分蘖期水稻地上部和空气间的NO_X (NO,NO₂ ) 交换作用     

徐胜光  陈能场  周建民  吴启堂  毕德 《植物营养与肥料学报》2009,15(6):1357-1363

采用密闭箱法结合42 C型 NO-NO2-NOX 分析仪的快速线检测系统,在气候箱严密控光（L1）和室内自然光暗处理（L2）条件下,研究了分蘖期水稻地上部和空气间的NOX（NO, NO2 ）交换作用,结果表明: 1）试验用水稻品种具有较强的NO挥发能力,在L1、L2条件下水稻NO平均挥发速率 [按鲜质量（g, FW）计算] 分别达到0.0188、0.0239 g/（g·h）,并在环境空气NO浓度达100 g/m3条件下水稻也能净排放NO;2）水稻能吸收空气NO2,L1、L2条件下水稻NO2平均净吸收速率为0.00084、0.00165 g/（g·h）;3）施氮能增强水稻NO挥发,在气候箱严密控光（L1）条件下,短期内（1～2 d）施氮在日间 6:00～10:00 弱光时段和 10:00～14:00强光时段有刺激水稻NOX （NO, NO2 ）挥发的效应, 但在14:00～18:00 时段,持续强光能削弱施氮对水稻NO挥发的刺激作用而增强水稻对NO2吸收。4）室内自然弱光条件下（L2）,施氮能提高日间水稻的NO净挥发速率,水稻NO2净吸收速率随着有光时间的延长而上升。夜间暗处理条件下,施氮对促进水稻NO的挥发无明显作用,水稻NO2吸收速率下降。试验结果显示,水稻地上部从空气中净吸收NO2的平均速率远低于NO净挥发速率,分蘖期水稻地上部分与空气间的NOX （NO, NO2 ）交换作用主要表现为NO的净挥发,相当于净损失纯N 10.95～12.5 g/（hm2 ·d）。  相似文献   

Ordinal regression models for predicting deoxynivalenol in winter wheat     

S. Landschoot  W. Waegeman  K. Audenaert  G. Haesaert  B. De Baets 《Plant pathology》2013,62(6):1319-1329

Deoxynivalenol (DON) is one of the most prevalent toxins in Fusarium‐infected wheat samples. Accurate forecasting systems that predict the presence of DON are useful to underpin decision making on the application of fungicides, to identify fields under risk, and to help minimize the risk of food and feed contamination with DON. To this end, existing forecasting systems often adopt statistical regression models, in which attempts are made to predict DON values as a continuous variable. In contrast, this paper advocates the use of ordinal regression models for the prediction of DON values, by defining thresholds for converting continuous DON values into a fixed number of well‐chosen risk classes. Objective criteria for selecting these thresholds in a meaningful way are proposed. The resulting approach was evaluated on a sizeable field experiment in Belgium, for which measurements of DON values and various types of predictor variables were collected at 18 locations during 2002–2011. The results demonstrate that modelling and evaluating DON values on an ordinal scale leads to a more accurate and more easily interpreted predictive performance. Compared to traditional regression models, an improvement could be observed for support vector ordinal regression models and proportional odds models.  相似文献   

A comparison of winter-sown tomato plants grown with restricted and unlimited water supply     

A. De Koning  R. G. Hurd 《The Journal of Horticultural Science and Biotechnology》2013,88(4):575-581

The morphology, anatomy and physiology of winter-sown tomato plants grown with a restricted water supply (producing ‘hard’ plants) were compared with those of plants given an unlimited water supply (‘soft’ plants). The stressed plants had smaller and fewer leaves on thinner stems; the reduction in leaf area was largely due to smaller cell size. The leaves and stems also had a higher percentage dry matter; in the stems this was associated with many more and larger starch grains. It is suggested that the improvement in earliness and in fruit quality found in stressed plants originates from this increase in stored carbohydrate.

