Influence of tree crown characteristics on the local PM10 distribution inside an urban street canyon in Antwerp (Belgium): A model and experimental approach

Apart from influencing the amount of leaf-deposited particles, tree crown morphology will influence the local distribution of atmospheric particles. Nevertheless, tree crowns are often represented very rudimentary in three-dimensional air quality models. Therefore, the influence of tree crown representation on the local ambient PM₁₀ concentration and resulting leaf-deposited PM₁₀ mass was evaluated, using the three-dimensional computational fluid dynamics (CFD) model ENVI-met^® and ground-based LiDAR imaging. The modelled leaf-deposited PM₁₀ mass was compared to gravimetric results within three different particle size fractions (0.2–3, 3–10 and >10 μm), obtained at 20 locations within the tree crown. Modelling of the LiDAR-derived tree crown resulted in altered atmospheric PM₁₀ concentrations in the vicinity of the tree crown. Although this model study was limited to a single tree and model configuration, our results demonstrate that improving tree crown characteristics (shape, dimensions and LAD) affects the resulting local PM₁₀ distribution in ENVI-met. An accurate tree crown representation seems, therefore, of great importance when aiming at modelling the local PM distribution.     

Growth and Physiological Characteristics of Rice Seedlings Raised with Long Mat by Hydroponics: —Comparison with young seedlings raised in soil—

Summary

Growth and physiological characteristics of rice seedlings raised with long mat by hydroponics (SLH) were compared with those of young seedlings raised in soil (YSS). When SLH and YSS were raised under the similar environmental conditions, the dry weight of shoot in SLH was significantly lighter than that in YSS at the time of seedling harvest, whereas the shoot in SLH was as long as that in YSS. The increase of dry weight of shoot and the decrease of dry weight of grain were smaller in SLH than in YSS during the raising of seedlings. In addition, the content of soluble sugars in the grain of SLH was apparently lower than that of YSS, indicating that the supply of carbohydrates from endosperm to shoot was less in SLH than in YSS. Crop growth rate and mean leaf area index of SLH were lower than those of YSS, while net assimilation rate of SLH was similar to that of YSS. The size of leaf blades in SLH was markedly smaller than that in YSS, whereas no significant difference was observed in the rates of photosynthesis and dark respiration in leaf blades between SLH and YSS. The results suggest that the leaf growth of SLH is reduced by the insufficient supply of carbohydrates from endosperm, and this is the major cause of lower levels of dry matter production in SLH as compared with that in YSS.     

Gene Expression of Enzymes for Starch and Sucrose Metabolism and Transport in Leaf Sheaths of Rice (Oryza sativa L.) during the Heading Period in Relation to the Sink to Source Transition

Abstract

Leaf sheaths of rice plants are known to temporarily accumulate starch prior to heading, which is subsequently remobilized and transported into the panicle after heading. We investigated the time course for both carbohydrate content and steady state mRNA levels of enzymes related to starch and sucrose metabolism in the rice leaf sheath (Oryza sativa L. cv. Nipponbare). Leaf sheaths from the second leaf below the flag leaf accumulated high levels of starch before heading but they rapidly decreased after heading. In contrast, the flag leaf sheath did not accumulate as much starch. In the second leaf sheath, the mRNA levels of enzymes involved in starch synthesis, ADP glucose pyrophosphorylase (EC 2. 7. 7. 27), soluble starch synthase (EC 2. 4. 1.21) and branching enzyme (EC 2. 4. 1. 18) were high before heading, which coincided with rapid accumulation of starch. The mRNA levels of sucrose synthesis enzymes, cytosolic FBPase (EC 3. 1. 3. 11) and sucrose phosphate synthase (EC 2. 4. 1. 14), and the sucrose transporter (OsSUTI) increased at the time of heading, which was largely coincident with a decrease in the mRNA levels of starch synthesis enzymes. In the flag leaf sheaths, changes in mRNA levels of starch synthesis enzymes were not pronounced, however mRNA levels of sucrose synthesis enzymes and the sucrose transporter showed a clear increase throughout the heading period. The different characteristics observed between the two leaf sheaths will be discussed in relation to the sink to source transition.     

Temporal and Spatial Variations of Carbohydrate Content in Rice Leaf Sheath and Their Varietal Differences

Abstract

In rice plant, carbohydrates accumulated in leaf sheaths before heading are translocated to grain and affect yield formation greatly. To clarify the intrinsic mechanism of carbohydrate metabolism in the leaf sheath, we investigated the temporal and spatial variations of carbohydrate metabolism in the third leaf sheath counted from the top and their varietal differences. The results revealed that the amount of carbohydrate decreased from the base to the tip of the leaf sheath, irrespective of variety and developmental stage. However, the proportion of starch content in the basal one-fifth of the leaf sheath to that in the whole sheath varied from 35% to 60% with the variety. Comparing the activities of enzymes related to starch metabolism at the base, middle and tip of the leaf sheath in IR65598-112-2 (New plant type) with those in Nipponbare, the activities of ADP-glucose pyrophosphorylase, branching enzyme and granule-bound starch synthase (GBSS) showed varietal differences. Particularly, the activity of GBSS may play an important role in the varietal difference in spatial variation of starch content in the leaf sheath. In IR65598-112-2, the sucrose content in the leaf sheath was extremely high, suggesting that sucrose may be one of the carbohydrate reserves in this line.     

