Bolting control by low temperatures in root chicory (Cichorium intybus var. sativum)

The effects of a vernalization treatment on bolting of root chicory were investigated and compared in four varieties.Experiments where plants were initially cultivated in controlled growth rooms, before transplanting in the field in late April or in early May, strongly suggested that low temperatures were responsible for the high percentages of bolting and flowering recorded in early-sown plants in the field. Effectiveness of a treatment at a constant 4 °C in inducing bolting depended on its duration, on the variety, and on plant age when vernalization started. Greatest sensitivity to cold occurred soon in plant's life, during seed imbibition. Fluctuating temperatures (16 h at 4 °C followed by 8 h at 15 °C) were also able to cause bolting. Vernalization effectiveness was affected by climatic variations after vernalization and the transfer of the plants in the field. The results are discussed in relation to information coming from studies on radicchio and Witloof chicories.     

Duration of the grain-filling period in maize is not affected by photoperiod and incident PPFD during the vegetative phase

Total number of initiated leaves and duration from sowing to silking increases when photoperiod is increased during the photoperiod-sensitive phase in maize (Zea mays L.). Little is known, however, about possible other effects of photoperiod and incident photosynthetic photon flux density (PPFD) on rate of development and duration of life cycle. A study was undertaken to quantify effects of photoperiod and incident PPFD from sowing to the 15-leaf stage on rate of leaf appearance and duration of the grain-filling period. The short-season maize hybrid Pioneer 3902 was grown in growth cabinets from sowing to the 15-leaf stage with either (i) a 10 h photoperiod at high PPFD (650 μmol m⁻² s⁻¹), (ii) a 20 h photoperiod consisting of 10 h of high PPFD followed by 10 h of low PPFD (5–50 μmol m⁻² s⁻¹), or (iii) a 20 h photoperiod of high PPFD. From the 15-leaf stage to maturity the plants were placed under a 16 h photoperiod in a growth room. Increasing photoperiod from 10 to 20 h increased final number of initiated leaves and delayed silking but did not affect rate of leaf appearance. Doubling incident PPFD to a value similar to that under Ontario field conditions during the summer resulted in a 16% increase in rate of leaf appearance and in a significant increase in total number of initiated leaves. Differences in final number of initiated leaves and in rate of leaf appearance from sowing to the 15-leaf stage among treatments resulted in a 4-day difference in silking date between the 10 h photoperiod treatment and the two 20 h photoperiod treatments. Duration of the grain-filling period did not differ among the three treatments.     

Variations in vernalization requirements among ecotypes of Festuca hallii

Plains rough fescue (Festuca hallii [Vasey] Piper) is an important forage grass species in the Northern Great Plains of Canada. Its seed is in demand for forage production and habitat restoration, but erratic seed production limits supply. A comprehensive understanding of factors influencing flowering and seed production in this species is needed. This study evaluated the morphological and phenological variation among six ecotypes of F. hallii from Saskatchewan and Manitoba. Seeds were germinated, and seedlings were grown in the field and then transplanted to a greenhouse in November. Plants not flowering in the greenhouse were vernalized under 5°C and 8-h light for 11 weeks. In a separate experiment, plants were subjected to temperature regimes of 15/5°C, 10/0°C and 5/−5°C with day-length treatments of 12 h, 8 h and a gradually changing daylength from 12 to 8 h respectively. This study demonstrated the existence of considerable variation in morphological and phenological characteristics, and in growth and vernalization requirements among ecotypes of F. hallii. Vernalization requirements were not met for the ecotype from the Moist Mixed Grassland Ecoregion when it was grown under common conditions, whereas ecotypes from other ecoregions were vernalized in at least one of the 2 years in the field experiment. Northern ecotypes tended to flower earlier after artificial vernalization treatments. Overall, 15/5 to 5/−5°C d per night temperature regimes with photoperiods between 12 and 8 h were effective in inducing flowering. The seed source of F. hallii should be regarded as an important consideration affecting its use, both for habitat restoration and for forage production.     

