Breeding and regulatory opportunities and constraints for developing broccoli cultivars adapted to organic agriculture

This thesis is about the regulatory and technical challenges to the organic seed and breeding sector. This study specifically explored the mutual influence of the regulatory environment for organic seed sector development in the United States (US), Europe Union (EU) and Mexico, and the extent to which cultivars performed differently under organic conditions compared to conventional conditions, measured by selected horticultural and phytochemical traits. Organic farming practices often differ substantially from conventional practices and in the diversity of their crop rotations and market outlets. Currently, organic farmers depend largely on cultivars bred for conventional farming systems. We investigated the requirements of organic growers for seed that allowed optimization of their production system, and fulfilled consumer expectations for high nutritional value. In addition, we discuss the implications for seed production and crop improvement. Broccoli is one of the most important horticultural crops in the world’s fastest growing organic product market, the US. The field research was based on stakeholder interviews, participant observation, documentary analyses, laboratory analyses and paired field trials (organic/conventional) conducted in two contrasting regions in the US, Northeast US (Maine) and Pacific Northwest (Oregon), over two seasons (spring, fall) and two years for a total of 16 trials with 23 cultivars. The main findings of the regulatory component were: (1) New organizations, procedural arrangements and activities have emerged in the US, EU and Mexico to support organic seed regulatory development, with both positive and negative results; (2) Official guidance on the interpretation of the regulation in the US has not been sufficiently decisive to prevent divergent interpretation and practice, and in consequence the needs of a rapidly growing economic sector are not being met; and (3) Growth of the organic seed sector is hindered by regulatory imbalances and trade incompatibilities within and between global markets. For the field studies the main findings were: (1) In the partitioning of variance, location and season had the largest effect on broccoli head weight. For glucoraphanin and lutein, genotype was the major source of total variation; for glucobrassicin, region and the interaction of location and season; and for neoglucobrassicin, both genotype and its interactions with season were important. For δ- and γ- tocopherols, season played the largest role in the total variation followed by location and genotype; for total carotenoids, genotype was the largest source of variation and its interactions with location and season. For both horticultural and phytochemical concentrations, Management main effect and G × M interactions were often small but G × M × E (location and season) were large; (2) Cultivars with both greater head weight and stability under conventional conditions generally had high head weight and stability under organic growing conditions, although there were exceptions in cultivar rank between management systems. Cultivars highest in tocopherols and carotenoids were open pollinated or early maturing F1hybrids. Distinct locations and seasons were identified where phytochemical performance was higher for each compound; (3) Larger genotypic variances and somewhat increased error variances were observed in organic compared to conventional management systems led to repeatabilities for several horticultural and phytochemical traits that were similar or even higher in organic compared to conventional conditions; (4) The ratio of correlated response (predicting performance under organic conditions when evaluated in conventional conditions) to direct response (predicted performance in organic when evaluated under organic conditions) for all traits was close to but less than 1.0 with the exception of bead uniformity. This would imply that in most cases, direct selection in an organic environment could result in a more rapid genetic gain than indirect selection in a conventional environment; (5) Correlations among phytochemical traits demonstrated that glucoraphanin was negatively correlated with the carotenoids and the carotenoids were highly correlated with one another; and (6) There was little or no association between phytochemical concentration and date of cultivar release, suggesting that modern breeding has not negatively influenced the level of tested compounds and there were no significant differences among cultivars from different seed companies. Based on the findings strategies for breeding and seed models are discussed.</p

Variation in Broccoli Cultivar Phytochemical Content under Organic and Conventional Management Systems: Implications in Breeding for Nutrition

Organic agriculture requires cultivars that can adapt to organic crop management systems without the use of synthetic pesticides as well as genotypes with improved nutritional value. The aim of this study encompassing 16 experiments was to compare 23 broccoli cultivars for the content of phytochemicals associated with health promotion grown under organic and conventional management in spring and fall plantings in two broccoli growing regions in the US (Oregon and Maine). The phytochemicals quantified included: glucosinolates (glucoraphanin, glucobrassicin, neoglucobrassin), tocopherols (d-, c-, a-tocopherol) and carotenoids (lutein, zeaxanthin, b-carotene). For glucoraphanin (17.5%) and lutein (13%), genotype was the major source of total variation; for glucobrassicin, region (36%) and the interaction of location and season (27.5%); and for neoglucobrassicin, both genotype (36.8%) and its interactions (34.4%) with season were important. For d- and ctocopherols, season played the largest role in the total variation followed by location and genotype; for total carotenoids, genotype (8.41–13.03%) was the largest source of variation and its interactions with location and season. Overall, phytochemicals were not significantly influenced by management system. We observed that the cultivars with the highest concentrations of glucoraphanin had the lowest for glucobrassicin and neoglucobrassicin. The genotypes with high concentrations of glucobrassicin and neoglucobrassicin were the same cultivars and were early maturing F1 hybrids. Cultivars highest in tocopherols and carotenoids were open pollinated or early maturing F1 hybrids. We identified distinct locations and seasons where phytochemical performance was higher for each compound. Correlations among horticulture traits and phytochemicals demonstrated that glucoraphanin was negatively correlated with the carotenoids and the carotenoids were correlated with one another. Little or no association between phytochemical concentration and date of cultivar release was observed, suggesting that modern breeding has not negatively influenced the level of tested compounds. We found no significant differences among cultivars from different seed companies

