L.C. Deleuran

Use of Multispectral Imaging in Varietal Identification of Tomato

Multispectral imaging is an emerging non-destructive technology. In this work its potential for varietal discrimination and identification of tomato cultivars of Nepal was investigated. Two sample sets were used for the study, one with two parents and their crosses and other with eleven cultivars to study parents and offspring relationship and varietal identification respectively. Normalized canonical discriminant analysis (nCDA) and principal component analysis (PCA) were used to analyze and compare the results for parents and offspring study. Both the results showed clear discrimination of parents and offspring. nCDA was also used for pairwise discrimination of the eleven cultivars, which correctly discriminated upto 100% and only few pairs below 85%. Partial least square discriminant analysis (PLS-DA) was further used to classify all the cultivars. The model displayed an overall classification accuracy of 82%, which was further improved to 96% and 86% with stepwise PLS-DA models on high (seven) and poor (four) sensitivity cultivars, respectively. The stepwise PLS-DA models had satisfactory classification errors for cross-validation and prediction 7% and 7%, respectively. The results obtained provide an opportunity of using multispectral imaging technology as a primary tool in a scientific community for identification/discrimination of plant varieties in regard to genetic purity and plant variety protection/registration.

Use of partial least squares discriminant analysis on visible-near infrared multispectral image data to examine germination ability and germ length in spinach seeds

Because of the difficulties in obtaining homogenous germination of spinach seeds for baby leaf production, the possibility of using partial least squares discriminant analysis (PLS‐DA) on features extracted from multispectral images of spinach seeds was investigated. The objective has been to discriminate between different seed sizes, as well as to predict germination ability and germ length. Images of 300 seeds including small, medium, and large seeds were taken, and the seeds were examined for germination ability and germ length. PLS‐DA loadings plots were used to reduce the multidimensional image features to a few important features. The PLS‐DA prediction resulted in an independent test set not only providing discrimination of seed size but also demonstrating how germination ability and germ length vary according to seed size. The result indicated that larger seeds had both a significantly higher germination potential and germ length compared with smaller seeds. The variable importance for projection method showed that the near infrared (NIR) wavelength region is important for germination predictability. However, the PLS‐DA model did not improve when only the NIR region was used. Copyright

Cultivar and row distance interactions in perennial ryegrass

Abstract To gain information about how widening of the row distance influences seed yields in first-year perennial ryegrass, experiments with four row distances in three types of perennial ryegrass were conducted at the University of Aarhus, Faculty of Agricultural Sciences. Perennial ryegrass was undersown at 12-, 24-, 36-, or 48-cm row distance in a cover crop of spring barley. The seeding rate in perennial ryegrass was 6 kg seeds ha−1 regardless of row distance. Although increasing the row distance from 12 to 48 cm had a negative effect on the yield component number of reproductive tillers, the yield was not affected in the first-year seed production in three perennial ryegrass cultivars. Regardless of row distance the seed rate was 6 kg ha−1 and hence in-row plant density in autumn and spring was higher at 48 compared with 12 cm; however, in all three cultivars the highest number of reproductive tillers was recorded at 12-cm row distance. Row distance affected seed yields of only the diploid amenity cultivar ‘Allegro’, where a row distance of 48 cm reduced the seed yield compared with 12- and 24-cm row distance. When data from the three cultivars were merged there was a positive correlation between the seed yield and seed weight (r=0.72***), whereas the correlation between seed yield and the number of reproductive tillers was negatively correlated (r= − 0.49***). This may reflect choice of cultivars in the experiment with the tetraploid forage cultivar ‘Tivoli’ having the lowest number of reproductive tillers, highest seed weight, and highest seed yield, and the diploid amenity cultivar ‘Allegro’ having the highest number of reproductive tillers, lowest seed weight, and the lowest seed yield. When the three cultivars were merged, there was a positive and highly significant correlation between seed weight and seed yield (r=0.72***). In contrast, there was no correlation between seed weight and seed yield when data were analysed for the individual cultivars. This suggests a cultivar-dependent relationship between seed weight and seed yield and furthermore between number of reproductive tillers and seed yield.

