Photoperiod-temperature Regimes Research Articles

Key factors affecting the spring emergence of pea moth (Cydia nigricana).

The hypothesis that spring emergence of the pea moth Cydia nigricana is regulated by environmental factors, particularly photoperiod and temperature, was examined in this study. A long-term field study was conducted in two distinct pea-growing areas in Hesse and Saxony, Germany. Strong correlations between the flight phenology of pea moth in spring and air temperature, soil temperature, solar radiation and day length were demonstrated for three consecutive years. In laboratory experiments, we elucidated the interaction of different photoperiod-temperature regimes, verifying cumulative day-degree data in relation to pea moth emergence rates in the field. C. nigricana temperature sensitivity is apparently initiated by long day conditions with a critical day length of about 14 h L:D. The overall results contribute to the theory that photoperiod and temperature interact as regulatory cues for spring emergence of C. nigricana. The findings are discussed in terms of the development of predictive models and decision support systems for pea moth control.

Single Injections of Human Chorionic Gonadotropin or Mammalian Gonadotropin Releasing Hormone Analog at Low Dosages Induce Ovulation in White Bass

Abstract Spawning trials were conducted to determine an efficacious dosage of human chorionic gonadotropin (hCG) and to investigate the potential of mammalian gonadotropin releasing hormone analog (mGnRHa) to induce ovulation in white bass Morone chrysops. White bass broodstock were habituated to indoor tanks and subjected over several months to photoperiod-temperature regimes simulating the seasons to induce gonadal maturation. Various hCG dosages (0, 10, 25, 50, 150, 170, 250, 280, and 830 IU/kg body weight) were tested in single injections. We demonstrated that white bass can be successfully spawned with an hCG dosage as low as 50 IU/kg. However, this dosage did not result in all fish ovulating in a subsequent trial. We found no significant differences between 150 IU hCG/kg and higher dosages in ovulation response (ovulation success and time to ovulation), egg production (number of eggs/kg), or egg quality (fertility and hatch rates). Single injection of mGnRHa at 50 μg/kg did not consistently cause ov...

Photoperiod, Temperature, and Plant Age Interact to Affect Short-day Onion Cold Hardiness

Proper acclimation of onion (Allium cepa L.) seedlings can enhance winter freeze survival; therefore, the effects of photoperiod-temperature combinations, photoperiod, and plant age on the cold hardiness of short-day onions were investigated. Following acclimation at various photoperiod-temperature regimes, different-aged plants were frozen to various subzero temperatures in an ethylene glycol bath and evaluated for cold hardiness. Older plants were more cold hardy than younger plants. An 11-hour photoperiod-decreasing temperature (20/15 to 10/5C day/night) treatment improved plant cold hardiness over other photoperiod-temperature regimes. Various photoperiods (8-, 11-, 14-, and 24-hour) applied during a 14-day, 3C acclimation treatment before freezing had little effect on plant cold hardiness. However, day 7 foliar and day 14 root evaluations indicated that 81-day-old plants given an 8- or 11-hour photoperiod during the 3C acclimation treatment were less cold hardy than older plants (91 or 112 days) given the same acclimation photoperiod.

Effects of constant photoperiod-temperature regimes on ovarian activity during the annual reproductive cycle in the murrel, Channa punctatus (Bloch)

Two experiments were conducted to study the effects of LD 16:8 and LD 8: 16–30°C regimes on ovarian activity during the annual reproductive cycle in Channa punctatus. Long photoperiod-warm temperature regime stimulates ovarian recrudescence and prolongs the spawning period, while short photoperiod-warm temperature regime inhibits ovarian development and causes ovarian regression. The analysis of variance of ovarian GSIs also revealed the significant contribution of photoperiod and temperature for ovarian recrudescence. The LD 16: 8–30°C regime provides better conditions for ovarian recrudescence than the LD 8: 16–30°C regime and control group.

In vitro regeneration of plantlets from embryonic and seedling explants of Engelmann spruce (Picea engelmannii Parry).

A protocol has been developed for the in vitro production of plantlets of Engelmann spruce. Embryos and various parts of Engelmann spruce seedlings formed multiple shoots when cultured on defined media containing a cytokinin. The site and time of occurrence of the shoot buds, as well as their number, differed in the various explants. The frequency of shoot-forming explants was influenced by the salt formulation used, the type and concentrations of cytokinins and their mode of application. Development of buds was achieved by transferring the explants to basal medium containing no growth regulators. Elongation of shoots was stimulated by reducing the concentration of salts and sugar, addition of activated charcoal and transferral to increased photoperiod and lower temperature regimes. Maximum rooting was induced by giving a pulse of high concentration of indolebutyric acid to the shoots. The roots developed within 8-10 weeks and the regenerated plantlets were transferred to soil under non-sterile conditions.

