Modeling plant morphology and development of petunia in response to temperature and photosynthetic daily light integral

The effects of mean daily temperature (MDT) and mean photosynthetic daily light integral (MDLI) on flowering during the finish stage of two petunia (Petunia × hybrida) cultivars were quantified. Petunia ‘Easy Wave Coral Reef’ and ‘Wave Purple’ were grown in glass-glazed greenhouses at 14–23 °C or 14–26 °C and under 4–19 mol m⁻² d⁻¹ with a 16-h photoperiod. The flower developmental rate was predicted using a model that included a linear MDT function with a base temperature multiplied by an exponential MDLI saturation function. The flower developmental rate increased and time to flower decreased as MDT increased within the temperature range studied. For example, under a MDLI of 12 mol m⁻² d⁻¹, as MDT increased from 14 to 23 °C, time to flower of ‘Easy Wave Coral Reef’ and ‘Wave Purple’ decreased from 51 to 22 d and 62 to 30 d, respectively. Flower developmental rate increased as MDLI increased until saturation at 14.1–14.4 mol m⁻² d⁻¹. Nonlinear models were generated for effects of MDT and MDLI on flower bud number and plant height at flowering. The number of flower buds at flowering increased as MDT decreased and MDLI increased. For example, at an MDT of 14 °C with 18 mol m⁻² d⁻¹, plants had 2.5–2.9 times more flower buds than those grown at 23 °C and 4 mol m⁻² d⁻¹. Models were validated with an independent data set, and the predicted time to flower, flower bud number, and plant height were within ±7 d, ±20 flowers, and ±4 cm, respectively, for 96–100%, 62–87%, and 93–100% of the observations, respectively. The models could be used during greenhouse crop production to improve scheduling and predict plant quality of these petunia cultivars.     

Effect of 16 and 24 hours daily radiation (light) on lettuce growth

A 50% increase in total radiation by extending the photoperiod from 16 to 24 hr doubled the weight of all cultivars of loose-leaf lettuce (Lactuca sativa L.) 'Grand Rapids Forcing', 'Waldmanns Green', 'Salad Bowl', and 'RubyConn', but not a Butterhead cultivar, 'Salina'. When total daily radiation (moles of photons) was the same, plants under continuous radiation weighed 30% to 50% more than plants under a 16 hr photoperiod. By using continuous radiation on loose-leaf lettuce, fewer lamp fixtures were required and yield was increased.     

Genotypic variation in the response of pepper to salinity

Using 102 pepper (Capsicum annuum) genotypes, a greenhouse experiment has been conducted to study genotypic variation in tolerance to 100 mM sodium chloride (NaCl) in nutrient solution. Based on the severity of leaf symptoms caused by the NaCl treatment there was a substantial genotypic variation in salt tolerance. From this screening experiment, six sensitive and six tolerant genotypes were chosen to study dry matter production and root and shoot concentrations of sodium (Na), potassium (K) and calcium (Ca) in a growth chamber experiment in a nutrient solution with and without 150 mM NaCl. The genotypes selected as sensitive were highly damaged and developed severe chlorosis and necrosis under NaCl treatment, while the genotypes selected as tolerant were slightly affected. On average, decreases in shoot dry matter production caused by NaCl were greater in the sensitive than the tolerant genotypes. Application of salt increased shoot Na concentration at greater amount in the sensitive than the tolerant genotypes. Of the tolerant genotypes, the genotype Cac (Capsicum annuum var. cerasiforme) and 1245 F1 had around 2.45% Na in shoot while the sensitive genotypes Kandil and Pazarcik contained, on average, 5.4% Na. All sensitive and tolerant genotypes exhibited more or less similar shoot concentrations of K and Ca. There was very significant and positive correlation between severity of leaf symptoms and shoot Na concentration, but no correlation could be found in the case of K or Ca concentrations with the severity of leaf symptoms. The results indicate existence of substantial genotypic variation in tolerance to NaCl stress in pepper. It seems very likely that exclusion of Na from roots into growth medium plays a critical role in expression of high Na tolerance in pepper.     

Adaptation of Chrysanthemum morifolium to low light levels

Fourteen genotypes of Chrysanthemum morifolium were induced to flower under a gradient that ran from 3 to 35 W m⁻² visible light at a daylength of 9 h. The first sign of light stress was a reduction in number of flowers, followed by delayed flowering and finally, with increasing stress, no flowering at all. The minimum irradiance required for flowering may be as low as 5 W m⁻² for some cultivars, which is considerably lower than the irradiance of 16 W m⁻² falling on the plants in the greenhouse in winter. Large cultivar-differences in minimum light requirement for flowering were detected.At lower temperatures, the minimum level of light required for flowering increased.     