Differential accumulation of sulfur-rich and sulfur-poor wheat flour proteins is affected by temperature and mineral nutrition during grain development

Hard red spring wheat (Triticum aestivum cv Butte86) was grown under controlled environmental conditions and grain produced under 24/17 °C, 37/17 °C or 37/28 °C day/night regimens with or without post-anthesis N supplied as NPK. Flour proteins were analyzed and quantified by differential fractionation and RP-HPLC, and endosperm proteins were assessed by two-dimensional gel electrophoresis (2-DE). High temperature or NPK during grain fill increased protein percentage and altered the proportions of S-rich and S-poor proteins. Addition of NPK increased protein accumulation per grain under the 24/17 °C but not the 37/28 °C regimen. However, flour protein composition was similar for grain produced with NPK at 24/17 °C or 37/28 °C. 2-DE of gluten proteins during grain development revealed that NPK or high temperature increased the accumulation rate for S-poor proteins more than for S-rich proteins. Flour S content did not indicate S-deficiency, however, and addition of post-anthesis S had no effect on protein composition. Although, high-protein flour from grain produced under the 37/28 °C regimen with or without NPK had loaf volumes comparable to flour produced at 24/17 °C with NPK, mixing tolerance was decreased by the high temperature regimen.     

Synthesis and physical properties of mono-estolides with varying chain lengths

Saturated mono-estolide methyl esters and enriched saturated mono-estolide 2-EH esters were synthesized from oleic and different saturated fatty acids under three different synthetic routes. Estolide numbers (EN), the average number of fatty acid units added to a base fatty acid, varied with synthetic conditions. The attempts at obtaining saturated mono-estolide 2-EH esters, EN = 1, via distillation proved to be challenging, which lead to estolide samples with EN > 1 and the pour point values followed the same trend as the high EN estolides. The other synthetic routes provided saturated mono-estolide methyl esters with EN = 1. The resulting pour point values showed a linear relationship between the saturated capping chain length and pour point. As the saturated capping chain length increased the pour points also increased (higher temperatures): C-2 capped ?30 °C, C-10 capped ?12 °C, and C-18 capped 3 °C.The saturated mono-estolide methyl ester viscosities also showed an increase in viscosity at 40 and 100 °C as the saturated chain lengths increased. The viscosities for the C-4 saturated mono-estolide methyl ester was 9.5 cSt at 40 °C and 2.6 cSt at 100 °C, while medium chain length derivations (C-10 saturated mono-estolide methyl ester) were 19.7 cSt at 40 °C and 4.2 cSt at 100 °C, and at the longer chain length derivations (C-18 mono-estolide methyl esters) were 27.6 cSt at 40 °C and 10.7 cSt at 100 °C. In general, a new series of saturated oleic mono-estolide methyl esters were synthesized and physical properties were collected. The physical property data indicated that both chain length and EN affect low temperature properties.     

Extraction of simmondsin and oil in one step from jojoba seeds

Approximately all simmondsin and oil can be easily removed in one step by repeated extraction with water at 90 °C from ground jojoba seeds. The optimum time and temperature of extraction were respectively 1.5 h and 90 °C. Quantitative analysis of simmondsin was made by HLPC method using adenosine as internal standard.     

