Average Relative Growth Rate Research Articles

Agro-Climatic Factors and Their Influence on Sustainable Soybean Production

This research explores the impact of intercropping corn and soybean, along with the combined effects of Azolla pinnata dose, the best soybean variety, and cytokinin concentration, on enhancing the physiology and agronomy of the plants. The study was conducted using 36 experimental units in a plot between soybean and corn. Various parameters were observed, including seed viability and vigor, soil analysis, nutrient content analysis of POC Azolla pinnata, temperature, air humidity, sunlight radiation, rainfall, pest infestation, diseases, and weeds. Additionally, plant height, leaf count, secondary branch count, total plant dry weight, leaf chlorophyll, leaf area ratio, leaf chlorophyll index, and stomatal conductance were measured. The data were analyzed using Djajasukanta and Sitompul-Guritno calculations, focusing on the average relative growth rate (RGR), average net assimilation rate (NAR), and root-shoot ratio (RSR). The results demonstrated that intercropping corn and soybean with the combination of Azolla pinnata dose, the best soybean variety, and cytokinin concentration had a positive impact on soybean production and quality. The Anjasmoro variety showed favorable outcomes in various parameters, such as plant height, leaf count, and branch count. Physiological leaf analysis revealed that the treatment combination with the Anjasmoro variety exhibited optimal photosynthetic rates and chlorophyll content, indicating higher photosynthesis efficiency. Moreover, the treatment with the Dega 1 variety displayed faster growth and efficient resource allocation, as evident from the high RSR value. The selection of the best soybean variety, Azolla pinnata dose, and cytokinin concentration can lead to sustainable improvements in soybean crop yield. These findings hold significant implications for agricultural management and enhancing food security.

Effects of two diets on growth and condition factor of Chitala lopis

The giant featherback Chitala lopis is fully protected fish species according to Indonesia's official list. The conservation of aquatic resources is achieved through implementing fish farming practices and optimizing feed utilization. This study aims to investigate the impact of different feeding rate on the growth patterns, performance, and condition factors of the first generation of giant featherback. The first generation of the fish were collected from the natural reproduction of broodstock in the earthen ponds. Fish were randomly divided at three different groups replicated three times and reared in the nine net cages installed in the earthen pond. The stocking density of the fish in each group was three fish per cage. The feed treatment involved fish bycatch as control (T0) (5% of the total weight) and freshwater shrimp, Caridina sp. with two different feeding rates including 5% (T1) and 7% (T2) of the total weight, respectively. The mean initial weight of the fish was 41 ± 3.85 g. The survival and absolute growth rate of T1 were highest (29.9±6.38 g, 78± 11%), but it is not significantly different (p0.05). The average relative growth rate of T1 is also highest (76.28±18.61%) and significantly different (p0.05). The growth pattern of the fish at the beginning of the study was negative allometric (0.54), which was low correlated (0.03), and at the end became positive allometric (4.17), which was moderately correlated (0.66). The highest condition factor was T2 (0.78±0.03) and had a significant effect (p0.05). Caridina sp. has a good impact on the first generation of giant featherback weight growth compared to other treatments in this study.Keywords:CultivationFeeding rateGiant featherbackCaridina sp.Rasbora sp.

Effects of different feeding rate on growth and condition factor of Chitala lopis