Effects of water state of soil on ecological boundary of leaf Surface ofpopulus davidiana

The effect of water state of soil on eco-boundary over leaf surface was disscussed by takingPopulus davidiana as experimental material. The results show that to change soil water state by some methods was to adjust and control the forming quality of eco-boundary in fact. The plant in good water condition must be accompanied by thinner eco-boundary. This eco-boundary is beneficial to exchange and flow of the substances between plant and environment. Suifenhe Animal and Plant Quarantine Bureau The study was supported by The Chinese Natural Science Foundation, No. 39470136 (Responsible Editor: Chai Ruihai)     

葡萄枝叶自然青贮中优选乳酸菌的分离与鉴定

本研究旨在对葡萄枝叶青贮饲料中天然附着优势乳酸菌进行分离培养和鉴定,为葡萄枝叶资源的饲料化利用提供可靠的乳酸菌资源。利用分子生物学鉴定法(16S rDNA序列分析)与传统的微生物鉴定法对分离出的乳酸菌进行鉴定,最终得到5株乳酸菌菌株,其中Q1菌株鉴定为肠膜明串珠菌(Leuconostoc mesenterica),Q2和Q5菌株鉴定为屎肠球菌(Enterococcus faecium),Q3菌株鉴定为铅黄色肠球菌(Enterococcus casseliflavus),Q4菌株鉴定为海氏肠球菌(Enterococcus hirae)。所筛选出的乳酸菌除L.mesenterica在pH为9时不能生长,其余菌株均能在pH 3～9,4℃～45℃,3%和6.5% NaCl浓度环境下生长;其中E.hirae菌株在培养至24 h后其菌液pH可达到4.11,OD值为1.42,表现出最强的生长及产酸能力。     

盐胁迫对无芒雀麦幼苗叶片形态及解剖结构的影响

为了探究盐胁迫下无芒雀麦（Bromus inermis）幼苗叶片形态及解剖结构的适应性变化,本研究以‘乌苏一号’无芒雀麦（Bromus inermis Leyss.‘Wusu No.1’）为材料,分别采用NaCl：Na₂SO₄：Na₂CO₃=4：1：0（A盐）,NaCl：Na₂SO₄：Na₂CO₃=1：4：0（B盐）和NaCl：Na₂SO₄：Na₂CO₃=1：1：8（C盐）3种混合盐进行胁迫处理,其中A,B盐为中性盐,C为碱性盐,每种混合盐均设置四个不同的电导率（Electrical conductivity,EC）梯度5,10,15,20 ms·cm^-1,以浇灌自来水为对照组（CK）。试验结果表明,当C盐EC值为15 ms·cm^-1,A和B盐EC值均为20 ms·cm^-1时,各处理下幼苗的生长受到明显抑制;3种混合盐处理下,随着EC的增加,中脉厚度、主脉维管束直径、上下表皮细胞厚度、木质部面积变化均呈显著下降趋势,而上角质层厚度、韧皮部面积则表现出先增后降的变化趋势。总之,EC值<10 ms·cm^-1时,碱性盐比中性盐更促进无芒雀麦叶片各项指标的增长,当EC值>10 ms·cm^-1时,碱性盐对幼苗的抑制作用显著大于中性盐。     

Effect of increasing climatic water deficit on some leaf and stomatal parameters of wild and cultivated almonds under Mediterranean conditions

The prevailing environmental conditions, temperature in particular, drive seasonal changes both in leaf development and stomatal characteristics. In order to ascertain the effect of increases in climatic water deficit on some leaf and stomatal parameters under field conditions, a study was carried out on two sets of leaves (spring and summer) on a large sample of Amygdalus communis L. cultivars in comparison with several Amygdalus webbii Spach seedlings, a species more adapted to arid environments and probable ancestor of cultivated almonds. Observations were performed between spring and summer of a particularly hot season. The results showed a significant and general reduction of both leaf area and stomatal frequency and an increase in stomatal size. Nevertheless, there were evident differences between cultivated and wild almonds. A stronger reduction of leaf area was observed in A. webbii (−31%) with respect to A. communis (−14%); on the contrary, the latter reduced stomatal frequency more than the former (−25% and −19%, respectively). The examined cultivated almonds, in response to the increase in climatic water deficit, tended to arrange their stomatal structures like those of wild almonds. Finally, increasing the climatic water deficit, the slope of the linear regressions between stomatal frequency and size did not change in either species, leading to a better understanding of the mechanisms of almond acclimation to environmental stresses.     