Photoperiod-temperature interactions on liver and plasma metabolites in the goldfish, Carassius auratus

1. 1. Plasma and liver metabolites were measured in goldfish after 3 weeks acclimation to one of four different photoperiod-temperature regimes (16L/8D-22°C; 16L/8D-13°C; 8L/16D-22°C; 8L/16D-13°C) during September and April. Samples were taken at the mid-light and mid-dark point of each photoregime. 2. 2. Photoperiod altered levels of plasma protein and plasma cholesterol. 3. 3. Temperature affected the levels of liver glycogen, plasma glucose, organic bound phosphorus and protein. 4. 4. Time of sampling was important in assessing both photoperiod and temperature effects on metabolites. 5. 5. Interaction between photoperiod and temperature was observed in the levels of liver glycogen and plasma glucose. The interaction was dependent on sampling time. 6. 6. Seasonal differences were noted in the day-night variation of specific metabolites and of the photoperiod effects on plasma cholesterol levels.

The effects of pinealectomy on pituitary and plasma gonadotropin levels in Carassius auratus exposed to various photoperiod–temperature regimes

The effects of pinealectomy on pituitary and plasma gonadotropin levels and gonadal development in female goldfish exposed to various photoperiod‐temperature regimes during different seasons were examined. Pinealectomy during autumn had no effect on either pituitary or plasma hormone levels or gonadal development. When goldfish are pinealectomized in spring and exposed to long photoperiod conditions, the ovaries regress and plasma gonadotropin levels are significantly depressed compared to sham operated animals. Sham operated goldfish exposed to short photoperiod conditions in spring had regressing ovaries whereas pinealectomized animals under this regime either spawned or had ovaries in the late vitellogenic phase. Plasma gonadotropin titres in the pinealectomized group were significantly lower than those of sham operated animals. The pineal can be either stimulatory or inhibitory to gonadal development depending on the photoperiod regime to which the animals are exposed. The pineal apparently influences gonadal activity by modulating gonadotropin secretion. A diurnal variation in plasma gonadotropin levels was also observed in both sham operated and pinealectomized goldfish exposed to a long photoperiod warm‐temperature regime in spring.

The effects of pinealectomy on pituitary prolactin levels in Carassius auratus exposed to various photoperiod-temperature regimes.

Pinealectomy has an influence on pituitary prolactin levels in goldfish maintained under certain photoperiod-temperature regimes. The effects of pinealectomy on pituitary prolactin content depend on photoperiod and time of sampling. Thus, differences between pinealectomized and sham operated animals may be due to a shift of a daily variation in pituitary prolactin levels. The pineal in fishes may thus be involved in photoperiod influences on daily prolactin rhythms.

Effects of Long-Term Exposure to Constant Photoperiod-Temperature Regimes on Gonadal Activity and Energy Reserves in the Golden Shiner, Notemigonus crysoleucas

Effects of Long-Term Exposure to Constant Photoperiod-Temperature Regimes on Gonadal Activity and Energy Reserves in the Golden Shiner, Notemigonus crysoleucas

Effects of photoperiod-temperature regimes on pituitary gonadotrophs, pituitary gonadotropin potency and hypothalamic gonadotropin releasing acitivity in the teleost notemigonus crysoleucas

1. 1.|The effects of various photoperiod-temperature regimes on gonadal activity, hypothalamic gonadotropin releasing activity, pituitary gonadotropin potency and pituitary gonadotrophs were examined in the teleost, Notemigonus crysoleucas. 2. 2.|In fish maintained on a long photoperiod-high temperature regime final gonadal maturation occurs. Under these conditions hypothalamic gonadotropin releasing activity is high, stainable gonadotrophs make up a low percentage of pituitary area and pituitary gonadotropin potency is relatively low. 3. 3.|Gonadotrophs make up a relatively large area of the pituitary and adenohypophyseal gonadotropin activity is high in fish exposed to long photoperiod-low temperature regimes. Long photoperiod-low temperature regimes do not stimulate final gonadal maturation. 4. 4.|Short photoperiod-high temperature conditions retard gonadal development or cause gonadal regression in Notemigonus. The area of the pituitary occupied by gonadotrophs and hypothalamic gonadotropin releasing activity are low in fish exposed to these conditions. Pituitary gonadotropin potency, however, is relatively high in fish maintained on short photoperiod-high temperature regimes. 5. 5.|Gonadotrophs were infrequent in the pituitary and pituitary gonadotropin potency was low in animals maintained on short photoperiod-low temperature regimes. These conditions do not promote the final stages of gonadal maturation in Notemigonus. 6. 6.|Light intensities of below 151x are insufficient to induce spawning in Notemigonus. Light intensities above 151x increase the incidence of spawning.