Chitala lopis, also known as giant featherback, is a fully protected fish species on Indonesian official list due to the susceptibility to exploitation. Several studies showed that the conservation of aquatic resources, such as giant featherback, could be achieved through the implementation of fish farming practices and optimization of feed use. Therefore, this study aimed to determine effect of different feeding rate on growth pattern, performance, and condition factor of the first generation of giant featherback. The first generation of fish was collected from the natural reproduction of broodstock in the earthen ponds. A total of 5 samples were then randomly divided into three treatment groups and reared in the nine net cages installed in the earthen pond. The stocking density in each group was three fish per cage, and the treatments were carried out in triplicates. Feed given comprised fish bycatch as control (T0) (5% of the total weight) and freshwater shrimp, Caridina sp. with two different feeding rates, namely 5% (T1) and 7% (T2) of the total weight. The mean initial weight of all the samples in this study was 41 ± 3.85 g. The results showed that the highest survival and absolute growth rates (29.9±6.38 g, 78± 11%) were obtained in T1, but were not significantly different (p0.05). Furthermore, the highest average relative growth rate was also found in T1 (76.28±18.61%) and significantly different compared to other treatments (p0.05). Growth pattern of fish at the beginning of the experiment was negative allometric (0.54), showing a low correlation (0.03), but became positive allometric (4.17) at the end, with moderate correlation (0.66). The results also showed that the highest condition factor was obtained in T2 (0.78±0.03), and there was a significant effect (p0.05). Based on the results, Caridina sp. had a positive and significant impact on the weight growth of the first generation of giant featherback compared to other studies.Keywords:CultivationFeeding rateGiant featherbackCaridina sp.Rasbora sp.

The Effect of Adding Licorice Extract and Sodium Bicarbonate to Drinking Water on the Productive Performance of Broilers Raised under Elevated Temperatures

The practical aspect of the research was carried out in the field of the Department of Animal Production - College of Agriculture and Forestry - University of Mosul. 200 Arbo Rekar chicks were used in standard breeding from one day old to 56 days old. At the age of 22 days, the chicks were randomly distributed among the study treatments, taking into account the homogeneity of chick weights for the replicates, while exposing all treatments to a gradual periodic temperature of (25-36-25) ±2°C. The design of the experiment included five treatments: the first was a control (without adding a control), the second and the third were licorice extract at a concentration of 800 and 1200 mg/liter of water, respectively, and for the fourth and fifth, sodium bicarbonate was added at a concentration of 0.4% and 0.6% to Drinking water straight. Feed and water were provided freely with Ad Libitum throughout the study period and for all treatments. The results of the statistical analysis showed a significant improvement (p≤0.05) in favor of the fifth treatment in the averages of final live body weight, total weight gain, total relative growth rate and total feed consumption compared to the rest of the treatments. The second and fourth treatments also showed a significant increase (p ≤ 0.05) in the mean total weight gain. Also, the fourth treatment was significantly (p≤0.05) superior in the average overall relative growth rate over the rest of the treatments. While the percentage of fatalities decreased significantly in the second, third and fourth treatments compared to the control treatment. While the results did not show any significant differences in the averages of the total feed conversion factor, the productivity index, the percentages of dressing, the mean relative weight of the main and secondary carcass pieces, visceral edible and visceral fat.

Effect of Different Types of Plant Media Composition on Growth And Physiology of Tomato

The study aims to determine the effect of several planting media on the growth and physiology of tomato plant seedlings except for soil. This research was conducted from March to May 2021 at the Greenhouse and Laboratory of Agronomy and Horticulture, Faculty of Agriculture, Jenderal Sudirman University, Purwokerto. The research method was the Completely Randomized Block Design (CRBD) with one factor and three replicated designs. The data obtained were analyzed using the F test with a 5% level, followed by Duncan's Multiple Range Test (DMRT) with a 5% level. The result shows that the planting medium of husk ash and compost (1:1) gave the best effect on average several observation parameters on plant height 25.17 cm, number of leaves 25 strands, leaf area 12.75 cm2, fresh crown weight 6.55 g, dry crown weight 1.32 g, root length 17.92 cm, fresh root weight 0.86 g, dry root weight 0.286 cm. While, the average relative growth rate of 0.341 g/day, and the net assimilation rate was 0.036 g/cm2/day. Other results showed that the composition of the planting media which includes a combination of sand, cocopeat, burnt husks, husk ash, and compost has an influence on the growth and physiology of seedlings but does not increase the chlorophyll content and greenness of the leaves of tomato plant seeds.

