Sugarcane response to row spacing-induced competition for light

Information about crop response to row spacing (RS) in sugarcane is often contradictory and there is a lack of understanding of competition for light. This study aimed to gain a better understanding of how competition for light affects leaf and tiller development, radiation capture and conversion to biomass, and its partitioning between leaves and stalks. A first ratoon crop of cultivar NCo376 was started on 29 August 2003 (when the plant crop was cut back) at Mount Edgecombe, South Africa (29°42′18.4″S, 31°02′48.5″E, 105 m). A wagon wheel design was used with RS ranging from 0.36 m to 2.66 m and the crop received adequate water and nutrients. Radiation interception was measured within cane rows (FI_INTRA) and across cane rows (FI_INTER). FI_INTRA was not affected by RS and maximum FI_INTRA (defined as the first value above 0.9) was reached simultaneously for all RS. The progression of FI_INTER differed substantially between the different RS. Maximum green leaf number was attained when FI_INTRA reached 90% and coincided with the occurrence of peak tiller density. Thereafter there was a gradual decline in green leaf number caused by intra-row competition for light. As soon as FI_INTER exceeded a value of 90%, there was a drastic reduction in green leaf number due to a sharp acceleration in leaf senescence rate induced by inter-row competition for light. Inter-row competition had an effect on aboveground biomass accumulation of RS of less than 1.37 m from before the first sampling at 730 °Cd (base temperature of 16 °C). For RS of 1.73 m the competition effect commenced sometime between the first and second sampling (at 948 °Cd). There appeared to be no inter-row competition effect for RS of 2.15 m and more. Radiation use efficiency seemed unaffected by RS (average value of 1.50 g MJ⁻¹), although the increase in biomass yield (22% per metre reduction in RS) could not be fully explained by a concurrent increase in intercepted radiation (source size—18% per metre reduction in RS). Sink size (stalk density) responded more to a decrease in RS than source size (intercepted radiation) and the latter became insufficient to fill the sink to capacity when row spacing was less than 1.37 m. Conversely, sink size appeared to be the limiting factor for wider RS as evidenced by a similar mass per stalk for different RS. The stalk partition fraction of biomass increments was unaffected by row spacing, although the start of stalk growth was delayed with decreasing RS in terms of the threshold biomass required for stalk partitioning to commence. This resulted in lower final stalk fractions for narrower RS. The information obtained in this study enabled important new insights into underlying mechanisms of row spacing-induced competition effects on sugarcane growth and development. It should be useful for improving crop models’ ability to predict crop response to row spacing more accurately and in a more functional manner. The improved understanding could highlight avenues for effective crop improvement (e.g. ideal canopy development sub-traits) and crop management (e.g. weed and water management).     

Development of an algorithm for relating pasture nitrogen status to yield response curves

Determination of optimum nitrogen (N) fertilization rates which maximize pasture growth is challenging due to variability in plant requirements and likely near‐future supply of N by the soil. Remote sensing can be used for mapping N nutrition status of plants and to rapidly assess the spatial variability within a field. An algorithm is, however, lacking which relates the N status of the plants to the expected yield response to additions of N. An algorithm was developed based on a simulation study carried out using the APSIM model. Simulations were performed for an irrigated ryegrass pasture in Canterbury, New Zealand. Nitrogen fertilizer was applied monthly at different rates, ranging from 0 to 150 kg N/ha. To obtain a range of different pasture N contents, a total of 1456 different fertilization rules were set up and evaluated over 20 different years of weather giving 29,120 combinations of pasture herbage N contents and growth responses for each month. The analysis focused on November (spring), a month with generally vigorous growth. A three‐dimensional surface response function, based on the Mitscherlich yield response function, was developed. This function was used to determine required N fertilization rates, which achieve 90% of the maximum yield, based on the antecedent pasture N content. At low pasture herbage N contents (25 g/kg), the required fertilization rate was estimated as 130 kg N/ha, whereas at N contents of 40 g/kg, only 60 kg N/ha was required to obtain the same yield, reflecting the much higher supply of N by the soil.     

Circadian phase-shifting effects of a laboratory environment: a clinical trial with bright and dim light

Background  

Our aims were to examine the influence of different bright light schedules on mood, sleep, and circadian organization in older adults (n = 60, ages 60–79 years) with insomnia and/or depression, contrasting with responses of young, healthy controls (n = 30, ages 20–40 years).     

