Suboptimal Temperature Conditions Research Articles

Impact of low temperature on bacterial community dynamics and process efficiency in anaerobic ammonia removal: A network analysis of metagenomic data

The implementation of anaerobic ammonia removal has potential for reducing the operating costs in wastewater treatment plants. However, the application of this process in mainstream treatment presents various challenges, particularly due to the sensitivity of anammox bacteria to low temperatures. To address these challenges, changes in the bacterial community were investigated under decreasing temperatures (from 30 to 12 °C) within a deammonification process conducted in a 10-L sequencing batch reactor (SBR) over a period of 114 days. The aim of the study was to determine which groups of microorganisms are most strongly linked by ecological relationships with anammox bacteria and how these relationships change in response to decreasing temperature. Community dynamics were analyzed by combining metagenomics, network analysis, and specific process rates. The nitrification process was most efficient at 25 °C, as indicated by high values of the ammonia and nitrite utilization rate, and nitrate production rate, all of which declined as the temperature decreased. In contrast, the activity and abundance of anammox bacteria remained stable throughout all phases of the experiment. The decreasing temperature negatively impacted Nitrospira bacteria, the main competitors of anammox in the deammonification system. Despite the reduced process efficiency, the SBR maintained stable functionality even at temperatures as low as 12 °C. Network analysis identified which bacterial groups most frequently co-occurred and interacted, as well as those most sensitive to temperature fluctuations. Among the bacterial nodes, Nitrospira, Phycisphaerae, and Prosthecobacter exhibited the highest degree of connectivity, suggesting that they participate in multiple interactions, such as metabolite exchange, cooperation, or competition. Nevertheless, the temperature node had a greater number of connections than any bacterial node, indicating that this environmental factor had a more important effect on microbial community formation than direct ecological relationships. These results contribute to a comprehensive understanding of the role of anammox bacteria in deammonification systems, their ecological interactions within microbial networks, and their activity under suboptimal temperature conditions, which is crucial for future practical applications.

Effects of mandarin peel powder on growth, biochemical, immune, and intestinal health in Oreochromis niloticus at suboptimal temperatures

This 60-day study aimed to examine the efficacy of a diet supplemented with mandarin peel powder (MP) in enhancing the health and survival of Oreochromis niloticus under suboptimal temperature conditions (21 ℃). One hundred and eighty Nile tilapia fish (22.51 ± 0.04 g) were randomly distributed into four experimental groups; each of 3 replicates (15 fish per replicate). The first group (CONT) received a basal diet without MP. The second (MP10%), third (MP15%), and fourth (MP20%) groups were fed diets containing 10, 15, and 20% MP powder, respectively. At the end of the feeding trail, growth performance, serum growth hormone, α-amylase enzyme, lysozyme activity, nitric oxide, protease activity, globulin, serum levels of IL-1ß, antioxidant status, and intestinal histology were measured. The results showed insignificant differences between CONT, MP15%, and MP20% groups in the final body weight and specific growth rate. The growth hormones in the MP15% and MP20% groups did not show a significant difference compared to fish fed a normal basal diet (CONT). However, the amylase enzymes were significantly greater in both groups. The MP20% and MP15% groups showed a significant increase in antioxidant, lysozyme, nitric oxide, and protease activities compared to CONT. The results also showed that fish that were fed a diet with MP had significantly less of the pro-inflammatory cytokine interleukin-1 beta, and their intestinal villi got wider, especially in the MP20% group. It could be concluded that feeding tilapia on a diet with 20% MP is an effective strategy to improve their health when the temperature is below 21 °C. This is because the fish exhibit higher levels of antioxidant activity, reduced pro-inflammatory responses, and improved intestinal health without difference in the growth performance in compared to control group.