Extremely high relative growth rate makes the cabbage white, Pieris rapae, a global pest with highly abundant and migratory nature

The small cabbage white butterfly, Pieris rapae, is an extraordinarily abundant migratory pest of cabbage that causes severe damage worldwide without known reasons. I here show that the average relative growth rate (RGR: the ratio of the daily increase of biomass to total biomass) of herbivore (Gh; an indicator of the growth speed of herbivore) of P. rapae on cabbage during the larval period is larger by far than those of all other insect–plant pairs tested. It exceeds 1.15 (/day),—meaning that the biomass more than doubles each day—compared to 0.1–0.7 for most insect–plant pairs, including that of Pieris melete, a sibling of P. rapae which never becomes a pest of cabbage. My data further showed the RGR in the larval stage (larval Gh), positively correlates with abundance and/or migratoriness of insect herbivores. These results together with my mathematical food web model suggest that the extraordinarily high larval Gh of P. rapae is the primary reason for its ubiquitously severe pest status accompanied with its abundance and migratoriness, and that the RGR of herbivores, Gh, characterizing the plant–herbivore interface at the bottom of the food webs is an important factor affecting whole ecosystems, including animal abundance, fauna size, plant damage levels, competitiveness among herbivorous species, determination of hostplant, invasiveness, and the evolution of animal traits involved in the so-called r/K strategy, such as migratoriness. Knowledge about Gh will be crucial to controlling pests and improving the negative effects of human activity on ecosystems including faunal decline (or defaunation).

Ammonium-nitrate mixtures dominated by NH4+-N promote the growth of pecan (Carya illinoinensis) through enhanced N uptake and assimilation.

Nitrogen (N) limits plant productivity, and its uptake and assimilation may be regulated by N sources, N assimilating enzymes, and N assimilation genes. Mastering the regulatory mechanisms of N uptake and assimilation is a key way to improve plant nitrogen use efficiency (NUE). However, it is poorly known how these factors interact to influence the growth process of pecans. In this study, the growth, nutrient uptake and N assimilation characteristics of pecan were analyzed by aeroponic cultivation at varying / ratios (0/0, 0/100,25/75, 50/50, 75/25,100/0 as CK, T1, T2, T3, T4, and T5). The results showed that T4 and T5 treatments optimally promoted the growth, nutrient uptake and N assimilating enzyme activities of pecan, which significantly increased aboveground biomass, average relative growth rate (RGR), root area, root activity, free amino acid (FAA) and total organic carbon (TOC) concentrations, nitrate reductase (NR), nitrite reductase (NiR), glutamine synthetase (GS), glutamate synthase (Fd-GOGAT and NADH-GOGAT), and glutamate dehydrogenase (GDH) activities. According to the qRT-PCR results, most of the N assimilation genes were expressed at higher levels in leaves and were mainly significantly up-regulated under T1 and T4 treatments. Correlation analysis showed that a correlation between N assimilating enzymes and N assimilating genes did not necessarily exist. The results of partial least squares path model (PLS-PM) analysis indicated that N assimilation genes could affect the growth of pecan by regulating N assimilation enzymes and nutrients. In summary, we suggested that the / ratio of 75:25 was more beneficial to improve the growth and NUE of pecan. Meanwhile, we believe that the determination of plant N assimilation capacity should be the result of a comprehensive analysis of N concentration, N assimilation enzymes and related genes.

Life history strategies among soil bacteria—dichotomy for few, continuum for many

