Assessment of a three-stage sampling strategy to investigate the spatial distribution and population density of Aphelenchoides besseyi among Oryza sativa seeds

Nematology ◽  
2010 ◽  
Vol 12 (3) ◽  
pp. 373-380
Author(s):  
Katsumi Togashi ◽  
Shigeru Hoshino
Keyword(s):  
Spatial Distribution ◽  
Oryza Sativa ◽  
Paddy Field ◽  
Rice Plant ◽  
Spatial Scales ◽  
Sampling Strategy ◽  
Paddy Fields ◽  
Nematode Density ◽  
Aphelenchoides Besseyi ◽  
The Mean

AbstractThis study aimed to determine the spatial distribution patterns of Aphelenchoides besseyi among Oryza sativa seeds on panicle, plant hill, and paddy field spatial scales and to present a three-stage sampling method for estimating the mean density per seed in paddy fields. Living and dead nematodes were extracted individually from 20 seeds sampled from each of five panicles, which were sampled from each of six rice plant hills in each of eight paddy fields, where all plants had leaves exhibiting the 'white tip' symptom. Nested ANOVA indicated that A. besseyi density per seed was significantly different among the eight paddy fields, among rice plant hills in paddy fields, and among panicles in rice plant hills. The proportion of nematode-infested seeds (prevalence) increased and reached an upper limit as the mean density per seed on the panicle scale increased, whereas linear relationships were observed between nematode prevalence and the mean density on plant hill and paddy field scales. Relationships between mean density and mean crowding of nematodes per seed indicated that the nematodes exhibited clumped distribution on each of panicle, plant hill and field scales. Using these relationships, a three-stage sampling plan for estimating nematode density per seed at a specified precision level is presented.

Distribution pattern and mortality of the white tip nematode, Aphelenchoides besseyi (Nematoda: Aphelenchoididae), among rice seeds

Nematology ◽  
2001 ◽  
Vol 3 (1) ◽  
pp. 17-24 ◽  
Author(s):  
Katsumi Togashi ◽  
Shigeru Hoshino
Keyword(s):  
Paddy Field ◽  
Rice Plant ◽  
Significant Negative Correlation ◽  
Rice Seed ◽  
Ecological Features ◽  
Degree Of Swelling ◽  
Aphelenchoides Besseyi ◽  
The Mean ◽  
Different Levels ◽  
Nematode Mortality

AbstractAphelenchoides besseyi is a seed-borne nematode and the causal agent of rice white tip disease. To determine the relationships between nematode numbers per seed, size of seed harbouring nematodes, and nematode mortality, 18 panicles were collected from 12 paddy fields showing three different levels of white tip disease. The panicles were investigated after storage for 30-82 days at 4°C. There was no nematode mortality within seeds during storage. Mean nematode number per seed increased and mean degree of seed swelling decreased as the paddy field infestation of white tip disease increased. For paddy field means, there was a significant, negative correlation between the mean nematode number per seed and the mean degree of rice seed swelling. Intriguingly, for individual seeds, the mean degree of swelling increased up to that typical of well-developed seeds with increasing nematode number per seed. Nematode mortality occurred in an inversely density-dependent fashion within individual seeds. The nematode exhibited a clumped distribution among seeds in each paddy field. Such ecological features of the nematode might contribute to its persistence in rice plant population.

scholarly journals A new method for indirectly estimating infiltration of paddy fields in situ

2018 ◽  
Vol 379 ◽  
pp. 205-210
Author(s):  
Yunqiang Xu ◽  
Baolin Su ◽  
Hongqi Wang ◽  
Jingyi He
Keyword(s):  
Water Depth ◽  
Paddy Field ◽  
Crop Coefficient ◽  
Paddy Fields ◽  
New Method ◽  
Lake Basin ◽  
The Mean ◽  
Monteith Equation ◽  
Coefficient Method

Abstract. Infiltration is one of the major procedures in water balance research and pollution load estimation in paddy fields. In this study, a new method for indirectly estimating infiltration of paddy fields in situ was proposed and implemented in Taihu Lake basin. Since when there were no rainfall, irrigation and artificial drainage, the water depth variation process of a paddy field is only influenced by evapotranspiration and infiltration (E+F). Firstly, (E+F) was estimated by deciding the steady decreasing rate of water depth; then the evapotranspiration (ET) of the paddy field was calculated by using the crop coefficient method with the recommended FAO-56 Penman-Monteith equation; finally, the infiltration of the paddy field was obtained by subtracting ET from (E+F). Results show that the mean infiltration of the studied paddy field during rice jointing-booting period was 7.41 mm day−1, and the mean vertical infiltration and lateral seepage of the paddy field were 5.46 and 1.95 mm day−1 respectively.

scholarly journals Total mercury in rice plant (Oryza sativa) collected from Sekinchan, Selangor, Malaysia and associated health risks