Design and Implementation of a Biogas Pilot Plant for Bioaugmentation Strategies in a rural municipality

The transition towards renewable energy sources is imperative for achieving sustainability and mitigating climate change impacts. Among various renewable energies, biogas stands out for its dual role in waste management and energy production. This study introduces the design and implementation of a biogas pilot plant aimed at exploring bioaugmentation strategies to enhance biogas yield and quality. The pilot plant, located at Aras de los Olmos, features two independent 3.4m3 digesters, allowing for parallel comparison between standard anaerobic digestion and digestion with microbial enhancements. The plant is equipped with monitoring and control systems for precise regulation of environmental conditions, such as temperature, and for real-time measurement of biogas composition. Some initial experiments using a mix of agricultural wastes demonstrated the plant's capability to adapt to varied feedstock. Despite suboptimal temperature conditions, preliminary results indicated a high methane content, suggesting significant potential for bioaugmentation to improve biogas production efficiency. The study highlights the importance of controlled environmental conditions and introduces a novel bioaugmented digestion approach using selected microbial consortia. This research contributes to the broader goal of enhancing biogas technology's efficiency and sustainability, offering insights into the practical application of bioaugmentation in biogas production.

Evidence for seasonal shift in the reproduction of Aldabra giant tortoises (Aldabrachelys gigantea) in managed care in the Northern hemisphere compared to the natural habitat in the Southern hemisphere.

Ex situ breeding constitutes an important tool for species conservation; however, many reptile species are not managed sustainably under human care due to poor fecundity in ex situ settings. In this study, we tested whether the translocation of a seasonally reproducing species to a different environment results in decoupling of extrinsic signals and intrinsic conditions. The endocrinological patterns of plasma steroid sex hormones, follicular development, and mating behaviour of two female and two male sexually mature Aldabra tortoises (Aldabrachelys gigantea) in a zoological institution in the Northern hemisphere was aligned with enclosure climate data (mean monthly daylight duration, temperature, and precipitation) and compared with respective hormone patterns of wild individuals and climate conditions in the native habitat on the Aldabra Atoll in the Southern hemisphere. Whereas occurrence of mating behaviour was not considered a limiting factor, lack of ovulation and subsequent follicular atresia was the main reason for the lack of reproductive output. While it was impossible to elucidate the triggering factors of ovulation and the multifactorial complexity of reproduction was not fully addressed, this study indicates suboptimal temperature conditions and relative temporal shifts of interacting external triggers (temperature and photoperiod) in the zoo setting.

The Influence of the Work Environment and Organizational Commitment on the Performance of the State Civil Apparatus at the Regional Education Office of North Sulawesi Province

In an initial survey conducted at the North Sulawesi Provincial Education Office, there were several deficiencies in the work environment, including uneven internet connectivity, outdated equipment, and suboptimal room temperature conditions. This study was quantitative using a cross sectional design, involving 143 ASN with a sample of 60 people selected using a simple random sampling method. Data was collected through questionnaires and observations. The research results show that good working environmental conditions have a positive and significant influence on the performance and organizational commitment of ASN in the service. Based on these findings, it is recommended to improve facilities and infrastructure and create a conducive working atmosphere. This will support the transformation of quality education services, increasing the sense of pride and belonging among employees.

Effects of Inulin and Mannan-oligosaccharide on growth, feed utilization, fatty acid profiles, and intestinal morphology of Chamo strain Nile tilapia (Oreochromis niloticus) fry reared under suboptimal temperature

The effects of inulin and mannan-oligosaccharide (MOS) on growth, feed utilization, fatty acid profiles, and intestinal morphology of Chamo strain Nile tilapia (Oreochromis niloticus) fry reared at suboptimal temperature were investigated in this study. Chamo strain Nile tilapia is a local strain in Ethiopia that has been selected for fast growth and disease resistance under tropical conditions. However, its performance under cold stress or sub-optimal temperature is unknown. Four experimental diets were formulated to contain 0% (control), 5 g kg-1 inulin, 6 g kg-1MOS and a combination of 2.5 g kg-1 inulin and 3 g kg-1 MOS. Each diet was fed to triplicate groups of Nile tilapia fry (initial weight 1.6 ± 0.074 g) for nine weeks at a suboptimal temperature of 22.88 ± 0.48 oC. The results showed that prebiotic supplementation did not significantly affect the survival, final weight, weight gain, SGR, FCR and ash content of the fish except for the slight improvements observed with MOS alone and in combination with inulin. However, MOS alone or a combination with inulin improved the villi length and width, and some PUFA levels of the fish compared to the control group. The fish fed with the combination of inulin and MOS had the highest crude lipid content and villi length in the proximal and middle intestine among all groups. The fish fed with MOS alone had the highest villi width and some PUFA levels among all groups. These results suggest additions of these prebiotics have improved the villi length and width, and some PUFA levels of Chamo strain Nile tilapia and could be used as sustainable additive in tilapia nutrition under suboptimal temperature conditions Therefore; further studies are needed to optimize the prebiotic supplementation for Nile tilapia under different conditions.