Dietary strategies to improve the iron and zinc nutriture of young women following a vegetarian diet

Dietary strategies to enhance the content and bioavailability of iron and zinc in vegetarian diets were compiled. Strategies included increasing promoters and decreasing antagonists of iron and zinc absorption, adopting food preparation and processing methods which hydrolyze the phytate content of cereals and legumes, and using iron cookware. These strategies were used to devise two vegetarian menus based on food consumption patterns derived from three day weighed food records of 78 Canadian lacto-ovo-vegetarian adolescents. The iron and zinc, as well as calcium, phosphorus, thiamin, riboflavin, niacin, vitamin A, protein and energy content of the devised menus were all higher than the actual intakes and the corresponding Canadian recommended nutrient intakes. Results show the overall nutrient adequacy of the recommended vegetarian menus and indicate that young lacto-vegetarian women can potentially meet their estimated dietary requirements for absorbed iron and zinc through modest modifications to the diet. Laboratory studies designed to measure the total amount of iron and zinc absorbed from these diets by young vegetarian women are needed to verify the efficacy of the devised menus.     

Tuberization in potato at high temperatures: response of physiologically young plants to disbudding and growth inhibitors

Summary In physiologically young plants (Solanum tuberosum L., cv. Sebago), abscisic acid (ABA) and chlorethyltrimethylammonium chloride (CCC) promoted tuberization at day/night temperatures of 32°/18°C, but not at 32°/28°C, in contrast to earlier experiments with physiologically old plants. Disbudding promoted tuberization at both temperatures. These results suggest that physiologically young plants have a greater capacity for increased gibberelling synthesis in the buds at high temperatures.     

The response of potato (Solanum spp.) to photoperiod and light intensity under high temperatures

Summary The growth, development and yield of seven cultivars were evaluated under field conditions with photoperiods from 11.5 to 16 hours and light intensities from full light (≧12 MJ/m²/day) to only 42% light in in 3 experiments in the Philippines. The longer photoperiod significantly delayed and reduced tuberization, promoted profuse haulm growth, resulting in: more branching, increased plant height, more flowering, many secondary stems and delayed plant senescence. ‘DTO-33’ was least affected by long photoperiod, followed by ‘Red Pontiac’ and ‘Désirée’. Shading resulted in delayed tuber initiation, taller plants, thinner stems, smaller leaves but longer canopy duration and a slightly larger canopy. ‘DTO-33’ was least affected by shading followed by ‘Désirée’, ‘LT-2’ and ’Red Pontiac’. ‘LT-5’ and ‘P-3’ suffered the greatest tuber yield reduction through shading.     

Growth, photosynthesis and root reserpine concentrations of two Rauvolfia species in response to a light gradient

Growth and secondary metabolites responses to light environment can be useful measurements to determine favourable habitat conditions for the cultivation and conservation of medicinal plants. We analyzed the growth, photosynthesis and root reserpine concentrations in seedlings of Rauvolfia vomitoria Afzel and Rauvolfia verticillatae (Lour.) Baill, two important medicinal plants yielding anti-hypertension alkaloids, at four different light levels (20%, 52%, 75% and 100% of full sunlight) in a shade house. Across all light intensities, seedlings of R. vomitoria grew faster with higher relative growth rate (RGR) than R. verticillatae, attributed to its higher photosynthetic capacities (light-saturated photosynthetic rate, A_max) and leaf area ratio (LAR). Typical shade-sun morphological responses to increasing light levels included decreased specific leaf area and LAR, whereas RGR and A_max was highest at median light levels for both species. R. vomitoria allocated higher leaf mass fraction and fine-root mass fraction, similar coarse root mass fraction, but lower stem biomass fraction than R. verticillatae. For fine roots, R. vomitoria had greater specific root length and small diameter than R. verticillatae, indicating its higher resource (water and nutrition) capture abilities. Both species had higher nitrogen concentration and lower reserpine concentration in fine roots than those of coarse roots. Neither reserpine concentration nor nitrogen was affected by light intensities. The reserpine concentration in coarse roots of R. vomitoria increased, whereas that of R. verticillatae decreased with increasing irradiance. Although not significantly, reserpine concentrations in coarse roots were positively correlated with A_max and RGR for both species across all light intensities. Shade or photosynthesis inhibition apparently did not increase alkaloid synthesis, which contrasted with the carbon/nutrient balance theory of plant defense. These results suggested that R. vomitoria and R. verticillatae could attain high biomass and yield of reserpine in high-light habitats (with max. in 75% sunlight), and intermediate-light habitats (with max. in 25–52% sunlight), respectively.     

