A dynamic model of crop growth and partitioning of biomass

A model is presented of growth and partitioning to leaves, stems and roots in herbaceous, vegetative crops in response to atmospheric conditions and water supply. It comprises 12 state variables and 33 parameters (including four functional relationships), all of direct physiological significance. The important characteristic of the model is the simultaneous consideration of crop assimilate and water balances achieved by calculations made at short time steps (1 h or less) in order to capture the physiological responses of crop growth and water use as they respond to diurnal environmental patterns.In the model, root-zone water content decreases with transpiration and soil evaporation, and increases with rainfall, irrigation and deepening of the root zone as the crop develops. Photosynthesis depends upon intercepted radiation and temperature and also on canopy conductance determined from crop water status. Respiration of organs is calculated as separate requirements for maintenance and growth. Transpiration proceeds with photosynthesis but in response to evaporative demand, reducing crop water content, which is in turn replenished from the root zone based on its water content and the root length that explores it. Partitioning of assimilate to leaves, stems, and roots depends upon diurnal oscillations in assimilate supply, temperature, and crop water content within limits set by phenological development. Phenological development, here the initiation and expansion of leaves and the maturity and senescence of canopy and root systems, is determined by temperature. Examples, and trends, of model performance are compared with measured physiological and agronomic responses of sunflower to strategies of irrigation.     

Glycogen synthase kinase 3, circadian rhythms, and bipolar disorder: a molecular link in the therapeutic action of lithium

Background  

Bipolar disorder (BPD) is a widespread condition characterized by recurring states of mania and depression. Lithium, a direct inhibitor of glycogen synthase kinase 3 (GSK3) activity, and a mainstay in BPD therapeutics, has been proposed to target GSK3 as a mechanism of mood stabilization. In addition to mood imbalances, patients with BPD often suffer from circadian disturbances. GSK3, an essential kinase with widespread roles in development, cell survival, and metabolism has been demonstrated to be an essential component of the Drosophila circadian clock. We sought to investigate the role of GSK3 in the mammalian clock mechanism, as a possible mediator of lithium's therapeutic effects.     

Ergonomic mapping of skin deformation in dynamic postures to provide fundamental data for functional design lines of outdoor pants

Outdoor brands often use streamlined cutting lines to design high-performance outdoor pants. Inappropriate design lines combined with the accompanying sewing lines can cause discomfort or even restrict body movement. To reduce such discomfort, we need to find the appropriate location for cutting lines that do not interfere with body movement. In this research, we conducted ergonomic mapping of skin deformation in dynamic postures to provide fundamental data for selecting functional design lines of pants that will not hinder various movements. To analyze the lower body skin deformation depending on the posture, we marked dots at 3 cm intervals on the leg. We then measured the change in length between the points for three different postures using a three-dimensional scanner and the Rapidform program. The results were shown as a skin deformation map; this is expected to be used as reference data for the functional design lines of streamlined outdoor pants.     

A three-dimensional biomechanical model for numerical simulation of dynamic pressure functional performances of graduated compression stocking (GCS)

The beneficial effects of graduated compression stockings (GCS) in prophylaxis and treatment of venous disorders of human lower extremity have been recognized. However, their pressure functional performances are variable and unstable in practical applications, and the exact mechanisms of action remain controversial. Direct surface pressure measurements and indirect material properties testing are not enough for fully understanding the interaction between stocking and leg. A three-dimensional (3D) biomechanical mathematical model for numerically simulating the interaction between leg and GCS in dynamic wear was developed based on the actual geometry of the female leg obtained from 3D reconstruction of MR images and the real size and mechanical properties of the compression stocking prototype. The biomechanical solid leg model consists of bones and soft tissues, and an orthotropic shell model is built for the stocking hose. The dynamic putting-on process is simulated by defining the contact of finite relative sliding between the two objects. The surface pressure magnitude and distribution along the different height levels of the leg and stress profiles of stockings were simulated. As well, their dynamic alterations with time processing were quantitatively analyzed. Through validation, the simulated results showed a reasonable agreement with the experimental measurements, and the simulated pressure gradient distribution from the ankle to the thigh (100:67:30) accorded with the advised criterion by the European committee for standardization. The developed model can be used to predict and visualize the dynamic pressure and stress performances exerted by compression stocking in wear, and to optimize the material mechanical properties in stocking design, thus, helping us understand mechanisms of compression action and improving medical functions of GCS.     

