Image_1_Cover crop-based reduced tillage management impacts organic squash yield, pest pressure, and management time.jpg

Cover crop-based reduced tillage (CCBRT) systems can provide multiple benefits in cucurbit cropping systems, including potential to reduce spread of soil-borne pathogens, minimize erosion, and decrease weed pressure. Despite benefits and farmer interest, adoption has been limited, in part due to inconsistent weed suppression and potential for reduced yields. Prior studies have suggested that N competition, allelopathy, and lower temperature may be factors in reducing vegetable yield in CCBRT systems. A strip tillage approach has been suggested as one strategy that could mitigate those issues, but cucurbit yields using these systems have shown mixed results in prior studies, some of which did not include other important considerations for growers such as the impact on weed and pest pressure. In 2018 and 2019, CCBRT strip till practices for organic acorn winter squash (Cucurbita pepo L.) production were assessed in Wisconsin on certified organic land. Combinations of different between-row (aisle) and in-row mulches were compared to attempt to identify reduced tillage combinations that effectively manage weeds while resulting in yields comparable to full tillage production, testing our hypothesis that no differences between production systems would be observed due to strip tillage and plastic mulch warming soil and minimizing competition while promoting cash crop growth. Aisle treatments included roller-crimped cereal rye (Secale cereale L.) mulch, straw mulch and cultivated bare ground, and in-row treatments included plastic mulch, ground straw mulch, and cultivated ground. Weed and pest counts, weed management time, and yields were compared between treatments. Plots managed with rye and straw in the aisles had significantly less weed pressure as compared to cultivated aisle treatments, although rye required more weed management time than ground straw mulch. In addition, rye resulted in lower marketable yield due to higher proportion unmarketable fruit in 2018, likely related to a 25 cm rain event 2 weeks prior to harvest. A significant row mulch × aisle mulch interaction was observed for marketable fruit m−1, showing that yield was not significantly affected by the type of in-row mulch in plots with crimped rye mulch in the aisle. Pressure from squash bugs (Anasa tristis) was also higher in treatments with organic or synthetic mulches (straw in aisles or rows, rye in aisles, and plastic in rows). Our results support previous evidence that crimped rye can be an effective mulching strategy to reduce weed pressure, with more efficient management than traditional straw mulch. However, crimped rye systems may have negative implications for yield and pest pressure regardless of the use of a strip-tillage approach, indicating that more research is needed to refine the production system.</p

Image_2_Cover crop-based reduced tillage management impacts organic squash yield, pest pressure, and management time.jpg

Cover crop-based reduced tillage (CCBRT) systems can provide multiple benefits in cucurbit cropping systems, including potential to reduce spread of soil-borne pathogens, minimize erosion, and decrease weed pressure. Despite benefits and farmer interest, adoption has been limited, in part due to inconsistent weed suppression and potential for reduced yields. Prior studies have suggested that N competition, allelopathy, and lower temperature may be factors in reducing vegetable yield in CCBRT systems. A strip tillage approach has been suggested as one strategy that could mitigate those issues, but cucurbit yields using these systems have shown mixed results in prior studies, some of which did not include other important considerations for growers such as the impact on weed and pest pressure. In 2018 and 2019, CCBRT strip till practices for organic acorn winter squash (Cucurbita pepo L.) production were assessed in Wisconsin on certified organic land. Combinations of different between-row (aisle) and in-row mulches were compared to attempt to identify reduced tillage combinations that effectively manage weeds while resulting in yields comparable to full tillage production, testing our hypothesis that no differences between production systems would be observed due to strip tillage and plastic mulch warming soil and minimizing competition while promoting cash crop growth. Aisle treatments included roller-crimped cereal rye (Secale cereale L.) mulch, straw mulch and cultivated bare ground, and in-row treatments included plastic mulch, ground straw mulch, and cultivated ground. Weed and pest counts, weed management time, and yields were compared between treatments. Plots managed with rye and straw in the aisles had significantly less weed pressure as compared to cultivated aisle treatments, although rye required more weed management time than ground straw mulch. In addition, rye resulted in lower marketable yield due to higher proportion unmarketable fruit in 2018, likely related to a 25 cm rain event 2 weeks prior to harvest. A significant row mulch × aisle mulch interaction was observed for marketable fruit m−1, showing that yield was not significantly affected by the type of in-row mulch in plots with crimped rye mulch in the aisle. Pressure from squash bugs (Anasa tristis) was also higher in treatments with organic or synthetic mulches (straw in aisles or rows, rye in aisles, and plastic in rows). Our results support previous evidence that crimped rye can be an effective mulching strategy to reduce weed pressure, with more efficient management than traditional straw mulch. However, crimped rye systems may have negative implications for yield and pest pressure regardless of the use of a strip-tillage approach, indicating that more research is needed to refine the production system.</p

Table_1_Cover crop-based reduced tillage management impacts organic squash yield, pest pressure, and management time.docx