Physiological and transcriptomic analysis of tomato in response to sub-optimal temperature stress

ABSTRACT Tomato (Solanum lycopersicum L.) is one of the most important economic crops in China. However, its quality and yield are susceptible to the adverse effects of low temperatures. In our study, two tomato cultivars, showing different tolerance to low temperatures, namely the cold-sensitive tomato cultivar (S708) and cold-tolerant tomato cultivar (T722), were grown at optimal (25/18°C) and sub-optimal (15/10°C) temperature conditions for 5 days. Our study aimed to explore the effect of sub-optimal temperature on fresh weight, chlorophyll content and chlorophyll fluorescence, soluble sugars and proline content of two tomato cultivars. Moreover, we employed RNA-Seq to analyze the transcriptomic response of tomato roots to sub-optimal temperature. The results revealed that S708 showed a more significant reduction in fresh weight, chlorophyll content, photochemical efficiency of PSII (YII), maximum quantum yield of PSII (Fv/Fm), photochemical quenching (qP) and electron transport rate (ETR) compared to T722 under the sub-optimal temperature condition. Notably, T722 maintained higher level of soluble sugars and proline in comparison to S708 uner sub-optimal temperature. RNA-seq data showed that up-regulated DEGs in both tomato cultivars were involved in “plant-pathogen interaction”, “MAPK signaling pathway”, “plant hormone signal transduction”, and “phosphatidylinositol signaling system”. Furthermore, “Amino sugar and nucleotide sugar metabolism” pathway was enriched only in T722. Moreover, under sub-optimal temperature, transcription factor genes and osmoregulation genes showed varying degrees of response in both tomato cultivars. Conclusion: In summary, our results offer detailed insights into the response characteristics of tomato to sub-optimal temperature, providing valuable references for the practical management of tomato crops under sub-optimal temperature condition.

Invasive alien plant brush piles reduce invasive seedling growth and increase animal abundance

Management of alien invasive species is an essential action necessary to help reverse biodiversity loss. Here, we measure the effectiveness of brush piles constructed from invasive alien plant material to suppress the growth of invasive plant seedlings. We found invasive seedling recruitment was fully suppressed in brush pile plots compared to control plots due to suboptimal growth light and temperature conditions created by the piles. Further, brush piles supported 2‐fold to +7‐fold more animals than control plots. This method offers a promising solution for restoration practitioners' need for accessible, low‐cost management intervention for the on‐site disposal of removed plant biomass, which we demonstrated can also enhance native wildlife abundance.

Immunological effects of vitamin c and zinc on tilapia (Orechromis niloticus) exposed to cold water stress.

This study investigates the immunological and growth effects of Vitamin C and Zinc supplementation on Nile tilapia (Oreochromis niloticus) subjected to cold water stress. Nile tilapia fingerlings were housed in eight 20-gallon tanks at Purdue University, acclimated to 26 ± 2°C water conditions before the experiment. The tilapia was divided into groups with varying water temperatures and feed supplements: control fish in warm water, and experimental groups in cold water with increased levels of Vitamin C and Zinc. Stress was induced by lowering the water temperature to 15 ± 2°C in four tanks, while the remaining tanks were kept at the optimal growth temperature. Results demonstrated that Vitamin C and Zinc supplementation significantly enhanced immune response and muscle regeneration in cold-stressed tilapia, allowing them to achieve growth rates comparable to those of control fish in optimal warm water conditions. These findings highlight the potential benefits of combined Vitamin C and Zinc supplementation in improving the immune response and growth performance of tilapia under suboptimal temperature conditions.

Solid matrix priming improves cauliflower and broccoli seed germination and early growth under the suboptimal temperature conditions.

