Photoperiod Regimes Research Articles

Characterization of light-dependent rhythm of courtship vibrational signals in Nilaparvata lugens: essential involvement of cryptochrome genes.

Vibrational signal plays a crucial role in courtship communication in many insects. However, it remains unclear whether insect vibrational signals exhibit daily rhythmicity in response to changes in environmental cues. In this study, we observed daily rhythms of both female vibrational signals (FVS) and male vibrational signals (MVS) in the brown planthopper (BPH), Nilaparvata lugens (Stål), one of the most notorious rice pests across Asia. Notably, oscillations of FVS and MVS in paired BPHs were synchronized as part of male-female duetting interactions, displaying significant day-night rhythmicity. Furthermore, we observed light dependency of FVS emissions under different photoperiodic regimes (18 L:6 D and 6 L:18 D) and illumination intensity levels (>300 lx, 50 lx, and 25 lx). Subsequently, the potential role of circadian clock genes cryptochromes (Nlcry1 and Nlcry2) in regulating FVS daily oscillations was examined using gene knockdown via RNA interference. We observed sharp declines and disrupted rhythms in FVS frequencies when either of the Nlcrys was downregulated, with Nlcry2 knockdown showing a more prominent effect. Moreover, we recorded a novel FVS variant (with a dominant frequency of 361.76 ± 4.31 Hz) emitted by dsNlcry1-treated BPH females, which significantly diminished the impact of courtship stimuli on receptive males. We observed light-dependent daily rhythms of substrate-borne vibrational signals (SBVS) in BPH and demonstrated essential yet distinct roles of the two Nlcrys. These findings enhanced our understanding of insect SBVS and illustrated the potential of novel precision physical control strategies for disrupting mating behaviors in this rice pest. © 2023 Society of Chemical Industry.

Real-Time Monitoring of Translocation, Dissipation, and Cumulative Risk of Maleic Hydrazide in Potato Plants and Tubers by Ion Exclusion Chromatography.

In this paper, a high-performance ion exclusion chromatographic (ICE) method was developed and applied for monitoring maleic hydrazide (MH) translocation in complex potato plant tissue and tuber matrices. After middle leaf uptake, most MH was trapped and dissipated in the middle leaf, and the rest was transported to other parts mainly through the phloem. Soil absorption significantly reduced the uptake efficiency of the root system, in which MH was partitioned to dissipate in root protoplasts or transfer through the xylem and persisted in the plant. Tuber uptake enabled MH to remain in the flesh and maintain stable levels under storage conditions, but during germination, MH was translocated from the flesh to the growing buds, where it dissipated through the short-day photoperiodic regime. The results demonstrated successful application of the ICE method and provided necessary insights for real-time monitoring of MH translocation behavior to effectively improve potato edible safety.

‘Single-Seed-SpeedBulks:’ a protocol that combines ‘speed breeding’ with a cost-efficient modified single-seed descent method for rapid-generation-advancement in oat (Avena sativa L.)

BackgroundIn plant breeding, one of the most cost-effective and efficient ways to increase genetic gain is to reduce the breeding cycle time. In general, modern breeding methods for self-pollinated crops should strive to develop fixed lines at the lowest possible cost and in the minimum possible amount of time. Previous studies on spring oat (Avena sativa L.) showed that combining high plant density with limited soil fertility and moisture levels in a growth media like sand effectively decreases the time and cost of generating fixed single-seed descent lines. More recently, ‘speed breeding,’ or the exposure to prolonged photoperiod regimes of 22 h, has been shown to decrease flowering time in oat significantly. The goal of this study was to combine ‘speed breeding’ with high-density planting in a limited soil fertility media to reduce further the costs and time required to develop oat single-seed-descent lines.ResultsWe grew oat plants at low density in potting-mix (control), high density in potting-mix (HD-soil), and high density in sand (HD-sand) under 16 and 22 h of day length. We observed that oat plants grown in HD-sand and exposed to 22 h day length reduced their flowering time by around 20 and 5 days on average compared to those grown in control conditions at 16 and 22 h, respectively. We also observed that 85% of plants grown at high density in sand produced a single seed when grown in bulk conditions. In contrast, only 40% of plants grown at high density in potting-mix produced a single seed.ConclusionsOur novel protocol showed that oat plants grown in high-density bulks, using sand media and 22-hour day length, reduced their flowering time by 20 days compared to control conditions and produced plants with single seeds, following closely single-seed descent assumptions while significantly reducing labor costs and greenhouse space. This methodology can be deployed in oat breeding programs to help them accelerate their rate of genetic grain for multiple traits.