Study of life history strategies may help predict the performance of microorganisms in nature by organizing the complexity of microbial communities into groups of organisms with similar strategies. Here, we tested the extent that one common application of life history theory, the copiotroph-oligotroph framework, could predict the relative population growth rate of bacterial taxa in soils from four different ecosystems. We measured the change of in situ relative growth rate to added glucose and ammonium using both 18O–H2O and 13C quantitative stable isotope probing to test whether bacterial taxa sorted into copiotrophic and oligotrophic groups. We saw considerable overlap in nutrient responses across most bacteria regardless of phyla, with many taxa growing slowly and few taxa that grew quickly. To define plausible life history boundaries based on in situ relative growth rates, we applied Gaussian mixture models to organisms’ joint 18O–13C signatures and found that across experimental replicates, few taxa could consistently be assigned as copiotrophs, despite their potential for fast growth. When life history classifications were assigned based on average relative growth rate at varying taxonomic levels, finer resolutions (e.g., genus level) were significantly more effective in capturing changes in nutrient response than broad taxonomic resolution (e.g., phylum level). Our results demonstrate the difficulty in generalizing bacterial life history strategies to broad lineages, and even to single organisms across a range of soils and experimental conditions. We conclude that there is a continued need for the direct measurement of microbial communities in soil to advance ecologically realistic frameworks.

Combined effect of diabetes and frailty on mortality among Chinese older adults: A follow-up study.

Frailty and diabetes are two important health problems associated with aging in older individuals. This paper seeks to analyze the frailty in older adults suffering from diabetes and the combined effect of diabetes and frailty on mortality risk. The frailty index (FI) model was employed when evaluating frailty among the older adults based on the baseline data conducted in 2009; and death as outcome variables collected in 2020 were analyzed. The influence of diabetes on age-related changes in frailty in the older adults and resulting mortality rates was analyzed. Cox regression and Kaplan-Meier curves were applied to evaluate the influence on the risk of death and the 11-year survival of the older adults with varying diabetes and frailty statuses. Ultimately, 1,213 older people aged between 60 and 101, with an average age of (74.79 ± 8.58) at baseline, were included in the analysis. By 2020, there had been 447 deaths with mortality at 36.9% (447/1,213); there were 271 cases of diabetes, with a prevalence of 22.3% (271/1,213). The mean FI value for older adults with diabetes was higher than that of those without regardless of age, and the average annual relative growth rate of the FI value for older adults with diabetes was higher than that of those without diabetes (β = 0.039 vs. β = 0.035, t = 8.367, P < 0.001). For all FI value levels, the mortality rate among older adults with diabetes was higher than that of those without. The Cox Regression analysis showed that, compared with those suffering from neither diabetes nor frailty, older adults with both had the higher mortality risk (HR = 1.760.P < 0.001), followed by older adults suffering from frailty alone (HR = 1.594, P = 0.006), and then by older adults suffering from only diabetes (HR = 1.475, P = 0.033). The survival analysis showed that the median survival of those suffering from diabetes and frailty to be the shortest at just 57.23 (95% CI: 54.05 to 60.41) months, lower than the 83.78 (95% CI: 79.33 to 88.23) months in those suffering from frailty alone, and 119.93 (95% CI: 113.84 to 126.02) months in those with only diabetes, and 124.39 (95% CI: 119.76 to 129.02) months in older adults with neither diabetes nor frailty (P < 0.001). Frailty is common among older adults suffering from diabetes, and there is an increased risk of poor health outcomes, such as death, among older adults suffering from diabetes and frailty. When diagnosing, treating, and dealing with older adults with diabetes, attention should be paid to screening and assessing frailty in hopes of identifying it early so that appropriate measures of intervention can be taken to avoid or delay the resulting adverse effects.

Modeling the growth dynamics of water lettuce, Pistia stratiotes L. in wastewater

