Effect of Poultry and Goat Manures on the Nutrient Content of Sesamum alatum Leafy Vegetables

Sesamum alatum Thonn. is one of the less-popular but nutritious leafy vegetables that is still collected from the wild or as weeds among crops in South Africa. The plant is also used in medicines and cosmetics in Africa and elsewhere. Despite its importance, the cultivation of S. alatum under different agronomic systems for improved harvestable yield and nutrient content is still lacking. The study aimed to determine the response of S. alatum nutrient content to the application of poultry and goat manures. Plants were grown in pots under rain-fed shade cloth conditions, with poultry and goat manures applied at 0, 1, 2, and 3 t ha–1 each, and they were laid in a completely randomized design. Shoot tips were harvested at 60 days after planting and analyzed for nutrient content. Shoots contained better nutrients in S. alatum plants grown during the first than the second season, with minor exceptions. Poultry and goat manure application led to an increase in Ca, Mg, K, P, and micro-nutrients. Goat manure had potential to increase the nutrient content in S. alatum than poultry manure, although differences were not substantial. Therefore, both manures could be equally used to improve nutrient content of S. alatum.

Spectral Blocking of Solar Radiation in High Tunnels by Poly Covers: Its Impact on Nutritional Quality Regarding Essential Nutrients and Health-Promoting Phytochemicals in Lettuce and Tomato

Spectral characteristics of solar radiation have a major role in plant growth and development and the overall metabolism, including secondary metabolism, which is important for the accumulation of health-promoting phytochemicals in plants. The primary focus of this study was to determine the effect of spectral characteristics of solar radiation on the nutritional quality of lettuce (Lactuca sativa L., cv. red leaf ‘New Red Fire’ and green leaf ‘Two Star’ and tomato (Solanum lycopersicum L., cv. BHN-589) grown in high tunnels in relation to the accumulation of essential nutrients and phytochemicals. Solar spectrum received by crops was modified using photo-selective poly covers. Treatments included commonly used standard poly, luminescence poly (diffuse poly), clear poly, UV blocking poly, exposure of crops grown under the standard poly to full sun 2 weeks prior to harvest (akin to movable tunnel), and 55% shade cloth on the standard poly. All the poly covers and shade cloth reduced the PAR levels in the high tunnels, and the largest reduction was by the shade cloth, which reduced the solar PAR by approximately 48%. Clear poly allowed the maximum UV-A and UV-B radiation, while standard poly allowed only a small fraction of the solar UV-A and UV-B (between 15.8% and 16.2%). Clear poly, which allowed a higher percentage of solar UV-A (60.5%) and UV-B (65%) than other poly covers, increased the total phenolic concentration and the antioxidant capacity in red leaf lettuce. It also increased the accumulation of flavonoids, including quercetin-3-glucoside, luteolin-7-glucoside, and apigenin-3-glucoside in red leaf lettuce, compared to the standard poly. Brief exposure of crops grown in high tunnels to full sun prior to harvest produced the largest increase in the accumulation of quercetin-3-glucoside, and it also resulted in an increase in luteolin-7-glucoside and apigenin-3-glucoside in red leaf lettuce. Thus, clear poly and brief exposure of red leaf lettuce to the full sun, which can increase UV exposure to the plants, produced a positive impact on its nutritional quality. In contrast, shade cloth which allowed the lowest levels of solar PAR, UV-A and UV-B relative to the other poly covers had a negative impact on the accumulation of the phenolic compounds in red leaf lettuce. However, in green leaf lettuce, luminesce poly, clear poly, UV-block poly, and shade treatments increased the accumulation of many essential nutrients, including protein, magnesium, and sulfur in green leaf lettuce compared to the standard poly. Poly cover treatments including shade treatment did not affect the accumulation of either carotenoids (lutein, β-carotene, and lycopene) or essential nutrients in mature tomato fruits. The results show that clear poly cover can enhance the accumulation of many phenolic compounds in red leaf lettuce, as does the brief exposure of the crop to the full sun prior to harvest. Thus, UV radiation plays an important role in the accumulation of phenolic compounds in red leaf lettuce while the overall spectral quality of solar radiation has a significant influence on the accumulation of essential nutrients in green leaf lettuce.