Impact of redox agents on the physico-chemistry of wheat gluten proteins during hydrothermal treatment

The impact of the oxidants potassium bromate and potassium iodate and the reducing agent dithiothreitol (DTT) on the rheological behaviour of 20% (w/v) gluten-in-water suspensions during thermal treatment was monitored with the rapid visco analyser (RVA). The suspensions were subjected to a linear temperature increase from 40 to 95 °C in 14 min, a holding step of 40 min at 95 °C, a cooling step (7 min) with a linear temperature decrease to 50 °C, and a final holding step at 50 °C (13 min). Potassium iodate (1.18 and 1.77 μmol/g protein) and potassium bromate (1.52 and 15.2 μmol/g protein) decreased RVA viscosities in the holding step and increased sodium dodecyl sulphate (SDS) protein extractabilities suggesting a greater heat resistance and decreased gliadin–glutenin cross-linking. In contrast, in the presence of DTT (1.65 and 3.30 μmol/g protein) RVA viscosity increased at lower temperatures and lowered SDS extractabilities. It is postulated that low concentrations of reducing agent facilitate gliadin–glutenin cross-linking during heating while oxidants hinder gluten polymerization due to decreased levels of free sulphydryl groups and less flexibility of the glutenin chains.     

Comparison on the total phenol contents and the color of fresh and infrared dried olive leaves

The color (L*, a*, b* parameters), the total phenols content and the global chemical composition (moisture, protein, fat, carbohydrates and ash) of four fresh varieties of olive leaves (Chemlali, Chemchali, Zarrazi and Chetoui) were determined. Fresh olive leaves are characterized by a green color (greenness parameter, a*, varying from ?5.01 ± 0.26 to ?9.14 ± 1.21), an intermediate moisture content (0.85 to 1.00 g/g dry matter, i.e. 46 to 50 g/100 g fresh matter) and a variable amount of total phenols according to the olive leaf variety (from ≈2.32 to ≈1.40 g caffeic acid/100 g dry matter).Fresh leaves were submitted to blanching and/or infrared drying at 40, 50, 60 and 70 °C in order to be stabilized by reducing their moisture contents. The impact of IR drying temperature on some quality attributes (color, total phenols and moisture rate removal) was evaluated. Nevertheless, the effect of prior blanching treatment on the quality attributes of dried leaves is less significant and it depends on the olive leaf variety. The infrared drying induces a considerable moisture removal from the fresh leaves (more than 85%) and short drying durations (varying from ≈162 at 40 °C to 15 min at 70 °C). IR drying temperature showed a significant effect of on total phenols content and the color of the leaves whatever the leaf variety. In fact, total phenols content of dried olive leaves increased if compared to fresh ones. For example, total phenols of Chemlali leaves increased from 1.38 ± 0.02 (fresh leaves) to 2.13 ± 0.29 (dried at 40 °C) and to 5.14 ± 0.60 g caffeic acid/100 g dry matter (dried at 70 °C). IR drying allows preserving the greenness color of fresh leaves and enhancing their luminosity. It could be suggested for preserving olives leaves before their use in food or cosmetic applications.     

Responses of sunflower yield and grain quality to alternating day/night high temperature regimes during grain filling: Effects of timing,duration and intensity of exposure to stress

In order to quantify the effects, at different stages during grain filling, of alternating day/night high temperature regimes on sunflower grain yield and quality, heads were exposed to high temperatures during 7 or 6 days starting either 10–12 days after anthesis (daa, HT1), 18 daa (HT2) or 24 daa (HT3). Also, heads were exposed to high temperatures for periods of 2, 4 or 6 days in each of HT1 and HT2. Temperatures covered a range of mean daily grain temperature of 20–40 °C and peak grain temperatures (i.e., those prevailing during the central 5 h of the daylight period) of 26–45 °C. High temperature stress for periods of 4 days or longer produced significant (p < 0.05) reductions in grain yield and grain quality. Early (HT1) exposure to stress reduced yield by 6%/°C above a mean grain temperature threshold of 29 °C; later (HT2 + HT3) exposures reduced yield by 4%/°C above a threshold of 33 °C. These reductions in yield were attributable to reductions in unit grain weight at all positions (periphery, intermediate, central) on the head, and an increase in the proportion of very small (10–30 mg) grains, termed half-full (HF) grains in this paper. In both full and HF grains, stress in either HT1 or HT2 reduced final pericarp weight, associated with fewer number of cell layers and thinner cell walls in the schlerenchyma. High temperatures reduced both the rate and duration of oil deposition in the grain, with the greatest effects being found with early (HT1) exposures. The unsaturation (oleic acid/linoleic acid) ratio of oil from mature grain was altered only when exposure to heat stress overlapped with the cessation of deposition of storage lipids. The effects of duration and intensity of heat stress on relative (to control) grain yield and oil content could be reasonably summarized using a linear response to cumulative hourly heat load calculated with a base temperature of 30 °C. We conclude that: (i) 4 days of alternating day/night temperatures resulting in mean daily grain temperatures of >30 °C can reduce sunflower grain yield and quality; (ii) the magnitude of these effects is strongly dependent on the timing of exposure and their nature on the grain growth processes active at the time of stress; and (iii) an hourly heat load (base = 30 °C) provides a useful integrative estimator of the effects of exposure to heat stress on grain yield and oil content for a given phase of grain filling.     

