Shaded Environments Research Articles

Shading stress increases chalkiness by postponing caryopsis development and disturbing starch characteristics of rice grains

Chalkiness, one of the key factors in determining the market price and quality of rice grains, is markedly influenced by the environment. This study aimed to investigate the effectiveness of shading on rice chalkiness by conducting a field experiment in Wenjiang, Sichuan, China, in 2013 and 2015. Rice cultivars IIyou 498 and Yixiangyou 2115 were selected and shaded during the grain filling period; this resulted in a 53% shading environment. The results showed that chalkiness, caryopsis and amyloplast development, amylose content, and amylopectin chain-length distribution of rice grains, were markedly affected by shading. Shading significantly increased chalky rice rate and chalkiness degree of rice grains at the bottom of the panicle, which contributed to the increase in chalkiness of the entire panicle. Shading had a greater influence on grains at the bottom spikelet positions than on those at the top and middle positions. More loosely packed amyloplasts with greater airspace and reduction in amylose content of grains at the bottom spikelet positions were possibly due to the significant delay in the development of caryopsis. Furthermore, except for the bottom spikelet positions of Yixiangyou 2115, a reduction in short-length chains coupled to an increase in long-length chains of amylopectin was noted under shading. Shading increased rice chalkiness primarily by postponing caryopsis development at the bottom spikelet positions and disturbing the starch characteristics of rice grains. Therefore, more attention needs to be focused on the grains positioned at the bottom of panicle.

SEEDLING GROWTH OF TREE SPECIES UNDER DOSES OF HYDROGEL AND TWO LEVELS OF LUMINOSITY

ABSTRACT Hydrogels (polyacrylamide compounds) are recommended in agriculture and forestry as soil conditioners because they are able to absorb water and increase its stocks in the soil. The aim of this study was to determine the most suitable dose of hydrogel to establish seedlings of Enterolobium contortisilliquum (Vell.) Morong under two levels of luminosity. Seedlings of Enterolobium contortisilliquum (Vell.) Morong were planted in pots, following a design of subdivided plots, consisting of two levels of luminosity in the plots: full sun and 50% luminosity, and 10 doses of hydrogel in the sub-plots: 0.0, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5 and 6.0 g L-1. Seventy-two days after the seedlings were transplanted to the pots, plant height and diameter were determined, together with the height to diameter ratio, root length and diameter, shoot and root dry weight, and the shoot to root ratio. The lowest ratios between height and stem diameter (8.50 and 8.68) occurred in the seedlings in full sun at the doses of 0 and 2 g hydrogel L-1 respectively. For shaded seedlings the lowest ratio (8.14) occurred at the dose of 3.0 g L-1, but with a lower coefficient of determination (R2 = 0.68). Shoot dry weight increased with the dose of 2 g L-1 in full sun, and 3.5 g L-1 under shaded conditions. The doses of hydrogel giving the best initial development in seedlings under evaluation were 2 g L-1 in full sun and 3.5 g L-1 in the shaded environment. Although a response by the species to the doses of hydrogel was found, the benefits of the polymer were not evident under the conditions of the present study.

Heart rate, cardiac vagal tone, respiratory rate, and rectal temperature in dairy calves exposed to heat stress in a continental region.