Seed priming is an effective method for imparting stress tolerance to plants. This study aimed to analyze the effects of solid matrix priming (SMP) on cauliflower and broccoli seed germination and early seedling growth under suboptimal temperature conditions. The SMP method used in this study included the following steps: (1) mixing seeds with vermiculite and water at a ratio of 2:3:2.5 (w/w/v) and incubating for 2 days in the dark at 20°C; (2) drying the SM-primed seed; (3) germinating the SM-primed and the nonprimed seeds at 10, 15, 20, and 25°C; (4) analyzing the antioxidant enzyme activities of SM-primed and nonprimed germinating broccoli and cauliflower seeds in the early germination stage at 10, 15, 20, and 25°C; and (5) testing the emergence of SM-primed and nonprimed control seeds in the early spring glasshouse. The results showed that the SMP improved seed germination vigor and early seedling growth and increased the activities of peroxidase and ascorbate peroxidase in the germinating cauliflower and broccoli seeds under the suboptimal temperature conditions in the early germination stage compared with nonprimed seeds. It was observed that the suboptimal temperature conditions (i.e., 10 and 15°C) suppressed SM-primed and nonprimed seed germination and early seedling growth of cauliflower and broccoli. Inside a greenhouse, the SMP improved the emergence of cauliflower and broccoli seeds during the early spring season. SMP is an effective method for improving seed germination and the emergence of cauliflower and broccoli under suboptimal temperature conditions.

The results of single well chemical tracer tests to assess the effectiveness of surfactant-polymer exposure at the Kholmogorskoye field

Methods of enhanced oil recovery in general and surfactant-polymer flooding in particular are considered as tertiary methods for the development of mature oil fields in Western Siberia, with the potential to increase oil recovery to 60-70% of the initial geological reserves.
 To select an effective mixture of surfactants and polymer for surfactantpolymer flooding, laboratory tests were carried out in which the thermal stability, phase behaviour, interfacial tension and rheology of the formulations were tested. Filtration experiments were also carried out to optimize the volumes of injected fringes and the concentrations of reagents in them. At the final stage, single well chemical tracer tests (SWCTT) were carried out to assess the effectiveness of surfactant-polymer flooding on two wells of the Kholmogorskoye field. In order to investigate different technical and economic models of surfactant-polymer exposure, SWCTT tests were conducted with the same surfactant, but with a different design. The results of the SWCTT tests showed that the residual oil saturation in the affected area after injection of the surfactant-polymer solution decreased by about 11% compared to water flooding, which is about a third of the residual oil after flooding. The tested surfactant showed acceptable efficiency under suboptimal temperature conditions, which is favorable for the use of the selected surfactant-polymer composition for neighboring deposits and formations with different reservoir temperatures, but similar water composition.
 In general, the results of the conducted field tests correlate with the results of the main laboratory experiments for the selected surfactant.

Global climate change and human health: Pathways and possible solutions

Global warming has been changing the planet’s climate pattern, leading to increasing frequency, intensity and duration of extreme weather events and natural disasters. These climate-changing events affect various health outcomes adversely through complicated pathways. This paper reviews the main signs of climate change so far, e.g., suboptimal ambient temperature, sea-level rise and other conditions, and depicts the interactive pathways between different climate-changing events such as suboptimal temperature, wildfires, and floods with a broad range of health outcomes. Meanwhile, the modifying effect of socioeconomic, demographic and environmental factors on the pathways is summarised, such that the youth, elderly, females, poor and those living in coastal regions are particularly susceptible to climate change. Although Earth as a whole is expected to suffer from climate change, this review article discusses some potential benefits for certain regions, e.g., a more liveable environment and sufficient food supply. Finally, we summarise certain mitigation and adaptation strategies against climate change and how these strategies may benefit human health in other ways. This review article provides a comprehensive and concise introduction of the pathways between climate change and human health and possible solutions, which may map directions for future research.

How do suboptimal temperatures affect polyploid sterlet Acipenser ruthenus during early development?

