Effect Of Different Photoperiods Research Articles

Cannibalism rate and mLeptin expression are influenced by photoperiod and diets in Piracanjuba, Brycon orbignyanus (Valenciennes, 1850) larvae

Piracanjuba (Brycon orbignyanus) is a species with great productive potential, and during its larval phase, it presents intense cannibal activity. The photoperiod and diet are primary feed behaviour and cannibalism modulators to fishes. This experiment aimed to verify the effect of different photoperiods and diets in Piracanjuba larviculture. Larvae were kept under different photoperiods - 12 h light: 12 h dark (12 L: 12D); 24 h light:00 h dark (24hL: 00D) – Larvae were fed with Artemia nauplii and a formulated micro-diet in a factorial scheme for 10 days, and at the end of the experimental period, the influences of the treatments on performance and quantitative expression of mLeptin and mBmall1 were evaluated. In order to quantify the expression of mLeptin and mBmall1, qPCR adopting β-actin and Elongation Factor 1 as endogenous genes was used. The primers for all the analysed transcripts were obtained through multiple sequences alignments of different fish species. It was observed that the diet and photoperiod influence the performance of Piracanjuba (B. orbignyanus) larvae in the initial phase of larviculture. Feeding with artemia nauplii and the photoperiod of 24 L:00D reduce cannibalism rates in intensive Piracanjuba larviculture. The results on the rate of cannibalism, rate of survival and the relative expression of mLeptin are related to the survival rate of the larvae, and it is inversely proportional to the cannibalism rate. The expression levels of mBmall1 showed a correlation with the final weight of the larvae. Piracanjuba Larvae under a photoperiod of 24 light and fed Artemia nauplii showed more significant levels of mLeptin expression.

Effects of different photoperiods on growth performance and health status of largemouth bass (Micropterus salmoides) juveniles

This study investigated the effects of photoperiod duration on growth, heamatological and blood biochemical parameters, and antioxidant capacity of largemouth bass (Micropterus salmoides). Triplicate groups of juvenile fish (33.22 ± 4.68 g) were kept in a recirculating aquaculture system and exposed to five different photoperiods [light/dark (L/D), h] as follows: 8L:16D; 12L:12D; 16L:8D; 20L:4D and 24L:0D. All the fish were fed a commercial diet at a fixed ratio of 1% body mass with daily inspection of the consumed feed. The experiment lasted 16 weeks and fish growth was monitored at 4-week intervals. The results revealed the significant effect of photoperiod duration on growth rate and feed utilization. The constant light exposure (24L:0D) benefited weight gain (WG) only during the first four weeks while thereafter negative impacts were noticed. At the end of the feeding trial, the highest WG and specific growth rate were obtained in the 8L:16D group which significantly differed from those of the 12L:12D and 16L:8D groups. Although fish feed intake was not influenced by photoperiod duration, better feed conversion ratio was found in the 8L:16D group. Moreover, the same group exhibited the highest hepatosomatic and gonadosomatic indices, and haemoglobin concentration. The highest plasma total protein and globulin concentrations were recorded for the 16L:8D group. Plasma glucose concentration decreased by prolongation of light duration while opposite trends were observed for plasma ammonia concentration and creatinine kinase activity. The highest alanine aminotransferase and aspartate aminotransferase activities were found in 20L:4D and 12L:12D groups, respectively. Moreover, plasma alkaline phosphatase activity significantly decreased in 12L:12D and 16L:8D groups. Longer light duration led to remarkable increase of thiobarbituric acid reactive substances (TBARS) concentration in fish liver, brain and gill indicating the incidence of oxidative stress. Likewise, boosted antioxidant responses were found in liver [glutathione (GSH) and glutathione S-transferase (GST)], brain (GST) and kidney (superoxide dismutase) as light duration extended. These findings suggest that 8 L:16D is favouring better growth, organosomatic index and antioxidant capacity of largemouth bass juveniles reared in RAS.

Untargeted LC-MS-based metabonomic analysis of the effect of photoperiod on the testes of broiler roosters.