Changes in non-invasive stress biomarkers were studied in shaded (n = 8) and non-shaded (n = 8) Holstein bull calves exposed to extreme heat load conditions in a continental region. Ambient temperature and humidity data were recorded for the S and NS hutch and exercise pen environments. Temperature-humidity-index (THI) was also calculated. Respiratory rate, rectal temperature, heart rate, and the root mean square of successive differences between R-R intervals (RMSSD) were recorded as animal-based indicators during three periods: (1) day 1, control day, during which all calves were shaded for 24h (shade removal from non-shaded calves at 2400h); (2) day 2, heat stress day, with shade over shaded calves; and (3) days 3-5, post-stress period, with shade over shaded calves. On the heat stress day, the maximum temperatures were 44.3 and 46.7°C for the non-shaded hutch and pen environments, respectively. The temperatures were with 6.2 and 6.9°C (P = 0.015 and P = 0.008) and the THIs were with 5.9 and 4.2units higher (P = 0.020 and P = 0.032) in the non-shaded than in the shaded environment for the hutch and exercise pen, respectively. Shaded calves had with 42.3 ± 3.2 breaths/min higher respiratory rate than non-shaded ones on the heat stress day at 1200h (P = 0.001), which was moderated to 20.1 ± 2.4 breaths/min at 1600h (P = 0.023). Significant differences in respiratory rate occurred earlier than in any other animal-based parameter between shaded and non-shaded calves on day 2. The only significant group difference in rectal temperature was found at 1200h on day 2 when THI exceeded 91units, with 0.59°C higher values for non-shaded calves (P = 0.045). The heart rate on days 2 and 3 was higher for non-shaded calves than for shaded ones. Group differences were also significant at 0800h (18.2 ± 1.2 beats/min, P = 0.008), 1200h (22.3 ± 1.4 beats/min, P = 0.003), 1600h (15.3 ± 0.8 beats/min, P = 0.012), and 2000h (19.0 ± 1.1 beats/min, P = 0.010) on day 2. Following a rapid daytime reduction, RMSSD showed a nighttime overcompensation in non-shaded calves on day 3 (between 0000 and 0600h) and day 4 (between 0000 and 0800h), exceeding the levels recorded on day 1 (control) and the levels for shaded calves, thus suggesting a recovery of the autonomic nervous system from heat stress. Based on our results, shading effectively reduced heat stress as evidenced by heart rate and RMSSD in addition to traditional measures of heat stress. Respiratory rate and heart rates exhibited by non-shaded calves support that the well-being of pre-weaned calves can be impaired in continental regions during following a heat stress day without providing shade.

Assessment of heat stress in 7-week old dairy calves with non-invasive physiological parameters in different thermal environments.

We estimated thermal stress in 7-week old Holstein bull calves during a warm episode in summer to study acute physiological responses of calves to heat stress. Data were collected over a 5-day period: day 1 (control), day 2 (heat stress), and a 3-day post-stress period in shaded (n = 8) and unshaded (n = 8) thermal environments. On the control day, both groups were shaded. Thermal environment was characterized by relative humidity, ambient temperature, and the temperature–humidity index (THI). Physiological variables included respiratory rate, rectal temperature, ear skin temperature and heart rate. Correlations between animal-based and meteorological indices were calculated, and ambient temperature correlated slightly better with physiological measures than THI. Rectal temperature was the only animal-based parameter that showed stronger correlations with the thermal indices when calculated for the shaded than for the unshaded environment [r = 0.42 vs. r = 0.47, P = 0.032 (ambient temperature), r = –0.39 vs. r = –0.45, P = 0.012 P = 0.015 (relative humidity), r = 0.41 vs. r = 0.46, P = 0.022 (THI)]. No differences were found between groups during the control day for any of the physiological parameters. During days 2 and 3, average and maximal values of respiratory and heart rates were higher in unshaded calves than in shaded ones. Maximal respiratory rates were in average by 25.9, 17.8 and 10.1 breaths/min lower in shaded calves than in unshaded calves for days 2, 3 and 4, respectively (P < 0.001, P < 0.001 and P = 0.024). Maximal heart rate was 127.4 ± 8.5 vs. 99.2 ± 6.3 beats/min on the heat stress day (P < 0.001), and 121.0 ± 6.9 vs. 103.4 ± 7.7 beats/min on day 3 (P = 0.006) in unshaded and shaded calves, respectively. Maximal body temperatures were higher measured either in the rectum or on the ear skin in unshaded calves than in shaded ones (with 0.5 and 1.6°C, P = 0.040 and P = 0.018, respectively), but only on the heat stress day. Based on our results, shading of young calves may be adequate for alleviating acute heat stress in continental regions. Ambient temperature is appropriate to estimate acute heat stress in dairy calves.

