Protection to thermal impact of solar radiation: evaluation of selected reflective fabrics

Prolonged exposure to solar radiation can cause considerable heat stress. The application of reflective materials in garments or sunscreens is generally considered as an appropriate protective strategy. In this study, we aimed to compare a range of reflective and control fabrics on their ability to reduce the thermal impact of solar radiation. We evaluated 16 reflective and 5 control fabrics, varying in applicability for garments and/or sunscreens. Transmission of ultraviolet, visible light and infrared radiation was studied using artificial solar light. Thermal impact reduction was first studied using artificial infrared light and secondly using natural sunlight, measuring temperature right at the back and 10 cm behind the fabric after a 10-minute exposure. Most samples showed comparably low radiation transmission (<10%). However, substantially higher transmission was observed in perforated and mesh-like reflective fabrics, as well as light-colored controls and coldblack® treated fabric. This resulted in larger temperature increases at 10 cm behind the fabric (+1-4°C in sunlight). Contact temperature at the back of the black fabrics ended up higher than at the back of the reflective and white control fabrics (T: 5-10°C in sunlight), the latter two showing minor mutual differences (T<3°C). In conclusion, the reflective fabrics (excluding perforated, mesh and coldblack®) showed minor mutual differences, lower heat absorption than the black control fabrics and lower heat transmission than the white ones. The results suggest that reflective or white fabrics are preferable for most garment applications, while reflective or possibly black fabrics are preferable for sunscreen applications.

Albion Strawberry Responds to Mulch Treatments and Low Tunnels Covered with Photoselective Films

The impact of photoselective films on strawberry plants in a low tunnel system has not been well investigated in the northeastern United States, nor have there been studies looking at the effect of mulch color in a plasticulture system. During two separate years (2016 and 2017), we evaluated ‘Albion’ in an annual system with three ground mulch treatments (black plastic, white-on-black plastic, and no plastic) and under six cover treatments. Five of the cover treatments were low tunnel films that varied in their ultraviolet, photosynthetically active, and near-infrared radiation transmission profiles: Tufflite IVTM (TIV), KoolLite Plus (KLP), Trioplast (TRP), and custom-manufactured UV-transparent (UVT) and UV-blocking (UVO) films. The sixth cover treatment was the traditional open bed environment (no low tunnel). ‘Albion’ produced fruit for 18 to 19 continuous weeks during both years until as late as Thanksgiving (24 Nov.) in 2016. Overall, the average marketable yield was greater in 2017 (486 g/plant) than in 2016 (350 g/plant), and it was greater on black mulch than on no mulch (445 vs. 380 g/plant, respectively); white mulch was intermediate (419 g/plant) (P ≤ 0.05). There was not a significant increase in marketable yield under low tunnels compared with open beds. The average fruit mass was greater under KLP and UVO than open beds (TIV and UVT were intermediate), and greater on beds with no mulch than black mulch (white mulch was intermediate). Across cover treatments, plants on black mulch produced more runners than plants on white or no mulch, and the black mulch/open bed treatment generated the greatest number of runners in both years, more than double most other treatments in 2016. The present study demonstrates that mulch selection is important for maximizing the yield of ‘Albion’ in the Northeast region, and that both mulch and cover impact runnering and fruit size. For plant propagators producing ‘Albion’ tips in a field environment, the results of this study suggest they are likely to maximize runner quantity by cultivating plants on black mulch without low tunnel cover.

Effect of sowing density on the agronomic performance of Quinoa Nariño cultivar and the transmissivity of photosynthetically active radiation in the high tropics of Colombia

Quinoa is a promissory crop in the Andean region, on average, grain yield was 1.62 t ha-1 with nearly 2,000 t in the year 2017. This study examined the response of quinoa to the radiation transmission, growth, and development of the crop in different stages, under three planting densities in order todetermine the differential responses and identify which aspects are determinants in the planting and development process and crop yield. For the present experiment, quinoa was sowed in three differentdensities: D1 65,500, D2 83,333, and D3 156,250 plants per ha. This study measured the percentage of canopy PAR transmission, distribution of matter on root, stem, leaf, and panicle, leaf development in leaf area and leaf area index, yield components, weight of 1,000 grains, and harvest index. The results showed that sowing density had no impact on PAR transmission, lower sowing densities obtained the best dry weight of panicle at the end of the production cycle, better yields, and best grain weight. To conclude, the sowing density affects different yield components, while all of them allow theplant to generate the best response within the production cycle.