Optimizing the number of consecutive seed harvests in red fescue (Festuca rubra L.) and perennial ryegrass (Lolium perenne L.) for yield, yield components and economic return

Abstract Crop production must continuously be adjusted according to economic return and fluctuating prices on inputs versus harvested plant products and calls for continuous revision of the crop rotation and flexible management systems. This study describes grass seed production of three different types, respectively, of perennial ryegrass (Lolium perenne L.) and red fescue (Festuca rubra L.) and their optimum number of growing seasons in terms of yield, selected yield components and economic gain. Three harvest years gave the maximum yield in the red fescue type with long stolons (cv. Pernille) and the highest number of fertile tillers in all three red fescue cultivars. Four harvest years gave the maximum yield for types with short stolons (cv. Suzette) and without stolons (cv. Tamara). The fifth year significantly reduced the yield compared to the highest obtained yield within each cultivar. The diploid amenity cv. Allegro and forage type cv. Borvi of perennial ryegrass can be harvested in five consecutive years without a significant yield reduction. The tetraploid type cv. Tivoli had the highest thousand seed weight and a significant yield decrease from the first to the second year of seed harvest and a continuous decline in seed yield is observed from the first to the fifth harvest year in this cultivar. Yet, when the economic incentive was calculated it was found that optimum harvest years cannot be determined by yield considerations alone. A combination of high grass seed price and low cereal price shows that red fescue can be grown up to four years and perennial ryegrass up to five years with high economic returns.

Effect of seed rate and row spacing in seed production of Festulolium

Abstract Festulolium (×Festulolium) is a cross between the two species fescue (Festuca L.) and ryegrass (Lolium L.) and is a promising forage and seed crop. To stimulate the production of Danish organic festulolium seeds a three-year field experiment was performed from 1999 to 2002 in a ryegrass-type festulolium, Paulita, and in a fescue-type festulolium, Hykor. The objectives were to examine the influence of row spacing (12, 24, and 36 cm) and seed rate (8, 12, or 16 kg ha−1) on plant establishment, development, and seed yield. Observations of autumn and spring in-row plant densities indicated satisfactory plant establishment in all combinations of seed rate and row spacing. The number of reproductive tillers was in the range from 800 to 2200 m−2 in Paulita and from 500 to 1300 m−2 in Hykor. Row spacing had an effect on the number of reproductive tillers and in both cultivars the highest number was achieved at 12-cm row spacing. Seed yields in the Italian ryegrass type averaged from 1050 to 1150 kg ha−1 and in the tall fescue type from 650 to 800 kg ha−1. Doubling row spacing from 12 to 24 cm had no effect on seed yield in Hykor, while a further increase of row spacing to 36 cm showed a decrease in seed yield. No effect of row spacing on seed yield was observed in Paulita. Neither of the two types was affected in seed yield by seed rate. The fact that row spacing in both types can be increased to 24 cm without having a concomitant negative effect on seed yield implies that mechanical weed control is an optional management technique. Therefore our results have important implications in/for organic grass-seed production.

Establishment techniques in under-sown perennial ryegrass for seed production

Abstract Establishment methods have proven to be of major importance for grass-seed production. The objective of this research was to test the effect of different sowing techniques on plant establishment and the subsequent seed yield. Perennial ryegrass (Lolium perenne L.) is used as the model grass due to its large importance in Danish agriculture. In a three-year trial six different methods of under-sowing of perennial ryegrass in a spring barley cover crop were employed. Perennial ryegrass was either sown directly at different depths within the spring barley (Hordeum vulgare L.) rows or placed 2, 6, or 12 cm from the spring barley rows. Results of dry-matter yield indicate that the best establishment of the grass occurred when placing the grass 6 or 12 cm from the cover-crop row, and this is of importance in less vigorous grasses. Overall, no seed-yield difference has been observed for perennial ryegrass when placing the grass 2, 6, or 12 cm from the cover-crop row. Placement of the ryegrass seed crop 6 cm from the cereal row showed that a significant yield increase of 34–71 kg ha−1 can be obtained compared with sowing in the cereal row.