Light shading improves the yield and quality of seed in oil-seed peony (Paeonia ostii Feng Dan)

Tree peony seed is unique for its super-high content of unsaturated fatty acid and is thus considered as an important source of woody oil. However, photosynthetic production is greatly reduced under high light intensity and air temperature during the seed filling period, which negatively affects seed yield and quality. The objective of this study was to determine if appropriate shading improves yield and quality of seed in oilseed peony. In this study, oilseed peony trees were shaded by different density polyethylene nets from four weeks after flowering to harvest stages to form light, moderate, and severe shadings, equivalent to about 80, 40, and 20% of full solar exposure, respectively. The effects of different shadings on some physiological parameters, yield and yield components, and nutritional composition of seed were examined. Averaged across two years, light shading increased the actual net photosynthetic rate (Pn) by 16.8%, the maximum net photosynthetic rate (Pmax) by 81.4%, chlorophyll (Chl) content by 52.8%, auxin (IAA) content by 38.1%, and gibberellic acid (GA3) content in leaves by 6.3%; it decreased the accumulation of H2O2 in leaves by 24.8%, malondialdehyde (MDA) by 22%, and endogenous abscisic acid (ABA) by 8.8%, indicating that leaf senescence in late season was considerably delayed. Light shading increased seed yield, and contents of crude fat and unsaturated fatty acids by 9.7, 5.6, and 9.6%, respectively, while moderate or severe shading significantly reduced all the three parameters. Light shading increased seed weight, but moderate or severe shading reduced seed weight or follicle density. The improved seed yield under light shading was mainly due to increased seed weight, while the reduced seed yield under moderate or severe shading was mainly attributed to reduce follicle density and seed weight. The improved seed weight and content of unsaturated fatty acids under light shading was possibly due to the delayed leaf senescence. The overall results indicated that light shading is beneficial to yield and quality parameters of seed in oilseed peony. Cultivating oilseed peony under a light shading environments such as partially closed forests would better increase total output and income per unit land area than that under full solar exposure.

Sugar beet development under dynamic shade environments in temperate conditions

Abstract In Wallonia (Belgium) almost half of the arable land undergoes a four-year crop rotation. Winter crops often follow spring crops within the rotation scheme. This is a challenging context to implement silvoarable agroforestry (AF) systems, in terms of species choice, plot design, and tree management, since the periods of crop resource capture clearly differ. AF is defined here as the deliberate introduction of trees in the cropped area. Combining spring crops with trees induces an important overlap of the growing period of both plants which has an impact on one of the primary resources for both plants: light. In this study, we monitored an important spring crop for the region, sugar beet (Beta vulgaris L.). We quantified the impact of the shade environment on sugar beet morphology, growth dynamic, productivity and quality. We used artificial shade to isolate the impact of shade from other possible interactions in agroforestry systems. The field experiment was conducted over two consecutive years (2015 and 2016) on the experimental farm of Gembloux Agro-Bio Tech, Belgium. We installed the shade structures so as to reproduce a North-South and East-West tree line orientation. The experiment simulated canopy shade of late-flushing hybrid walnut by overlapping military camouflage netting. In 2015, the North-South orientation induced two distinct shade conditions: periodic shade (PS) and continuous shade (CS). In 2016, the East-West orientation created two periodic shade treatments, one during the morning (PSam) and one in the afternoon (PSpm). In both experimental years, shading was imposed from mid-June until harvest, resulting in 132 days of shade in 2015, and 140 days in 2016 on a growing season of 192 (2015) and 188 (2016) days in total. Sugar beet under shade tended to produce longer petioles. In 2015, at the first sampling date, we observed a higher specific leaf area and single leaf area under the CS and PS treatment, while there were no differences in 2016. All the shade treatments significantly changed the dry matter partitioning between the sugar beets compartments. Under the shade treatments, the quantity of biomass allocated to the leaves was significantly reduced as compared to the proportion of biomass for the petioles. Likewise, quantity of root dry matter formed per gram of shoot dry matter was reduced under shade. Thus, at harvest, all the shade treatments significantly reduced the final root dry matter and sugar yield. Furthermore, sugar beet quality, and more specifically sugar extractability, was affected by shading but to a lesser extent than for the final root dry matter and sugar yield.