Can varying photoperiod regimes alter the growth response, behaviour and physiology of <i>Clarias gariepinus</i>?

To understand the welfare implication of photoperiod manipulation on Clarias gariepinus, fingerlings (n = 108) and juveniles (n = 108) of C. gariepinus with a mean weight of 3.75±0.03 g and 21.7±2.88 g were exposed to zero light (0L:24D)-T1, average light (12L:12D)-T2 and continuous light (24L:0D)-T3 in triplicates for 35 days. The highest mortality rate was recorded in T2 and T3 for the fingerlings (13.9%) and juveniles (22.2%). T1 recorded a significantly higher (p = 0.03) weekly growth rate and mean weight gain (MWG). Specific Growth Rate (SGR) and Feed Conversion Ratio (FCR) were highest in T1 for both fingerlings and juveniles. Lowest average swimming rate was observed in T1 while the highest aggressive act, bruises, and scars were recorded in T3 for fingerlings and juveniles. The highest (58.6 mg/dl and 56.9 mg/dl) plasma glucose was found in T3 for both fish categories. There were no significant differences (P = 0.11) among the average cortisol levels of both categories of fish at the different photoperiod regimes. Fingerlings and juveniles exposed to 24-hour darkness had a higher MWG, survival rate, SGR and FCR without any physiological stress. A photoperiod regime of 24-hour darkness is recommended for the culture of fingerlings and juveniles of C. gariepinus to boost fish production in the Aquaculture sector.

Photoperiodic Induction of Diapause Character and Sorbitol Level in the Silkworm Eggs of APM1, MU303 and PM Strains/Races

Embryonic diapause is the suspended animation responsible for the onset of Voltinism in the silkworm. The embryo is completely arrested during the developmental event to overcome unfavourable environmental conditions. This further results in the synthesis of sorbitol from glucose and examines the differences between sorbitol levels in the diapause-induced silkworm eggs of APM1, MU303 and PM strains by exposure to photoperiodic regime of 16L:08D, 14L:10D and 12L:12D. The results obtained revealed the fact that the sorbitol level is high during the 6th day in all the selected strains at their 7th and 8th generation. This indicates that the enhancement of the sorbitol is independent of the induced diapause in all three strains of the mulberry silkworm. Further, it is also clear that the enhancement of sorbitol concentration is devoid of a photoperiodic regime.

MiR-155 Regulates Photoperiod Induced Gonadal Development in Atlantic Salmon (Salmo salar) by Targeting Brain-Derived Neurotrophic Factor

This study was designed to explore the impact of the photoperiod on the gonadal development and somatic growth of Atlantic salmon raised in recirculating aquaculture systems (RASs), with specific focus on the role that microRNA (miR)-155 plays as a regulator in the Atlantic salmon’s photoperiodic reproduction. These salmon were reared for 5 months under six different photoperiod regimens, including two with changing photoperiods (LL–SL = 24L:0D–8L:16D and SL–LL = 8L:16D–24L:0D) and four with constant photoperiods (24L:0D, 18L:6D, 12L:12D, and 8L:16D). The longer photoperiod groups (LL–SL and 24L:0D) were ultimately associated with higher gonadosomatic index (GSI) values and an increased proportion of mature fish relative to other exposure groups, indicating that the photoperiod positively impacted the Atlantic salmon’s gonadal development in RAS environments. Hypothalamic miR-155 expression in these Atlantic salmon was also found to be influenced by the photoperiod, showing a markedly decreased expression in salmon exposed to a long photoperiod and upregulation following rearing under a short photoperiod. Functionally, miR-155 was found to suppress the expression of gonadal axis-related genes, including FSH and GnRH, through its ability to target the brain-derived neurotrophic factor (BDNF) and to thereby regulate photoperiod reproduction. Overall, these results suggested that the photoperiod could regulate gonad development in Atlantic salmon with miRNA-155 being involved in this process by targeting the BDNF.