Effect of Light Characteristics on the Sensory Properties of Red Lettuce (Lactuca sativa)

Leafy green production in high tunnels (HTs) results in increased yields, improved visual quality, and extended production with polyethylene (poly) film and/or shade cloth coverings. However, altering visible and ultra-violet light with HT coverings may reduce phytochemicals, thus influencing plant pigmentation and taste. The objective of this study was to examine various HT coverings on the sensory perceptions, soil temperature, color, and anthocyanin accumulation of red leaf lettuce. The coverings included standard poly, standard poly with removal two weeks prior to harvest (movable), diffuse poly, clear poly, UV-A/B blocking poly (block), standard poly with 55% shade cloth, and the open field. A highly trained descriptive panel evaluated the samples using a scale from 0 (none) to 15 (extremely high) and determined a list of 20 sensory attributes. The color intensity attribute had the most differentiation between coverings, and the open field was higher (i.e., darker) than the others at 7.5 (p < 0.0001), followed by clear and movable coverings at 6.8, and the shade covering scored a 2. Strong relationships existed between both colorimetric (hue°) and anthocyanin analysis to panelist-based scores (R2 = 0.847 and 0.640, respectively). The initial crispness was similar for movable, standard, diffuse, and block coverings at 5.3 on average, which was higher than the open field at 4 (p < 0.01). The open field lettuce grew under cooler soil temperatures, which may have slowed down maturation and resulted in softer tissue. Based on this study, HT growers can implement specific coverings to cater to markets that value visual quality.

Controversy over the Use of “Shade Covers” to Avoid Water Evaporation in Water Reservoirs

Water scarcity and sustainability are main current concerns affecting billions of people worldwide. Apart from policies designed to guarantee water supply, technologies and procedures have been developed to optimize the uses of water and water recycling as well as to minimize water scarcity. Among these technologies, those based on the use of bioinspired fibres, membranes, nanomaterials, liquid-liquid extraction methods using ionic liquids or approaches involving plants or microbes have been successfully carried out. One of the main problems associated with most of these technologies is the high cost of their implementation and maintenance. Consequently, other cheaper strategies have been explored, such as the use of shade covers. The objective of this work is to summarize the most recent findings on the use of shade covers (suspended shade cloth covers and shade objects) on water reservoirs, mainly agricultural water reservoirs (AWRs). Reflections on the investment-benefit relationship of this technological proposal are also herein discussed. Apart from traditional shade cloth clover, more recently, other covers like shade balls/squares/hexagons (shady objects) have also been proposed as promising approaches to save water and keep its quality. However, the manufacturing of shady objects, mainly made of polyethylene plastic, results in: (i) high cost (high energy cost and use of raw materials like crude oil and natural gas); (ii) significant production of residues, and (iii) visual environmental pollution. The main conclusion reached from this review is that the controversy over the use of shade covers continues in the spotlight of scientists, water managers, and related companies; although this approach saves water and prevents water quality deterioration, a large number of recalcitrant residues are produced, not only during their production, but also when they must be replaced due to deterioration.

Dairy Heifer Motivation for Access to a Shaded Area

We used an operant conditioning paradigm to test the motivation of non-pregnant dairy heifers to access shade during the summer and autumn months (January to June) in southern Brazil. Dairy heifers (n = 18) were trained to push a weighted gate to access either an experimental area containing both a shaded (simple tree shade and shade cloth) and unshaded area (WITH SHADE) or an experimental area with no shade (BARREN). The latency to push the weighted gate, and the maximum weight pushed by each heifer, were recorded in both the summer and the autumn. Temperature and humidity were recorded continuously for the duration of the study and were used to calculate the heat index. The maximum weight pushed to enter the WITH SHADE area was greater in summer than in autumn, and was inversely related to the latency to push the weighted gate. Heifers refused to work for access to the BARREN environment. As expected, both the maximum ambient temperatures and heat index were higher in summer than in autumn, and also higher in the non-shaded areas than under the shade in both seasons. Heifers of higher social rank displaced other heifers more often, and spent more time in the shaded areas, particularly in the area with trees plus a shade cloth, than the intermediate and subordinate heifers. We conclude that shade is an important and valued resource for heifers reared on pasture-based systems in sub-tropical environments, particularly during the hot summer months.