PHOTOPERIODIC CONTROL OF DEVELOPMENT AND PHENOTYPE IN A SUBARCTIC POPULATION OF PIERIS OCCIDENTALIS (LEPIDOPTERA: PIERIDAE)

AbstractPieris occidentalis nelsoni W. H. Edwards from Fairbanks, Alaska, was reared under a variety of photoperiod–temperature regimes. The source population is presumably univoltine and monophenic, with a phenotype resembling the vernal one produced by multivoltine, diphenic P. o. occidentalis Reakirt in Colorado and California. Photoperiods of 10 or 15 h produced 100% diapause pupae at 15 °C and circa 65% at 25 °C. Under continuous light 22% diapaused at 15 °C and < 1% at 25 °C. About 20% of non-diapause pupae produced adults resembling the estival phenotype of P. o. occidentalis, which is unknown in wild P. o. nelsoni. Although nelsoni is more likely to diapause than the nominate subspecies from the Sierra Nevada, its potential for direct development and polyphenism is interpreted as evidence that it is derived from a multivoltine ancestor.

EFFECTS OF PHOTOPERIOD AND TEMPERATURE ON GONADAL ACTIVITY IN THE CYPRINID TELEOST, NOTEMIGONUS CRYSOLEUCAS

1. The effects of various photoperiod-temperature regimes on gonadal activity in the cyprinid teleost, Notemigonus crysoleucas, were examined during several different phases of the annual reproductive cycle.2. Regardless of the time of year when the experiment is initiated a long photoperiod-warm temperature regime stimulates gonadal development to the prespawning condition or induces spawning. Neither a warm temperature alone nor a long photoperiod alone will stimulate final gonadal maturation.3. Notemigonus is not refractory to long photoperiod-warm temperature gonadal activation during the postspawning season.4. Short photoperiods in combination with warm temperatures cause gonadal regression in this species. A low temperature-short photoperiod regime does not induce gonadal involution.5. Spermatocyte formation and proliferation as well as the early phases of vitellogenesis occur independently of environmental factors. Final gonadal maturation and the rate of gametogenesis, however, depend on specifi...

Effects of pinealectomy on gonadal activity in the cyprinid teleost, Notemigonus crysoleucas

Investigations were initiated to examine the effects of pinealectomy on gonadal activity in the cyprinid teleost, Notemigonus crysoleucas, during different phases of the reproductive cycle and maintained under different photoperiod-temperature regimes. The effects of pinealectomy varied depending on the phase of the natural reproductive cycle when the organ was removed, as well as, with the photoperiod-temperature regime under which the experimental animals were maintained. Pinealectomy causes testicular regression during the gonadal preparatory and prespawning season and retards final testicular maturation during the spawning season in fish maintained on a long photoperiod-warm temperature regime. Under these conditions epiphysectomy retarded ovarian development or caused ovarian involution during all phases of the gonadal maturation cycle. In Notemigonus maintained on a long photoperiod-low temperature regime, pinealectomy had no apparent effects on gonadal development during the preparatory and spawning seasons. During the prespawning season pinealectomy repressed ovarian development and caused testicular regression in fish exposed to a long photoperiod-low temperature regime. During the prespawning and spawning seasons pinealectomy stimulated gonadal activity in fish maintained on a short photoperiod-warm temperature regime. Under these same conditions epiphysectomy failed to alter gonadal activity during the gonadal preparatory season. No obvious changes could be detected in gonadal activity in pinealectomized fish exposed to short photoperiodlow temperature regimes during any phase of the gonadal maturation cycle. These data suggest that the pineal in Notemigonus may be either stimulatory or inhibitory to gonadal development depending on the photoperiod-temperature regime to which the fish are exposed.