Circadian rhythm and its role in malignancy

Circadian rhythms are daily oscillations of multiple biological processes directed by endogenous clocks. The circadian timing system comprises peripheral oscillators located in most tissues of the body and a central pacemaker located in the suprachiasmatic nucleus (SCN) of the hypothalamus. Circadian genes and the proteins produced by these genes constitute the molecular components of the circadian oscillator which form positive/negative feedback loops and generate circadian rhythms. The circadian regulation extends beyond clock genes to involve various clock-controlled genes (CCGs) including various cell cycle genes. Aberrant expression of circadian clock genes could have important consequences on the transactivation of downstream targets that control the cell cycle and on the ability of cells to undergo apoptosis. This may lead to genomic instability and accelerated cellular proliferation potentially promoting carcinogenesis. Different lines of evidence in mice and humans suggest that cancer may be a circadian-related disorder. The genetic or functional disruption of the molecular circadian clock has been found in various cancers including breast, ovarian, endometrial, prostate and hematological cancers. The acquisition of current data in circadian clock mechanism may help chronotherapy, which takes into consideration the biological time to improve treatments by devising new therapeutic approaches for treating circadian-related disorders, especially cancer.     

Long-term consumption of beef extended with soy protein by children,women and men: III. Iron absorption by adult men

Forty-nine ostensibly healthy men consumed either patties of all-beef or beef extended with soy-isolate, -concentrate or -flour as the principal protein source in 1 to 2 meals daily for 180 days. Iron status was monitored by absorption of radioiron from a reference dose of ferrous ascorbate and by serum ferritin concentration. In addition, nonheme iron absorption from a test meal of the respective beef pattie consumed for the 180 days was estimated by the extrinsic tag procedure. There was no detrimental effect on iron stores as indexed by reference ferrous ascorbate absorption or serum ferritin concentration. Absorption of nonheme iron from the test meals was low except for individuals having indices of low iron stores. When adjusted for the effect of level of iron stores the relative absorption of nonheme iron from soy-isolate and -flour containing meals was greater than from the all-beef meal, indicating marked differences in the effect on iron absorption by different soy products. Consumption of soy-extended beef should have no detrimental effect on iron status of adult men if consumed in mixed diets at the level used in this study.     

Utilization of potatoes for life support in space v. evaluation of cultivars in response to continuous light and high temperature

Twenty-four potato (Solanum tuberosum L.) cultivars from different regions of the world were evaluated in terms of their responses to continuous light (24 h photoperiod) and to high temperature (30 C) in two separate experiments under controlled environments. In each experiment, a first evaluation of the cultivars was made at day 35 after transplanting, at which time 12 cultivars exhibiting best growth and tuber initiation were selected. A final evaluation of the 12 cultivars was made after an additional 21 days of growth, at which time plant height, total dry weight, tuber dry weight, and tuber number were determined. In the continuous light evaluation, the 12 selected cultivars were Alaska 114, Atlantic, Bintje, Denali, Desiree, Haig, New York 81, Ottar, Rutt, Snogg, Snowchip, and Troll. In the high temperature evaluation, the 12 selected cultivars were Alpha, Atlantic, Bake King, Denali, Desiree, Haig, Kennebec, Norland, Russet Burbank, Rutt, Superior, and Troll. Among the cultivars selected under continuous irradiation, Desiree, Ottar, Haig, Rutt, Denali and Alaska showed the best potential for high productivity whereas New York 81 and Bintje showed the least production capability. Among the cultivars selected under high temperature, Rutt, Haig, Troll and Bake King had best performance whereas Atlantic, Alpha, Kennebec and Russet Burbank exhibited the least production potential. Thus, Haig and Rutt were the two cultivars that performed well under continuous irradiation and high temperature conditions, and could have maximum potential for adaptation to varying stress environments. These two cultivars may have the best potential for use in future space farming in which continuous light and/or high temperature conditions may exist. However, cultivar responses under combined conditions of continuous light and high temperature remains for further validation.     

Utilization of potatoes for life support in space. V. Evaluation of cultivars in response to continuous light and high temperature

