of a breeding programme. Some of t... more The breeder can supply specific strategies to achieve the aims of a breeding programme. Some of these, such as, general combining ability, specific combining ability, cumulative effect of favourable genes, corrective mating, and repeated back crossing are briefly described. The phenomena of the interaction of genotype and environment and its implication are also discussed.
The aim of Phase II evaluations is to assess various rootstock/scion combinations in different pr... more The aim of Phase II evaluations is to assess various rootstock/scion combinations in different production areas to select the best producing and quality combinations for a given area. The ITSC Phase II scion program involves planting the promising selections from the breeding and selection program, and imported cultivars at different sites on three different rootstocks, namely Duke 7, Thomas and Barr-Duke. The rootstock evaluation program consists of grafting new rootstock cultivars and promising selections from the rootstock breeding program with Fuerte, Hass, Pinkerton and Ryan scions. This program is currently progressing smoothly with 92 different scion combinations and 20 different rootstock combinations planted at two different locations.
Development and selection of Phytophthora tolerant avocado rootstocks is one of the major researc... more Development and selection of Phytophthora tolerant avocado rootstocks is one of the major research objectives of the avocado breeding program of the ITSC. During 1992 and 1993, a total of 27 Phytophthora cinnamomi tolerant avocado rootstocks were selected in primary screening trials, Phytophthora tolerance of these selected rootstocks will be verified in second phase laboratory tests.
The new breeding programme was initiated in 1991 after a visit of Dr Du Plooy to California. This... more The new breeding programme was initiated in 1991 after a visit of Dr Du Plooy to California. This new breeding programme consists of two parts namely rootstock breeding and scion breeding. Both of these programmes are based on the establishment of a genesource, introduction of promising overseas materials, self-pollination, cross pollination and poly-cross nurseries. Satisfactory progress was made since the strategy for the new breeding programme was announced. This progress is discussed in the various sections that were mentioned.
The new breeding programme was initiated in 1991 after a visit of Dr Du Plooy to California. This... more The new breeding programme was initiated in 1991 after a visit of Dr Du Plooy to California. This new breeding programme consists of two parts namely rootstock breeding and scion breeding. Both of these programmes are based on the establishment of a genesource, introduction of promising overseas materials, selfpollination, cross pollination and poly-cross nurseries. Satisfactory progress was made since the strategy for the new breeding programme was announced. This progress is discussed in the various sections that were mentioned.
The aim of Phase II evaluations is to assess various rootstock/scion combinations in different pr... more The aim of Phase II evaluations is to assess various rootstock/scion combinations in different production areas to select the best producing and quality combinations for a given area. The ITSC Phase II scion program involves planting the promising selections from the breeding and selection program, and imported cultivars at different sites on three different rootstocks, namely Duke 7, Thomas and Barr-Duke. The rootstock evaluation program consists of grafting new rootstock cultivars and promising selections from the rootstock breeding program with Fuerte, Hass, Pinkerton and Ryan scions. This program is currently progressing smoothly with 92 different scion combinations and 20 different rootstock combinations planted at two different locations.
Development and selection of Phytophthora tolerant avocado rootstocks is one of the major researc... more Development and selection of Phytophthora tolerant avocado rootstocks is one of the major research objectives of the avocado breeding program of the ITSC. During 1992 and 1993, a total of 27 Phytophthora cinnamomi tolerant avocado rootstocks were selected in primary screening trials, Phytophthora tolerance of these selected rootstocks will be verified in second phase laboratory tests.
An avocado breeding programme was initiated in 1991 by the Institute for Tropical and Subtropical... more An avocado breeding programme was initiated in 1991 by the Institute for Tropical and Subtropical Crops (ITSC) in order to develop superior cultivars for Southern Africa. The programme consists of two main parts, namely rootstock and scion breeding, followed by extensive Phase II evaluation. The breeding programmes were founded on the establishment of a gene source, continued introduction of improved overseas material, controlled self- and cross pollinations and evaluations in Phase I orchards. Since the inception of the scion breeding programme, 5,240 seedlings have been established. Eleven local seedlings were selected for Phase II evaluation. The rootstock breeding programme is devoted exclusively to the selection of Phytophthora tolerant types. Over the past three seasons 25,000 seedlings were grown under conditions of severe artificial infection with Phytophthora. Thirty three seedlings were selected for further screening. The breeding and selection programmes are followed by P...
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