Rates of photosynthesis per unit leaf area were the same in both groups of plants when measured under laboratory conditions. The leaf cell sap had the same osmotic potential but there was a greater proportion of apoplastic water in the leaves of the stressed plants. Transpiration rates in the glasshouse were lower in the stressed plants. Possibilities for the control of plant water status to optimize early yield quantity and quality are considered.  相似文献   

Effects of CO2 on leaf conductance and canopy transpiration of greenhouse grown cucumber and tomato     

E. M. Nederhoff  R. De Graaf 《The Journal of Horticultural Science and Biotechnology》2013,88(6):925-937

The effects of carbon dioxide (CO₂) on stomatal opening and canopy transpiration were investigated in cucumber (Cucumis sativus L., cv. Jessica) and tomato (Lycopersicon esculentum Mill., cv. Calypso). Stomatal opening (i.e. leaf conductance, g) was measured with a porometer, and canopy transpiration rate (E) with weighing lysimeters on intact plants in large greenhouses. Regression analysis was applied to account for the effects of radiation, air humidity, leaf temperature and CO₂ on g. The effect of CO₂ on E, which is primarily through g and secondarily through adjusted air humidity, was investigated by combining the regression equation for g with the Penman-Monteith equation for E. The relative effect of CO₂, as calculated with the fitted regression equations, was a decrease of about 4% in g for cucumber and of about 3% for tomato, per 100 μol mol-1 increase in CO₂, in the range of about 300 to 1200 μmol mol^?1 CO₂. The effect of CO₂ on E was smaller than on g and the extent of the effect depended on the conditions, mainly ventilation rate. The ratio K (relative change in calculated E divided by relative change in calculated g) was estimated at less than 0.2, except at low radiation. In reality, K will be even lower, because feedback mechanisms enforce the reduction in g and counteract the reduction in E. So the reduction of the transpiration rate of greenhouse cucumber and tomato caused by moderate CO₂ enrichment is small and mostly negligible, except under low light conditions.  相似文献   

Rose flower production as related to plant architecture and carbohydrate content: Effect of harvesting method and plant type     

M. T. N. Kool  R. De Graaf  C. H. M. Rou-Haest 《The Journal of Horticultural Science and Biotechnology》2013,88(4):623-633

Summary

The dependence between flowering cycles and woody stem parts of a rose crop was studied, with respect to plant architecture and carbohydrate content. Two harvesting methods (“control” versus “flush”) and two plant types (“control” versus “one stemmed”) were compared. Crop growth and partitioning of dry matter were studied as influenced by crop management during 18 months of culture. For a full-productive year, flush harvesting generally promoted bud break as compared with continuous harvesting but at the same time, also due to lower light interception, blind-shoot formation was enhanced and the individual flower weight reduced. Numbers of basal shoots were hardly related to flower production over a full cropping year. Flower production was much more sensitive to the number and diameter of branches at the height of cutting the flowers. The treatments did not affect carbohydrate allocation in the plant. Total carbohydrate storage was much too low to argue a clear role for the possible use of movement of carbohydrate reserves towards new growth. Maximum starch concentration was found at the beginning of summer and gradually dropped to a minimum in December and then increased again to a spring maximum. A cold treatment did increase the total non-structural carbohydrate (TNC) concentration but no positive influence on new basal-shoot formation was observed. No starch gradient was found in basal stem parts.  相似文献   

ALCEPAS,an onion growth model based on SUCROS87.I. Development of the model     

C. L. M. De Visser 《The Journal of Horticultural Science and Biotechnology》2013,88(3):501-518

Summary

A dynamic simulation model for onion crop growth is presented that is based on SUCROS87, a Simple and Universal Crop Growth Simulator. Onion specific values of parameters and relations of SUCROS87 were established using results from field experiments. The model simulates potential crop growth when weeds, pests, diseases and soil conditions are not limiting growth and there is ample supply of water and nutrients. The model accounts for the influence of sowing date and plant density. The combined influence of environmental factors on leaf growth, bulb initiation and maturity is incorporated. The potential use of the model is discussed.  相似文献   

ALCEPAS,an onion growth model based on SUCROS87. II. Validation of the model     

C. L. M. De Visser 《The Journal of Horticultural Science and Biotechnology》2013,88(3):519-525

Summary

A dynamic simulation model for onion growth at potential production level (ALCEPAS), presented in a previous paper, was validated using data on leaf area index, bulb and green leaf dry-matter production, bulb formation and day of fall-over from independent trials at four locations. The model performance in terms of bulb dry-matter production was good under environmental conditions close to the optimum, but insufficient under stress situations. The model overestimated leaf area index and green leaf dry matter. Bulb formation was simulated satisfactorily, while the time of 50% fall-over was simulated too early at low plant densities.  相似文献   