Potato growth in response to relative humidity

Potato plants (Solanum tuberosum L. cvs. Russet Burbank, Norland, and Denali) were grown for 56 days in controlled-environment rooms under continuous light at 20C and 50% or 85% RH. No significant differences in total plant dry weight were measured between the humidity treatments, but plants grown under 85% RH produced higher tuber yields. Leaf areas were greater under 50% RH and leaves tended to be larger and darker green than at 85% RH.     

Pepper (Capsicum annuum L.) root growth and its relation to shoot growth in response to nitrogen

Summary

The main objective of this work was to investigate shoot and root morphology of pepper (Capsicum annuum L.) (cvs Early Calwonder, Keystone Resistant Giant, Jupiter, Shamrock and Gator Belle) grown in sand culture at three N-levels, 56,84 and 112 mg l^?1. Shoot, root, and root components were evaluated 40, 50 and 60 days after seeding. Tap, basal and lateral root accounted for 1%, 40% and 53%, respectively, of the total root dry weight. Shoot: root ratios did not differ between cultivars. Basal root length, basal root number and first-order lateral root number increased with increasing N. Cultivars with either long lateral roots or basal roots had short basal roots or lateral roots respectively, although only small differences were observed in other root and shoot characteristics. In this greenhouse environment, shoot/root ratio was constant. Nitrogen stimulated root and shoot growth, and this effect was significantly different for the root components.     

Mannitol-producing tobacco exposed to varying levels of water,light, temperature and paraquat

Summary

Transgenic mannitol-producing (+mtlD) and wild-type (–mtlD) tobacco plants were exposed to water deficit, varying light intensities, low temperatures, and paraquat applications to test whether mannitol was involved in protection against abiotic stresses. In the water deficit experiment, –mtlD and +mtlD plants were fully irrigated [100% evapotranspiration (ET)] or received 25% ET for 40 d. Water deficit reduced the relative water content (RWC) of both types of plant, starting on day 22, and the total stem length (TSL) of –mtlD 25% ET plants after 11 d, whereas the TSL of +mtlD 25% ET plants was reduced only after 34 d. After 30 d of water deficit, a higher percentage of mature foliage was retained by +mtlD 25% ET plants compared to –mtlD 25% ET plants. The mannitol-1-phosphate dehydrogenase activity of +mtlD plants was not affected by water deficit. The photosynthetic rates of +mtlD and –mtlD plants were measured at PPFD levels ranging from 0 to >2,000 μmol m^–2 s^–1. No differences in quantum yield, saturation and compensation points, or dark respiration were observed between the +mtlD and –mtlD plants. Exposing the leaves of +mtlD and –mtlD plants to 0°C for 24 h caused significant injury to cell membranes and was similar in both types of plant. The application of 0.2 mM paraquat onto expanding –mtlD leaves produced a higher percentage of necrotic leaf area (4.3%) compared to +mtlD leaves (0.48%). The amount of mannitol produced by +mtlD plants could not provide significant osmotic protection, or increases in photosynthesis, whereas it may provide a specific system to protect cells from free radical-induced damage.     

In vitro morphogenesis and growth of Narcissus in response to temperature

In vitro morphogenesis and growth of tissues of the Narcissus cultivar ‘Lord Nelson’ have been assessed in constant and alternating temperatures. Tissue of leaf-base and scape origin, producing leafy shoots and bulblets on a defined sterile medium, were grown at constant and alternating temperatures of 15, 20, 25 or 30°C and 15–25 or 20–25°C, respectively, in a 16-h daily photoperiod. The number of leaves, leaf length, volume of tissues, fresh weight (but not percentage dry matter), and the number of shoots that would ultimately produce bulbs, were maximal at a constant temperature of 25°C as compared with all other temperature-regimes tested.     