Molecular signatures of host specificity linked to habitat specialization in Exaiptasia sea anemones.

Rising ocean temperatures associated with global climate change induce breakdown of the symbiosis between coelenterates and photosynthetic microalgae of the genus Symbiodinium. Association with more thermotolerant partners could contribute to resilience, but the genetic mechanisms controlling specificity of hosts for particular Symbiodinium types are poorly known. Here, we characterize wild populations of a sea anemone laboratory model system for anthozoan symbiosis, from contrasting environments in Caribbean Panama. Patterns of anemone abundance and symbiont diversity were consistent with specialization of holobionts for particular habitats, with Exaiptasia pallida/S. minutum (ITS2 type B1) abundant on vertical substrate in thermally stable, shaded environments but E. brasiliensis/Symbiodinium sp. (ITS2 clade A) more common in shallow areas subject to high temperature and irradiance. Population genomic sequencing revealed a novel E. pallida population from the Bocas del Toro Archipelago that only harbors S. minutum. Loci most strongly associated with divergence of the Bocas‐specific population were enriched in genes with putative roles in cnidarian symbiosis, including activators of the complement pathway of the innate immune system, thrombospondin‐type‐1 repeat domain proteins, and coordinators of endocytic recycling. Our findings underscore the importance of unmasking cryptic diversity in natural populations and the role of long‐term evolutionary history in mediating interactions with Symbiodinium.

Performance of Soybean Genotypes Selected on Shade Environment Under Rubber Stands

Research was aimed to evaluate performance of new genotypes of soybean selected in shaded environment under rubber stands and compare it with superior soybean varieties. Field experiment was arranged in a simple Randomized Block Design. Treatments comprised five levels namely four soybean genotypes selected in artificial shade and one shade tolerant superior soybean variety as a check. Each treatment was replicated 5 times. Experimental unit was a plot with size 3 m x 2 m with 100 plant population. Ten plants were used as samples. Observations were made on growth and yield variables. Such variables were plant height, number of branches, and stem diameter, while the observed yield variables included number of pod per plant, 100 seed weight, and seed weight of 10 plants. Observed data were analyzed by Analysis of Variance and continued by Duncan Multiple Range Test at α 5% level to compare the tested genotypes. Results showed that all the tested soybean genotypes gave the same performance with superior varieties of Anjasmoro in terms of stem diameter, number of branches, number of pods per plant, weight of 100 seeds, and seed weight of 10 stems of the plant. The difference was seen in of plant height where the selection genotypes were significantly shorter than Anjasmoro Variety.

Multiplicação in vitro de Codonanthe devosiana

Codonanthe devosiana is a species endemic to Brazil belonging to the family Gesneriaceae. It features ornamental potential for use in hanging pots and shaded environments. The aim is to evaluate the effects of the combination of different concentrations of BAP and GA3 on the multiplication and development of in vitro explants of C. devosiana. We used MS media supplemented with concentrations of 0.0, 0.2 and 0.4 mg L-1 of BAP and 0.0, 0.25 and 0.50 mg L-1 of GA3 . The number, bud dry matter and height, callus dry matter and presence of roots were evaluated in agglomerates with multiple buds. The interaction between BAP and GA3 concentrations was verified for number of shoots, shoot dry matter and callus dry matter. For shoot height and root formation, only BAP concentrations were observed. The highest number of shoots (4.8) occurred when combined with the concentration of BAP 0.2 mg L-1 and 0.5 mg L-1 GA3 . The lowest shoot height was observed without the use of BAP, as well as the greatest rooting. It is concluded that the combination of 0.2 mg L-1 of BAP with 0.5 mg L-1 of GA3 allows for a more efficient multiplication of C. devosiana explants

Effects of bud-flushing strategies on tree growth.