Effect of Photoperiod and Transfer Time on Atlantic Salmon Smolt Quality and Growth in Freshwater and Seawater Aquaculture Systems

Smoltification is a key process in Atlantic salmon aquaculture, given it prepares the fish for a successful transit from fresh to seawater. However, industry players have not yet reached a consensus on the best protocols to produce high-quality smolts. In this study, we assessed how the combination of two photoperiod regimes in freshwater (continuous light or LL, and natural photoperiod or LDN) and four transfer times to seawater (February, March, April, and May) affected smolt development and their subsequent growth in seawater until slaughter during commercial production. The results demonstrated that smoltification and growth in freshwater were only slightly modulated by the photoperiod treatment and were instead much more affected by the limiting effect of the low water temperature during that period. In seawater, the growth rate was the highest in the same groups, which had, however, experienced a delay in growth when in freshwater, and consequently, no differences in the final body weight between the eight treatments were found. Such compensatory growth in the sea was probably enhanced by the increasing smolt quality, which could allow for better performance in seawater. A significant link between the weight at slaughter and weight at transfer was observed only in the groups with a lower smolt quality (LL-Feb, LDN-Feb and LDN-Mar), which suggests that larger individuals could cope better with a saline environment. In contrast, smaller smolts probably suffered greater osmotic stress that hindered their performance at sea. Afterwards, as smolt quality increased in the subsequent transfer groups, the relevance of this size effect decreased. This means that the industry may benefit from transferring larger smolts to seawater, especially if these are suspected of having developed suboptimal seawater tolerance. Those individuals are likely to cope better with saline conditions than smaller smolts. Future research should focus on the possible long-term effects of freshwater-rearing regimes on smolt performance in the seawater phase.

Ecological aspect of the larval parasitoid Diadegma hiraii (Hymenoptera: Ichneumonidae) as a potential biological control agent of soybean pod borer Leguminivora glycinivorella (Lepidoptera: Tortricidae).

The larval parasitoid Diadegma hiraii (Kusigemati) was evaluated as a potential biological control agent of the soybean pod borer, Leguminivora glycinivorella (Matsumura). The timing of adult emergence after overwintering was ascertained, and land-use factors that enhance population density were analyzed. Host cocoons were collected and exposed to different temperatures and photoperiod regimes. Subsequently, the emergence of parasitoid was monitored. Land-use types were categorized into 4 land-use types (Poaceae, Fabaceae, Brassicaceae, and forest). Adult parasitoid emergence was dependent on temperature, but largely unaffected by photoperiod. The estimated emergence time of parasitoid was 3 months before the occurrence of the host, suggesting that the overwintered generation may lay eggs in alternate hosts. Parasitism rate was positively correlated with the area covered by Poaceae plants within a 500-m radius of the soybean field. Based on the results of the overwintering ecology and landscape analysis, D. hiraii probably completes its life cycle in the agroecosystems. The parasitoid's effectiveness as a biological control agent may be influenced by the arrangement of land-use types in the agroecosystems surrounding soybean fields. However, the pest control provided by D. hiraii is limited because of approximately 30% of parasitism rate. Consequently, a combination of this species and cultural control and/or other biological control agents is suggested for sustainable soybean cultivation.