Flowering of Brussels sprouts in response to low temperature treatment at different stages of growth

Studies on the vernalisation requirements of 7 cultivars of Brussels sprouts showed that, although the puberty stage of glasshouse-grown plants of all cultivars was reached at different chronological ages, they all flowered in response to a low temperature treatment given when they had produced about 15 true leaves and up to a further 15 leaf initials. Plants of different cultivars but either of the same chronological age (91-days old), or at a similar stage of development (20 green leaves), showed differences in response to the duration of low temperature treatment. It is concluded that although all cultivars need to develop approximately 30 nodes (leaves + leaf initials) before they reach puberty, the quantitative response to low temperature is quite different for early, mid-season and late-maturing cultivars.     

Content levels of various fruit metabolites in the ‘Conference’ pear response to branch bending

The response of ‘Conference’ pear subjected to branch bending in the content levels of various metabolites in its fruit was investigated. The fruits in commercial maturity were sampled in 2004 and 2005 from branches bent in the late summer of 2003 (the summer treatment), from branches bent in the late spring of 2004 (the spring treatment) and from control branches. The content levels of carbohydrates, organic acids and phenolic compounds were compared among treatments in two successive years. The fruit revealed various responses in content levels of metabolites. In the first year after bending, no significant differences were found in the content of each carbohydrate, but in 2005 by far the highest content level of glucose and fructose and the lowest content level of sucrose were found in fruits from the control. The control fruit showed significantly higher content levels of malic acid and lower content levels of some phenolics (chlorogenic and vanillic acid) in the first year after bending, but in the next year the opposite reaction occurred—the control fruit had the lowest content level of malic acid and the highest content level of epicatechin, quercetin-3-d-galactoside and quercetin-3-β-d-glucoside. The comparison of the two bending treatments alone in 2004 showed that the summer treatment often produced a slightly higher value of each phenolic in comparison to the spring treatment. However, in 2005 the significantly highest content of chlorogenic acid was in fruit from the spring treatment. Sorbitol, as well as citric acid, catechin and sinapic acid showed no clear tendency among treatments, neither in 2004 nor in 2005. It is suggested that these variations of ‘Conference’ fruit subjected to different bending treatments could not be the result of bending alone, but that they could be indirectly affected by other physiological responses of the fruit tree. However, it seemed that variations are affected by the time of bending and by the year-to-year, and such responses can be attributed to the ‘Conference’ genotype only.     

葡萄ZTL、COP1基因的鉴定及其在不同光质和转光条件下的表达分析

【目的】在葡萄试管苗离体培养下,研究不同波长对基因ZTL、COP1表达的影响。【方法】以‘红地球’葡萄(Vitis vinifera‘Red Globe’)试管苗为材料,经RT-PCR法克隆获得葡萄ZTL、COP1基因全长cDNA,并利用生物信息学分析了以上基因的理化性质、蛋白质二级结构、亚细胞定位以及系统进化树。利用q RT-PCR技术分析了以上基因在不同光质处理下表达量的变化情况。利用荧光参数系统分析不同光质对葡萄试管苗生长的影响。【结果】ZTL的分子式为C1972H3107N553O576S20,是亲水性稳定蛋白,脂溶性较差;COP1的分子式为C832H1291N209O225S9,是疏水性稳定蛋白,脂溶性较好。ZTL和COP1的二级结构均由α-螺旋、β-转角、无规则卷曲和延伸链结构组成;亚细胞定位分析结果显示,ZTL、COP1均位于细胞质中;系统进化分析表明,ZTL与桃的亲缘关系最近,COP1与其他物种的亲缘关系均较远,单独聚为一个亚族。在不同光质处理后ZTL均为上调表达,其中白光转蓝光、红光、红光转白光、红光转蓝光和蓝光转红光处理后分别上调达11.2、22.3、12.0、32.9和19.6倍。不同光质处理后COP1基因的表达呈现不同的变化趋势:红光转蓝光处理后,COP1上调1.97倍,红光处理后表达量无显著变化,其他光质处理后均为下调表达,其中蓝光转白光和蓝光转红光处理后下调达18倍。荧光参数分析表明,qP、qN、NPQ和F_v/F_m在转光培养中表达活跃,均在红光转蓝光的转光培养下表达量最高。【结论】ZTL在葡萄转光培养中表达活跃,均呈显著上调趋势,而COP1总体表现为下调趋势。     

Topographic variation in the climatic change response of a larch forest in Northeastern China

Context

Due to the spatial heterogeneity of the disturbance regimes and community assemblages along topoclimatic gradients, the response of forest ecosystem to climate change varies at the landscape scale.

Objectives

Our objective was to quantify the possible changes in forest ecosystems and the relative effects of climate warming and fire regime changes in different topographic positions.