Photoperiod is an important factor that stimulates the reproductive performance of broiler breeder roosters. However, the mechanism by which photoperiod affects the reproductive performance of broiler breeder roosters has not been fully studied. To study the effects of different photoperiods on the reproductive performance of broiler breeder roosters, 120 Arbor Acres broiler breeder roosters aged 20weeks were randomly assigned to three groups (n=40), and the three groups were treated with different photoperiod regimes: control (CTR; 12.5h of light and 11.5h of dark, 12.5 L: 11.5 D), short day (SD; 16 L: 8 D) and long day (LD; 8 L: 16 D). Serum and testes were collected after 4weeks of feeding, and testosterone-related indices were detected. We found that testosterone synthesis in the testes of broiler roosters was boosted with prolonged of photoperiod. Subsequently, metabonomics was used to identify the differential endogenous metabolites that may affect the function of the testes in breeder roosters. We found compared with other groups, the concentrations of creatine, uridine monophosphate, phosphoribosyl pyrophosphate, dCMP, α-D-glucose and citric acid in the SD group decreased significantly (p<0.05), and glyoxylic acid, D-ribose 5-phosphate, deoxyuridine and orotic acid in the SD group increased significantly (p<0.05), while the CTR group and LD group showed no significant difference (p>0.05). The concentrations of linoleic acid and α-linolenic acid in the LD group were increased significantly (p<0.05) than those in the CTR and SD groups. Compared with the CTR group, the concentrations of histamine in the SD and LD groups were significant increased (p<0.05). The 13 of the different metabolites could be used as candidate biomarkers for different photoperiods affecting testosterone synthesis, may be used to molecular breeding of high reproductive performance broiler roosters.

The effect of storage temperature on biochemical changes in autumn daffodil bulbs (Sternbergia lutea (L.) Ker Gawl. ex Spreng.) and its impact on interactions with photoperiod and morphological indices

Understanding bulb dormancy while examining temperature-related requirements and photoperiod are essential for successful commercialization and the greenhouse forcing of autumn daffodil (Sternbergia lutea). In this study, autumn daffodil bulbs were stored at 5, 15 and 25 °C for one month. Then, one group of bulbs were evaluated in terms of biochemical characteristics in three parts of each bulb (scale, central bud and basal plate). A second group of bulbs were planted in a greenhouse for a separate experiment to study the effects of different photoperiods (short, moderate and long) on morphological traits. The heat map of treatments in the first experiment revealed that the bulb storage temperatures of 15 °C and 25 °C had somewhat similar effects on all three parts of the bulb but, conversely, 5 °C had discrete effects. The 5 °C resulted in higher contents of proline in the scale, along with more H2O2 and malondialdehyde (MDA) in the basal plate. The highest activity of peroxidase (POD) and superoxide dismutase (SOD) were observed at 15 °C in the basal plate and at 5 °C in the central bud, respectively. In the second experiment, the time required for bulb sprouting and time to flowering were as follows: 5 °C > 25 °C > 15 °C. The heat map analysis indicated that temperature played a more substantial role than what photoperiod did in shaping the morphological traits. The interaction between 15 °C and the moderate photoperiod led to the highest value of most vegetative traits and of flowering percentage (70%). Therefore, this treatment can be considered as optimum for breaking relative bulb dormancy and to succeed better in growth and flowering.