A Review of Rapid Generation Advancement (RGA) in Crop Improvement

The use of the speed breeding method is widely considered to be the wave of the future in plant breeding. The term "speed breeding" is used to describe a rapid generational advancement technique that is used to minimise the time it takes from seed to seed, therefore reducing the length of a crop plant's typical life cycle. Plants that are not sensitive to light may have as many as six generations in a single year using this method, whereas other plants can only expect two or three generations every year. With this technique, the photoperiodic and temperature needs of crops produced in controlled-poly homes may be altered. This methodology, when combined with other cutting-edge tools like genome editing and high-throughput genotyping systems, may help breed new kinds of crops at a much quicker pace. Spacefaring food producers: NASA first conceived of this notion. Breeder's equation may be used to determine whether speed breeding is applicable to a certain crop. Light, photoperiodic regime, temperature, and humidity modification make up the backbone of the fast-breeding formula. Accelerated breeding, expedited genomic selection, improved transgenic and CRISPR-Cas9 pipelines, and the investigation of critically important agricultural plant physiological properties are just some of the numerous uses for this approach.

Parameters of Lipid Metabolism in Underyearlings of Atlantic Salmon <i>Salmo salar</i> Reared under Different Regimes of Photoperiod and Feeding Modes in Aquaculture in the Sourthern Region of Russia

A comparative study of the lipid and fatty acid composition of Atlantic salmon underyearlings reared under natural and continuous light in commercial aquaculture in the summer-autumn period in North Ossetia-Alania was carried out. A stable change in the main indicators of lipid metabolism in salmon underyearlings from September to November was found, aimed at preparing juveniles for smoltification. A change in key fatty acid indicators was detected: an increase in the content of PUFAs due to (n-3) PUFAs, and the “marine” type of PUFA – 22:6 (n-3), high values of the ratios (n-3)(n-6) PUFA, 18:3(n-3)/18:2 (n-6), 22:6(n-3)/ 18:3(n-3). It has been shown the stimulating effect of the combined and stable action of the continuous photoperiod and feeding in the summer-autumn period on the preparation for smoltification of Atlantic salmon fingerlings grown under aquaculture conditions.

Sneak-peek into the chlorophyll content, antioxidant activity, targeted and non-targeted UHPLC-QTOF LC/MS metabolomic fingerprints of pulse microgreens grown under different photoperiod regimes

Pulse microgreens (mung bean, chickpea and lentil) were evaluated for compositional changes as a function of photoperiod. The pulse microgreens were cultivated under photoperiod of 16 and 22 h, with an optimum growing temperature of 22 °C in light and 17 °C in dark in polypropylene trays containing moist cotton bed. The photoperiodic response of pulse microgreens in terms of plant height, chlorophyll content, antioxidant activity, phenolic profile, sugar profile and secondary metabolites were undertaken as the experimental factors. The targeted phenolic and sugar profile varied significantly with photoperiod. The various phenolic acids, especially chlorogenic acid and p-coumaric acid increased amongst different microgreens on extending photoperiod. The increase in sugar and their derivatives reflected the upregulation of carbohydrate metabolism under longer photoperiod. Also, the plant height, total chlorophyll content and antioxidant activity of pulse microgreen increased significantly on prolonging the photoperiod. The non-targeted analysis by UHPLC-QTOF LC/MS revealed the presence of secondary metabolites of five major classes, which were known to have beneficial effects in biological system. DIMBOA-glucoside, an organic compound was exclusively present in mung bean microgreens which further increased in longer photoperiod. The extraordinary supply of secondary metabolites makes the pulse microgreens excellent ingredient for therapeutic functional foods.

The Impact of Diet and Photoperiodism on the Life History of Thanatophilus sinuatus (Coleoptera: Silphidae).

The forensically important genus Thanatophilus Leach, 1815 (Coleoptera: Silphidae) is a widespread group of carrion beetles that occupies the Holarctic and Afrotropical realms. It has recently received more recognition, as its species are frequently detected on large carrion, including humans, and can be useful in estimating the time of colonization (TOC) and the post-mortem interval (PMI). The immature stages of Thanatophilus sinuatus (Fabricius, 1775) were reared on three different meat diets (pork liver, pork muscle, and chicken muscle). Diet influence on some of the essential life history traits of the species was examined for different populations. Our findings indicated an accelerated development on pork muscle followed closely by pork liver and a prolonged development on chicken muscle. The diet significantly affected the size, and the body condition (weight/ size) as both pork muscle and liver produced individuals in better physical condition (larger and heavier). The impact of two cyclic photoperiod regimes (16 h Light (L): 8 h Dark (D) and 12 h L: 12 h D) was further evaluated and indicated no significant variability.