This study was aimed at assessing water lettuce (Pistia stratiotes L.) biomass growth, which was tested at the Faculty of Civil Engineering and Architecture of Nis under partially controlled conditions during a 70-day-long test, with a mixture of communal wastewater and water from the shaft at the hydraulic engineering demonstration facility as a source of nutrient matter. The biomass measured after the 70-day experiment ranged from 4.31 to 4.71 kg WW/m2 (average 4.48 kg WW/ m2). The daily absolute growth rate (AGR) was 58.81 g/m2 day, the daily increase rate (DIR) was 16.16 %/day, the average daily relative growth rate (RGR) was 0.0359 g/g day, and the biomass doubling time (DT) was 32.94 days. The following models were used to model the dynamics of water lettuce biomass growth: the exponential model (average MSE 0.0485, average coefficient of determination (R2) to 0.9757); the logistic model (mean squared error (MSE) 0.0049, R2 0.9976), and the sigmoidal model (average MSE 0.0003, average R2 0.9999). All models have a high accuracy; however, the exponential models give a continuous increase in biomass over time, practically to infinity, without taking into account that under conditions of increased plant density and reduced availability of resources, biomass growth slows down and, therefore, they are not suitable for application in real conditions. The logistic model (environmental capacity 6.1680 kg/m2 after about 150 days, ti 53.8587 days, ta 32.8295 days, tb 74.8879), and sigmoidal model (environmental capacity 5.2903 kg/m2 after about 150 days, ti 50.2972 days, ta 34.3072 days, tb 66.2872 days) adequately describe the biomass growth of the growth phase of water lettuce with high precision, which is essential for planning appropriate preventive and active measures to control the spread of water lettuce as an invasive plant and minimize negative impacts on waterbodies in Serbia.

Climatic origin of provenances of Corymbia calophylla affects canker disease susceptibility, caused by Quambalaria coyrecup, and interactions with drought stress

AbstractMany forest ecosystems are in decline around the world due to increasing biotic and abiotic stresses. Marri (Corymbia calophylla) is an endemic and common eucalypt species of southwestern Australia, which is in decline primarily due to stem canker caused by the pathogenic fungus Quambalaria coyrecup. This study determined to what extent disease susceptibility and plant growth were associated with climate at origin for eight provenances of marri. Plants of all provenances were grown in a common garden with or without pathogen inoculation. Disease development and physiological performance of plants were monitored during an initial irrigated and subsequent terminal drought period. Provenances from drier regions were more susceptible to the fungal pathogen than those from wetter regions, having on average 31% higher incidence rates at 20 days post‐inoculation (dpi) and larger canker lesions at 130 dpi (on average 49% increase) and 230 dpi (on average 42% increase). However, canker development for each provenance was fastest during the initial irrigated wetter growing period. Overall, the average relative canker growth rate was 4‐fold higher during the irrigated period compared to the terminal drought period (p &lt; .001). There were no significant differences between the provenances in leaf water status, photosynthetic rates, or relative growth rates (p &gt; .05). Canker infection reduced both photosynthetic rates and growth rates but only during the later part of the terminal drought period, with significant (p &lt; .05) reductions observed in two out of eight provenances, when plants had relatively large canker sizes. This effect tended to be strongest in the provenances from drier regions as they had relatively larger canker sizes than the provenances from wetter regions. We propose that the increased susceptibility of drier provenances is related to their lower exposure to the pathogen in their drier habitats. Since this is potentially due to suboptimal defence responses, using provenances from drier locations to ‘future‐proof’ local restoration outcomes in a drying climate may be counterproductive due to plant–pathogen interactions.

Differences in Density Dependence among Tree Mycorrhizal Types Affect Tree Species Diversity and Relative Growth Rates.

Conspecific negative density dependence (CNDD) may vary by tree mycorrhizal type. However, whether arbuscular mycorrhizal (AM)-associated tree species suffer from stronger CNDD than ectomycorrhizal (EcM) and ericoid mycorrhizal (ErM)-associated tree species at different tree life stages, and whether EcM tree species can promote AM and ErM saplings and adults growth, remain to be studied. Based on the subtropical evergreen broad-leaved forest data in eastern China, the generalized linear mixed-effects model was used to analyze the effects of the conspecific density and heterospecific density grouped by symbiont mycorrhizal type on different tree life stages of different tree mycorrhizal types. The results showed that compared to other tree mycorrhizal types at the same growth stage, EcM saplings and AM adults experienced stronger CNDD. Heterospecific EcM density had a stronger positive effect on AM and ErM individuals. Species diversity and average relative growth rate (RGR) first increased and then decreased with increasing basal area (BA) ratios of EcM to AM tree species. These results suggested that the stronger CNDD of EcM saplings and AM adults favored local species diversity over other tree mycorrhizal types. The EcM tree species better facilitated the growth of AM and ErM tree species in the neighborhood, increasing the forest carbon sink rate. Interestingly, species diversity and average RGR decreased when EcM or AM tree species predominated. Therefore, our study highlights that manipulating the BA ratio of EcM to AM tree species will play a nonnegligible role in maintaining biodiversity and increasing forest carbon sink rates.