Impact of Shade and Fogging on High Tunnel Production and Mineral Content of Organically Grown Lettuce, Basil, and Arugula in Georgia

This study evaluated the impact of shade cloth and fogging systems on the microclimate at the plant canopy level and yield of basil (Oscimum basilicum L.), arugula (Eruca vesicaria subsp. Sativa L.), and lettuce (Lactuca sativa L.) planted in mid-September and early October in high tunnels. Fogging systems were installed at canopy level in plots within shaded (30%) and non-shaded high tunnels. Average air temperatures in the shaded high tunnels were 0.9 °C lower than non-shaded high tunnels during the day. Shade cloth significantly reduced soil temperatures during the day and night periods by 1.5 °C and 1.3 °C, respectively, compared to non-shaded treatments. Fogging systems did not have an impact on air temperature, soil temperature, or relative humidity, but did increase canopy leaf wetness. Shade and fogging did not impact the yield of any of the crops grown. Yield was impacted by planting date, with earlier planting result in higher yields of lettuce and basil. Yields for arugula were greater during the second planting date than the first. Planting date and shade cloth interacted to affect the concentrations of macronutrients.

MORPHOFUNCTIONAL ECOLOGY OF SEEDLINGS FOUND IN A TROPICAL RAINFOREST SEED BANK, IN THE NORTHEAST OF BRAZIL

The aim of this study was to evaluate the identification and floristic composition of seedlings of tree species, located in the soil seed bank of a remnant of the Dense Ombrophilous Forest of the Lowlands, in the Northeast of Brazil, from a morphofunctional ecology standpoint. A hundred and fifty two soil samples (0.2 m x 0.15 m x 0.05 m) were taken from a forest remnant, stored in polyethylene bags, identified and then taken to the Forest Nursery at the Federal Rural University of Pernambuco, where they were placed in polyethylene boxes under a 70% shade cloth and evaluated daily for a period of seven months. The seedlings emerged were photographed, separated into morphospecies, identified at the family and gender level and, when possible, at the species level. The density and absolute frequency, as well as the successional and morphological classification of the seedling cotyledons were estimated. In total, 1,577 seedlings of 31 morphospecies were cataloged. Melastomataceae was the family that presented the greatest richness, representing 48% of the species identified. The average density was 344.62 seeds.m-2, with higher densities for species of the family Melastomataceae, together with Maprounea guianensis and Cecropia palmata. There was a predominance of seedlings with epigeal and phanerocotylar germination, and with foliaceous cotyledons, corresponding to 93.56%. The seed bank was composed, predominantly, by pioneer species such as Cecropia palmata, Henriettea succosa, Miconia hypoleuca and Miconia tomentosa. Seedlings with epigeal germination, foliaceous and phanerocotylar cotyledons predominated for being easily established in more open areas.

Cerium (Ce) Affects the Phenological Cycle and the Quality of Tulip (Tulipa gesneriana L.)

Objective: To study the effect of Ce applied in a nutrient solution during the productive cycle, on the duration of the phases of the phenological cycle of tulip cv. Jan van Nes. Design/Methodology/Approach: Commercial bulbs (caliber 12+) were planted under shade cloth conditions during the autumn-winter period. The levels of Ce used were 5, 15 and 15 µM from CeCl3 7H2O; Ce was applied in the nutrient solution from the first day of the sowing, apart from the control without its application. Results: The different concentrations of Ce bulb sprouting. The low concentration of Ce (5 ?M) promoted the early formation of floral buds and their coloration. Hence, the application of 5 ?M Ce advances flowering of the tulip without exhibiting changes in the period of time to reach senescence. When 25 ?M Ce were applied, the opposite effects were observed. The duration of the flower was not significantly affected by the treatments. Study Limitations/Implications: This study was made only in one cultivar of tulip. Findings/Conclusions: The application of 5 µM of Ce had a positive effect in the tulip cycle, by stimulating bulb sprouting, the formation of the floral bud, the coloration, and the advance of the flowering cycle