Influence of light intensity and photoperiod on the pigment and, lipid production of Dunaliella tertiolecta and Nannochloropsis oculata under three different culture medium

Microalgal biomass has the ability to store huge amount of triacylglycerides as fatty ester methyl esters (FAME) and carotenoids which has made algae as potential candidate for biorefinery approach. Essential fatty acid such as palmitic acid, stearic acid, arachidonic acid and eicospentanoic acid have been produced which are known for their various applications. The present study was aimed to evaluate the influence of different light intensities (120 and 250 μE/m2/s) and photoperiod (16:8h and 13:11h light/dark cycle) on the production of lipid, biomass and lutein. Dunaliella tertiolecta and Nannochloropsis oculata was grown for 23 days in F/2, sea salt media (SSM, Distilled water (DW) and SSM (natural seawater media,NSW) under two different light intensities and photoperiod regimes at 25 ᵒC. SSM (NSW) showed maximum accumulation of lipid in D.tertiolecta (34.56 mg/L/d). SSM (DW)- biomass showed 1.5 times higher lutein productivity of 0.253 mg/L/d under 13:11h light/dark cycle at 250 μE/m2/s compared to same medium under 16:8h light/dark cycles at 120 μE/m2/s. Where as in N.oculata, F/2 biomass showed higher lipid and lutein productivity of 15.69 and 0.279 mg/L/d, respectively The laboratory scale cultivation parameters and related media cost showed the suitability of different culture media adaptation to large scale production.

Tuning of meristem maturation rate increases yield in multiple Triticum aestivum cultivars.

Breeding programs aim to improve crop yield and environmental stability for enhanced food security. The principal methodology in breeding for stable yield gain relies on the indirect selection of beneficial genetics by yield evaluation across diverse environmental conditions. This methodology requires substantial resources while delivering a slow pace of yield gain and environmental adaptation. Alternative methods are required to accelerate gain and adaptation, becoming even more imperative in a changing climate. New molecular tools and approaches can enable accelerated creation and deployment of multiple alleles of genes identified to control key traits. With the advent of tools that enable breeding by targeted allelic selection, identifying gene targets associated with an improved crop performance ideotype will become crucial. Previous studies have shown that altered photoperiod regimes increase yield in wheat (Triticum aestivum). In the current study, we have employed such treatments to study the resulting yield ideotype in five spring wheat cultivars. We found that the photoperiod treatment creates a yield ideotype arising from delayed spike establishment rates that are accompanied by increased early shoot expression of TARGET OF EAT1 (TaTOE1) genes. Genes identified in this way could be used for ideotype-based improve crop performance through targeted allele creation and selection in relevant environments.

Photoperiod-independent diurnal feeding improved the growth and feed utilization of juvenile rainbow trout (Oncorhynchus mykiss) by inducing food anticipatory activity