Broccoli cultivar performance under organic and conventional management systems and implications for crop improvement

To determine if present commercial broccoli cultivars meet the diverse needs of organic management systems, such as adaptation to low N input, mechanical weed management, and no chemical pesticide use, and to propose the selection environments for crop improvement for organic production, we compared horticultural trait performance of 23 broccoli cultivars (G) under two management (M) systems (organic and conventional) in two regions of the United States (Oregon and Maine), including spring and fall trials. In our trials, location and season had the largest effect on broccoli head weight, with Oregon outperforming Maine, and fall trials outperforming spring plantings. M main effects and G × M interactions were often small, but G × M × E (location and season) were large. Cultivars with both greater head weight and stability under conventional conditions generally had high head weight and stability under organic growing conditions, although there were exceptions in cultivar rank between management systems. Larger genotypic variances and somewhat increased error variances observed in organic compared with conventional management systems led to repeatability for head weight and other horticultural traits that were similar or even higher in organic compared with conventional conditions. The ratio of correlated response (predicting performance under organic conditions when evaluated in conventional conditions) to direct response (predicted performance in organic when evaluated under organic conditions) for all traits was close to but less than 1.0 with the exception of bead uniformity. This would imply that in most cases, direct selection in an organic environment could result in a more rapid genetic gain than indirect selection in a conventional environment

Breeding for specific bioregions: a genotype by environment study of horticultural and nutritional traits integrating breeder and farmer priorities for organic broccoli cultivar improvement

The genotype by environment interaction study of broccoli, amongst others demonstrates that traits of a cultivar are sometimes ranked differently when grown in an organic production system compared to a conventional system. This has strong implications for breeding strategies. The breeders interviewed acknowledged that more attention on abiotic and biotic stress resistance in a broccoli breeding programme is needed which is in accordance with the farmers' varietal requirements. The first findings of the field trials show that cultivar performance is influenced by season and region, and differences in treatment (organic versus conventional management). The field trials showed that there are cultivars with broad adaptation such as "Green Goliath". These cultivars performed across locations, seasons and treatments within the sub-top group, however, organic farmers would benefit more from cultivars specifically adapted to their region and season. The trial results showed a wide range of glucosinolate levels. Glucoraphanin was very genotype dependent, while glucobrassicin and neoglucobrassicin were more influenced by abiotic and biotic environmental factors. Therefore, there are opportunities for nutritional performance enhancement under organic conditions which would provide an added value to the product quality with respect to human and plant health. Further elaboration of the dataset will contribute to the design of regional breeding strategies for improved broccoli cultivars for the organic market

Variation in Broccoli Cultivar Phytochemical Content under Organic and Conventional Management Systems: Implications in Breeding for Nutrition

Organic agriculture requires cultivars that can adapt to organic crop management systems without the use of synthetic pesticides as well as genotypes with improved nutritional value. The aim of this study encompassing 16 experiments was to compare 23 broccoli cultivars for the content of phytochemicals associated with health promotion grown under organic and conventional management in spring and fall plantings in two broccoli growing regions in the US (Oregon and Maine). The phytochemicals quantified included: glucosinolates (glucoraphanin, glucobrassicin, neoglucobrassin), tocopherols (d-, ¿-, a-tocopherol) and carotenoids (lutein, zeaxanthin, ß-carotene). For glucoraphanin (17.5%) and lutein (13%), genotype was the major source of total variation; for glucobrassicin, region (36%) and the interaction of location and season (27.5%); and for neoglucobrassicin, both genotype (36.8%) and its interactions (34.4%) with season were important. For d- and ¿- tocopherols, season played the largest role in the total variation followed by location and genotype; for total carotenoids, genotype (8.41–13.03%) was the largest source of variation and its interactions with location and season. Overall, phytochemicals were not significantly influenced by management system. We observed that the cultivars with the highest concentrations of glucoraphanin had the lowest for glucobrassicin and neoglucobrassicin. The genotypes with high concentrations of glucobrassicin and neoglucobrassicin were the same cultivars and were early maturing F1 hybrids. Cultivars highest in tocopherols and carotenoids were open pollinated or early maturing F1 hybrids. We identified distinct locations and seasons where phytochemical performance was higher for each compound. Correlations among horticulture traits and phytochemicals demonstrated that glucoraphanin was negatively correlated with the carotenoids and the carotenoids were correlated with one another. Little or no association between phytochemical concentration and date of cultivar release was observed, suggesting that modern breeding has not negatively influenced the level of tested compounds. We found no significant differences among cultivars from different seed companies