温度和光周期协同作用对蒙古栎幼苗春季物候的影响

植物物候对气候变化非常敏感，但关于物候对不同气候因子协同作用的响应机制仍不清楚。为此，以蒙古栎为研究对象，针对蒙古栎物候的主要影响因子温度和光周期，利用大型人工气候室，模拟研究了温度与光周期协同作用（对照、增温1.5℃、增温2.0℃，不同光周期（10 h、14 h、18 h）及其协同作用（对照处理、增温1.5℃×18 h、增温1.5℃×10 h、增温2.0℃×18 h、增温2.0℃×10 h））对蒙古栎春季物候的影响与机制。结果表明：（1）相同水分条件下，不同升温程度对蒙古栎幼苗春季物候的影响不同。温升1.5℃促进蒙古栎幼苗春季物候（芽膨大期、芽开放期、展叶始期和展叶盛期）提前；而温升2.0℃则对不同春季物候的影响不同，表现为促进芽休眠解除和芽开放，但抑制叶片展开。（2）相同水分条件下，不同光周期对蒙古栎幼苗不同春季物候的影响存在差异。长光周期对蒙古栎幼苗展叶盛期影响最大，短光周期对芽膨大期影响最大，但均表现为抑制作用。（3）相同水分条件下，温度升高与光周期增加协同作用有助于促进蒙古栎幼苗春季物候提前，但温度升高与光周期缩短协同作用则对春季物候有抑制作用。（4）蒙古栎幼苗春季物候变化与前期气候胁迫程度存在显著正相关，表明前期气候因子也是物候变化的重要影响因子。研究结果丰富了蒙古栎物候响应多气候因子协同作用的认知，有助于促进物候模型的完善。;Plant phenology is very sensitive to climate change. However, the interactive effects of different climatic variables on plant phenology are still unclear. Thus, taking Quercus mongolica as the research object, we studied the interactive effects of different warming and changing photoperiod (control treatment (CK), 1.5℃ warming, 2.0℃ warming; different photoperiods (10 h, 14 h, and 18 h); CK, 1.5℃ warming×18 h, 1.5℃ warming×10 h, 2.0℃ warming×18 h, 2.0℃ warming×10 h) on the spring phenology of Quercus mongolica seedlings based on the experimental data of large artificial climate simulation chamber in the context of global warming. The results are as follows:(1) Under the same water condition, different warming had different effects on the spring phenology of Quercus mongolica seedlings. The 1.5℃ warming promoted the spring phenology, including bud swelling (BS), bud opening (BO), first full leaf (F1), and 50% leaves unfolded (LU) stages. The influence of 2.0℃ warming on different spring phenology was different. 2.0℃ warming promoted the release of bud dormancy and leaf BO, but inhibited the leaf extension. (2) Under the same water condition, the effect of different photoperiods on the spring phenology of Quercus mongolica seedlings was different. The long photoperiod had the greatest influence on the 50% LU stage, while the short photoperiod had the greatest influence on the BS stage, but they all showed negative effects. (3) Under the same water condition, prolonging photoperiod under warming treatments was helpful to promote the spring phenology of Quercus mongolica seedlings, including the BO, F1 and 50% LU stages. While shortening of photoperiod under warming treatments inhibited the spring phenology of Quercus mongolica seedlings, including the BS, F1 and 50% LU stages. (4) There was a significant correlation between spring phenological changes of Quercus mongolica seedlings and previous climate stress, implying that the previous climatic variables should be the significantly controlling factors to phenological changes. The results could enrich the cognition of the interactive effects of multiple climatic variables in Quercus mongolica phenology, and are helpful to promote plant phenology simulation.

The effect of photoperiod and melatonin on plasma prolactin concentrations in female guanaco (Lama guanicoe) in captivity.

The present study examined the effects of different photoperiods and melatonin treatment on plasma prolactin concentrations in guanacos, a South American camelid, in captivity. Fourteen adult female guanacos, not gestating or lactating and isolated from males, were studied. The control group was exposed to natural daylight, during short days (N=7, 10L:14D) and long days (N=7, 16L:8D). The treatment group (N=7, 10L:14D) received melatonin implants every 23days for 6weeks during long days. Blood samples were taken at intervals of 1week for 3weeks, starting the third week of treatment. Prolactin concentrations were measured using competitive ELISA. Plasma concentrations of prolactin in non-lactating female guanacos have seasonal changes, with a higher concentration (p<.001) in short days (3.50±2.24ng/ml) than long days (1.10±0.91ng/ml). Melatonin treatment significantly decreases (p<.05) plasma concentrations of prolactin on the 21st day after the treatment. These findings are the first report of an endogenous circannual rhythm of plasma prolactin concentration and the action of melatonin treatment on prolactin secretion in this wild camelid.

Increasing Growth of Lettuce and Mizuna under Sole-Source LED Lighting Using Longer Photoperiods with the Same Daily Light Integral