Increasing Liana Abundance and Associated Reductions in Tree Growth in Secondary Seasonally Dry Tropical Forest

Lianas are thought to be increasing and altering tree growth and ecosystem productivity in tropical forests, but less research has focused on secondary or seasonally dry tropical forest. We report on an 11-year study of tree growth and liana presence from Guanacaste, Costa Rica, where we measured the diameter growth and liana presence on more than 1,700 trees in regenerating forest of different ages. We find that the proportion of trees without lianas is decreasing and the number of trees with lianas occupying more than 10% of tree’s crowns is increasing. We also find that lianas are affecting the diameter growth of trees. The 11-year average relative growth rates of trees with lianas in more than 10% of the tree’s crown are lower than the relative growth of trees with no lianas or lianas in less than 10% of their crown. Year-to-year, tree relative growth rate is related to annual precipitation and tree diameter. However, trees that were heavily infested with lianas (i.e., with lianas in more than 50% of their crowns) had lower relative growth and a weaker precipitation-growth relationship. This work underscores the value of long-term longitudinal data in secondary forest and adds critical data on dry forest liana abundance change.

Physicochemical and Biological Contribution of Native Macrophytes in the Constructed Wetlands to Treat Municipal Wastewater: A Pilot-Scale Experiment in a Sub-Tropical Climate Region

In this study, the physicochemical and biological contributions of different macrophytes in horizontal sub-surface flow constructed wetlands (HSSF-CWs) to treat low-strength municipal wastewater operated at high hydraulic loads under a sub-tropical climatic region is investigated. Out of the four identical beds, three were planted with locally available macrophytes (P. australis, Sagittaria, and Iris), whereas one bed was kept as a control. The beds were filled with media and operated in parallel continuously for eight months, with increasing the surface loading rate (SLR) from 0.19 to 2.78 m day−1. The results indicate that the planted beds performed significantly (p &lt; 0.01) better to remove TSS (70% to 78%), BOD5 (66% to 77%), COD (59% to 75%), NO3-N (56% to 64%), NH4-N (41% to 69%), TN (36% to 41%), and TP (44% to 61%) as compared to the unplanted bed for the same parameters (48%, 39%, 40%, 33%, 18%, 20%, and 29%, respectively). The presence of macrophytes in HSSF-CWs was found to be highly significant. The average relative growth rate (RGR) was observed in the order of P. australis (0.0086 day−1) &gt; Sagittaria (0.0061 day−1) &gt; Iris (0.0059 day−1). When compared to the performances of the species used, Sagittaria and P. australis produced better results than Iris. The investigations on biomass showed that Sagittaria yielded higher production, followed by P. australis and Iris. The proportions of uptake by the macrophytes were found to be 9.3%, 6.3%, and 3.9% of mass N removal, and 7.6%, 5.1%, and 4.4% of mass p removal in Sagittaria, P. australis, and Iris, respectively. This study contributes to the effective response to the environment, which validates a major role of macrophytes and their disparate response to pollutant removal processes by different species from municipal wastewater through HSSF-CWs.

