[Effect of Soil Contamination on the Reflective Properties of Reflective Groundcovers]

The objective of the present work was to study the effects of contamination on the reflective properties of groundcovers used for enhancing fruit colouration in the orchard. Contamination also affects longevity and possible sustainable re-use of materials. A white, woven textile (polypropylene Lumilys™) and silver aluminium foil were experimentally contaminated with soil, similar to the situation after an autumn storm in a fruit orchard. Clean material served as control.Using a spectrophotometer (StellarNet; Tampa, FL, USA), vertically directed (0°) and diffuse (45°) light reflection in the range of 500-850 nm was compared from clean and contaminated groundcover in the laboratory. Reflection from vertically directed aluminium foil exceeded that of Lumilys™; however, the highest reflection in all spectral measurements was at 45° (diffuse) from the clean woven textile, i.e., in all directions, and exceeded that of aluminium foil. In contrast, the contaminated vertically directed (0°) aluminium foil reflected less light than the clear foil but, surprisingly, reflected much more light at 45° than the clean foil. Both materials showed reflection peaks at 625-640 nm; light spectra and peaks remained unchanged irrespective of soil contamination.Light reflection in the visible range (PAR, 400-700 nm) was concomitantly measured in the field at CKA Klein-Altendorf near Bonn (50°N), Germany, at 0.5 m and 1 m height using a portable TRP‑3 light sensor (PP-Systems, Amesbury, MA, USA) on sunny and cloudy days at a solar angle of 49°. Surprisingly, in these field measurements, Lumilys and aluminium foil reflected most light in both directions (0° and 45°) when slightly to moderately contaminated. Only with heavy contamination did the reflection decrease. Both groundcovers reflected more light than the grass in alleyways of fruit orchards or open soil under the trees.UV‑B reflection (280-315 nm) was examined in parallel in the field using an X1 optometer (Gigahertz Optik, Türkenfels, Deutschland), as it enhances anthocyanin biosynthesis and red fruit colouration in combination with PAR and low temperature. Straight (0°) UV‑B reflection from aluminium foil exceeded that from white woven textile (Lumilys™) on both clear and overcast autumn days. As expected, straight (0°) UV‑B reflection from aluminium foil decreased with soil contamination to a certain extent, but it unexpectedly increased from the woven textile with soil contamination.Surface roughness in dependence of contamination was measured non-destructively by a profilometer type VR5200 (Keyence, Osaka, Japan). The roughness index, Sa, increased from 22 to 28 µm with soil contamination of the woven textile and from to 2 to 11 µm with aluminium foil, possibly explaining differences in the observed reflectivity.Overall, the expected severe decline in light reflection (PAR and UV-B) was not seen. In contrast, light (2-3 g soil/m²) and moderate (4-12 g soil/m²) contamination improved light reflection of PAR (400-700 nm) and UV‑B (280-315 nm) by woven textile (Lumilys™) and aluminum foil. Thus, with slight contamination the materials can be reused, whereas severe contamination (24-51 g soil/m²) reduces light reflection.

Why is the beautyberry so colourful? Evolution, biogeography, and diversification of fruit colours in Callicarpa (Lamiaceae)

Fruit colour is essential to seed dispersal, speciation, and biological diversity in global ecosystems. The relationship between fruit-colour variation and species diversification has long been of interest in evolutionary biology, but remains poorly understood at the genus level. Here, we used Callicarpa, a typical representative of pantropical angiosperm, to analyse whether fruit colours are correlated with biogeographic distribution, dispersal events, and diversification rate. We estimated a time-calibrated phylogeny for Callicarpa and reconstructed ancestral fruit colour. Utilizing phylogenetic methods, we estimated the major dispersal events across the phylogenetic tree and the most likely fruit colours related to each dispersal event, and tested whether the dispersal frequencies and distances of the four fruit colours between major biogeographical areas were equal. We then tested whether fruit colours are correlated with latitude, elevation, and diversification rate. Biogeographical reconstructions showed that Callicarpa originated in the East Asia and Southeast Asia during the Eocene (∼35.53 Ma) and diverse species diverged mainly in the Miocene and lasted into the Pleistocene. Large-scale dispersal events were significantly associated with violet-fruited lineages. Furthermore, different fruit colours were markedly correlated with different latitudes and elevations (e.g., violet fruits were correlated with higher latitudes and elevations; red fruits and black fruits with lower latitudes; white fruits with higher elevations). Notably, violet fruits were statistically associated with highest diversification rates, driving fruit colour variation among different regions globally. Our results contribute to further understanding why fruit colour is so variable at the genus level of angiosperms in different areas around the world.