Physical properties of triglyceride estolides from lesquerella and castor oils

Lesquerella is a developing hydroxy oilseed crop suitable for rotation in the arid Southwestern United States. The hydroxy oil of lesquerella makes it suitable for esterification into triglyceride estolides. The estolide functionality imparts unique physical properties that make this class of materials suitable for functional fluid applications. Lesquerella and castor hydroxy triglycerides were converted to their corresponding estolides by reacting the oils with saturated fatty acids (C2–C18) in the presence of a tin 2-ethylhexanoate catalyst (0.1 wt.%) and utilizing the condensation of hydroxy with corresponding anhydride or heating under vacuum at 200 °C. Two homologous series of estolides for each triglyceride were synthesized for comparison, mono-capped (one hydroxy functionality per triglyceride molecule) and full-capped (all hydroxy functionalities per triglyceride molecule). Physical properties (pour point, cloud point, viscosity, and oxidative stability) were compared for this estolide series. The longer chain saturate capped estolides (C14–C18) had the highest pour points for both mono-capped (9 °C, C18:0) and full-capped (24 °C, C18:0) lesquerella estolides. Castor mono-capped (9 °C) and full-capped (18 °C) triglyceride estolides gave similar properties. However, pour points improved linearly when the shorter saturated fatty acid capping chain lengths were esterified with the hydroxy triglycerides. Lesquerella capped with a C6:0 fatty acid had pour points of −33 °C for the mono-capped and −36 °C for the full-capped and castor had −36 and −45 °C, respectively. Oxidative stabilities of the estolides were compared for oleic, lauric and lauric-hydrogenated mono- and full-capped materials by rotating bomb oxygen test (RBOT). RBOT times for oleic and lauric capped estolides were low and similar with times centered around 15 min. However, when antioxidant (4 wt.%) was added the RBOT times increased to 688 min for the hydrogenated full-capped lesquerella lauric estolide. The antioxidant had little effect on RBOT times when 2 wt.% or less antioxidant was added for all the estolides except those that were hydrogenated. The hydrogenated estolides showed improvements in oxidative stability at all concentrations of antioxidant tested. Viscosity index ranged from 130 to 202 for all estolides with the shorter chain length capped estolides gave the lower viscosity index values. Viscosity at 100 °C ranged from 13.9 to 26.6 cSt and the 40 °C viscosity ranged from 74.7 to 260.4 cSt where the longer chain length capped estolides gave the highest viscosities.     