Allocation of carbohydrates between competing organs is fundamental to plant development, growth and productivity. Carbohydrates are synthesized in mature leaves and distributed via the phloem vasculature to developing buds where they are consumed to produce new biomass. The distribution and mass-allocation processes within the plant remain poorly understood and may involve complex feedbacks between different plant functions, with implications for the emergent structure of the plant. Here, we investigate how the order in which dormant buds are flushed affects the development of tree size and reproductive output during the first 20 years of growth in full light and shaded canopy environments. We report the following findings: (i) Bud-flushing strategies strongly affect the temporal dynamics of height, mass and the size of reproduction pool, as well as the resulting architectures. (ii) Bud-flushing strategies affect tree growth by altering the rate of growth and final size of trees. (iii) No single bud-flushing strategy performs best when both the size and allocation for reproduction of the resulting trees are compared. However, we observe that the strategy that optimizes the net carbon gain for the entire tree architecture always results in a high reproduction output. (iv) Branch turnover and meristem regeneration enhance the performance of certain strategies with respect to the measured quantities. These results highlight the importance of employing generic models of architecture (i.e., non-species-specific) to identify general mechanisms of carbon allocation and the spatial distribution of newly formed biomass in growing trees.

Mitigation of Hot-Spots in Photovoltaic Systems Using Distributed Power Electronics

In the presence of partial shading and other mismatch factors, bypass diodes may not offer complete elimination of excessive power dissipation due to cell reverse biasing, commonly referred to as hot-spotting in photovoltaic (PV) systems. As a result, PV systems may experience higher failure rates and accelerated ageing. In this paper, a cell-level simulation model is used to assess occurrence of hot-spotting events in a representative residential rooftop system scenario featuring a moderate shading environment. The approach is further used to examine how well distributed power electronics converters mitigate the effects of partial shading and other sources of mismatch by preventing activation of bypass diodes and thereby reducing the chances of heavy power dissipation and hot-spotting in mismatched cells. The simulation results confirm that the occurrence of heavy power dissipation is reduced in all distributed power electronics architectures, and that submodule-level converters offer nearly 100% mitigation of hot-spotting. In addition, the paper further elaborates on the possibility of hot-spot-induced permanent damage, predicting a lifetime energy loss above 15%. This energy loss is fully recoverable with submodule-level power converters that mitigate hot-spotting and prevent the damage.

Effects of bud-flushing strategies on tree growth.

Allocation of carbohydrates between competing organs is fundamental to plant development, growth and productivity. Carbohydrates are synthesized in mature leaves and distributed via the phloem vasculature to developing buds where they are consumed to produce new biomass. The distribution and mass-allocation processes within the plant remain poorly understood and may involve complex feedbacks between different plant functions, with implications for the emergent structure of the plant. Here, we investigate how the order in which dormant buds are flushed affects the development of tree size and reproductive output during the first 20 years of growth in full light and shaded canopy environments. We report the following findings: (i) Bud-flushing strategies strongly affect the temporal dynamics of height, mass and the size of reproduction pool, as well as the resulting architectures. (ii) Bud-flushing strategies affect tree growth by altering the rate of growth and final size of trees. (iii) No single bud-flushing strategy performs best when both the size and allocation for reproduction of the resulting trees are compared. However, we observe that the strategy that optimizes the net carbon gain for the entire tree architecture always results in a high reproduction output. (iv) Branch turnover and meristem regeneration enhance the performance of certain strategies with respect to the measured quantities. These results highlight the importance of employing generic models of architecture (i.e., non-species-specific) to identify general mechanisms of carbon allocation and the spatial distribution of newly formed biomass in growing trees.