Maintenance of a fruit colour polymorphism along an elevational gradient in the Southern Alps of New Zealand

Many plants produce colour-polymorphic fruits. However, the processes responsible for the evolution and maintenance of fruit colour polymorphisms are poorly understood. We investigated the fruit colour polymorphism in Gaultheria depressa var. novae-zealandiae (Ericaceae), a predominantly bird-dispersed, alpine shrub from New Zealand, by testing whether colour morph frequencies vary geographically to maximise fruit-foliage colour contrasts. We also conducted a seed germination experiment to test whether fruit colour morphs vary in their susceptibility to UV damage. Results showed that 'red' fruits were more abundant at lower elevations, while 'white' fruits were predominant at higher elevations. Leaf colours shifted from 'green' in appearance at lower elevations to 'red' at higher elevations. Analyses of fruit-foliage colour contrasts showed that 'red' fruits were more conspicuous at lower elevations, and 'white' fruits were more conspicuous at higher elevations, which was consistent with the hypothesis that colour morph frequencies vary geographically to maximise their conspicuousness to dispersers. However, 'red' fruits were generally more conspicuous than 'white' fruits, regardless of elevation, indicating that the maintenance of the polymorphism could not be attributed to fruit-foliage colour contrasts alone. The seed germination experiment showed that 'white' fruits were more resistant to UV damage, suggesting the preponderance of 'white' fruited individuals in the landscape results from a greater degree of protection from UV damage. The fruit colour polymorphism in Gaultheria depressa var. novae-zealandiae therefore appears to be maintained by trade-offs between conspicuousness to dispersers and tolerance to UV damage, advocating a pluralistic approach to the problem in the future.

Chemical components change along the ontogeny of a bat fruit (Neolamarckia cadamba) with ripening asynchrony in favour of its fruit selection and seed dispersal

An asynchronous fruit-ripening strategy can enhance the chance of seed dispersal by providing ripe fruits for an extended period to foragers. However, mechanisms associated with this strategy that can facilitate seed dispersal are understudied. This study aimed to investigate whether the chemical components (minerals and secondary metabolites) of a bat fruit with ripening asynchrony change along its ontogeny (Rubiaceae: Neolamarckia cadamba). We predicted that the seed-to-pulp ratio would increase along with fruit ripeness. The chemical components of the fruit were also predicted to change along their ontogenesis in favour of fruit selection and seed dispersal by fruit bats. Our study shows that the asynchronous fruiting strategy limited the number of ripe fruits daily so that fruits were available at a steady rate. As predicted, the seed-to-pulp ratio of each fruit increased along with fruit development. A fruit's mineral concentration also increased as fruit developed, with a sharp jump at full ripeness, when fruit colour also changed. In contrast, the concentration of secondary metabolite compositions decreased gradually during the process of ontogeny. Fruit bats (Pteropodidae: Pteropus giganteus and Cynopterus sphinx) were the only nocturnal frugivore visitors of these trees and their fruit selection was driven by fruit size and colour. Both bats preferably consumed ripe fruits, which had a higher concentration of attractants (essential minerals) and a lower concentration of deterrents (secondary metabolites), supplemented with a higher seed-to-pulp ratio. The bats exhibited different foraging patterns and home ranges resulting in dispersal (as measured by feeding roost location) occurring across different spatial scales. Our study shows that the chemical components involved in an asynchronous fruit-ripening process could select for extended fruit availability by intensifying the demand for each ripe fruit among legitimate seed dispersers, which increases the likelihood of fruits being dispersed away from parent crowns.

Anthocyanin synthesis and light utilisation can be enhanced by reflective mulch - Visualisation of light penetration into a tree canopy

With the increasing use of hailnets and decrease in light availability in the ripening period of apple fruit, insufficient light exposure often causes poor colouration viz anthocyanin synthesis on certain parts of the fruit and on certain fruit within the tree. The aim of this study was to investigate the potential of improving anthocyanin synthesis, in terms of fruit colouration, the major incentive for a consumer. Therefore, the reflective ground cover Lumilys® was spread between 'Braeburn Mariri Red' apple rows under a crystalline hailnet seven weeks prior to harvest and colour measured on 240 attached apple fruit. The reflective ground cover increased the reflected light by 1.6 to 3.9 times 1.0 m above ground. The improved light utilization led to an improved peel colouration, especially on the shaded side of the apple fruit and fruit in the lower inner part of the canopy, A coloured visualization from orange (high light intensity), yellow (medium) to green (low light intensity) as a result of the individual PAR measurements every 20 cm inside the canopy showed how the reflective mulch influences the light penetration into the different parts of the tree canopy.

Genetic mapping of ovary colour and quantitative trait loci for carotenoid content in the fruit of Cucurbita maxima Duchesne

The high content of carotenoids, sugars, dry matter, vitamins and minerals makes the fruit of winter squash (Cucurbita maxima Duchesne) a valuable fresh-market vegetable and an interesting material for the food industry. Due to their nutritional value, long shelf-life and health protective properties, winter squash fruits have gained increased interest from researchers in recent years. Despite these advantages, the genetic and genomic resources available for C. maxima are still limited. The aim of this study was to use the genetic mapping approach to map the ovary colour locus and to identify the quantitative trait loci (QTLs) for high carotenoid content and flesh colour. An F₆ recombinant inbred line (RIL) mapping population was developed and used for evaluations of ovary colour, carotenoid content and fruit flesh colour. SSR markers and DArTseq genotyping-by-sequencing were used to construct an advanced genetic map that consisted of 1824 molecular markers distributed across linkage groups corresponding to 20 chromosomes of C. maxima. Total map length was 2208 cM and the average distance between markers was 1.21 cM. The locus affecting ovary colour was mapped at the end of chromosome 14. The identified QTLs for carotenoid content in the fruit and fruit flesh colour shared locations on chromosomes 2, 4 and 14. QTLs on chromosomes 2 and 4 were the most meaningful. A correlation was clearly confirmed between fruit flesh colour as described by the chroma value and carotenoid content in the fruit. A high-density genetic map of C. maxima with mapped loci for important fruit quality traits is a valuable resource for winter squash improvement programmes.