The effect of different stock densities on the performance of giant prawns (Macrobracium rosenbergii) and rice production in the minapadi system

Minapadi is a prawn rearing system in rice fields that is carried out with rice plants. This study aims to increase the income of farmers with high productivity of rice yields and increase the production of giant prawns. The method used is a Completely Randomized Design (CRD) experiment with 3 treatments and 3 replications. The treatments were : P1 = stocking density of 100 ind/plot, P2 = stocking density of 200 ind/plot, P3 = stocking density of 300 ind/plot. This research was conducted for 90 days. Parameters observed were rice productivity and growth. The results showed that the best treatment was P2 = stocking density of 200 ind/plot. By producing an average rice productivity of 5.5 kg/50 m2 and the average relative growth rate of 4.72%. From the results of this study, the application of the Minapadi system with giant prawns had a positive impact on the observed parameters (P&lt;0.05) and thus will provide benefits for farmers.

Effects of light source and photoperiod on growth of duckweed Landoltia punctata and its water quality

This study investigated the effects of light source [LED white (LW), fluorescent white (T5) and LED blue (LB)] and photoperiod (12:12, 16:08, 24:00 light/dark) on growth of duckweed Landoltia punctata and the resulting effects on its water quality for 16 days. The average daily relative growth rate (RGR) reached about 0.519 g d−1. Both light source and photoperiod had no significant difference on the mean RGR; however, their interaction had significant effects on duckweed's growth (p ≤ 0.05). Moreover, except T5 (24:00) > [T5 (12:12) ≥ T5 (16:08) ≥ LB (24:00)], LW (12:12) > [T5 (16:08) ≥ LB (24:00)], and LB (12:12) > LB (24:00), there were no differences in RGR in all pair-comparisons of treatment (p ≤ 0.05). Nitrate (NO3−) mostly influenced weight increment (WI), 70%. For light source and photoperiod effects on water quality, no total ammonia nitrogen (TAN) was detected in all treatments after 16 days, while NO3− increased gradually. In addition, results show that most of the total nitrogen (TN) was contributed from NO3− (R2 = 0.9999). Overall, our findings could contribute on producing duckweed in a controlled and programmed condition for maximum production and quality. Constructed models and practical application contribute in predicting nutrients sensitivity and proven useful in water management or water quality assessments.

A Sustainable Solution to Obtain P-K-Mn Glass Fertilizers from Cheap and Readily Available Wastes.

The sustainable economy framework imposes the adoption of new ways for waste reuse and recycling. In this context, this paper proposes a new alternative to obtain glass fertilizers (agriglasses) by reusing two cheap and easily available wastes, wood ash and manganese rich sludge resulting from drinking water treatment processes for groundwater sources. Glasses were obtained using different amounts of wastes together with (NH4)2HPO4 and K2CO3 as raw materials. The P-K-Mn nutrient solubilization from the obtained glasses was investigated using a citric acid solution. The kinetics of the leaching process was studied after 1, 7, 14, 21 and 28 days, respectively. The intraparticle diffusion model was used to interpret kinetic data. Two distinct stages of the ion leaching process were recorded for all of the studied compositions: first through intraparticle diffusion (the rate-controlling stage) and second through diffusion through the particle–medium interface. The fertilization effect of the obtained agriglasses was studied on a barley crop. The specific plant growth parameters of germination percentage, average plant height, biomass and relative growth rate were determinate. The positive impact of the agriglasses upon the plants biomass and relative growth rate was highlighted. The effects of agriglasses can be tuned through glass compositions that affect the solubility of the nutrients.

Aquatic worms (Tubificidae) facilitate productivity of macrophyte Azolla filiculoides in a wastewater biocascade system