Light recommendations for horticultural crops often focus on the optimal daily light integral (DLI) without regard to how that light is delivered throughout each day. Because photosynthesis is more efficient at lower photosynthetic photon flux density (PPFD), we hypothesized that longer photoperiods with lower PPFD results in faster growth than shorter photoperiods with higher PPFD and the same DLI. We quantified the effect of different photoperiods, all providing the same DLI, on photosynthesis and growth of two leafy greens. Mizuna (Brassica rapa var. japonica) and lettuce (Lactuca sativa) “Little Gem” were grown from seed in a controlled environment chamber (20 °C and 819 µmol·mol−1 CO2) under six photoperiods (10, 12, 14, 16, 18, and 20 h). LED fixtures provided white light and PPFD was adjusted so each treatment received a DLI of 16 mol·m−2·d−1. Mizuna and lettuce were harvested 30 and 41 days after planting, respectively. Longer photoperiods with lower PPFD increased light interception, chlorophyll content index, quantum yield of photosystem II, and aboveground biomass, but decreased instantaneous CO2 assimilation of lettuce and mizuna. Aboveground biomass increased 16.0% in lettuce and 18.7% in mizuna in response to increasing the photoperiod from 10 to 20 h. In summary, extending the photoperiod and lowering PPFD increases growth of lettuce and mizuna by increasing light interception and the quantum yield of photosystem II.

Effects of photoperiod, potassium, and growth regulators on micropropagation of Ocimum basilicum L. ‘Genovese’

Medicinal plants are important in the pharmaceutical, cosmetic, and food industry owing to the diversity of their chemical composition. Basil (Ocimum basilicum L.) is a medicinal plant that is frequently used to produce cosmetics and food. However, the effects of factors such as photoperiod, growth regulators, and nutrients on growth during micropropagation are not comprehensively understood. The objective of this study was to assess the effect of different photoperiods and growth regulators on in-vitro growth and biochemical activity of the O. Basilicum 'Genovese' cultivated using a potassium-supplemented culture medium. The experiments were carried out in a completely causalized design and were conducted using a Murashige and Skoog culture medium plus sucrose and agar. In the first experiment, seeds were inoculated at three different photoperiods in the presence or absence of growth regulators. In the second experiment, growth media containing five different concentrations of potassium iodide (KI) (0, 25, 50, 75, and 100 μM) were used. Basil seedlings grown at photoperiods of 16h and 24h produced more leaves and larger length and shoot mass, and addition of growth regulators showed no effect. However, the root systems produced the highest average values at a photoperiod of 16 h and when growth regulators were supplemented (0.23 g ±0,08). Antioxidant activity and the concentration of ascorbate peroxidase were higher under the 16 h light treatment and with addition of growth regulators. Addition of potassium to the growth medium had no beneficial effects on seedlings. Antioxidant activity was not affected by potassium concentrations, but it remained high (above 13.5%) when compared with the previous treatment. Catalase activity was the highest in seedlings grown at the highest concentrations of KI. The catalase enzyme is considered a stress indicator, so in higher concentrations of KI there is evidence that the basil plants may have had oxidative damage

Opposite effects of photoperiod and temperature on circadian rhythms of pineal arylalkylamine N-acetyltransferas (AANAT) activity and circulating levels of thyroid hormones in airbreathing catfish, Clarias gariepinus

ABSTRACT Effects of different photoperiods (9L-15D, 12L-12D and 15L-9D at a constant temperature 25 ± 1°C) and simulated temperatures (15°C, 25°C and 35°C under a common photoperiod 12L-12D) were investigated on the circadian rhythms of plasma levels of thyroid hormones [thyroxine (T4) and triiodothyronine (T3)] and pineal arylalkylamine N-acetyltransferase (AANAT) activity in the fish, Clarias gariepinus during winter and summer seasons. Irrespective of the seasons, plasma levels of thyroid hormones (THs) and pineal AANAT activity exhibited circadian rhythm under all the photoperiodic regimes and simulated temperatures. The levels of THs were found to be directly related to the length of photoperiod as well as temperature. In contrast, pineal AANAT activity was inversely related to the length of photoperiod and temperature. On the basis of these findings, we suggest that photoperiod and temperature jointly regulate the inverse temporal relationship between the circadian rhythms of plasma levels of THs and pineal AANAT activity in C. gariepinus.

Variation in Morphological and Quality Parameters in Garlic (Allium sativum L.) Bulb Influenced by Different Photoperiod, Temperature, Sowing and Harvesting Time.