Twenty-four potato (Solanum tuberosum L.) cultivars from different regions of the world were evaluated in terms of their responses to continuous light (24 h photoperiod) and to high temperature (30 C) in two separate experiments under controlled environments. In each experiment, a first evaluation of the cultivars was made at day 35 after transplanting, at which time 12 cultivars exhibiting best growth and tuber initiation were selected. A final evaluation of the 12 cultivars was made after an additional 21 days of growth, at which time plant height, total dry weight, tuber dry weight, and tuber number were determined. In the continuous light evaluation, the 12 selected cultivars were Alaska 114, Atlantic, Bintje, Denali, Desiree, Haig, New York 81, Ottar, Rutt, Snogg, Snowchip, and Troll. In the high temperature evaluation, the 12 selected cultivars were Alpha, Atlantic, Bake King, Denali, Desiree, Haig, Kennebec, Norland, Russet Burbank, Rutt, Superior, and Troll. Among the cultivars selected under continuous irradiation, Desiree, Ottar, Haig, Rutt, Denali and Alaska showed the best potential for high productivity whereas New York 81 and Bintje showed the least production capability. Among the cultivars selected under high temperature, Rutt, Haig, Troll and Bake King had best performance whereas Atlantic, Alpha, Kennebec and Russet Burbank exhibited the least production potential. Thus, Haig and Rutt were the two cultivars that performed well under continuous irradiation and high temperature conditions, and could have maximum potential for adaptation to varying stress environments. These two cultivars may have the best potential for use in future space farming in which continuous light and/or high temperature conditions may exist. However, cultivar responses under combined conditions of continuous light and high temperature remains for further validation.     

Immune modulation in response to stress and relaxation

Traditional medical science has kept the mind separate from the body. Recently people realize the effect of mind on health and psychoneuroimmunology is the new evolved science that describes the interactions between psyche and soma. In this review through a typical psycho-neuro-endocrino-immune network the effects of psychological stress (acute, brief naturalistic and chronic) and relaxation on immune modulation has been shown. From this network Corticotrophin Releasing Factor (CRF), Adrenocorticotrophic Hormone (ACTH), Glucocorticoids (GC), alpha-endorphin and Met-enkephalin are found as important endocrine components and T cells, B cells, monocytes/macrophages, Natural Killer (NK) cells and their cytokines that is Tumor Necrosis Factor-alpha (TNF-alpha), Interferon Gamma (IFN-alpha) and interleukins such as IL-1, IL-2, IL-4, IL-6, IL-10, IL-12 etc. are found as important immune components. Finally, it has been shown that, acute, brief naturalistic and chronic stress have different immune modulatory activities which are harmful to one's homeostasis and relaxation can help to maintain that homeostasis.     

Use of Lorenz curves and Gini coefficients to assess yield inequality within paddocks

The opportunity for site-specific management of crops depends on both the magnitude and spatial structure of yield variation. This study explored the applicability of Lorenz curves and Gini coefficients (G) to characterise the magnitude of the variation in grain yield. Maize crops were grown in farmers fields in a semi-arid region of central Argentina. Major sources of yield variation between and within paddocks included season, soil type and topography, rate of nitrogen fertiliser (nil to 132 kg N ha⁻¹), and the interactions among these factors. Nitrogen treatments were applied in a complete block strip trial (strip size700 m×9.8 m) with three replicates. Data were collected with an AgLeader™ yield monitor, and GIS software was used to create 9.8 m×9.8 m grids over the observations. Average yield in 0.7–2.8 ha field sections ranged from 1.6 to 7.0 t ha⁻¹. Gini coefficient ranged from 0.027 to 0.191 whereas its theoretical limits are 0 for a perfectly uniform population, and 1 for a theoretical population of infinite size where all units but one yield 0. Conditions conducive to high yield, e.g. adequate availability of nitrogen and water, reduced crop yield inequality, as quantified with G. The agronomic relevance of G was summarised in an inverse relationship with yield. Lorenz curves seemed particularly apt to present crop heterogeneity in terms of inequality, and to highlight the relative contribution of low- and high-yielding sections of the field to total paddock yield. Lorenz curves and Gini coefficients provide a potentially useful extension tool, a complement to yield maps and other statistical indices of yield variation, and further contact points between site-specific management, economics and ecology.     

The effect of temperature and light during storage of young seed potatoes on initial plant development at early plantings

Summary Young seed tubers of several cultivars were exposed to storage temperatures of 4–24°C in light and dark intended to optimise their growth vigour following early plantings. In five experiments during four autumn and winter periods, the effects of storage conditions on subsequent initial plant development in the glasshouse were studied. Storage of seed potatoes for 2 months at temperatures of 12°C or higher greatly increased early plant development of five cultivars following early plantings. Light during storage had a favourable effect, but desprouting before planting was greatly disadvantageous.     

Long-term consumption of beef extended with soy protein by men,women and children: II. Effects on iron status

The iron status of men, women and children consuming beef extended with soy protein was evaluated by measuring serum ferritin and clinical parameters of iron status during a six-month study. Fifty-two families (245 participants) were randomly assigned to consume, for 180 days, 1 of 7 beef products: all beef, beef extended with either soy isolate, soy concentrate or soy flour (20% reconstituted soy product, 80% beef), or beef extended with each of the three soy products fortified with 60 mg Fe and 25 mg Zn/100 g protein. The beef product was consumed by the subjects as their principal source of protein for 1 meal a day (children 1–18 yr) or 1–2 meals a day (11 per week; adult men and women). A control group consumed their usual self-selected diets. No evidence was found that consumption of beef extended with soy protein deleteriously affected the iron status of men, women or children. Consumption of beef extended with soy protein, at the levels used in this study, by military men and women and by school lunch participants would not appear to impose a risk in these population groups.     