Low temperature-induced sterility in rice: Evidence for the effects of temperature before panicle initiation

Spikelet sterility of rice (Oryza sativa L.) results from low temperatures during panicle development. However, this temperature alone cannot fully explain the fluctuations in sterility observed in the field, since the susceptibility of rice plants to low temperature often changes according to its physiological status during sensitive stages. In the present study, we examined whether temperatures before the panicle initiation stage (PI) influence the plant's susceptibility to sterility during panicle development. To test this, we conducted a 2-year pot study and an analysis of field data using a model of cooling degree-days (CDD). In the pot study, the air temperature (T_a) and water temperature (T_w) were controlled independently for 3 weeks during the vegetative growth stage before PI. After PI, the plants were submerged in a cool water bath at a critical temperature of 19.5 °C to induce floral sterility. We found that low T_w during vegetative growth significantly increased the sterility. Low T_a during vegetative growth also significantly increased the sterility, but this effect was diminished by warm T_w even at low T_a. There was a close and negative correlation between sterility and T_w during vegetative growth. In the analysis of field data, we introduced CDD using temperatures below a threshold level of 20 °C to represent the magnitude of the exposure to low temperature from PI to the heading stage. Data of T_a was used for this analysis because data of T_w was scare. The CDD model was applied to 77 independent data sets collected at nine Agricultural Research Centers during four typical cool summers (1980, 1988, 1993, and 2003) in northern Japan. Year-to-year variations in sterility at one site were roughly accounted for by the variations in CDD, but large deviations were observed among the years. The deviations were related to T_a averaged over the 30-day period before PI. For a similar level of CDD, the lower the T_a before PI, the greater the sterility. Similar deviations were observed in the between-site relationships between sterility and CDD, and these deviations were related with the T_a before PI. These results suggest that temperatures before PI, and especially T_w, change the susceptibility of a rice plant to low temperatures during panicle development.     

A cohort-based stochastic model of the population dynamic and long-term management of Conyza bonariensis in fruiting tree crops

Conyza bonariensis is currently a frequent and abundant weed in fruiting tree crops associated with non-tillage in Mediterranean climate areas, such as citrus groves and olive orchards. Because of the mild winters characteristic of this climate, an extended season of seedling emergence, from early autumn to early spring, is often found for this species, this leading to multiple annual cohorts. In this work, a cohort-based stochastic model of C. bonariensis population dynamics was developed and used to simulate the behaviour of the seed bank in Mediterranean fruiting tree crops under ten contrasting management strategies, including single or integrated herbicide and non chemical control measures. The demographic impact of tillage system (ploughing vs. no-till), the use of cover, and timing of herbicide applications was simulated. The model was parameterized with information taken from the literature. In the absence of any control and under no-tillage the modelled seed bank reached an average equilibrium density of 378,092 ± 10,865 seeds m⁻². The most effective management strategy integrated no-till, the use of cover and early and late applications of herbicides, which reduced the equilibrium densities of the seed bank by 78.7%. A sensitivity analysis indicated that C. bonariensis populations in Mediterranean fruiting tree crops are particularly sensitive to small changes in the demographic parameters associated with the earlier cohort and to the efficacy of early herbicide treatments. A diversified, integrated approach including different interventions of chemical and cultural nature appears to be the most successful strategy at the field level for controlling C. bonariensis in Mediterranean fruiting tree crops.     