Methods

We used a spatially explicit model (LANDIS PRO) combined with a gap model (LINKAGES) to predict the possible response of boreal larch forests to climate and fire regime changes, and examined how this response would vary in different topographic positions.

Results

The result showed that the proportion of landscape occupied by broadleaf species increased under warming climate and frequent fires scenarios. Shifts in species composition were strongly influenced by both climate warming and more frequent fires, while changes in age structure were mainly controlled by shifts in fire regime. These responses varied in the different topographic positions, with forests in valley bottoms being most resilient to climate-fire changes and forests in uplands being more likely to shift their composition from larch-dominant to mixed forests. Such variation in the topographic response may be induced by the heterogeneities of the environmental conditions and fire regime.

Conclusions

Fire disturbance could alter the equilibrium of ecosystems and accelerate the response of forests to climate warming. These effects are largely modulated by topographic variations. Our findings suggest that it is imperative to consider topographic complexities when developing appropriate fire management policies for mitigating the effects of climate change.

     

The growth rate and the variation in growth in relation to the stock plant of Hedera canariensis Willd. ‘Gloire de Marengo’

When leaf-bud cuttings from Hedera canariensis Willd. ‘Gloire de Marengo’ were prepared with various stem lengths, the subsequent shoot length was inversely correlated with the stem length below the axil. The shoot growth was also correlated with the size of the leaf of the cutting but not by the position along the stem of the stock plant. Certain stock plants yielded cuttings with significantly greater shoot lengths than did others.The shoot length obtained was variable (coefficient of variation 36%), and this variation was reduced neither by standardising the length of the stem below the axil, nor by standardising the area of the original leaf on the cuttings. However, some stock plants produced less variable cuttings than others, and variability was shown to be inversely correlated with the shoot length of the propagated plants.     

Revision and application of the LINKAGES model to simulate forest growth in central hardwood landscapes in response to climate change

Context

Global climate change impacts forest growth and methods of modeling those impacts at the landscape scale are needed to forecast future forest species composition change and abundance. Changes in forest landscapes will affect ecosystem processes and services such as succession and disturbance, wildlife habitat, and production of forest products at regional, landscape and global scales.

Objectives

LINKAGES 2.2 was revised to create LINKAGES 3.0 and used it to evaluate tree species growth potential and total biomass production under alternative climate scenarios. This information is needed to understand species potential under future climate and to parameterize forest landscape models (FLMs) used to evaluate forest succession under climate change.

Methods

We simulated total tree biomass and responses of individual tree species in each of the 74 ecological subsections across the central hardwood region of the United States under current climate and projected climate at the end of the century from two general circulation models and two representative greenhouse gas concentration pathways.

Results

Forest composition and abundance varied by ecological subsection with more dramatic changes occurring with greater changes in temperature and precipitation and on soils with lower water holding capacity. Biomass production across the region followed patterns of soil quality.

Conclusions

Linkages 3.0 predicted realistic responses to soil and climate gradients and its application was a useful approach for considering growth potential and maximum growing space under future climates. We suggest Linkages 3.0 can also can used to inform parameter estimates in FLMs such as species establishment and maximum growing space.

     

Vine growth and nitrogen metabolism of ‘Fujiminori’ grapevines in response to root restriction

Two-year-old ‘Fujiminori’ grapevines (Vitis Venifera × V. Labrasca) planted in plastic pots (10 L) were used to evaluate vine growth and nitrogen metabolism in response to root restriction. Results show that root restriction reduced shoot growth and photosynthetic rate, but promoted root growth in vines. NO₃⁻-N concentration in all plant parts, and total N concentrations in brown roots and new leaves were decreased by root restriction, and chlorophyll and carotenoid concentrations in mature leaves were also reduced. Nitrate and nitrite reductase activities in brown roots and mature leaves were significantly reduced in root-restricted vines. The results suggest that the reduction of nitrate and nitrite reductase activities caused the inhibition of nitrogen assimilation, and this might be an important reason for root restriction inhibiting shoot growth.     

