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101.
102.
Effects of chronic ozone exposure on growth, root respiration and nutrient uptake of rice plants 总被引:9,自引:0,他引:9
Nouchi I Ito O Harazono Y Kobayashi K 《Environmental pollution (Barking, Essex : 1987)》1991,74(2):149-164
To clarify the response of growth and root functions to low concentrations of ozone (O(3)), rice plants (Oryza sativa L.) were exposed to O(3) at 0.0 (control), 0.05 and 0.10 ppm for 8 weeks from vegetative to early heading stages. Exposure to 0.05 ppm O(3) tended to slightly stimulate the dry weight of whole plants up to 5 weeks and then slightly decrease the dry weight of whole plants. However, these effects were statistically significant only at 6 weeks. Exposure to 0.10 ppm O(3) reduced the dry weight of whole plants by 50% at 5 and 6 weeks, and thereafter the reduction of the dry weight of whole plants was gradually alleviated. Those changes in dry weight can be accounted for by a decrease or increase in the relative growth rate (RGR). The changes in the RGR caused by 0.05 and 0.10 ppm O(3) could be mainly attributed to the effect of O(3) on the net assimilation rate. Root/shoot ratio was lowered by both 0.05 and 0.10 ppm O(3) throughout the exposure period. The root/shoot ratio which had severely decreased at 0.10 ppm O(3) in the first half period of exposure (1-4 weeks) became close to the control in the latter part of exposure (5-8 weeks). Time-course changes in NH(4)-N root uptake rate were similar to those in the root/shoot ratio especially for 0.10 ppm O(3). On the other hand, root respiration increased from the middle to later periods. Since it is to be supposed that plants grown under stressed conditions change the ratio of plant organ weight to achieve balance between the proportion of shoots to roots in the plant and their activity for maintaining plant growth, these changes in root/shoot ratio and nitrogen uptake rate under long-term exposure can be considered to be an adaptive response to maintain rice growth under O(3) stress. 相似文献
103.
Ryota?L.?SakamotoEmail author Shin-Ichi?Morinaga Motomi?Ito Nobumitsu?Kawakubo 《Behavioral ecology and sociobiology》2012,66(5):669-674
Most estimations of the pollination efficiency of insects have been based on observation by the naked human eye. However,
insect behaviors are often too rapid to analyze sufficiently this way. Here we demonstrate the use of high-speed cameras to
analyze the fine-scale behaviors of Macroglossum pyrrhosticta, Xylocopa appendiculata, and Papilio dehaanii when visiting Clerodendrum trichotomum. The fine-scale nectar drinking time, number of contacts with anthers and/or stigmas, and frequencies of body part contact
with anthers and/or stigmas differed significantly among pollinator species. Pollination efficiency was not equal among pollinators.
In addition, M. pyrrhosticta made the least number of contacts with anthers and/or stigmas even though it showed the highest visitation frequency. These
results demonstrate that when examined from the viewpoint of rapid visitation behaviors, pollination dynamics differ among
pollinator species, and flower visits and pollination rates are not equal. 相似文献
104.
A two-dimensional individual-based model coupled with fish bioenergetics was developed to simulate migration and growth of Japanese sardine (Sardinops melanostictus) in the western North Pacific. In the model, fish movement is controlled by feeding and spawning migrations with passive transport by simulated ocean current. Feeding migration was assumed to be governed by search for local optimal habitats, which is estimated by the spatial distribution of net growth rate of a sardine bioenergetics model. The forage density is one of the most important factors which determines the geographical distributions of Japanese sardine during their feeding migrations. Spawning migration was modeled by an artificial neural network (ANN) with an input layer composed of five neurons that receive environmental information (surface temperature, temperature change experienced, current speed, day length and distance from land). Once the weight of the ANN was determined, the fish movement was solved by combining with the feeding migration model. To obtain the weights of the ANN, three experiments were conducted in which (1) the ANN was trained with back propagation (BP) method with optimum training data, (2) genetic algorithm (GA) was used to adjust the weights and (3) the weights of the ANN were decided by the GA with BP, respectively. BP is a supervised learning technique for training ANNs. GA is a search technique used in computing to find approximate solutions, such as optimization of parameters. Condition factor of sardine in the model is used as a factor of optimization in the GA works. The methods using only BP or GA did not work to search the appropriate weights in the ANN for spawning migration. In the third method, which is a combined approach of GA with BP, the model reproduced the most realistic spawning migration of Japanese sardine. The changes in temperature and day length are important factors for the orientation cues of Japanese sardine according to the sensitivity analysis of the weights of the ANN. 相似文献
105.