Spontaneous internal desynchronization of locomotor activity and body temperature rhythms from plasma melatonin rhythm in rats exposed to constant dim light

Background  

Daylight saving time is widely adopted. Little is known about its influence on the daily rest-activity cycles. We decided to explore the effects of transition into daylight saving time on the circadian rhythm of activity.     

Spontaneous internal desynchronization of locomotor activity and body temperature rhythms from plasma melatonin rhythm in rats exposed to constant dim light

Background  

We have recently reported that spontaneous internal desynchronization between the locomotor activity rhythm and the melatonin rhythm may occur in rats (30% of tested animals) when they are maintained in constant dim red light (LL_dim) for 60 days. Previous work has also shown that melatonin plays an important role in the modulation of the circadian rhythms of running wheel activity (R_w) and body temperature (T_b). The aim of the present study was to investigate the effect that desynchronization of the melatonin rhythm may have on the coupling and expression of circadian rhythms in R_w and T_b.     

A dynamic risk assessment model (FUMAgrain) of fumonisin synthesis by Fusarium verticillioides in maize grain in Italy

Fumonisin contamination of maize grain starts in the field. Forecasting Fusarium infection and fumonisin synthesis could allow operators in the field to control contamination during the growing season and to make the best agronomic decisions for high quality yields while respecting the limits imposed by the European Union.A research project to develop a decision support system for the control of field-phase fumonisin contamination began in Italy in 2003. This paper presents a preliminary version of the engine of the decision support tool: FUMAgrain, a dynamic risk assessment model developed with data from the north of Italy. The structure of FUMAgrain is based on the pathosystem formed by maize, F. verticillioides and Ostrinia nubilalis (European Corn Borer). The elements of the pathosystem are simulated by three sub-models: (i) maize development, (ii) F. verticillioides infection and fumonisin synthesis, (iii) European Corn Borer wounding activity on maize grain. Inputs to the model are (i) planting date, (ii) hourly meteorological data including temperature, relative humidity, wind speed and rain intensity, (iii) information on the phenological development of the hybrid planted (flowering and dry-down), and (iv) information about the chemical treatment against European Corn Borer. FUMAgrain gives an initial risk alert at the end of flowering based on the meteorological conditions during this phase. A second alert follows maturation when an assessment is made from (i) maize grain moisture, (ii) European Corn Borer damage to the ear, and (iii) fumonisin synthesis risk. Following calibration and validation with data FUMAgrain demonstrated its good capability to simulate fumonisin synthesis in maize grain in Italy (calibration: R² = 0.70; validation: R² = 0.71) and its usefulness for determining the optimal harvest date while respecting grain safety levels required by the international market and limiting moisture content, hence drying costs.     

A plant growth promoting rhizobacterium and temperature effects on performance of 18 clones of potato