Sturgeons are ancient fish exhibiting unique genome plasticity and a high tendency to produce spontaneously autopolyploid genome states. The temperature profiles of the rivers in which sturgeon live and reproduce have been severely altered by human intervention, and the effect of global warming is expected to cause further temperature shifts, which may be detrimental for early developmental stages with narrow windows of thermal tolerance. The comparison of the performance of diploid and autopolyploid sturgeon kept at unfavourable temperatures contributes to scientific knowledge of the effects of polyploid genome states on organisms and can shed light on the ability of polyploids to cope with human-induced alterations to natural conditions. Using the sterlet Acipenser ruthenus as a model species, we carried out conventional artificial fertilization, as well as the induction of the second polar body retention (SPBR), of the first mitotic division suppression (FMDS) and of the second polar body retention followed by the first mitotic division suppression (SPBR+FMDS). Two experiments were conducted to evaluate the effect of polyploidy on two basic performance parameters, survival and growth. In Experiment 1, fish belonging to untreated, SPBR-, FMDS- and SPBR+FMDS-induced groups were kept at 10, 16 and 20°C from the neurula stage until the end of endogenous feeding. In Experiment 2, larvae from the untreated and SPBR-induced groups were reared at 10, 16 and 20°C after their endogenous feeding transition for 3 weeks. Based on our findings, we report that the embryos, prelarvae and larvae of triploid A.ruthenus do not differ from diploids in their ability to survive, grow and develop under suboptimal temperature conditions, while the survival of tetraploids was significantly reduced even at the optimal temperature and even more so at temperatures far from the optimum. This was also the case in the 2n/4n mosaics observed in FMDS-induced group. Thus, we assume that in tetraploid and 2n/4n individuals, the limits of thermal tolerance are closer to the optimum than in diploids. We also conclude that the hexaploid genome state is probably lethal in A.ruthenus since none of the hexaploids or 3n/6n mosaics arising from the SPBR+FMDS induction survived the prelarval period.

Changes in Volatile Composition of Cape Hake Fillets under Modified Atmosphere Packaging Systems during Cold Storage.

Fresh ready-to-cook fish fillets are susceptible to loss of freshness and accumulation of off-odour due to accelerated microbial spoilage. Suboptimal storage temperature and packaging conditions accelerate this process, limiting the economic potential. This study investigated the effects of modified atmosphere packaging (MAP) and storage temperature (0 °C and 4 °C) on the volatile compounds (VOCs) of Cape hake (Merluccius capensis) fish fillets as a predictor of shelf life and quality. Fresh Cape hake fillets were packaged under active modified atmosphere (40% CO2 + 30% O2 + 30% N2) and passive modified atmosphere (0.039% CO2 + 20.95% O2 + 78% N2) with or without an absorbent pad and stored at 0 °C and 4 °C for 12 d. The results obtained demonstrated that changes in VOCs and concentration were significantly (p < 0.05) influenced by MAP conditions, storage temperature and duration. A total of 16 volatiles were identified in the packaged Cape hake fillets: 4 primary VOCs and 12 secondary VOCs. The spoilage VOCs identified include tri-methylamine (TMA) (ammonia-like), esters (sickeningly sweet) and sulphur group (putrid). The concentration of secondary VOCs increased continuously during storage. Active-MA-packaged fillets performed better and had lower TMA values of 0.31% at 0 °C on day 12 in comparison to 7.22% at 0 °C under passive on day 6. Ethyl acetate was detected in passive-MA-packaged fillets stored at 0 °C on day 3, and the levels increased to 3.26% on day 6, while active-MA-packaged fillets maintained freshness. This study showed that in conjunction with TMA, VOCs such as esters and sulphur-related compounds could be used as spoilage markers for Cape hake fish fillets.

Epigenetic regulation of thermomorphogenesis and heat stress tolerance.