Recruitment pattern of Scleractinian coral spats on neighbouring artificial substrates at Kurusadai Reef Complex, Gulf of Mannar, India

This study was conducted to assess the recruitment rate of coral spats and other invertebrates near to the coral reef ecosystem of Gulf of Mannar. The reef region examined was at Kurusadai Reef Complex (Gulf of Mannar) for this assessment. There were two sets of invertebrate settlement tripods deployed and exposed at a depth of 2m. Seventy two settlement tiles measuring 20x20 cm in two different angles were fixed in these tripods in the benthic reef ecosystem. In order to assess the impact of Sea surface temperature on the invertebrate settlement, Onset Hobo Pendant® Temperature logger was also attached with the tripods. The sediment traps in duplicate were also erected in the study site to assess the sedimentation rate of the reef ecosystem. About 80% of recruited coral spats were observed on the tiles which were exposed at 60° angle. Principal component analysis also supported that the most influencing species were coral spats followed by barnacles and bivalves in the 60° angle exposed settlement tiles. It was also observed that the most influencing place of coral spats’ recruitment was on the inner tiles. The mean sedimentation rate observed was 14.6 ± 4.8 mg.cm−2.d−1. The lower density of coral spats observed on 90° and 60° angle exposed outer tiles might be due to the observed sedimentation rate and it is believed that coral spats preferred the shaded environment initially for further perpetuation in the environment. Moreover, Bray-Curtis cluster analysis supported that the coral spats found on the inner tiles having 80% similarity in this assessment. The coral spats found in this assessment were species from Pocilloporidae and Poritidae.

Leaf non-structural carbohydrate allocation and C:N:P stoichiometry in response to light acclimation in seedlings of two subtropical shade-tolerant tree species

Light availability greatly affects plant growth and development. In shaded environments, plants must respond to reduced light intensity to ensure a regular rate of photosynthesis to maintain the dynamic balance of nutrients, such as leaf non-structural carbohydrates (NSCs), carbon (C), nitrogen (N) and phosphorus (P). To improve our understanding of the nutrient utilization strategies of understory shade-tolerant plants, we compared the variations in leaf NSCs, C, N and P in response to heterogeneous controlled light conditions between two subtropical evergreen broadleaf shade-tolerant species, Elaeocarpus sylvestris (E. sylvestris) and Illicium henryi (I. henryi). Light intensity treatments were applied at five levels (100%, 52%, 33%, 15% and 6% full sunlight) for 30 weeks to identify the effects of reduced light intensity on leaf NSC allocation patterns and leaf C:N:P stoichiometry characteristics. We found that leaf soluble sugar, starch and NSC concentrations in E. sylvestris showed decreasing trends with reduced light intensity, whereas I. henryi presented slightly increasing trends from 100% to 15% full sunlight and then significant decreases at extremely low light intensity (6% full sunlight). The soluble sugar/starch ratio of E. sylvestris decreased with decreasing light intensity, whereas that of I. henryi remained stable. Moreover, both species exhibited increasing trends in leaf N and P concentrations but limited leaf N:P and C:P ratio fluctuations with decreasing light intensity, revealing their adaptive strategies for poor light environments and their growth strategies under ideal light environments. There were highly significant correlations between leaf NSC variables and C:N:P stoichiometric variables in both species, revealing a trade-off in photosynthesis production between leaf NSC and carbon allocation. Thus, shade-tolerant plants readjusted their allocation of leaf NSCs, C, N and P in response to light acclimation. Redundancy analysis showed that leaf morphological features of both E. sylvestris and I. henryi affected their corresponding leaf nutrient traits. These results improve our understanding of the dynamic balance between leaf NSCs and leaf C, N and P components in the nutritional metabolism of shade-tolerant plants. Key messageTwo species of understory shade-tolerant plants responded differently to varying light intensities in terms of leaf non-structural carbohydrate allocation and the utilization of carbon, nitrogen and phosphorus to balance nutritional metabolism and adapt to environmental stress.