Interval between reproductive events is an important factor for iteroparous animals because it determines the number of clutches
throughout life. This study examined whether female size, clutch size, shell size and prenuptial molting affected the clutch
interval in the hermit crab Pagurus nigrivittatus. Precopulatory guarding pairs of P. nigrivittatus were sampled in the field and kept in the laboratory until the female extruded eggs. The clutch interval of each female was
assessed as one of two types of relatively “short” and “long” intervals by checking whether the guarded female had eggs and/or
egg cases from the preceding brood or not when the guarding pair was collected. The clutch interval was longer in females
with prenuptial molting than those without molting and these females usually grew larger at the prenuptial molt. This suggests
that female P. nigrivittatus with a long interval might allocate energy into growth at the expense of the number of clutches during the current reproductive
season. The allocation to growth is theoretically predicted to decrease with female size. Gastropod shell size is also known
to affect the reproductive activity in hermit crabs. However, female size did not significantly affect the clutch interval
in P. nigrivittatus, and the effect of gastropod shell size on clutch interval was not consistent with previous empirical studies. These results
may be caused by differences in the gastropod species of shell occupied by the females of P. nigrivittatus. 相似文献
106.
Combustible and incombustible speciation of Cl and S in various components of municipal solid waste 总被引:1,自引:0,他引:1
Chlorine (Cl) and sulfur (S) in municipal solid waste (MSW) are important reactive elements during combustion. They generate the acidic pollutants HCl and SOx, and, furthermore, produce and suppress organic chlorinated compounds. Nevertheless, few practical reports about Cl and S content in MSW have been published. In combustion and recycling processes, both combustible Cl and S, and incombustible Cl and S species are equally important. This paper presents the results of a comprehensive study about combustible and incombustible Cl and S in MSW components, including kitchen garbage, paper, textiles, wood and leaves, plastics and small chips. By integrating this collected data with data about MSW composition, not only the overall content of Cl and S in MSW, but also the origins of both combustible and incombustible Cl and S were estimated. The average Cl content in bulk MSW was 3.7 g/kg of raw MSW, of which 2.7 and 1.0 g/kg were combustible and incombustible, respectively. The Cl contribution from plastics was 76% and 27% with respect to combustible and incombustible states. The average S content in bulk MSW was 0.81 g/kg of raw MSW, of which 0.46 g/kg was combustible and 0.35 g/kg was incombustible. Combustible S was mainly due to synthetic textiles, while incombustible S was primarily from paper. 相似文献
107.
108.
Workers never mate in the large majority of ants, and they have usually lost the spermatheca, an organ specialized for long-term
storage of sperm. Such ‘non-sexual’ workers are restricted to laying unfertilized eggs that give rise to males, and they cannot
compete with the queens for the production of female offspring. In sharp contrast, workers in 200–300 species from phylogenetically
basal subfamilies can reproduce sexually (‘gamergates’) because they retain a functional spermatheca like the queens. Importantly,
‘non-sexual’ workers in closely related species have a vestigial spermatheca. In this study, we compared the reservoir epithelium
of ‘sexual’ workers to that of congeneric queens and ‘non-sexual’ workers using 21 species of Amblyoponinae, Ponerinae and
Ectatomminae. We show that a pronounced thickening of the epithelium near the opening of the sperm duct is strictly associated
with sexual reproduction in both castes. This is unlike ‘non-sexual’ workers in which this epithelium is always very thin,
with few organelles; but all other structures remain intact. We discuss this evolutionary degeneration of the spermatheca
and how it relates to behavioural or physiological modifications linked to mating. Our results help understand the loss of
sexual reproduction by ant workers, a critical step in the extreme specialization of their phenotype. 相似文献
109.
A blend of regioregular poly(3-hexylthiophene) (P3HT) and poly{[N,N′-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5′-(2,2′-bithiophene)} (P(NDI2OD-T2), which has the potential for polymer solar cells application, was prepared for current mode atomic force microscopy (C-AFM) measurements in this study. Phase-separated domains and the local electrical characteristics of P3HT/P(NDI2OD-T2) blends were investigated by the C-AFM. 相似文献
110.
Rodrigo Kerr Letícia C. da Cunha Ruy K. P. Kikuchi Paulo A. Horta Rosane G. Ito Marius N. Müller Iole B. M. Orselli Jannine M. Lencina-Avila Manoela R. de Orte Laura Sordo Bárbara R. Pinheiro Frédéric K. Bonou Nadine Schubert Ellie Bergstrom Margareth S. Copertino 《Environmental management》2016,57(3):740-752