Synthesis and characterization of hazelnut oil-based biodiesel

The demand for diesel fuel far exceeds the current and future biodiesel production capabilities of the vegetable oil and animal fat industries. New oilseed crops that do not compete with traditional food crop are needed to meet existing energy demands. Hybrid hazelnut oil is just such an attractive raw material for production of biodiesel. Hazelnut oil was extracted from hybrid hazelnuts and the crude oil was refined. Hazelnut oil-based biodiesel was prepared via the transesterification of the refined hazelnut oil with excess methanol using an alkaline catalyst. The effects of reaction temperature, time and catalyst concentration on the yield of diesel were examined, and selected physical and chemical properties of the biodiesel were evaluated. The biodiesel yield increased with increasing temperature from 25 to 65 °C and with increasing catalyst concentration from 0.1 to 0.7 wt%. The increase in yield with reaction time was nonlinear and characterized by an initial faster rate, followed by a slow rate. Hazelnut oil-based biodiesel had an average viscosity of 8.82 cP at 25 °C, which was slightly higher than that of the commercial soy-based diesel (7.92 cP at 25 °C). An approximate 12 °C higher onset oxidative temperature and a 10 °C lower cloud point of hazelnut oil biodiesel than those of its commercial soy counterpart indicated a better oxidative stability and flowability at low temperature. The average heat of combustion of hazelnut oil biodiesel was 40.23 kJ/g, and accounted for approximately 88% of energy content of diesel fuel. The fatty acid composition of hazelnut oil-based biodiesel was the same as the nature oil.     

Floret development and spike growth as affected by photoperiod during stem elongation in wheat

A longer duration of stem elongation (from terminal spikelet initiation to anthesis) would result in a higher wheat yield potential as a consequence of the increase in both spike dry weight and number of fertile florets at anthesis. It is not clearly understood, however, which processes are involved in the increased spike dry weight and whether this variable accounts for the higher number of fertile florets when duration of stem elongation is modified by photoperiod treatments. As vernalization interacts with photoperiod during the stem elongation phase, a better understanding of the role of vernalization is also required. A field experiment was carried out using two wheat cultivars (Buck Manantial (BM) and Eureka Ferrocarril Sur (EFS)) subjected to diverse periods of vernalization (V₁₅ and V₅₀, plants vernalized for 15 and 50 days, respectively) and exposed to different photoperiods (NP+0 and NP+6, natural and 6 h extended photoperiod, respectively) only during the stem elongation phase. Floret development together with stem and spike growth during the stem elongation phase were studied. When the stem elongation phase was exposed to short photoperiod (i) duration of spike growth increased without any change in its growth rate, and (ii) most of the spike growth occurred during minimum stem growth rate as the onset of maximum stem growth rate was delayed. In EFS, the vernalization-sensitive cultivar, the former (i) and (ii) was true only when vernalization requirements were met. For both cultivars, the survival of the initiated floret primordia under short photoperiod increased, independently of vernalization. Both partitioning of assimilates to the spike and a direct photoperiod effect seemed to have been involved in the survival of floret primordia when the stem elongation phase was exposed to short photoperiod.     

Modelling photoperiod and temperature responses of flowering in quinoa (Chenopodium quinoa Willd.)

Two modelling approaches were used to quantify photoperiod and temperature responses of time from emergence to visible flower buds in nine quinoa (Chenopodium quinoa Willd.) cultivars. The first, non-interactive model, considers temperature and photoperiod responses as independent, and the threshold photoperiod, critical photoperiod, and base temperatures as constants. The second, interactive model, considers these attributes as variable, and allows for interaction between photoperiod and temperature responses. Controlled-environment experiments with a factorial combination of temperature and photoperiod provided information on responses, and data from field experiments were utilized in tests of the predictive capacity of the models.The two models were very similar in their goodness of fit and predictive capacity, but testing revealed that some assumptions about the interactive model were not fulfilled, whereas the non-interactive model is more consistent with the data. Both the models failed to predict dates of visible flower buds when average temperatures during the phase were >20°C; it is proposed that interaction between irradiance receipt and high temperature in controlled environments result in lower optimum temperatures there than in the field. Differences between field data and predicted values were eliminated when predictions were recalculated assuming no optimum for the temperature response.All nine cultivars examined are short-day plants. A juvenile sub-phase was observed in the six cultivars for which it was tested; and its duration was negatively associated with the latitude of origin of the lines (R² = 0.9, p < 0.05). Photoperiod sensitivity was negatively associated with the latitude of origin of the lines (R² = 0.55, p < 0.05) and positively associated with duration of the basic vegetative phase (minimal time between emergence and visible flower buds) (R² = 0.55, p < 0.05) using the non-interactive model. Photoperiod and temperature response parameters were not significantly associated with the latitude of origin for the interactive model (p > 0.05).     