Photoperiod (light) and temperature as abiotic factors having significant impact on the garlic bulb morphology and quality. In various bulb plants including garlic, bulbing is affected by photoperiod, temperature, sowing date and the plant age. In this backdrop experiments were performed to understand the effect of different photoperiods (10 h/14 h, 12 h/12 h and 14 h/10 h (light/dark)), temperatures (25 °C/18 °C and 30 °C/20 °C (light/dark)), sowing dates (D0801: 1st August, D0901: 1st September and D1001: 1st October) and plant ages (A80, A60 and A40: 80, 60 and 40 days after planting) on garlic cultivars viz; G103, G024 and G2011-5. Parameters including morphological (plant height, fresh weight and pseudostem diameter), bulb attributes (diameter, weight, height and bulbing index), growth period and bulb quality related traits (total soluble solid (TSS), contents of soluble protein, soluble sugar, total sugar, glucose, sucrose, fructose, starch, total phenol and total flavonoid) were assayed. Longer photoperiod (14 h), higher temperature (30 °C), early sowing (D0801) and maximum plant age (A80) had maximum morphological and bulb quality related traits for cv. G103. These results showed that early sowing, maximum plant age, longer photoperiod and higher temperature are important for garlic bulb formation and quality. Moreover, the regulation of garlic bulb morphology and quality is achievable over the switch of sowing date, plant age, light and growth temperature.

Effect of Different Photoperiods on Quality Attributes and Oxidative Stability of Breast Meat (M. Pectoralis Major) from Broilers

ObjectivesIn the broiler industry, high photoperiod (the duration of light exposure per day) regimes have traditionally been utilized to increase yield of breast meat, as well as maximize feed intake and growth rate in the growing period. However, recent literature reports this practice may have adverse effects on broiler welfare, resulting in impaired mobility and increased incidence of leg abnormalities. However, little information available in the current literature regarding effects of photoperiod on meat quality attributes and oxidative stability of broiler meat. Thus, the objective of this study was to evaluate the quality characteristics and lipid/protein oxidative stability of breast meat from broilers that were exposed to different photoperiod combinations.Materials and MethodsA total of 432 Ross 308 broiler chicks were allocated among 4 rooms each subjected to one of the following photoperiod treatments (hours Light: Dark): 20L:4D, 18L:6D, 16L:8D and 12L:12D, with 6 pens per treatment. At d 42, 2 broilers per pen (12 broilers/treatment) were randomly selected, harvested and air chilled for 24 h at 2°C. At l day postmortem, paired breast muscles (M. pectoralis) were collected for the meat quality analyses such as, water-holding capacity (drip/purge/cook loss), Warner-Bratzler shear force (WBSF), and display color for 7 d under fluorescent light (1450 lx). Lipid oxidation was assessed via the TBARS assay and protein oxidation by thiol content measured at d 1 and d 7 of display. The experimental design was randomized complete block design. Data were analyzed using the PROC MIXED procedure of SAS, and means were separated using least significant differences (P &lt; 0.05).ResultsPhotoperiod had no effect on fillet yield and pH (P &gt; 0.05). No significant difference in WBSF was found between treatments, although 12L:12D had a trend of higher WBSF (P = 0.08). Higher moisture loss during carcass chilling was found in carcasses from 20L:4D compared to 16L:8D and 12L:12D treatments (P &lt; 0.05). No other measure of water-holding capacity was affected, though the 16L:8D treatment demonstrated a trend of higher freezing/thawing loss compared to other treatments (P = 0.06). Proximate moisture, protein and lipid contents were unaffected by photoperiod (P &gt; 0.05), but higher ash was observed in 16L:8D over 20L:4D and 18L:6D (P &lt; 0.05). Different photoperiod combinations affected color stability of breast meat during display (P &lt; 0.05). Of note, fillets from 20L:4D maintained highest L* and hue angle, and least a* values (P &lt; 0.05), indicating inferior color stability compared to other treatments. Oxidation increased with display, and fillets from 20L:4D and 18L:6D had higher TBARS over 12L:12D (P &lt; 0.05); no photoperiod effect was observed in thiol content (P &gt; 0.05).ConclusionResults suggest 20L:4D photoperiod regimes may be detrimental to meat quality, as carcasses from this treatment group had higher moisture loss during chilling, and color measurements characterized these fillets as being paler and more discolored than other treatments. Fillets from 12L:12D maintained lower TBARS than 20L:4D and 18L:6D, suggesting photoperiod regimes allowing more hours of dark may be beneficial in improving oxidative stability. Further studies determining the effects of photoperiod on quality and protein functionality of chicken meat for processing technological would be highly warranted.