A three-month culture experiment was designed to assess the effects of photoperiod and feeding regime on growth, feed utilization, and food anticipatory activity (FAA) of juvenile rainbow trout. The experiment included two photoperiods: 24L:0D (LL) and 12L:12D (LD); three feeding regimes: random feeding (R), mid-dark stage feeding (D), and mid-light stage feeding (L). A total of six treatment groups (R-LL, D-LL, L-LL, R-LD, D-LD, L-LD) were defined. The experimental results showed that the growth and feed utilization of the scheduled feeding groups (D and L groups) were significantly higher than those of the R group under both photoperiods, and there was no statistical difference between the D and L groups. A typical FAA was observed in the L group, independent of the photoperiod. Also, the digestive enzyme activity of the L group was synchronized by the feeding time under both photoperiods. There were rhythms in serum levels of glucose (GLU), triglyceride (TG), and total-cholesterol (T-CHO) in the D and L groups. Serum GLU also had a rhythm in the R group, but the peaks occurred at the feeding point (LL group) or after the feeding point (LD group), reflecting a possible passive rise in GLU after feeding. Serum cortisol was higher in the R group than in the scheduled feeding group, indicating that random feeding caused stress to juvenile rainbow trout. Serum insulin levels were found to increase before feeding in all three feeding regimes, probably reflecting the anticipation of food induced by the last meal. Serum melatonin levels were suppressed by the LL group. Serum 5-HT levels were synchronized by meal time in the R and L groups. Finally, rhythms of appetite-related genes were observed under all three feeding regimes, and more genes were rhythmic under LL, suggesting that food can strongly synchronize the feeding rhythm of juvenile rainbow trout when lacking light zeitgeber. In summary, this study concluded that diurnal feeding (L group) independent of photoperiod induced typical FAA in juvenile rainbow trout and that the LD (12L:12D) photoperiod and L (mid-light phase) feeding were recommended in the juvenile rainbow trout aquaculture.

Susceptibility of Tetranychus cinnabarinus and Tetranychus urticae (Trombidiformes: Tetranychidae) to Neozygites floridana (Entomophthorales: Neozygitaceae)

Abstract Tetranychus urticae (Koch) (Trombidiformes: Tetranychidae) is a cosmopolitan spider mite species that infests more than 900 species of plants, including commercial species. Tetranychus cinnabarinus (Boudreaux) is characterized by a red coloration, in contrast to the green-colored T. urticae. Both are occasionally found coexisting in warm environments, and, for that reason, they are considered by some to be synonyms. In this study, we identified specimens of the two morphospecies using optical and electron microscopy and amplification of a segment of the mitochondrial cytochrome oxidase I (COI) gene. Bioassays determined the level of susceptibility and survival of both morphospecies when they were infected with the entomopathogenic fungus Neozygites floridana (Weiser and Muma). For the evaluation of the susceptibility of these morphospecies to N. floridana, bioassays were conducted under conditions of 25 ± 2°C, 60 ± 5% relative humidity, and a 12:12-h photoperiod regime. From these bioassays, we found that T. cinnabarinus was less susceptible to N. floridana and that there is a higher level of fertility, survival, and development in the T. cinnabarinus than in the T. urticae mites. Within a mass rearing system, T. cinnabarinus appears be a more efficaceous functional food for predatory mites, such as Phytoseiulus persimilis (Athias-Henriot) (Mesostigmata: Phytoseiidae), than T. urticae to support rearing and release of biological agents for integrated pest management.

Photoperiodic-dependent morpho-biometric changes in the excurrent duct system of sexually-matured helmeted guinea fowl (Numida meleagris)

Photoperiod is considered to be one of the most effective environmental factor in controlling the reproductive cycle and gonadal maturation in some mammalian species, but very limited information are available on its effects on reproductive biology of the guinea fowl. Therein, we investigated the effects of varying photoperiodic treatments on morpho-biometry of the excurrent duct system of helmeted guinea fowl (Numida meleagris). A total of twenty-one (21) apparently healthy sexually-matured helmeted guinea fowls were randomly assigned into three (3) photoperiodic regimes; mainly [Group I: Short daylight (SD; 8 HL (Hour of light, Group II: Moderate daylight (MD; 12 HL) and Group III: Long daylight (LD; 16 HL)] of seven birds per group (n=7). After 8 weeks of experimentation, the excurrent ducts were excised and freed of all adhering connective tissues for gross-morphological and morphometric evaluations. The bio-morphometric data (weight and diameter) were significantly increased (p< 0.05) in the epididymis and ductus deferens of guinea fowl exposed to 16 HL, as compared to other treatments. However, no significant (p> 0.05) effect was observed in body weight and length of the excurrent ducts regardless of photoperiod. The observed changes in weight and diameter of the epididymis and ductus deferens of helmeted guinea fowl are thus a consequence of the stimulatory effects of long photoperiod exposure to reproductive activity. Thus, these findings would therefore be useful to guinea fowl breeders in designing appropriate intervention programs necessary to improve their reproduction efficacy and to preserve this species.