A survey of genotypic responses to beneficial bacterium (Pseudomonas sp. strain PsJN) was conductedin vitro andex vitro, under two temperature conditions, using eighteen clones of potato of different heat stress tolerance: temperate adapted cultivars Kennebec and Russet Burbank; heat tolerant DTO-2, DTO-28, DTO-33, LT-1, LT-2, LT-5, LT-6, LT-7, LT-8, LT-9, Y84-02, NDD277-2, Désirée, and Maine-47; and heat sensitive abscissic acid (ABA)-deficient mutants 11401-01 and 9120-05. Nodal explants taken from 6-week-old bacterized and non-bacterized control plantlets were culturedin vitro on a hormone-free potato nodal cutting medium, and placed at either 20/15 C or 33/25 C day/night temperature, 12h photoperiod and 250 µE m^?2 s^?1 mixture of fluorescent and incandescent light, for six weeks. The tuberization response was studiedex vitro after two weeks acclimation of 2-week old plantlets at 33/25C. The acclimated plantlets were transplanted to 3L plastic nursery pots containing peat-based Pro-Mix growing medium and placed in growth chambers at either 20/15 or 33/25 C day/night temperature, 12 h photoperiod, 475 μE m^?2 s^?1 light and ≈80% RH, for 12 weeks. Compared to the non-bacterized controls, bacterization significantly increased stem length of 12, shoot biomass of 9, and root biomass of 2 clones at 20/15C; and stem length of 14, shoot biomass of 15, and root biomass of 13 clones at 33/25C. High temperature increased length of internodes and had either no effect or slightly decreased node number. Temperature increase had the most dramatic effect on root development. An average shoot to root ratio decreased from 3.7 at 20/15 C to 1.7 at 33/25 C for non-bacterized plantlets and, respectively, from 4.3 to 1.5 for bacterized. The beneficial effect of bacterization on root biomass was the most pronounced in LT-1 and Maine-47 at 20/15 C and LT-8, Maine 47, DTO-2, Kennebec, NDD277-2 and 11401-01 at 33/25C. The temperature elevation did not significantly affect root biomass of LT-6, DTO-28 and Désirée. Temperature stress caused severe reduction in tuber number and tuber fresh weight. ABA-deficient mutants did not produce any tubers and LT-8, LT-9, Y84-027 and DTO-28 tuberized very poorly at 33/25C. DTO-33, Désirée, LT-1 and Kennebec gave the highest number of tubers per pot and Kennebec, LT-1, Désirée and LT-7 the highest yields at this temperature. There was no significant effect of bacterization on tuberization at 20/15 C but at 33/25 C bacterization significantly enhanced tuber number and weight in LT-7 and reduced tuber weight in DTO-2. Although there was no clear link between thein vitro response of particular clones to bacterization and their heat stress tolerance, improvement ofex vitro performance of heat tolerant LT-7 indicates that rhizosphere bacteria may play a role in clonal adaptation of potato to heat stress.     

A comparison of continuous grazing systems for milk production

In two experiments conducted with Ayrshire dairy cows in 1974 and 1975 on swards of S23 perennial ryegrass, four systems of continuous grazing were investigated. The leys received 345 and 370 kg ha^-1 fertilizer nitrogen in 1974 and 1975 respectively and were stocked at the rate of five cows per ha. In 1974, a comparison was made between two systems which either integrated silage making with, or separated it from, the continuous grazing. The provision of a silage aftermath in late July increased milk yield after that time, but had no significant effect on milk yield over the 19-week experimental period. In 1975, a comparison between weekly and monthly applications of fertilizer N showed no significant differences between milk yields in a 20-week period. The feeding of supplementary concentrates from late July onwards significantly increased milk yield. The treatments in both years had only small and mainly non-significant effects on milk composition. On average, excluding the concentrate treatment, the annual output of milk was 10,800 kg ha^-1 using spring-calved cows.     

A QTL on mouse chromosome 12 for the genetic variance in free-running circadian period between inbred strains of mice

Background  

Many genes control circadian period in mice. Prior studies suggested a quantitative trait locus (QTL) on proximal mouse chromosome 12 for interstrain differences in circadian period. Since the B6.D2NAhr ^d /J strain has DBA/2 alleles for a portion of proximal chromosome 12 introgressed onto its C57BL/6J background, we hypothesized that these mice would have a shorter circadian period than C57BL/6J mice.     

Rapid phase adjustment of melatonin and core body temperature rhythms following a 6-h advance of the light/dark cycle in the horse

Background  

Rapid displacement across multiple time zones results in a conflict between the new cycle of light and dark and the previously entrained program of the internal circadian clock, a phenomenon known as jet lag. In humans, jet lag is often characterized by malaise, appetite loss, fatigue, disturbed sleep and performance deficit, the consequences of which are of particular concern to athletes hoping to perform optimally at an international destination. As a species renowned for its capacity for athletic performance, the consequences of jet lag are also relevant for the horse. However, the duration and severity of jet lag related circadian disruption is presently unknown in this species. We investigated the rates of re-entrainment of serum melatonin and core body temperature (BT) rhythms following an abrupt 6-h phase advance of the LD cycle in the horse.     