Layering contrasting photoselective filters improves the simulation of foliar shade

Background Neutral density shade cloth is commonly used for simulating foliar shade, in which it reduces light intensity without altering spectral quality. However, foliar shade also alters spectral quality, reducing the ratio of red to far-red (R:FR) light and altering the ratio of blue to green (B:G) light. Unlike shade cloth, photoselective filters can alter spectral quality, but the filters used have not simulated foliar shade well. We examined the spectral quality of sunlight under color temperature blue (CTB), plus green (PG), and neutral density (ND) filters from LEE Filters, Rosco e-colour+, and Rosco Cinegel brands either alone or layered, hypothesizing that the contrasting qualities of the different filters would improve simulations. As a proof-of-concept, we collected spectral data under foliar shade to compare to data collected under photoselective filters. Results Under foliar shade reductions in the R:FR ratio ranged from 0.11–0.54 (~ 1.18 in full sun), while reductions in the B:G ratio (~ 0.87 in full sun) were as low as 0.53 (deep shade), or were as high as 1.11 (moderate shade). Neutral density filters led to near-neutral reductions in photosynthetically active radiation and reduced the R:FR ratio similar to foliar shade. Color temperature blue filters simulated the increased B:G ratio observed under moderate foliar shade; however, these filters did not reduce the R:FR ratio low enough. On their own, PG filters did not simulate any type of foliar shade. Different brands of the same filter type also had disparate effects on spectral quality. Layered CTB and ND filters improved the accuracy of moderate foliar shade simulations, and layering CTB, PG, and ND filters led to accurate simulations of deep foliar shade. Conclusions Layering photoselective filters with contrasting effects on the spectral quality of sunlight results in more accurate simulations of foliar shade compared to when these filters are used separately. Layered filters can re-create the spectral motifs of moderate and foliar shade, and could be used to simulate shade scenarios found in different cropping systems. Photoselective filters offer numerous advantages over neutral density shade cloth, and could be a direct replacement for researchers using neutral density shade cloth in their experiments.

Evaluating shade cloth to simulate Palmer amaranth (Amaranthus palmeri) competition in sweetpotato

Field studies were conducted in 2019 and 2020 to compare the effects of shade cloth light interception and Palmer amaranth (Amaranthus palmeri S. Watson) competition on ‘Covington’ sweetpotato [Ipomoea batatas (L.) Lam.]. Treatments consisted of a seven by two factorial arrangement, in which the first factor included shade cloth with an average measured light interception of 41%, 59%, 76%, and 94% and A. palmeri thinned to 0.6 or 3.1 plants m−2 or a nontreated weed-free check; and the second factor included shade cloth or A. palmeri removal timing at 6 or 10 wk after planting (WAP). Amaranthus palmeri light interception peaked around 710 to 840 growing degree days (base 10 C) (6 to 7 WAP) with a maximum light interception of 67% and 84% for the 0.6 and 3.1 plants m−2 densities, respectively. Increasing shade cloth light interception by 1% linearly increased yield loss by 1% for No. 1, jumbo, and total yield. Yield loss increased by 36%, 23%, and 35% as shade cloth removal was delayed from 6 to 10 WAP for No. 1, jumbo, and total yield, respectively. F-tests comparing reduced versus full models of yield loss provided no evidence that the presence of yield loss from A. palmeri light interception caused yield loss different than that explained by the shade cloth at similar light-interception levels. Results indicate that shade cloth structures could be used to simulate Covington sweetpotato yield loss from A. palmeri competition, and light interception could be used as a predictor for expected yield loss from A. palmeri competition.