Plant biometric characterization and leaf micromorphometry of Talinum triangulare (Jacq.) Willd cultivated under shade

ABSTRACT Talinum triangulare (Jacq.) Willd, known as Ceylon spinach, Surinam purslane, or waterleaf, is cultivated for medicinal and food purposes. Among environmental factors, light is an important regulator of primary production, contributing to plant growth. However, the success of each plant species depends on its morphoanatomical responses to light. The aim of this study was to determine whether T. triangulare leaf micromorphometry is affected when grown in full sun and under shade, and if so, which plant biometric variables are affected. T. triangulare cultivation was tested in beds arranged in blocks under shade levels of 0, 18, 30, and 50%. Each bed was considered a basic experimental unit, totaling four replications per treatment. Plant height, stem diameter, leaf area, leaf fresh weight, stem fresh weight, specific leaf area, leaf area ratio, abaxial epidermis, and mesophyll thickness were higher as shade levels increased. However, there was a decrease in the number of leaves, root to shoot ratio, stomatal density on abaxial and adaxial surfaces, and palisade parenchyma thickness. Nevertheless, root length, leaf and stem dry weights, leaf weight ratio, adaxial stomatal index, adaxial epidermis, and spongy parenchyma thickness remained constant. Plants responded differently to shade, with morphological and anatomical changes, suggesting a phenotypic plasticity and raising the possibility of being grown both in shaded environments and in full sunlight.

Environmental Factors Moderate Glyphosate-induced Antagonism of POST Herbicides on the Rapid Response Biotype of Glyphosate-Resistant Giant Ragweed (Ambrosia trifida)

AbstractIn the rapid response (RR) biotype of glyphosate-resistant (GR) giant ragweed (Ambrosia trifidaL.), exposure to glyphosate elicits H2O2production in mature leaves, resulting in foliage loss and reduced glyphosate translocation. When glyphosate is applied with POST herbicides intended to improve control ofA. trifida, the RR to glyphosate has the propensity to antagonize these herbicide combinations. This research documents how transient changes in air temperature, soil moisture, and light intensity during a 6-d period surrounding herbicide application regulate induction of the RR and the effect on POST herbicide interactions with glyphosate. Air temperature had the greatest influence on H2O2accumulation in leaf disks following treatment with glyphosate, as plants at 30 C produced more than twice the amount of H2O2at 2.5 h after treatment compared with 10 C. Plants under field capacity conditions accumulated nearly 50% more H2O2than those at one-third field capacity, while those under no shade had only 18% more H2O2compared with those in a shaded environment. Despite these initial results, dry weight reduction at 21 d after treatment never differed by more than 8% between levels of environmental factors, thus indicating a negligible influence on glyphosate efficacy. The magnitude of glyphosate-induced antagonism was generally greater at 30 C (12% to 21% less than expected control) versus 10 C (11% to 16%) on atrazine, cloransulam, dicamba, and topramezone and was greater at field capacity (20% to 24%) versus one-third field capacity (11% to 15%) on cloransulam and topramezone. These results indicate air temperatures and soil moisture levels conducive to optimal plant growth accelerate the RR to glyphosate, thereby increasing the likelihood of glyphosate-induced antagonism on several translocated herbicides.

Validation of the Total Body Score/Accumulated Degree-Day Model at Three Human Decomposition Facilities

A few studies have examined the accuracy of the Megyesi et al. (2005) total body score/accumulated degree-day (TBS/ADD) method; however, no study has investigated the validity of the method using human remains at known ADD intervals. The current study validates the TBS method for human cadavers placed in three different human decomposition facilities in the United States. Twenty-eight donated cadavers, with known ADD and dates of death, in the first (fresh) stage of decomposition, were placed in sun and shade environments four times per year. The validity of the method was examined by conducting an interobserver error test of the TBS and analyzing the accuracy of the equation at predicting ADD. Nine individuals, experienced with the TBS method, participated in the interobserver error test. The results of the interclass correlation coefficient show that there was no statistically significant difference between observers for any of the body sections (trunk = 0.975, head = 0.959, limbs = 0.940, p < 0.001). Using the TBS regression equation, mean ADD with error ranges was calculated for all subjects and compared to actual ADDs of 100, 300, 500, and 1,000. Results show that mean ADD estimates do not correlate well with actual ADD for any of the actual ADDs (100, 300, 500, and 1,000). The accuracy of the TBS equation is insufficient in estimating mean ADD and error is largely unpredictable, other than it increases with postmortem time. KEYWORDS: forensic anthropology, taphonomy, total body score, accumulated degree-days