Food Research ◽  
2021 ◽  
Vol 5 (S1) ◽  
pp. 132-136
Author(s):  
A.C. Soong ◽  
N.M. Isa ◽  
A.Z. Aris ◽  
H. Haris ◽  
L.J. Looi
Keyword(s):  
Oryza Sativa ◽  
Rice Plant ◽  
Total Mercury ◽  
Mercury Contamination ◽  
Potential Health ◽  
Plant Parts ◽  
Food Regulation ◽  
Direct Mercury Analyzer ◽  
Mercury Analyzer ◽  
The Mean

Consumption of mercury-contaminated rice could pose a potential health risk to humans. In this study, total mercury (THg) concentrations in various parts (roots, stems, leaves, and grains) of rice plant (Oryza sativa) collected from Sekinchan, Selangor, Malaysia were analysed for risk assessment. The THg concentrations in collected samples were analysed by Direct Mercury Analyzer (DMA-80). The mean concentrations found in plant parts were as follows: root, 47.01±0.42 µg/kg; stem, 6.43±1.77 µg/kg; leaf, 26.25±4.71 µg/kg; grain, 2.64±0.42 µg/kg. THg distribution in rice plants was roots > leaves > stems and grains. The mean THg concentration in grain (2.64±0.42 µg/kg) was below the maximum permitted proportion stipulated by Malaysian Food Regulation 1985 (50.0 µg/ kg). The estimated weekly intake (EWI) of THg through rice was 0.07±0.01 µg/kg bw/ week for 60 kg adult, below the provisional tolerable weekly intakes (PTWI) as suggested by JECFA indicating unlikely to cause impairment of public health due to consumption of rice planted in this region. However, periodical monitoring of mercury pollution in Selangor area is crucial because mercury contamination in crops could jeopardize food safety and security

Long-term population dynamics of Aphelenchoides besseyi on Oryza sativa in a paddy field, and changes in the pathological and ecological traits of the two populations

Nematology ◽  
2021 ◽  
pp. 1-17
Author(s):  
Shigeru Hoshino ◽  
Katsumi Togashi
Keyword(s):  
Population Dynamics ◽  
Oryza Sativa ◽  
The Other ◽  
Ecological Traits ◽  
Reproduction Curve ◽  
Aphelenchoides Besseyi ◽  
The Mean ◽  
Two Peaks ◽  
Two Populations

Summary An Oryza sativa cultivar inoculated with the white tip nematode, Aphelenchoides besseyi, was cultivated over 18 years to investigate the population dynamics of the nematode and the change in the virulence of nematodes and tolerance/resistance of plants. The mean number of living nematodes per seed (S) showed two peaks, each of which was followed by a 3-year decrease in the S value, during the initial 10 years. The annual reproduction curve between in year and in year t had a peak in a range of of <1.1. The incidence of white tip disease increased with increasing mean number of living nematodes seed−1 in the previous year, whereas the proportion of seeds with living nematodes increased with increasing mean number of living nematodes seed−1 in the current year. Inoculation tests of the nematode cohorts on the seedling cohorts derived from seeds harvested in the same or different years indicated that the initial 6-year interaction between the rice and nematode populations caused the nematodes to increase the incidence of white tip disease and to decrease the degree of seed swelling and the proportion of heavy seeds. On the other hand, the interaction caused the rice plants to prevent the incidence of disease from increasing and the degree of seed swelling and the proportion of heavy seeds from decreasing.

scholarly journals EFFECT OF AMELIORANT ON GROWTH AND YIELD OF RICE AT TIDAL PADDY FIELD

2021 ◽  
Vol 22 (2) ◽  
pp. 85
Author(s):  
Sri Minarsih ◽  
Sri Karyaningsih ◽  
Samijan Samijan ◽  
Agus Supriyo ◽  
Yulis Hindarwati ◽  
...  
Keyword(s):  
Oryza Sativa ◽  
Humic Acid ◽  
Paddy Field ◽  
Organic Fertilizer ◽  
Paddy Fields ◽  
Growth And Yield ◽  
Food Crop ◽  
Rice Varieties ◽  
Main Plot ◽  
Plot Design

<p>Rice (<em>Oryza sativa </em>L.) is the most important and strategic food crop in Indonesia, but low productivity in tidal paddy fields is a serious problem that must be overcome. The application of ameliorant would be worthy to increase the growth and yield of rice in tidal paddy fields. The study aimed to investigate the effect of ameliorant application on growth and yield of rice varieties in tidal paddy fields. The study was arranged in a split plot design with five replications. Rice varieties tested were Inpari 34, Dendang, Inpara 9, Inpari 35, and Ciherang as the main plot, and ameliorant types studied were humic acid, gypsum, zeolite, and organic fertilizer as the subplot. The results showed that the use of different rice varieties and amelioran types significantly increased the growth and yield of rice. Inpara 9 produced 7.6 t.ha-1 dry milled grain (DMG) or increased by 33.3% compared to Ciherang variety. Humic acid application at 25 kg ha-1 increased grain yield by 21.3% higher than that without ameliorant treatment. The best treatment to increase the growth and yield of rice in tidal paddy field was a combination of humic acid 25 kg.ha-1 and Inpari 34 which produced the DMG of 8.6 t ha-1 or 41% higher compared to Ciherang without ameliorant.</p>

scholarly journals A Comparison of Aquatic Invertebrate Diversity between Paddy Fields under Traditional and Modern Management in Western Japan