Many environmental conditions fluctuate and organisms need to respond effectively. This is especially true for temperature cues that can change in minutes to seasons and often follow a diurnal rhythm. Plants cannot migrate and most cannot regulate their temperature. Therefore, a broad array of responses have evolved to deal with temperature cues from freezing to heat stress. A particular response to mildly elevated temperatures is called thermomorphogenesis, a suite of morphological adaptations that includes thermonasty, formation of thin leaves and elongation growth of petioles and hypocotyl. Thermomorphogenesis allows for optimal performance in suboptimal temperature conditions by enhancing the cooling capacity. When temperatures rise further, heat stress tolerance mechanisms can be induced that enable the plant to survive the stressful temperature, which typically comprises cellular protection mechanisms and memory thereof. Induction of thermomorphogenesis, heat stress tolerance and stress memory depend on gene expression regulation, governed by diverse epigenetic processes. In this Tansley review we update on the current knowledge of epigenetic regulation of heat stress tolerance and elevated temperature signalling and response, with a focus on thermomorphogenesis regulation and heat stress memory. In particular we highlight the emerging role of H3K4 methylation marks in diverse temperature signalling pathways.

Enhancements provided by the use of an Ascophyllum nodosum extract can be transferred through archeospores in the red alga Neopyropia yezoensis (Ueda) L.-E. Yang & J. Brodie

The use of seaweed extracts as biostimulants to promote enhancements in other seaweed crops is gaining momentum. Here we examined if the seaweed-derived biostimulant Ascophyllum marine plant extract powder – AMPEP, enhanced growth and thermal tolerance of cultured thalli of Neopyropia yezoensis when grown under optimal and sub-optimal temperature conditions. We also examined if enhancements could be transferred to new blades through archeospore germination. Area, specific growth rate, reactive oxygen species (ROS) and protein content of thalli were measured as indicators of potential enhancement. The application of AMPEP significantly increased growth rates in thalli of N. yezoensis grown under optimal temperature conditions, whilst the thalli showed no indications of improved thermal tolerance. The collated data suggested that growth enhancement could be transferred from treated thalli to newly formed blades, which developed from archeospores. This study provides new evidence of the far-reaching potential of using extracts of selected seaweeds as biostimulants to support the cultivation of economically important Neopyropia species.

Breeding for Low Temperature Germinability in Temperate Japonica Rice Varieties: Analysis of Candidate Genes in Associated QTLs

In temperate areas, rice deals with low temperatures that can affect plant growth and crop yield. Rapid germination is required for adequate plant establishment in the field, therefore obtaining cultivars that maintain this phenotype under suboptimal temperature conditions is a challenge for rice breeders. Our study aimed to investigate temperature-induced expression changes in genes underlying quantitative trait loci (QTLs) associated to this trait (low temperature germinability, LTG) that were detected in a previous genome wide association study (GWAS). In the context of a breeding program for japonica rice cultivars adapted to cultivation in Spain, we obtained two biparental families of lines derived from hybridization with two cold tolerant Italian cultivars, and we have studied the effect on the LTG phenotype of introgressing these QTLs. A wide region in chromosome 3 was related to significant increases in seedling growth rate at 15 °C, although the extent of the effect depended on the analyzed family. In parallel, we studied the pattern of expression during germination at different temperatures of 10 genes located in the LTG-associated QTLs, in five japonica rice cultivars and in a biparental family of recombinant inbred lines (RILs). Cold induced changes in the expression of the 10 analyzed genes, with significant differences among genotypes. Variation in LTG phenotype was consistently associated with changes in the pattern of expression of five genes from the tagged regions in rice chromosome 3, which encoded for enzymes implicated in phytohormone metabolism (OsFBK12, Os3Bglu6), oxidative stress (SPL35, OsSRO1c) and Mn homeostasis maintenance (OsMTP8.1). Differential expression induced by cold in two regulatory genes (Os02g0824000 and Os06g06400) also contributed to explain low temperature tolerance during rice germination. In conclusion, introgression in defective cultivars of favorable alleles for these genes would contribute to the genetic improvement of LTG in japonica rice varieties.