Probability of prickliness detection in a model of populations of fiber ends prickling human skin

Although it is relatively easy to judge whether the fabric is prickly, and it is very difficult in quantifying human capability of detection and judgment of fabric-evoked prickliness. As so far, no mathematical relationship is proposed to measure this detectability. On the basis of the neurophysiological property of Aδ-fiber nociceptors responsible for fabricevoked prickliness and the statistical distributions of short-coarse fiber ends protruding above a fabric surface, the present study develops a model to simulate the activation probability of nociceptors, and discusses its sensitivity to the change of the typical features characterizing physical properties of coarse fiber ends and the typical physiological features of Aδ-fiber nociceptors. The results show that the developed model is significantly sensitive to the changing spatial density of Aδ-fiber nociceptors and their mechanothresholds, which reflects differences among person’s capability in detecting and judging fabric-evoked prickliness. In terms of the effect of physical features of coarse fiber ends on the detection of prickliness, the activation probability of populations of nociceptors represents a consistent phenomenon with the subjective evaluation results in literatures. Therefore, the developed model gives a good link between somatosensory physiology and physical cues to fabric-evoked prickliness, and with psychophysical method provides an alternative prediction for the detection of fabricevoked prickliness at the probabilistic level.     

Varietal difference in the effects of low temperature on tassel development in hybrid maize

In 2003, severe barrenness due to low temperatures in hybrid maize (Zea mays L.) cultivar occurred in the Konsen region, one of the coldest areas in Japan. Varietal difference in grain set, and abnormal flowering habits and tassel growth were observed in the field in 2003. For the cultivar 39B29, which was affected severely, anthesis occurred several days after silking, and tassel size was reduced. For the cultivar Papirika, which was not affected by low temperature, anthesis began 0–1 d before silking, and tassel size was similar to that in previous years. In a 2011–2013 experiment, three varieties, Papirika, 39B29, and Kwiss were treated at 10 °C for 7 d at 6- to 9-leaf stage. Following the treatment, anthesis was delayed, and tassel length was reduced, in 39B29 and Kwiss, but not in Papirika. The relative tassel length (RTL, ratio of tassel length of experimental plants to that of untreated control plants) was around 60 in 39B29, 80 in Papirika, and 30 in Kwiss on average over 3 years. Based on field observations in 2003 and the pot experiment in 2011–2013, a cultivar whose RTL was 60 or less was deemed sensitive, and a cultivar whose RTL was 80 or more was deemed less sensitive to low-temperature stress during the tassel development stage.     

Preliminary evidence for a change in spectral sensitivity of the circadian system at night

Background  

It is well established that the absolute sensitivity of the suprachiasmatic nucleus to photic stimulation received through the retino-hypothalamic tract changes throughout the 24-hour day. It is also believed that a combination of classical photoreceptors (rods and cones) and melanopsin-containing retinal ganglion cells participate in circadian phototransduction, with a spectral sensitivity peaking between 440 and 500 nm. It is still unknown, however, whether the spectral sensitivity of the circadian system also changes throughout the solar day. Reported here is a new study that was designed to determine whether the spectral sensitivity of the circadian retinal phototransduction mechanism, measured through melatonin suppression and iris constriction, varies at night.     

A comparison of insecticide treatments for the control of frit fly in seedling ryegrass

Laboratory experiments gave useful indications of the effectiveness of insecticide treatments to control larvae of frit fly ( Oscinella frit L.). Lightly infested field experiments provided confirmatory evidence. Several seed treatments, insecticide granules combine-drilled with the seed and post-emergence sprays were very effective. The feasibility of delivering granules with seed must be confirmed for each granular formulation. Post-emergence sprays were most effective if applied at approximately the time of oviposition but several also gave a strong residual effect if applied earlier and a remedial effect if applied after larval establishment in the seedlings. More detailed conclusions are discussed.