2016 ◽  
Vol 1 (1) ◽  
pp. 25
Author(s):  
Didot Budi Prasetyo ◽  
Shinsaku Koji ◽  
Nobuko Tuno
Keyword(s):  
Paddy Field ◽  
Management Practices ◽  
Aquatic Invertebrate ◽  
Paddy Fields ◽  
Taxon Richness ◽  
Modern Management ◽  
Invertebrate Diversity ◽  
Wiener Diversity Index ◽  
The Mean ◽  
Over Time

<p><em>We compared aquatic invertebrate diversity in paddy fields under traditional and modern management practices. We also examined the general factors that may be related to diversity within each paddy field. The Kitadan area was farmed with traditional management practices, with much longer periods of irrigations compared with the Kahoku area, which was farmed with modern agricultural practices using intermittent irrigation. We measured physicochemical factors and collected aquatic invertebrates from the two areas. Collected animal specimens were taxonomically identified and classified based by desiccation tolerance ability. At Kitadan, the total biodiversity parameters increased over time, while, biodiversity fluctuated temporally at Kahoku. The mean Shannon</em><em>-</em><em>Wiener diversity index was higher at Kitadan than at Kahoku. However, the mean taxon richness was not significantly different between locations. Both paddy fields were dominated by highly desiccation-tolerant invertebrates at the beginning of the rice cultivation period. Over time, the ratio of desiccation-sensitive invertebrates increased more at Kitadan than at Kahoku. Our canonical correspondence analysis showed that the time since rice transplanting, water permanence, pH, water depth, and chlorophyll a were significant factors affecting faunal assemblage composition. Our results indicate that water management practices have important roles in the aquatic biodiversity of paddy-field ecosystems.</em><strong><em></em></strong></p>

Trade-off between dispersal and reproduction of a seed-borne nematode, Aphelenchoides besseyi, parasitic on rice plants

Nematology ◽  
2003 ◽  
Vol 5 (6) ◽  
pp. 821-829 ◽  
Author(s):  
Katsumi Togashi ◽  
Shigeru Hoshino
Keyword(s):  
Oryza Sativa ◽  
Parasitic Nematode ◽  
Oryza Sativa L ◽  
Rice Seed ◽  
Trade Off ◽  
Rice Plants ◽  
Aphelenchoides Besseyi ◽  
Seminal Roots ◽  
The Mean ◽  
Nematode Mortality

AbstractThe effect of nematode infestation on dispersal and survival of both host plant and parasitic nematode was investigated experimentally using rice plants, Oryza sativa L. and Aphelenchoides besseyi Christie, a seed-borne ectoparasite. Nematode-inoculated plants produced a greater proportion of light seeds floating on water than non-inoculated plants. Nematode mortality was greater in light seeds than in heavy seeds. In the case of light seeds, the mean degree of seed swelling increased as the number of nematodes harboured increased, whereas it was constant with increasing numbers of nematodes for the intermediate and heavy seed groups. A smaller proportion of light seeds germinated and these took longer for seminal roots to protrude than from heavy seeds, irrespective of whether they derived from nematode-inoculated or non-inoculated plants. These results indicate a trade-off for rice seed specific gravity between dispersal and competition of rice seeds and another trade-off between dispersal and reproduction of nematodes harboured in the seed.

scholarly journals Effects of field margins and other uncultivated fields on Orthoptera assemblages in the mountainous paddy field area of northeast Japan

2019 ◽  
Vol 29 (1) ◽  
pp. 52-64
Author(s):  
Masatoshi Takeuchi ◽  
Teruaki Irie
Keyword(s):  
Species Composition ◽  
Community Composition ◽  
Paddy Field ◽  
Habitat Heterogeneity ◽  
Forest Cover ◽  
Spatial Scales ◽  
Community Diversity ◽  
Paddy Fields ◽  
Field Margins ◽  
The Impact

To understand how farmlands help maintain biodiversity, we investigated the relationship between habitat heterogeneity and Orthoptera community composition on multiple spatial scales. First, we determined the impact of 12 environmental variables on the Orthoptera community diversity by sampling 37 quadrats in uncultivated fields over a broad spatial scale. Canonical correspondence analysis (CCA) demonstrated that environmental parameters influenced species composition. The first two canonical axes were associated with forest cover, grass (including harvested dried grass in some cases), bare or paddy fields, and plants with tall stems. Secondly, we conducted a local-scale survey of Orthoptera assemblages in an operational farm unit consisting of paddy fields, fallow fields, marginal grass fields, and secondary forests. Eleven Orthoptera species (46%) were found exclusively on specific vegetation types. Thirdly, we carried out a habitat-scale survey to elucidate the correspondence between consecutive spatial changes in vegetation and Orthoptera community composition in a paddy field and surrounding marginal fields. Even within narrower ranges, the compositional habitat heterogeneity induced changes in the dominant Orthoptera species composition. These results indicate that a high degree of habitat segregation occurs among Orthoptera species in field margins and in uncultivated fields, and that farmland management significantly affects spatial distribution of Orthoptera.

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