Low seed/nut productivity in cashew (Anacardium occidentale): Effects of self-incompatibility and honey bee (Apis mellifera) foraging behaviour     

J. P. De Holanda-Neto  D. M. Bueno  Z. B. De Araújo 《The Journal of Horticultural Science and Biotechnology》2013,88(2):226-231

Summary

The roles of self- versus cross-pollination and honey bee (Apis mellifera L.) foraging behaviour in low nut yield of cashew (Anacardium occidentale L.) were studied in NE Brazil in 1997 and 1998. It was shown that both self- and cross-pollination can set fruits in cashew, but most of fruits originating from self-pollination are shed 9–15 d after pollination, and fruits harvested are primarily from cross-pollination. Honey bees display foraging behaviour in cashew orchards conducive to cross-pollination, but in plantations originating from clonal material they failed to increase fruit yield despite cashew's dependence on insect pollination. It is concluded that cashew has a mechanism of selective abortion through which it discards self-pollinated fruits and that honey bees can contribute to increased fruit yield only when cashew trees of genetically diverse origin are found in the same orchard.  相似文献   

Urban forest governance: Towards a framework for comparing approaches     

Anna Lawrence  Rik De Vreese  Mark Johnston  Cecil C. Konijnendijk van den Bosch  Giovanni Sanesi 《Urban Forestry & Urban Greening》2013,12(4):464-473

  相似文献   

Effect of different rates of composted organic amendment on urban soil properties,growth and nutrient status of three Mediterranean native hedge species     

Barbara De Lucia  Giuseppe Cristiano  Lorenzo Vecchietti  Laura Bruno 《Urban Forestry & Urban Greening》2013,12(4):537-545

Increasing green space, especially in densely built-up areas is considered to be a valuable climate change adaptation response in order to reduce the threat of high temperatures to human health and comfort and to controlled global greenhouse gas emissions. Practical responses to climate change, under urban conditions, in order to avoid or reduce trees and shrubs vulnerability, can be considered drought resistant planting approaches, as the addition of organic amendeds to soil. The improvement of physical–chemical soil quality is a key step for carrying out xeriscaping programs of urban green spaces in Mediterranean semiarid areas. Organic amendments, particularly compost, have been receiving a renewed attention not only in horticulture but also in the context of restoring disturbed urban soils to address environmental issues as well as to improve trees and shrubs growth. The influence of increasing rates (0, 15, 30, and 45%) of composted sewage sludge (SSC) placed in the plantation hole on both urban soil properties and growth for three native Mediterranean woody hedge species was monitored over a 2-year period after planting. The experiment was supported by a xerogardening project in an urban context under semi-arid conditions. The results indicate that the urban soil physical characteristics were positively influenced by the addition of SSC: the 45% rate showed an increase in both moisture and infiltration values, thereby increasing the volume of plant-available water in the soil. The chemical properties of the amended soils were also directly affected by the SSC rate, but the effect of the compost on organic matter, nitrogen and potassium contents decreased over time. Our results prove that the hedge growth response to the compost treatments is also highly dependent on the rate of compost used. At the end of the trial, in Rhamnus and Myrthus plants 30% compost level guarantees the best performance; in fact, the further addition of 15% of compost led to a significant decrease in hedge and diameter values, in particular in Myrtle. This could be explained by the high pH at 45% compost, which would seem not to suit the physiology of the two species. On the other hand, in Phillyrea plants, the rate of 45% compost gives high performance equal to that of 30%; it would therefore seem that the high pH at 45% compost does not influence the nutritive elements’ absorption and, as a consequence, the growth. The use of composted sludge as an amendment for sclerophyllous could be feasible and, what is more, helpful to mitigate the environmental impact of organic waste disposal. Moreover more natural vegetation can be introduced into urban parks and green spaces in semi-arid environments to encourage sustainable landscaping and xerogardening.  相似文献