The development and implementation of organic seed regulation in the USA

This article reviews and analyses the evolution of organic seed regulation in the USA, as a model case of how challenges in a new regulatory area are being addressed. The study draws on formal interviews of key stakeholders, participant observation and documents generated in a 6-year period between 2007 and 2013. The article addresses three main issues: (1) how proposals for the wording and implementation of the regulation constrain seed choices and give rise to unintended consequences, (2) how emergent organizations and procedures have responded to the tension between sustaining seed differentiation to match the characteristics of local markets, organic production and agro-ecologies, and the narrowing of varietal choice in catalogued seed so as to expand commercial organic seed markets and encourage organic seed breeding and (3) why consensus on the content of formal seed policy has failed to develop despite a high level of stakeholder engagement. The study revealed that the official guidance on the interpretation of the regulation has not been sufficiently decisive to prevent divergent interpretation and practices, and therefore, the needs of a rapidly growing economic sector are not being met. The article concludes by drawing lessons for key areas of regulatory interpretation and practice and by identifying possible ways to make organic seed governance more effective

Breeding for specific bioregions: a genotype by environment study of horticultural and nutritional traits integrating breeder and farmer priorities for organic

The genotype by environment interaction study of broccoli, amongst others, demonstrates that traits of a cultivar are sometimes ranked differently when grown in an organic production system compared to a conventional system. This has strong implications for breeding strategies. The breeders interviewed acknowledged that more attention on abiotic and biotic stress resistance in a broccoli breeding programme is needed which is in accordance with the farmers' varietal requirements. The first findings of the field trials show that cultivar performance is influenced by season and region, and differences in treatment (organic versus conventional management). The field trials showed that there are cultivars with broad adaptation such as "Green Goliath". These cultivars performed across locations, seasons and treatments within the sub-top group, however, organic farmers would benefit more from cultivars specifically adapted to their region and season. The trial results showed a wide range of glucosinolate levels. Glucoraphanin was very genotype dependent, while glucobrassicin and neoglucobrassicin were more influenced by abiotic and biotic environmental factors. Therefore, there are opportunities for nutritional performance enhancement under organic conditions which would provide an added value to the product quality with respect to human and plant health. Further elaboration of the dataset will contribute to the design of regional breeding strategies for improved broccoli cultivars for the organic market

Broccoli Cultivar Performance under Organic and Conventional Management Systems and Implications for Crop Improvement

To determine if present commercial broccoli cultivars meet the diverse needs of organic management systems, such as adaptation to low N input, mechanical weed management, and no chemical pesticide use, and to propose the selection environments for crop improvement for organic production, we compared horticultural trait performance of 23 broccoli cultivars (G) under two management (M) systems (organic and conventional) in two regions of the United States (Oregon and Maine), including spring and fall trials. In our trials, location and season had the largest effect on broccoli head weight, with Oregon outperforming Maine, and fall trials outperforming spring plantings. M main effects and G × M interactions were often small, but G × M × E (location and season) were large. Cultivars with both greater head weight and stability under conventional conditions generally had high head weight and stability under organic growing conditions, although there were exceptions in cultivar rank between management systems. Larger genotypic variances and somewhat increased error variances observed in organic compared with conventional management systems led to repeatability for head weight and other horticultural traits that were similar or even higher in organic compared with conventional conditions. The ratio of correlated response (predicting performance under organic conditions when evaluated in conventional conditions) to direct response (predicted performance in organic when evaluated under organic conditions) for all traits was close to but less than 1.0 with the exception of bead uniformity. This would imply that in most cases, direct selection in an organic environment could result in a more rapid genetic gain than indirect selection in a conventional environmen