Establishment and seed production of smooth-stalked meadow grass and tall fescue undersown in spring rapeseed, linseed and field pea

In a 3-year field trial, undersowing of smooth-stalked meadow grass (Pia pratensis L.) and tall fescue (Festuca arundinacea Schreb.) seed crops in cover crops was studied. The selected cover; crops; spring rapeseed (Brassica napus L.), linseed (Linum usitatissimum L.) and field pea (Pisum sativum L.) were assumed to vary in canopy density and canopy closure date. The cover crops were sown in 12- and 24-cm spaced rows. This study shows good establishment and subsequent tiller and fertile tiller production of both grasses, when undersown in all the studied cover crops. Tall fescue undersown in field pea led to a higher seed yield than when undersown in spring rapeseed and linseed. Cover crop row spacing had no observed effect on tall fescue, whereas smooth-stalked meadow grass seed yield was increased when linseed was sown at 24 cm compared to 12 cm rows. When separating autumn tillers of smooth-stalked meadow grass into fractions of <1.5 mm, 1.5–2.0 mm and >2.0 mm stem base diameter all fractions of tillers were positively correlated (r=0.69; r=0.60; r=0.73, respectively) with seed yield.

Evaluation of the mature grain phytase candidate HvPAPhy_a gene in barley (Hordeum vulgare L.) using CRISPR/Cas9 and TALENs.

In the present study, we utilized TALEN- and CRISPR/Cas9-induced mutations to analyze the promoter of the barley phytase gene HvPAPhy_a. The purpose of the study was dual, validation of the PAPhy_a enzyme as the main contributor of the mature grain phytase activity (MGPA), as well as validating the importance of a specific promoter region of the PAPhy_a gene which contains three overlapping cis-acting regulatory elements (GCN4, Skn1 and the RY-element) known to be involved in gene expression during grain filling. The results confirm that the barley PAPhy_a enzyme is the main contributor to the MGPA as grains of knock-out lines show very low MGPA. Additionally, the analysis of the HvPAPhy_a promoter region containing the GCN4/Skn1/RY motif highlights its importance for HvPAPhy_a expression as the MGPA in grains of plant lines with mutations within this motif is significantly reduced. Interestingly, lines with deletions located downstream of the motif show even lower MGPA levels, indicating that the GCN4/SKn1/RY motif is not the only element responsible for the level of PAPhy_a expression during grain maturation. Mutant grains with very low MPGA showed delayed germination as compared to grains of wild type barley. As grains with high levels of preformed phytases would provide more readily available phosphorous needed for a fast germination, this indicates that faster germination may be implicated in the positive selection of the ancient PAPhy gene duplication that lead to the creation of the PAPhy_a gene.

Effect of Verticillium dahliae Soil Inoculum Levels on Spinach Seed Infection

Verticillium dahliae is a soilborne pathogen and a threat to spinach seed production. The aim of this study was to understand the relation between V. dahliae soil inoculum and infection in harvested seed. Quantitative polymerase chain reaction was used for quantification of the pathogen. Semifield experiments in which spinach was grown in soils with different inoculum levels enabled us to determine a threshold level for V. dahliae DNA of 0.003 ng/g of soil for seed infection to occur. Soils from production fields were sampled in 2013 and 2014 during and before planting, as well as the harvested seed. Seed from plants grown in infested soils were infected with V. dahliae in samples from both the semifield and open-field experiments. Lower levels of pathogen were found in seed from spinach grown in soils with a scattered distribution of V. dahliae (one or two positive of three soil subsamples) than in soils with a uniform distribution of the pathogen (three of three positive soil subsamples). Our results showed that infection of V. dahliae in harvested seed strongly depended on the presence of pathogen inoculum in the soil.

The quality turn in the Danish food scape: new food chains emerging – new territorial impacts?

Abstract Accounts of the ‘quality turn’ in agro-food literature suggest that there is a potential for growth in the market for ‘high-quality’ food, which utilises distinct notions like ‘quality’ and ‘place.’ These food chains are typically described as ‘alternative.’ Alterity might stem from alternative social or physical geographies of such food chains. This study is focused on exploring whether the utilisation of different notions of quality in emerging producer–consumer networks also translates into new patterns of rural development. This paper is based on data on various sub-sectors of Danish food chains on municipality scale for the period 2000–2005. Specifically, this study seeks to identify whether this is the case in the Danish context. First, the analysis considers the economic geography of Danish food chains on national level. Second, a deviant case on a regional level is considered, which runs counter to the trends on national level.