Responses of leaf photosynthesis and plant growth to altered source–sink balance in a Japanese and a Dutch tomato cultivar

We investigated the effects of altered source/sink ratio by leaf or fruit pruning on leaf photosynthetic characteristics and whole-plant growth of ‘Momotaro York’, a Japanese cultivar, and ‘Dundee’, a Dutch cultivar and verified a hypothesis for sink-limitation of plant growth proposed by Tanaka and Fujita (1974). Plants were grown hydroponically with a high-wire system in a greenhouse for 11 weeks. Light-saturated photosynthesis of young, fully expanded leaves measured at atmospheric CO₂ partial pressure of 37 Pa and at an intercellular CO₂ partial pressure of 20 Pa was not influenced by alteration of source/sink ratio for either cultivar. Although soluble sugars were accumulated in leaves under high source/sink conditions, the amount of ribulose-1,5-bisphosphate carboxylase/oxygenase, a rate-limiting factor for CO₂-limited photosynthesis, was not affected by the altered source–sink balance. Net assimilation rate of a whole plant increased with decreasing source/sink ratio, but this can be accounted for by the changes in light interception per unit leaf area, without taking the source–sink relationship into consideration. It was concluded that the altered source/sink ratio did not change leaf photosynthetic capacity and the sink-limitation hypothesis cannot be applied to either cultivar under the conditions of the present study.     

Horticultural performance of ‘Folha Murcha’ sweet orange onto twelve rootstocks

Despite its outstanding position, the Brazilian citriculture is established on a very limited pool of varieties that limits its expansion and restricts the fruit availability throughout the year. This situation determines the urgent necessity of developing alternative scion and rootstock cultivars, with good performance under local conditions. ‘Folha Murcha’ sweet orange (Citrus sinensis (L.) Osbeck) is a late-harvest cultivar, suitable both for the juice processing industry and the fresh fruit market, being described as tolerant to citrus canker (Xanthomonas citri subsp. citri Schaad et al.), and less affected by citrus variegated chlorosis (Xylella fastidiosa Wells et al.). A study was conducted in Bebedouro, São Paulo State, Brazil, to evaluate the horticultural performance of ‘Folha Murcha’ sweet orange budded onto 12 rootstocks: the citrandarin ‘Changsha’ mandarin (Citrus reticulata Blanco) × Poncirus trifoliata ‘English Small’; the hybrid ‘Rangpur’ lime (Citrus limonia Osbeck) × ‘Swingle’ citrumelo (P. trifoliata (L.) Raf. × Citrus paradisi Macfad.); the trifoliates (P. trifoliata (L.) Raf.) ‘Rubidoux’, ‘FCAV’, and ‘Flying Dragon’ (P. trifoliata var. monstrosa); the ‘Sun Chu Sha Kat’ mandarin (C. reticulata Blanco); the ‘Sunki’ mandarin (Citrus sunki (Hayata) Hort. ex. Tanaka); the ‘Rangpur’ limes (C. limonia Osbeck) ‘Cravo Limeira’ and ‘Cravo FCAV’; ‘Carrizo’ citrange (C. sinensis × P. trifoliata), ‘Swingle’ citrumelo (P. trifoliata × C. paradisi), and ‘Orlando’ tangelo (C. paradisi × Citrus tangerina cv. ‘Dancy’). The experimental grove was planted in 2001, using a 7 m × 4 m spacing, in a randomized block design, with five replications and two plants per plot. No supplementary irrigation was applied. Fruit yield, canopy volume, tree tolerance to drought and to citrus variegated chlorosis, and fruit quality were assessed for each rootstock. Trees grafted onto the ‘Flying Dragon’ trifoliate were smaller in size, but had largest yield efficiency when compared to those grafted onto other rootstocks. Lower alternate bearing index was observed on trees budded onto ‘Cravo FCAV’ ‘Rangpur’ lime. Both ‘Rangpur’ lime rootstocks and the ‘Sunki’ mandarin induced higher tree tolerance to drought. The ‘Flying Dragon’ trifoliate induced better fruit quality and higher tolerance to citrus variegated chlorosis (CVC) to ‘Folha Murcha’ trees. A cluster multivariate analysis identified three groups of rootstocks with similar effects on ‘Folha Murcha’ tree performance. Among the 12 evaluated rootstocks, the ‘Flying Dragon’ trifoliate has a unique effect on plant growth, tolerance to drought and CVC, fruit yield and fruit quality of ‘Folha Murcha’ trees, and may be better suited for high-density plantings.