Cover crop-based reduced tillage (CCBRT) systems can provide multiple benefits in cucurbit cropping systems, including potential to reduce spread of soil-borne pathogens, minimize erosion, and decrease weed pressure. Despite benefits and farmer interest, adoption has been limited, in part due to inconsistent weed suppression and potential for reduced yields. Prior studies have suggested that N competition, allelopathy, and lower temperature may be factors in reducing vegetable yield in CCBRT systems. A strip tillage approach has been suggested as one strategy that could mitigate those issues, but cucurbit yields using these systems have shown mixed results in prior studies, some of which did not include other important considerations for growers such as the impact on weed and pest pressure. In 2018 and 2019, CCBRT strip till practices for organic acorn winter squash (Cucurbita pepo L.) production were assessed in Wisconsin on certified organic land. Combinations of different between-row (aisle) and in-row mulches were compared to attempt to identify reduced tillage combinations that effectively manage weeds while resulting in yields comparable to full tillage production, testing our hypothesis that no differences between production systems would be observed due to strip tillage and plastic mulch warming soil and minimizing competition while promoting cash crop growth. Aisle treatments included roller-crimped cereal rye (Secale cereale L.) mulch, straw mulch and cultivated bare ground, and in-row treatments included plastic mulch, ground straw mulch, and cultivated ground. Weed and pest counts, weed management time, and yields were compared between treatments. Plots managed with rye and straw in the aisles had significantly less weed pressure as compared to cultivated aisle treatments, although rye required more weed management time than ground straw mulch. In addition, rye resulted in lower marketable yield due to higher proportion unmarketable fruit in 2018, likely related to a 25 cm rain event 2 weeks prior to harvest. A significant row mulch × aisle mulch interaction was observed for marketable fruit m−1, showing that yield was not significantly affected by the type of in-row mulch in plots with crimped rye mulch in the aisle. Pressure from squash bugs (Anasa tristis) was also higher in treatments with organic or synthetic mulches (straw in aisles or rows, rye in aisles, and plastic in rows). Our results support previous evidence that crimped rye can be an effective mulching strategy to reduce weed pressure, with more efficient management than traditional straw mulch. However, crimped rye systems may have negative implications for yield and pest pressure regardless of the use of a strip-tillage approach, indicating that more research is needed to refine the production system.</p

Assessment and Accessibility of Phenotypic and Genotypic Diversity of Carrot (<i>Daucus carota</i> L. var. sativus) Cultivars Commercially Available in the United States

<div><p>Increased use of intellectual property rights over plant germplasm has led to a complicated landscape for exchange among plant breeders. Our goal was to examine phenotypic and genotypic diversity present in commercially available carrot (<i>Daucus carota</i> L. var. sativus) germplasm in relation to the freedom to operate—the ability for plant breeders to access and use crop genetic diversity. A collection of 140 commercially available carrot cultivars were grown in replicated field trials in the Madison, WI area in 2013 and 2014. Phenotypic measurements were recorded for leaf and root characteristics. Illumina sequencing was used to conduct genotyping by sequencing analysis on all cultivars to understand the range of genetic diversity present. Additionally, the intellectual property rights associated with each cultivar was noted to determine the freedom to operate. We found that although one-third of the commercially available US carrot cultivars in our study are restricted through some form of intellectual property rights, the genetic and phenotypic variability of the protected cultivars does not represent a completely separate group from the available material. Phenotypic analyses including ANOVA and principal components analysis, suggest that many of the traits differed significantly based on market class, but not by whether the cultivar had freedom to operate. The principal components and F_st analyses on the genotyping by sequencing data revealed that carrot market classes (F_st = 0.065) and freedom to operate classes (F_st = 0.023) were not genetically distinct, and that principle components 1 and 2 account for only 10.1% of the total genotypic variation, implying that cultivated carrot germplasm in the US forms an unstructured population. Our findings suggest that the genetic diversity present in carrot cultivars that have freedom to operate is potentially large enough to support carrot breeding efforts in most market classes given present levels of intellectual property protection.</p></div

Results from an Analysis of Variance comparing effects of the model with different phenotypic traits as response variables.

<p>Chi square value is reported for random effects and F statistic is reported for fixed effects.</p

Factor loadings showing contributions of each trait to PC 1 and 2 for the principal components analysis of the phenotypic data.

<p>Factor loadings showing contributions of each trait to PC 1 and 2 for the principal components analysis of the phenotypic data.</p

Principal Components Analysis of phenotypic data estimated using LS means estimates and showing (a) PC 1 and 2 for commercial carrot cultivars color coded based on freedom to operate (FTO).

<p>A grey dot indicates the cultivar has no FTO for plant breeding and a black dot indicates the cultivar has FTO for plant breeding. Confidence ellipses shown are the 95% confidence level for the group with the corresponding color. (b) Shows the same PCA but is color coded based on carrot market class.</p

Broad sense heritability estimates (H²) for phenotypic traits measured based on the global variation in phenotype, the location (over both years) and site specific variance.

<p>Broad sense heritability estimates (H²) for phenotypic traits measured based on the global variation in phenotype, the location (over both years) and site specific variance.</p

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