Elasticity and loop analyses: tools for understanding forest landscape response to climatic change in spatial dynamic models

Spatially explicit dynamic forest landscape models have been important tools to study large-scale forest landscape response under global climatic change. However, the quantification of relative importance of different transition pathways among different forest types to forest landscape dynamics stands as a significant challenge. In this study, we propose a novel approach of elasticity and loop analyses to identify important transition pathways contributing to forest landscape dynamics. The elasticity analysis calculates the elasticity to measure the importance of one-directional transitions (transition from one forest type directly to another forest type); while the loop analysis is employed to measure the importance of different circular transition pathways (transition from one forest type through other forest types back to itself). We apply the proposed approach to a spatially explicit dynamic model, LANDIS-II, in a study of forest landscape response to climatic change in the Boundary Waters Canoe Area (BWCA) incorporating the uncertainties in climatic change predictions. Our results not only corroborate the findings of the previous studies on the most likely future forest compositions under simulated climatic variability, but also, through the novel application of the elasticity and loop analyses concepts, provide a quantitative assessment of the specific mechanisms leading to particular forest compositions, some of which might remain undetected with conventional model evaluation methods. By quantifying the importance of specific processes (transitions among forest types) to forest composition dynamics, the proposed approach can be a valuable tool for a more quantitative understanding of the relationship between processes and landscape composition/patterns.     

Interactions between root-zone temperature and light levels on growth,development and photosynthesis of Lycopersicon esculentum Mill. cultivar ‘Vendor’

Six-week-old tomato plants were subjected to 5 root-zone temperatures, ranging from 12 to 36°C, and 4 light levels in a factorial design. Large increases in shoot dry weight, leaf area and fruit development resulted from soil warming to 24°C when plants were grown under high light conditions. Shoot growth and fruit weight were reduced at 24°C root temperature under low light conditions. Total plant photosynthesis, leaf area index, net assimilation rates and leaf chlorophyll content were related to plant growth and flower development for the various treatments. Our experiments have shown an interaction between root-zone temperature and light levels for greenhouse tomatoes. Soil warming caused large increases in shoot dry weight and fruit development when light was not limiting plant growth, but had deleterious effects on flowering and fruit set under shaded conditions.     

Rooting ability of Persian walnut as affected by seedling vigour in response to stool layering

Summary

Walnut (Juglans regia L.) is an important nut crop with a “difficult-to-root” characteristic. In this study, the rooting ability of low-vigour and precocious seedlings of 3-year-old Persian walnut was compared with semi-vigorous and high-vigour seedlings using the stool layering method. The results indicated that low-vigour seedlings rooted more (40%) than semi-vigorous (31.42%) and high-vigour (17.14%) seedlings. The average number of roots per shoot (layer) and rooting score (on a scale of 1 – 5) in the low-vigour group were 7.83 and 4.19, respectively, which differed significantly from the high-vigour group. Moreover, most of the high quality adventitious roots formed on low-vigour seedlings appeared to originate from internal tissues compared to the low quality and brittle roots that originated from callus in high-vigour seedlings. Improved rooting of low-vigour seedlings, together with a significant negative correlation between layer size and root number (r = –0.29), reflects substantial structural or hormonal differences among seedlings of different vigour. Approx. 70% of rooted layers survived after transferring to field condition. Our results provide more support for the possibility of vegetative propagation of walnut by conventional stool layering, as well as the selection of easy-to-root, dwarf walnut cultivars or rootstocks on their own roots.     

Effects of light quantum and hematoporphyrin therapy on the growth of tumor in rats

AIM:To study the effect of photodynamic therapy on the growth of tumor in rats.METHODS:W256 tumor cells were implanted in 40 rats by subcutaneous vaccination at groin.Then,the rats were treated by photodynamic therapy (PDT).Total saperoxides dismutase (T-SOD) and malondialdehyde (MDA) in plasma,tumor tissue and liver were detected.RESULTS:(1) The growth of tumor was significantly slow after the rats were transfused blood with ultraviolet radiation,with hematoporphyrin or with both ultraviolet radiation and hematoporphyrin (P<0.05,P＜0.01).(2) The activity of SOD was obviously increased and the contents of MDA were decreased in plasma while the growth of tumor was significantly slow in the ultraviolet radiation group (P<0.05,P＜0.01).However,the activity of T-SOD was weakened and the contents of MDA were increased in hematoporphyrin group (P<0.01) and ultraviolet radiation combined with hematoporphyrin group (P<0.01).CONCLUSIONS:The results indicate that the growth of tumor is inhibited by means of transfusion blood with ultraviolet radiation of hematoporphyrin.The most remarkable inhibitory effect is in ultraviolet radiation and hematoporphyrin group.The generation of singlet oxygen by PDT may be one of the mechanisms of killing tumor cells.