The Effect of Photoperiods and Light Intensity on Mating Behavior and Reproduction of Grapholita molesta (Lepidoptera: Tortricidae).

Oriental fruit moth, Grapholita molesta (Busck), is a worldwide pest and is the dominant pest of rosaceous plants in northern China. Little is known, however, about the influence of abiotic factors on the daily life history events of this economically important pest, so here we evaluated the effect of different photoperiods (L:D) (0:24; 2:22; 4:20; 6:18; 8:16; 10:14; 12:12; 14:10; 15:9 [control]; 16:8; 18:6; 20:4; 22:2; and 24:0 h) and light intensities (50, 100, 200, 300, 400, and 500 lux) on the mating behavior and reproduction of oriental fruit moth. We found that oriental fruit moth adults with an 8, 9, or 10 h scotophase showed considerably more courtship behavior than those in other photoperiod treatments. Meanwhile, male fanning and male 'crawling in a circle' behaviors significantly decreased with increasing light intensity. Neither female or male oriental fruit moth longevity nor the egg hatch rate were influenced by photoperiod (P = 0.146; 0.271; 0.107) or light intensity (P = 0.268; 0.08; 0.123). In both photoperiod and light intensity treatments (P < 0.05), the number of eggs laid daily by females was significantly influenced by female age, decreasing with greater age. Female oriental fruit moth lifetime fecundity was influenced by photoperiod, with the 9, 10, 16, 18, and 22 h scotophase periods having higher fecundity than other treatments. Meanwhile, fecundity decreased with increasing light intensity.

The transcriptome sequencing and functional analysis of eyestalk ganglions in Chinese mitten crab (Eriocheir sinensis) treated with different photoperiods.

Photoperiod plays an important role in individual growth, development, and metabolism in crustaceans. The growth and reproduction of crabs are closely related to the photoperiod. However, as of yet, there are still no transcriptomic reports of eyestalk ganglions treated under different photoperiods in the Chinese mitten crab (Eriocheir sinensis), which is a benthonic crab with high commercial value in Asia. In this study, we collected the eyestalk ganglions of crabs that were reared under different photoperiods, including a control group (L: D = 12 h: 12 h, named CC), a constant light group (L: D = 24 h: 0 h, named LL) and a constant darkness group (L: D = 0 h: 24 h, named DD). RNA sequencing was performed on these tissues in order to examine the effects of different photoperiods. The total numbers of clean reads from the CC, LL and DD groups were 48,772,584 bp, 53,943,281 bp and 53,815,178 bp, respectively. After de novo assembly, 161,380 unigenes were obtained and were matched with different databases. The DEGs were significantly enriched in phototransduction and energy metabolism pathways. Results from RT-qPCR showed that TRP channel protein (TRP) in the phototransduction pathway had a significantly higher level of expression in LL and DD groups than in the CC group. We found that the downregulation of the pyruvate dehydrogenase complex (PDC) gene and the upregulation phosphoenolpyruvate carboxykinase (PPC) gene were involved in energy metabolism processes in LL or DD. In addition, we also found that the upregulation of the expression level of the genes Gαq, pyruvate kinase (PK), NADH peroxidase (NADH) and ATPase is involved in phototransduction and energy metabolism. These results may shed some light on the molecular mechanism underlying the effect of photoperiod in physiological activity of E. sinensis.

Effect of Different Photoperiods on Quality Attributes and Oxidative Stability of Breast Meat (M. Pectoralis Major) from Broilers