Seed germination response of cuphea to temperature

Cuphea (Cuphea viscosissima Jacq. × C. lanceolata W.T. Aiton; PSR23) is a potential new oilseed crop. Its oil is high in medium-chain fatty acids that are suitable for detergent/cleaner applications and also for cosmetics. The objective of this study was to determine the critical temperatures for cuphea seed germination. To determine the base, maximum, and optimum temperatures for seed germination, mature cuphea seeds were harvested from plants grown at Prosper, ND, in 2004, 2005, and 2006. Seeds were germinated on a temperature-gradient bar varying between 5 and 35 °C. Cumulative germination was calculated for each temperature treatment. Base temperature (T_b) and optimum temperature (T_o) were estimated from the third-order polynomial temperature-response functions for each year. In addition, germination rate per day was used in a linear model to estimate the base temperature below which germination rate was equal to zero (T_b), and the maximum temperature above which germination was equal to zero (T_m). The optimum temperature (T_o) was calculated as the intercept of sub-optimal and supra-optimal temperature-response functions. Through the third-order polynomial temperature-response functions and the sub-optimal/super-optimal intercept approaches, we were able to generate six estimates for each critical value. Estimates of the base temperature for cuphea seed germination ranged between 3.3 and 11 °C, with the most reliable estimates between 6 and 10 °C, similar to many warm-season crops such as corn (Zea mays L.) and sorghum (Sorghum bicolor L.). The optimum temperature for cuphea seed germination ranged between 18.5 and 24 °C with a mean value of 21 °C. The maximum temperature for seed germination ranged 33–38 °C. On this basis, a cuphea planting date after 20 May is recommended for east-central North Dakota.     

Synthesis and physical properties of estolides from lesquerella and castor fatty acid esters

Biodegradable, vegetable oil-based lubricants must have better low temperature properties as well as comparable cost to petroleum oils before they can become widely acceptable in the marketplace. The low temperature property usually measured is the pour point (pp), the minimum temperature at which the material will still pour. Viscosity and viscosity index also provide information about a fluid's properties where a high viscosity index denotes that a fluid has little viscosity change over a wide temperature range. Lesquerella oil is a good candidate for its development into a biodegradable lubricant as it is being developed as an alternative crop for the southwestern U.S. The hydroxy site on the fatty acid (FA) makes it a suitable site for esterification to yield estolides. Castor and lesquerella FA esters were combined with different types of saturated, unsaturated, and branched FAs to produce estolides. Castor and lesquerella estolide esters had the best cold temperature properties when capped with oleic (pp = −54 °C for castor and pp = −48 °C for lesquerella) or capped with a branched material, 2-ethylhexanoic acid (pp = −51 °C for castor and pp = −54 °C for lesquerella). As the saturation was increased in the estolide, pour and cloud points also increased. The increased saturation such as in stearic capped estolides allowed for sufficient alkyl stacking of these long saturated chains producing higher pour points. Oxidative stability of the estolides was compared between the oleic-castor estolide 2-ethylhexyl ester and the coco-castor estolide 2-ethylhexyl ester by the rotating bomb oxidation test (RBOT). The RBOT times for both estolides were low with a similar time of about 15 min. However, when the antioxidant package (3.5 wt.%) was added, the RBOT times increased to 403 min for the coco-castor estolide 2-ethylhexyl ester while still retaining its outstanding cold temperature properties, (pp = −36 °C and cp = −30 °C). The viscosity index ranged from 164 to 200 for these new hydroxy FA derived estolide 2-ethylhexyl esters. These oleic-castor and lesquerella estolide esters have displayed far superior low temperature properties (pp = −54 °C) than any other estolides reported to date. Due to the lack of solvent and catalysts, the cost of these estolides should be reasonable and more suitable as a base stock for biodegradable lubricants and functional fluids than current commercial materials.     