Enhancing growth environment for attached microalgae to populate onto spent coffee grounds in producing biodiesel

One of the economical approaches to harvest mature microalgal biomass is through the attached growth system, in which the microalgal cells form attachment onto support material to facilitate its separation from the cultivation medium. Hence, the spent coffee grounds (SCG) was employed as the support material, proffering alimentation, and platform for Chlorella vulgaris sp. microalgae, to populate its surface. The SCG dosage of 8 g L−1 was revealed as optimum in enhancing the attached microalgal growth, i.e., achieving the microalgae density of 2.43 ± 0.04 g g-SCG−1 under continuous illumination. The introduction of a 20:4 photoperiod regime with the dark period cycle of 4 h day−1 and the remaining 20 h day−1 of illumination yielded a maximum microalgal density of 3.970 ± 0.8 g g-SCG−1. In this regard, the dark period had allowed the attached microalgae to strengthen their mixotrophic growth, i.e., assimilating more carbon from SCG effectively amidst heterotrophic mode. Besides, the extension of the dark period to 20 h day−1 had been identified as the threshold requirement to stress the attached microalgae in accumulating a significant amount of lipid which was about fivefold more productive than the attached microalgae growing under the continuous illumination. The fatty acid methyl esters (FAME) profile derived from harvested attached microalgal biomass was loaded primarily with alkyl chains of C12 to C18. Also, the high saturation degree of FAME had indicated the stability of biodiesel produced from attached microalgae growing onto SCG feedstock.

Développement Testiculaire chez Poisson Combattant (Betta splendens), variété de Demi-lune, Subis 35 jours de Différents Régimes de Photopériodes

Fighting fish (Betta splendens) is one of the fresh water ornamental fish with highly commercial value. This fish has a distinctive morphological shape which is aesthetic and is easy to maintain. Demand for this fish increased leading to opportunities for cultivation. Quality and quantity of fries were constantly needed, and this could be achieved by manipulating reproduction. Photoperiod regimes could play a role to do this. The purpose of this study was to determine the effect of photoperiods on the testis development of halfmoon strains of fighting fish.
 A completely randomized design was run to test 3 treatments in quintuplicates. The fish were reared under treatment P1 (10 hours light L and 14 hours dark D), treatment P2 (14 hours L and 10 hours D) and treatment P0 (12 hours L and 12 hours D). The fish were maintained for 35-d, in Aquatic Resources Laboratory of FPIK Unsoed. The results showed that treatment P2 was significantly different (P<0.05), which the highest spermatogenesis stage (54.78 ± 16.64%) was obtained. The study concluded that male fighting fish under P2 photoperiod could accelerate testicular maturation.

Transcriptome profiling of barley and tomato shoot and root meristems unravels physiological variations underlying photoperiodic sensitivity.

The average sowing date of crops in temperate climate zones has been shifted forwards by several days, resulting in a changed photoperiod regime at the emergence stage. In the present study, we performed a global transcriptome profiling of plant development genes in the seedling stage of root and shoot apical meristems of a photoperiod-sensitive species (barley) and a photoperiod insensitive species (tomato) in short-day conditions (8h). Variant expression indicated differences in physiological development under this short day-length regime between species and tissues. The barley tissue transcriptome revealed reduced differentiation compared to tomato. In addition, decreased photosynthetic activity was observed in barley transcriptome and leaf chlorophyll content under 8h conditions, indicating a slower physiological development of shoot meristems than in tomatoes. The photomorphogenesis controlling cryptochrome gene cry1, with an effect on physiological differentiation, showed an underexpression in barley compared to tomato shoot meristems. This might lead to a cascade of suspended sink-source activities, which ultimately delay organ development and differentiation in barley shoot meristems under short photoperiods.