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

Abstract

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.

Diverse concepts of breeding for nitrogen use efficiency. A review

“…However, often, the N availability in the year of application is less than 100 kg N ha −1 which leads to yield reduction of N demanding crops such as potato and cabbage (Finckh et al 2006;Tiemens-Hulscher et al 2014). Renaud et al (2014) concluded from various trials comparing a set of 23 broccoli cultivars for their performance under conventional and organic conditions that overall the rankings of cultivars were similar (with exceptions) but that not all high-yielding genotypes were good performers with respect to yield stability across years and locations and were not very tolerant to N stress conditions, for example occurring in cold spring conditions. Organic crop management is not only characterized by specific ways of nitrogen husbandry but also by disease management; the latter can also affect the NUE of cultivars.…”

Key Traits and Promising Germplasm for an Organic Participatory Tomato Breeding Program in the U.S. Midwest

“…However, crop varieties bred in the location of intended use have been shown to be better performers than varieties bred outside of the intended region (Annicchiarico et al, 2012). Most breeding programs are also conducted using conventional farming practices though cultivars developed in these systems are not always the best performing ones in organic farming systems (Burger et al, 2008;Reid et al, 2011;Renaud et al, 2014a). In a large tomato germplasm screening trial conducted under organic management at three locations in Europe, Horneburg and Becker (2008) found that out of 3500 accessions, >71% of the most successful entries came from colleagues within the organic horticulture industry.…”

“…Low-input organic production systems also tend to be highly heterogeneous as a result of the wide range of soil and fertility management practices employed. Greater heterogeneity in organic systems supports the idea that direct selection would lead to varieties that are better adapted to organic systems, rather than indirect selection in high-input conventional systems (Reid et al, 2011;Renaud et al, 2014a). Trialing will need to occur under a wide range of conditions that characterize the breadth of organic farms, which is why participatory breeding has been successfully used to develop new potato, cabbage, cauliflower, and sweet corn cultivars optimally adapted to these systems (Almekinders et al, 2014;Chable et al, 2008;Shelton, 2014).…”

Cauliflower Cultivars Associated with Urochloa decumbens Straw Mulch in Integrated Weed Management

“…Particularly for cauliflower crops, adaptability varies widely according to cultivar and edaphoclimatic conditions (Morais Jr et al, 2012); thus, the study of more competitive genotypes adapted to a particular region may also complement weed control (Colquhoun et al, 2017;Cavalieri et al, 2018). Another aspect to be considered is that different cultivars of a particular vegetable may have different levels of adaptability to the same production system (Meagy et al, 2013;Renaud et al, 2014;Resende et al, 2016), and one should evaluate the viability of Brachiaria as a mulch option for cauliflower cultivation, as well as the adaptability of commercial cultivars in this cultivation system. Previous studies have shown that vegetables differ in their response to mulching (Resende et al, 2005;Santos et al, 2011;Ferreira et al, 2013).…”

“…Therefore, the evaluation of cultivars in environments with low use of chemical inputs allows the selection of more appropriate materials for a production system (Renaud et al, 2014), e.g., mulch without herbicides.…”