Due to high waste sludge disposal at wastewater treatment plants and increasing phosphorus scarcity, there is a need to combine waste removal and nutrient recovery. One way to achieve this is by incorporating ecological processes into wastewater treatment. Positive species interactions, such as facilitation, are critical to increase productivity of biomass and nutrient recovery. In this study we showed the potential of using ecological principles including interspecific facilitation processes of aquatic plants (Azolla filiculoides) and worms (Oligochaeta, Tubificidae) in waste recovery and biomass production. This was investigated by developing a biocascade with monocultures of plants and aquatic worms that was fed on activated sludge. Tubificidae had an average relative growth rate of 0.02 g g−1 DW d−1 whereby sludge predation resulted in 45% sludge reduction. When Tubificidae were present in the biocascade, A. filiculoides biomass production significantly increased to a relative growth rate of 0.15 g g−1 DW d−1. The activity of Tubificidae mostly affected total suspended solids, chemical oxygen demand and ammonium concentration in the first compartment of the biocascade. Additionally, nitrification rates increased and the water acidified, leading to increased carbon dioxide concentrations and dissolved phosphorus-binding metals (zinc, iron, aluminium and manganese) that stimulated A. filiculoides growth. The high sludge reduction (45%) and phosphorus sequestration (133 mmol m−3 d−1) show a strong potential of the biocascade for combined sludge waste reduction and phosphorus recovery from wastewater.

Climate influences the value of a plant structural defence against browsing

Abstract The circumstances that select for plant anti‐herbivore defences are not well understood. In New Zealand, the ‘divaricate’ cage‐like architecture of many woody plants may have arisen as a defence against avian browsing; it also has some ability to deter browsing by introduced deer. Its prominence on alluvial soils in frosty and droughty areas led us to hypothesize that structural defences are of most value where fertile soils coincide with climatic constraints that prevent plants from quickly growing out of the browse zone. We tested this hypothesis by growing seedlings of three divaricate species and their broadleaved congeners on fenced and unfenced plots beneath tree‐fall gaps at three humid frost‐free sites in the North Island of New Zealand, and at three colder and drier sites in the South Island. Soil total phosphorus levels were moderate to high at all sites (344–961 ppm), and pellet counts indicated similar average deer densities at North and South Island sites, enabling us to attribute variation in seedling growth and survival primarily to climatic differences between our sites. On fenced plots, average relative height growth rates in the North Island exceeded those on the southern sites by 64%, and growth of broadleaved species averaged 132% and 99% greater than that of divaricate congeners at North and South Island sites, respectively. On the northern sites, broadleaved species also held a large (137%) net height growth advantage over divaricates even on unfenced plots. In contrast, exposure to browsing on the coldest sites resulted in complete loss of the broadleaved net height growth advantage. Synthesis. Even in the presence of deer, divaricate plants were overgrown on humid frost‐free sites, but not on colder and drier sites, where browsing neutralized the superior growth potential of broadleaved species. The cost of structural defences therefore paid off only on sites where climatic adversity reduces the ability of plants lacking such defences to grow quickly out of the browse zone, in agreement with our hypothesis.

Variation in COVID-19 outbreaks at the US state and county levels

ObjectiveThe COVID-19 pandemic poses an unprecedented threat to the health and economic prosperity of the world's population. Yet, because not all regions are affected equally, this research aims to understand whether the relative growth rate of the initial outbreak in early 2020 varied significantly between the US states and counties. Study designBased on publicly available case data from across the USA, the initial outbreak is statistically modeled as an exponential curve. MethodsRegional differences are visually compared using geo maps and spaghetti lines. In addition, they are statistically analyzed as an unconditional model (one-way random effects analysis of variance estimated with HLM 7.03); the bias between state- and county-level models is evidenced with distribution tests and Bland–Altman plots (using SPSS 26). ResultsAt the state level, the outbreak rate follows a normal distribution with an average relative growth rate of 0.197 (doubling time 3.518 days). But there is a low degree of reliability between state-wide and county-specific data reported (Intraclass correlation coefficient ICC = 0.169, P < 0.001), with a bias of 0.070 (standard deviation 0.062) as shown with a Bland–Altman plot. Hence, there is a significant variation in the outbreak between the US states and counties. ConclusionsThe results emphasize the need for policy makers to look at the pandemic from the smallest population subdivision possible, so that countermeasures can be implemented, and critical resources provided effectively. Further research is needed to understand the reasons for these regional differences.