Cardinal temperatures for germination and early growth of two Lesquerella species

Lesquerella (Lesquerella fendleri) is a potential alternative crop that is being studied for commercial oilseed production. Understanding the minimum temperatures for germination and seedling growth is important for determining potential areas for lesquerella production. The objectives of this study were to determine the cardinal temperatures for germination and seedling growth, and to screen ecotypes for germination and growth characteristics. A temperature gradient table arrangement was used to observe seed germination over a range of temperatures, and time to germination and shoot appearance. Times to 5 mm root length and 5 mm shoot length were also measured to assess cardinal temperatures for seedling survival and growth. Two different species were examined, L. fendleri and a species we refer to as ‘L. pallida aff.’ because it differed from typical L. pallida plants in chromosome number and in oil quality. We concluded that both germination and growth of L. pallida aff. occurred fastest at 22 °C, whereas L. fendleri germinated earlier at 18 °C, but grew faster at 22 °C. L. pallida aff. also had lower germination than L. fendleri over the range studied. Non-dormant seeds of improved lines of L. fendleri had better performance at temperatures above 22 °C than did unimproved accessions. Lines of L. fendleri selected for high oil content and salt tolerance had similar temperature requirements for germination except for improved line WCL-LO3, the current line being used in production. This line had optimal temperatures 6 °C higher for germination and growth than the other improved lines. Accessions of L. fendleri collected from elevations above 2000 m performed better at warmer temperatures, whereas those collected from elevations below 2000 m tended to perform better at cooler temperatures. Dormant seeds of L. fendleri germinated more quickly at low temperatures and had lower base (<3 °C) and optimal (22 °C) temperatures than non-dormant seeds (>7 °C and 28 °C, respectively). We speculate that this partial dormancy trait allows populations of L. fendleri to exploit a wider range of temperature conditions in the wild in order to thrive in extreme environments.     

Contrasting Ppd alleles in wheat: effects on sensitivity to photoperiod in different phases

Photoperiod sensitivity is an important feature of flowering time regulation, which enables wheat plants to adapt to a wide range of environments. Although some work has been done on how time to heading or flowering respond to photoperiod in relation to particular Ppd alleles, there is little evidence on whether these alleles contribute to responses at different phases and to associated yield component generation. The aims of this paper were: (i) to analyse the effects of photoperiod on substitution lines with contrasting Ppd alleles, in terms of duration of particular phases, (ii) to determine if there is any relationship between these alleles and the parameters of photoperiod response (photoperiod sensitivity, optimum photoperiod and basic length of the phase), and (iii) to analyse the effects of different photoperiods applied before and after the onset of terminal spikelet on yield component generation. The effects of length and timing of photoperiod extensions on these traits were analysed under field conditions in Chinese Spring and two substitution lines differing in photoperiod sensitivity.Although time to anthesis was similar in the three genotypes in photoperiods longer than 14.5 h, they did differ in their response to photoperiod in particular phases. Sensitivity to photoperiod for daylengths shorter than 14.5 h was also markedly different. The number of leaves generated was affected by photoperiod, determining the duration of the phase from emergence to floral initiation (EM-FI). The length of the phase from floral initiation to terminal spikelet (FI-TS) was determined by the number of spikelets generated and their rate of initiation, which was also affected by photoperiod. The terminal spikelet to anthesis phase (TS-ANT) was only affected by photoperiod in the most sensitive genotype, in which direct photoperiod effects, other than the effects on leaf number and phyllochron, were evident. There was no apparent relation between photoperiod response parameters such as basic length of the phase (Lb) and optimum photoperiod (Po) and particular Ppd alleles.     