ObjectivesIn the broiler industry, high photoperiod (the duration of light exposure per day) regimes have traditionally been utilized to increase yield of breast meat, as well as maximize feed intake and growth rate in the growing period. However, recent literature reports this practice may have adverse effects on broiler welfare, resulting in impaired mobility and increased incidence of leg abnormalities. However, little information available in the current literature regarding effects of photoperiod on meat quality attributes and oxidative stability of broiler meat. Thus, the objective of this study was to evaluate the quality characteristics and lipid/protein oxidative stability of breast meat from broilers that were exposed to different photoperiod combinations.Materials and MethodsA total of 432 Ross 308 broiler chicks were allocated among 4 rooms each subjected to one of the following photoperiod treatments (hours Light: Dark): 20L:4D, 18L:6D, 16L:8D and 12L:12D, with 6 pens per treatment. At d 42, 2 broilers per pen (12 broilers/treatment) were randomly selected, harvested and air chilled for 24 h at 2°C. At l day postmortem, paired breast muscles (M. pectoralis) were collected for the meat quality analyses such as, water-holding capacity (drip/purge/cook loss), Warner-Bratzler shear force (WBSF), and display color for 7 d under fluorescent light (1450 lx). Lipid oxidation was assessed via the TBARS assay and protein oxidation by thiol content measured at d 1 and d 7 of display. The experimental design was randomized complete block design. Data were analyzed using the PROC MIXED procedure of SAS, and means were separated using least significant differences (P < 0.05).ResultsPhotoperiod had no effect on fillet yield and pH (P > 0.05). No significant difference in WBSF was found between treatments, although 12L:12D had a trend of higher WBSF (P = 0.08). Higher moisture loss during carcass chilling was found in carcasses from 20L:4D compared to 16L:8D and 12L:12D treatments (P < 0.05). No other measure of water-holding capacity was affected, though the 16L:8D treatment demonstrated a trend of higher freezing/thawing loss compared to other treatments (P = 0.06). Proximate moisture, protein and lipid contents were unaffected by photoperiod (P > 0.05), but higher ash was observed in 16L:8D over 20L:4D and 18L:6D (P < 0.05). Different photoperiod combinations affected color stability of breast meat during display (P < 0.05). Of note, fillets from 20L:4D maintained highest L* and hue angle, and least a* values (P < 0.05), indicating inferior color stability compared to other treatments. Oxidation increased with display, and fillets from 20L:4D and 18L:6D had higher TBARS over 12L:12D (P < 0.05); no photoperiod effect was observed in thiol content (P > 0.05).ConclusionResults suggest 20L:4D photoperiod regimes may be detrimental to meat quality, as carcasses from this treatment group had higher moisture loss during chilling, and color measurements characterized these fillets as being paler and more discolored than other treatments. Fillets from 12L:12D maintained lower TBARS than 20L:4D and 18L:6D, suggesting photoperiod regimes allowing more hours of dark may be beneficial in improving oxidative stability. Further studies determining the effects of photoperiod on quality and protein functionality of chicken meat for processing technological would be highly warranted.

Melatonin concentrations in Chinese mitten crabs (Eriocheir sinesis) are affected by artificial photoperiods

ABSTRACTMelatonin is a ubiquitous and conservative biogenic amine implicated in a variety of bio-physiological processes. Although the daily variations of melatonin concentrations have been determined in many crustacean species, results have been conflicting. The present study was undertaken to evaluate the effect of different photoperiods on the circadian rhythms of melatonin in Eriocheir sinensis by using high performance liquid chromatography. The circadian rhythms of melatonin in the eyestalk of E. sinensis were influenced by external light stimulation. When under consistent light (24L:0D) and consistent dark (0L:24D), the melatonin rhythm in eyestalks and hemolymph was disturbed with respect to that of the control group (12L:12D). However, disturbance owing to different photoperiod treatments decreased with increasing treatment duration. Our results underscore the exquisite sensitivity of melatonin content to different photoperiods. These findings may have real-world implications in terms of the disruption of circadian rhythms induced by exposure to different photoperiods.

Effect of photoperiod on the formation of cherry radish root

Radish root formation under short photoperiod is a common sense, however, cherry radish is a kind of four-season radish and the relation of photoperiod and cherry radish root formation is not clear until now. Effect of different photoperiods (8 h/16 h, 12 h/12 h, and 16 h/8 h) on the development and antioxidant ability of cherry radish as well as expression of relative genes was investigated in this study. Surprisingly, the most robust radish plant and largest biomass were found at the long photoperiod regime (16h/8 h), even though both the polyphenol content and antioxidant ability in terms of DPPH and FRAP were lower than those in 12/12 h photoperiod. Moreover, under 16h/8h photoperiod it can form the radish product organs in 30 d but not for the others. Gene expression analysis showed that eight non-coding miRNAs and coding RNAs were both involved in the regulation of radish root formation. MiR160, miR165, and miR396 were up-regulated by 16h/8 h photoperiod treatment while miR156 and miR157 were down-regulated. The up-regulation of miR160 and the opposite expression trend of ARF16 indicated that miR160 may mediate the light-respond root formation by targeting ARF16. An auxin response factor ARF6 and a cell wall structure related WRKY2 were also significantly up-regulated by the longer illumination treatment compared with the control. Thus, unlike other radish roots that form in short-day condition, the cherry radish roots grow fastest in long photoperiod and miR160-ARF16 are involved in the quick formation of cherry radish root.

