Protective rain shields alter leaf microclimate and photosynthesis in organic apple production

Plastic rain shields reduce the leaf and fruit wetness and protect apple trees against major leaf diseases and hail damage. Shielding the trees may reduce incoming radiation, especially in the ultraviolet (UV) region of the light spectrum, and affect the microclimate and photosynthesis. In July of 2014 and June of 2015, we measured the leaf microclimate and photosynthetic performance using chlorophyll fluorescence and gas exchange in the apple cultivar ‘Santana’ grown in three treatments. In one treatment the trees were exposed to natural light and sprayed (control), and in two treatments the trees were unsprayed and shielded with a plastic film not permeable to UV-light (UV-) or a plastic film permeable to UV-light (UV+). The light transmittance was reduced in the shielded treatments, protecting the leaves from high solar irradiance during noon on sunny days, and avoiding afternoon depression of photosynthesis. Due to this, the leaf photosynthetic rates were often higher in the protected trees in comparison to the control trees at similar high light intensities, whereas there were no differences between treatments on cloudy days. The effect of the UV+ film on photosynthesis did not differ from the UV- film, except there was a tendency for higher values accompanied with increased light transmittance of the UV+ film. We conclude that a microclimate with more diffused light maintained the photosynthetic yield, despite a lower light level under the rain shields

Overdækning forbedrer frugttræers helbred

Overdækkede frugttræer udvikler færre sygdomme og skader på blade og frugter. Samtidigt beskyttes bladenes fotosystemer og frugtudbyttet vedligeholdes

Protecting organic fruit trees from direct rain and sun

Fruit trees grown in orchards are highly nursed to maintain a specific growth structure for optimal yield and maintenance. Maintenance includes heavy spraying protocols to avoid fungal diseases both in conventional and organic orchards. Would it be possible to avoid fungal diseases by shielding the trees

Protecting apple trees from rain –better fruit quality and maintenance of yield

Plastic rain shields reduce the leaf and fruit wetness and protect apple trees against major leaf diseases and hail damage. Shielding the trees may reduce incoming radiation, especially in the ultraviolet (UV) region of the light spectrum, and affect the microclimate and photosynthesis

3D Laser Triangulation for Plant Phenotyping in Challenging Environments

To increase the understanding of how the plant phenotype is formed by genotype and environmental interactions, simple and robust high-throughput plant phenotyping methods should be developed and considered. This would not only broaden the application range of phenotyping in the plant research community, but also increase the ability for researchers to study plants in their natural environments. By studying plants in their natural environment in high temporal resolution, more knowledge on how multiple stresses interact in defining the plant phenotype could lead to a better understanding of the interaction between plant responses and epigenetic regulation. In the present paper, we evaluate a commercial 3D NIR-laser scanner (PlantEye, Phenospex B.V., Herleen, The Netherlands) to track daily changes in plant growth with high precision in challenging environments. Firstly, we demonstrate that the NIR laser beam of the scanner does not affect plant photosynthetic performance. Secondly, we demonstrate that it is possible to estimate phenotypic variation amongst the growth pattern of ten genotypes of Brassica napus L. (rapeseed), using a simple linear correlation between scanned parameters and destructive growth measurements. Our results demonstrate the high potential of 3D laser triangulation for simple measurements of phenotypic variation in challenging environments and in a high temporal resolution

The Evaluation of Growth Performance, Photosynthetic Capacity, and Primary and Secondary Metabolite Content of Leaf Lettuce Grown under Limited Irradiation of Blue and Red LED Light in an Urban Plant Factory

Plant production in urban areas is receiving much attention due to its potential role in feeding the rapidly growing population of city dwellers. However, higher energy demands in urban plant factories are among the key challenges that need to be addressed. Artificial lighting is responsible for the most significant levels of energy consumption in plant factories; therefore, lighting systems must be modulated in consideration of the sustainable food–energy nexus. In this context, low light irradiation using blue (B) and red (R) LED was applied in a plant factory for the growth of red leaf lettuce (Lactuca sativa L. var Lollo rosso) to evaluate the growth performance and functional quality. The tested B (450 nm) and R (660 nm) light ratios were B/R = 5:1; 3:1; 1:1; 1:3, and 1:5, with a photosynthetic photon flux density (PPFD) of 90 ± 3 µmol m−2 s−1. In the plant factory, the photoperiod, temperature, RH, and CO2 conditions were 16 h d−1, 20 ± 0.5 °C, 65% ± 5%, and 360 ± 10 μL L−1, respectively. The lettuce was harvested 10 and 20 days after the commencement of LED light treatment (DAT). In this study, normal photosynthetic activity and good visual quality of the lettuce were observed. The results show that a higher fraction of R (B/R = 1:5) significantly increased plant growth parameters such as plant height, leaf area, specific leaf area, plant fresh and dry weight, and carbohydrate content. By contrast, a higher fraction of B (B/R = 5:1) significantly increased the photosynthetic parameters and contents of pigment and phenolic compounds. The rate of photosynthetic performance, carbohydrates (except starch), and content of phenolic compounds were highest after 10 DAT, whereas the pigment contents did not significantly differ at the different growth stages. It is concluded that high R fractions favor plant growth and carbohydrate content, while high B fractions favor photosynthetic performance and the accumulation of pigments and phenolic compounds in red leaf lettuce under limited lighting conditions. This study will help in designing artificial lighting conditions for plant factory production to reduce energy demands

Allopolyploidization in Cucumis contributes to delayed leaf maturation with repression of redundant homoeologous genes

The important role of polyploidy in plant evolution is widely recognized. However, many questions remain to be explored to address how polyploidy affects the phenotype of the plant. To shed light on the phenotypic and molecular impacts of allopolyploidy, we investigated the leaf development of a synthesized allotetraploid (Cucumis × hytivus), with an emphasis on chlorophyll development. Delayed leaf maturation was identified in C. × hytivus, based on delayed leaf expansion, initial chlorophyll deficiency in the leaves and disordered sink‐source transition. Anatomical observations also revealed disturbed chloroplast development in C. ×hytivus. The determination of chlorophyll biosynthesis intermediates suggested that the chlorophyll biosynthesis pathway of C. × hytivus is blocked at the site at which uroporphyrinogen III is catalysed to coproporphyrinogen III. Three chlorophyll biosynthesis‐related genes, HEMA1, HEME2 and POR, were significantly repressed in C. × hytivus. Sequence alignment showed both synonymous and non‐synonymous substitutions in the HEMA1, HEME2 and POR genes of the parents. Cloning of the chlorophyll biosynthetic genes suggested the retention of homoeologs. In addition, a chimeric clone of the HEMA1 gene that consisted of homologous genes from the parents was identified in C. × hytivus. Overall, our results showed that allopolyploidization in Cucumis has resulted in disturbed chloroplast development and reduced chlorophyll biosynthesis caused by the repressed expression of duplicated homologous genes, which further led to delayed leaf maturation in the allotetraploid, C. × hytivus. The preferential retention/loss of certain types of genes and non‐reciprocal homoeologous recombination were also supported in the present study, which provides new insights into the impact of allopolyploidy