Effect of curing time on physical and mechanical properties of phenolic-treated bamboo strips

Effect of pressing time on physical and mechanical properties of phenolic-impregnated bamboo strips was evaluated. Bamboo strips (Gigantochloa scortechinii) were impregnated with low molecular weight phenol formaldehyde (LMwPF) resin. Samples were submerged in LMwPF resin using a vacuum chamber of 750 mmHg for 1 h before it was released within 1.5 h. Treated strips were dried in an oven with a temperature of 60 °C within 6–9 h. It was hot pressed at 14 kg m^?2 and a temperature of 140 °C for 5, 8, 11, 14 and 17 min. The physical and mechanical properties of the test indicated that the properties of phenolic-treated strips have significantly increased as compared to control samples. Dimensional stability (water absorption, thickness swelling and linear expansion) of the phenolic-treated properties were significantly lower than control after 5-min pressing time. The antishrink efficiency (ASE) of phenolic-treated strips increased when pressing time were extended from 5 to 17 min. The mean value of modulus of rupture (MOR) for the control samples (177 N mm^?2) showed a significant difference with phenolic-treated strips after 17-min pressing time (224 N mm^?2). However, there is no significant difference in compression parallel to grain. The MOE of phenolic-treated strips was 21,777 N mm^?2 and for control was 18,249 N mm^?2, whereas the compression parallel to grain values for phenolic-treated and control samples were 94 and at 77 N mm^?2, respectively.     

Thermal stability and pyrolysis kinetics of organosolv lignins obtained from Eucalyptus globulus

In the present work, thermogravimetric analysis of 17 organosolv lignin samples was carried out to determine their thermal stability and calculate the kinetic parameters of their pyrolysis. The thermal stability has been estimated by the measurement of the degradation temperature (T_d), calculated according to the maximum reaction rate. In addition, degradation temperature at 10% of conversion (T_10%) has been obtained in order to compare the initial stability of the samples with T_d for all samples. The values of T_d are comprised between 262 and 389 °C and the average value is 340 °C. The range for T_10% is 251–320 °C and the average value is 270 °C. The ashes content of the samples has been analyzed and all the residues presented values lower than 4 wt%. Kinetic parameters of lignin pyrolysis were calculated by Borchardt–Daniels’ method assuming nth order reaction. The activation energy values obtained are comprised between 17.9 and 42.5 kJ/mol and the average value is 28.1 kJ/mol. These results are in agreement with the bibliography.     

The impact of heating and cooling on the physico-chemical properties of wheat gluten–water suspensions

The rapid visco analysis (RVA) system was used to measure rheological behaviour in 20% (w/v) gluten-in-water suspensions upon applying temperature profiles. The temperature profiles included a linear temperature increase, a holding step, a cooling step with a linear temperature decrease to 50 °C, and a final holding step at 50 °C. Temperature and duration of the holding phase both affected RVA viscosity and protein extractability. Size-exclusion and reversed-phase HPLC showed that increasing the temperature (up to 95 °C) mainly decreased glutenin extractability. Holding at 95 °C resulted in polymerisation of both gliadin and glutenin. Above 80 °C, the RVA viscosity steadily increased with longer holding times while the gliadin and glutenin extractabilities decreased. Their reduced extractability in 60% ethanol showed that γ-gliadins were more affected after heating than α-gliadins and ω-gliadins. Enrichment of wheat gluten in either gliadin or glutenin showed that both gliadin and glutenin are necessary for the initial viscosity in the RVA profile. The formation of polymers through disulphide bonding caused a viscosity rise in the RVA profile. The amounts of free sulphydryl groups markedly decreased between 70 and 80 °C and when holding the temperature at 95 °C.