Productivity, Control, and Decomposition of Irrigated Forage Species under Glyphosate Doses and Shading

ABSTRACT: Light intensity available in growing environments may influence the susceptibility of plants to glyphosate and decomposition of their residues. This study aimed to assess the productivity, control, and decomposition of forage straw submitted to glyphosate doses and exposed to full sun and 50% shade. Two experiments were carried out, one for Piatã grass (Urochloa brizantha cv. Piatã) and other for Tanzania grass (Megathyrsus maximus cv. Tanzania). The experimental design was a randomized block design with strip-plot and four replications. Two growing environments (at full sun and under 50% shade) were installed in strips in the growing area, combined with six doses of glyphosate (0, 360, 720, 1,080, 1,440, and 1,800 g a.e. ha-1) used for forage desiccation. Shade did not change Tanzania grass productivity (p&lt;0.05), but it reduced Piatã grass productivity (p&gt;0.05), suggesting its low tolerance to light restriction. Tanzania grass is more tolerant to glyphosate when compared to Piatã grass, especially at full sun conditions. In general, the evaluated forages present a high susceptibility to glyphosate as incident radiation is reduced, which allows using lower doses to desiccate them in shaded environments. Straw decomposition of Piatã and Tanzania grasses was slower under shading. In this environment with light restriction, straw is more durable and has a better quality for the no-tillage system.

Trait variation of a generalist tree species (Eremanthus erythropappus, Asteraceae) in two adjacent mountain habitats: savanna and cloud forest

Cloud forests and savannas differ in several environmental aspects, particularly in light irradiance and water availability. Such differences can be selective for specific sets of leaves and architectural strategies to capture light and use water. In the present study we evaluated functional traits variation in a generalist species in two adjacent habitats experiencing an abrupt change in resource availability (light and water availability). We collected several leaf, stem and architectural traits of the tree species Eremanthus erythropappus (DC.) MacLeish in shrubland savanna (habitat facing higher drought stress and wind exposure) and cloud forest (shaded environment). Trees in the shrubland savanna exhibited functional trait values that enhance drought tolerance (i.e. higher wood density and leaf thickness) whereas trees in the cloud forest exhibited functional trait values that enhance light capture (i.e. taller individuals with higher leaf area and specific leaf area). Additionally, the individuals in the shrubland savanna had wider and deeper crowns, pointing that the benefits of a larger canopy area to capture light during the day and humidity from condensation at night exceed the higher risk of mechanical damage by falling debris due to high wind exposure. For all traits, variation among the individuals was lower than variation among habitats. Our results indicate the strong role of the environment as a driver of intraspecific variation and that architectural traits (usually poorly studied compared with other traits) should be included as an important parameter of variation in functional analyses when evaluating the effect of environmental conditions on tree performance.

Cessation of annual apical growth and partial death of cambium in stem of Abies sachalinensis under intensive shading.

This study evaluated variation in the height at which absent rings and internodes were detected along stem of Abies sachalinensis trees grown under shade for 39years. Eight sample trees planted in 1974 under a secondary forest in Japan were felled in 2013 and analyzed. A. sachalinensis is a monopodial species in which it is possible to measure annual apical growth using the distinct internodes. We applied microscopic analysis on 154 stem disks from the stem base to the top to evaluate the cessation of apical and radial growth caused by intensive shading. Cessation of apical stem growth for one or more years was found in 6 out of 8 sample trees. We termed this phenomenon as "absent internode". In addition, the absent growth rings were detected more frequently in the lower part of sample stems, and the number of absent rings at the stem base did not correspond with the number of absent internodes in the six trees. From cellular level observation, the five suppressed trees had no living cambial cells at the stem base but had living cells at the stem top. The cessation of the apical and radial growth did not occur synchronously but did occur independently under a shade environment in A. sachalinensis.