THE DETECTION OF THE TIME OF CONVERSION FROM VEGETATIVE TO REPRODUCTIVE GROWTH IN Swainsona formosa (FABACEAE)

The induction of chromosome doubling using antimitotic chemical will only be effective when the substance is applied at vegetative growth phase, as it works only during mitotic division within cells of actively growing tissues. Therefore, this investigation was carried out to determine the precise conversion time from vegetative into reproductive growth stage, that in turn can be used as a reliable reference for the application of antimitotic chemicals in doubling the chromosome number in Swainsona formosa. The conversion from vegetative to reproductive growth in Swainsona formosa was successfully determined with particular emphasis on the effect of different photoperiods. Although photoperiod affected the time required for first flower initiation, the number of nodes before the plant entering the reproductive stage was not affected by photoperiod and presumed to be set genetically. It was found that under artificial photoperiods of 16, 12 and 8 hours the 12th and 11th nodes were the critical nodes for the main and side stems, respectively. Meanwhile the 10th and 8th nodes were found to be critical for main and side stems of plants grown under natural photoperiods ranging from 12 to 16 hours during their life cycle. Histological examination indicated that when the plants were grown under 12 – 16 hours photoperiods the first floral bud formation was initiated within 56 – 60 days after germination, thus this period was considered as the critical time for the conversion from vegetative to reproductive growth in S. formosa.&#x0D; &#x0D; Keywords: Sturt’s desert pea, legume, ornamental plant, plant breeding.

Effect of different photoperiods on the longevity of male and female Moth of Eri silkworm (Philosamia ricini) L. (Saturniidae: Lepidoptera)

The effect of different photoperiods on longevity of male and female of Eri silkworm (P.ricini) was carried in P.G. Madhav Vigyan Mahavidhyalay, Ujjain (MP). The Eri silkworms reared under the exposure of different experimental photoperiods G1 (12L:12D),G2 (LL), G3 (10L:14D), G4 (08L;16D), G5 (05L:19D) and G6 (DD), at temperature (25±2oC) and relative humidity (75±5%).The longevity of male and female moths were maximum in G3 and minimum in G2, complete light.

Environmental conditions for Diaphorina citri Kuwayama (Hemiptera: Liviidae) take‐off

AbstractEnvironmental factors that influence flight activity of Diaphorina citri Kuwayama (Hemiptera: Liviidae) may have implications for Huanglongbing spread and management. In this work, four studies were conducted to evaluate the effect of environmental conditions on D. citri take‐off. In the first, insects were transferred to sweet orange seedlings and confined inside an acrylic cage to verify the take‐off periodicity and the effect of environmental factors on this process. In the second, take‐off temperature threshold was estimated by recording the number of insects that initiated flight from a platform when subjected to gradual temperature increases from 15 to 39°C. In the other studies, we evaluated the effect of different photoperiods and temperature regimes (third study) and of constant temperatures (fourth study) on the propensity for D. citri flight. Insects were confined in clear plastic bottle cages with tubes of 50 ml placed on the cab, to collect emerged adults that initiated flights. Results showed that a small portion of the tested population (maximum 10%) tends to take off from plants and this behaviour is more prevalent in the afternoon (14:00–16:00 h), coinciding with daytimes of lower humidity and higher thermal amplitude. Adults that were submitted to lower temperatures (18°C) and short light periods (10 h) showed less propensity to flight. In contrast, at constant 27°C, the insects were more prone to flight, and this result was confirmed when individuals were submitted to increases in temperature, indicating that 27.14°C is the take‐off temperature threshold of D. citri. Results show that temperature plays an important role in the flight activity of D. citri and suggest that control measures of the insect may be more effective in the morning and in temperatures below 27°C, when the probability to take off from a host is lower.

Effect of different photoperiods on the biochemical profile of the green algae C. vulgaris and S. obliquus

Effect of different photoperiods on the biochemical profile of the green algae <i>C. vulgaris</i> and <i>S. obliquus</i>