Effects of fasting and water temperatures during transition from freshwater to seawater on juvenile chum salmon growth and metabolism

We examined the combined effects of fasting in freshwater and water temperature during the transition from freshwater to seawater on growth/metabolic parameters in juvenile chum salmon Oncorhynchus keta. Juveniles of 1 g in freshwater were first subjected to a 5-day fasting period at 10 or 5 °C, acclimated to either 10 or 5 °C seawater and fed ad libitum for 30 days. Control fish were transferred from 10 °C freshwater to 10 °C seawater and fed ad libitum throughout the experimental period. Serum insulin-like growth factor (IGF)-I was measured to evaluate growth status/potential and liver glycogen as an index of energy storage. Fasting in freshwater for 5 days negatively affected body size. Growth of juveniles kept at colder temperatures was retarded in seawater for at least 20 days, which may partly be explained by a lower feeding rate in cold seawater. Serum IGF-I levels were lower in fasted fish in freshwater at both temperatures and colder seawater had a negative effect on restoring serum IGF-I levels after refeeding for 20 days. Liver glycogen content was low in fish fasted in freshwater for 5 days. After refeeding in seawater for 10 days, liver glycogen content increased significantly in juveniles kept at colder temperatures. Colder water temperatures in both salinities positively affected glycogen content for 30 days after transfer to seawater, suggesting that juveniles allocated energy stores to the liver rather than growth under suboptimal feeding and temperature conditions. The findings of the present study suggested that relatively cold freshwater could negatively affect juvenile chum salmon growth soon after sea entry.

Effect of biofertilizer on growth and yield of carrot (Daucus Carota L.) plants in different latitudes of Lombok Island

Carrot is an important sub-tropical vegetable, and in the tropics it is commonly cultivated in high elevated mountainous areas to provide suitable environment (particularly temperature) for the optimum growth and productivity. Availability of suitable cultivation areas in Indonesia is limited while demand for the crop is increased. This research evaluated growth and yield of carrot in warmer temperature of lower land elevations, and examined capability of biofertilizer to increase growth responses and yield of the crop under sub-optimal temperature conditions. The first and second experiments were conducted in medium latitudes of 650 m above sea level (asl) and 550 m asl, while the third experiment was conducted in low land of 170 m asl. The experiments compared growth and yield of carrot plants with biofertilizer and without biofertilizer applications. The growth and yield of carrot were enhancing by biofertilizer application when planted in ca. 650 and 550 m asl. The biofertilizer-treated plants were taller, had a higher number of leaves, higher yield, carrot diameter and sweater than non-treated plants. In low land, however, biofertilizer bio-EXTRIM had no effect on plant growth and yield but the carrots in biofertilizer treated plants were sweeter than non-treated plants.

Maximizing Productivity of Greenhouse-grown Hydroponic Lettuce during Winter

Operational cost of producing lettuce (Lactuca sativa) during the winter in greenhouses is high in the northern regions of the United States due to the addition of supplemental lighting (SL) and heating. Crop productivity in greenhouses should increase to offset high operational costs and maintain profits. Factors including SL composition, heating efficiency, suitability of production systems (PS), and cultivar performance can affect crop productivity. Research-based information on optimizing the above environmental- and production-related factors is limited. This information is critical for growers to make informed decisions and increase profits during winter hydroponic production. We evaluated the interactive effects of SL composition, solution temperature, PS, and cultivar treatments on lettuce shoot dry weight (SDW, g·m−2) and shoot water content (SWC, %) in a greenhouse maintained at suboptimal air temperature (13.7 °C) using a split-plot design. There were three light treatments (sunlight without SL, sunlight + narrow-spectrum SL at nighttime, and sunlight + full-spectrum SL at nighttime), two solution temperature levels [heated (18.8 °C) and unheated (13.2 °C)], two hydroponic PS [constant flood technique (CFT) and nutrient film technique (NFT)], and eight cultivars included in the study. Results indicated that 1) a narrow-spectrum SL at nighttime in combination with heated solution resulted in maximum SDW of lettuce, 2) the SDW and SWC (major determinant of economic yield) increase between the heated and unheated solution temperature treatments was higher in the CFT than in the NFT, and 3) the positive effects of using heated solution were seen mainly in the green-color cultivars. Our research identified the optimal spectral composition of nighttime SL, tested the positive effects of alternate heating methods using heated solution on plant growth under suboptimal air temperature conditions, compared the suitability of two hydroponic PS for lettuce production, and quantified yield potential of several lettuce cultivars in hydroponic production during winter. Growers can use our research findings to make informed decisions about their investment and to maximize hydroponic lettuce productivity and profits during winter.