Stress-strain curves and corresponding structural parameters in mulberry and non-mulberry silk fibers

Mulberry fiber (Bivoltine) and non-mulberry fiber (Tassar) were subjected to stress-strain studies and the corresponding samples were examined using wide angle X-ray scattering studies. Here we have two different characteristic stress-strain curves and this has been correlated with changes in crystallite shape ellipsoids in all the fibers. Exclusive crystal structure studies of Tassar fibers show interesting feature of transformation from antiparallel chains to parallel chains.     

Differential expression of the demosponge (Suberites domuncula) carotenoid oxygenases in response to light: protection mechanism against the self-produced toxic protein (Suberitine)

The demosponge Suberites domuncula has been described to contain high levels of a proteinaceous toxin, Suberitine, that displays haemolytic activityIn the present study this 7-8 kDa polypeptide has been isolated and was shown to exhibit also cytotoxic effects on cells of the same species. Addition of retinal, a recently identified metabolite of β-carotene that is abundantly present in S. domuncula was found to reduce both the haemolytic and the cell toxic activity of Suberitine at a molar ratio of 1:1. Spectroscopic analyses revealed that the interaction between β-carotene and Suberitine can be ascribed to a reversible energy transfer reaction. The enzyme that synthesises retinal in the sponge system is the β,β-carotene-15,15'-dioxygenase [carotene dioxygenase]. In order to clarify if this enzyme is the only β-carotene-metabolizing enzyme a further oxygenase had been identified and cloned, the (related) carotenoid oxygenase. In contrast to the dioxygenase, the carotenoid oxygenase could not degrade β-carotene or lycopene in Escherichia coli strains that produced these two carotenoids; therefore it had been termed related-carotenoid oxygenase. Exposure of primmorphs to light of different wavelengths from the visible spectrum resulted after 3 days in a strong upregulation of the dioxygenase in those 3D-cell aggregates that had been incubated with β-carotene. The strongest effect is seen with blue light at a maximum around 490 nm. It is concluded that the toxin Suberitine is non-covalently modified by retinal, the cleavage product from β-carotene via the enzyme carotene dioxygenase, a light inducible oxygenase. Hence, this study highlights that in S. domuncula the bioactive metabolite, retinal, has the property to detoxify its homologous toxin.     

Rice flowering in response to diurnal temperature amplitude

Temperature is an important determinant of crop development rate (DR). Some reports have shown that the response of DR to temperature is nonlinear over a wide range. Others indicate that DR is affected by the amplitude of the diurnal temperature fluctuation. However, the nonlinearity between DR and temperature and the temperature amplitude effect are often confounded, as the amplitude effect can be explained by the nonlinearity. This paper investigates the effect of temperature amplitude per se on development to flowering in rice (Oryza sativa L.), using controlled-environment data for 16 cultivars. The response of DR to diurnally constant temperatures was quantified by a nonlinear model and subsequently used to predict days to flowering under diurnally fluctuating temperatures. The often large discrepancies between predicted and observed days indicated an effect of the diurnal temperature amplitude on DR. This effect was significant at different probability levels in 11 cultivars, but not in the other five P > 0.10). The trend of this effect, where significant, also strongly differed among cultivars: temperature amplitude accelerated flowering in one cultivar but delayed flowering in others. The nonlinearity between DR and temperature and the effect of the temperature amplitude can explain a large part of the often observed variation among environments for thermal unit requirements for flowering.     

The physiological response to cutting in Italian ryegrass

The kinetics of decline in net photosynthesis and transpiration after cutting was followed in a batch of Lolium multiflorum leaves at light saturation in an assimilation chamber where air temperature, leaf temperature, carbon dioxide concentration and water vapour concentration were controlled. After leaf excision the rates of photosynthesis and transpiration increased or remained the same for 1–2 min and then decreased sharply following a curve with two breaks of slope at 15 min and 30 min. To investigate stomatal behaviour, fragments of leaf tissue were removed, fixed by freezing in liquid nitrogen, then examined by scanning electron microscopy. The stomata were optically closed by 15 min after excision. The practical implications for field drying of Italian ryegrass are discussed.     

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.