Influence of intercropping on the abundance, distribution and parasitism of Chilo spp. (Lepidoptera: Pyralidae) eggs

1997 ◽  
Vol 87 (5) ◽  
pp. 507-513 ◽  
Author(s):  
P. Päts ◽  
B. Ekbom ◽  
H. Skovgård
Keyword(s):  
East Africa ◽  
Chilo Partellus ◽  
Field Experiments ◽  
Plant Density ◽  
Coastal Areas ◽  
Positive Density ◽  
Abundance Distribution ◽  
Significant Difference ◽  
Egg Parasitism ◽  
Lepidoptera Pyralidae

AbstractTwo of the most common and serious pests of maize and sorghum in the coastal areas of East Africa are the pyralid species, Chilo partellus (Swinhoe) and C. orichalcociliellus (Strand). Maize monocrop (with high and low plant density) and maize/cowpea mixed intercrop field experiments were conducted in Kenya to test if intercropping decreased the number of egg batches laid, altered the distribution of the egg batches and influenced egg parasitism. There was no significant difference in the number of egg batches per plant between treatments and the egg batches were randomly distributed on and among plants in most of the plots for all three treatments. There was a tendency for higher egg parasitism in the intercrop. The proportion of eggs parasitized was significantly correlated with total number of eggs per plot suggesting a positive density dependent response. It is concluded that intercropping does not affect C. partellus nor C. orichalcociliellus oviposition behaviour but egg parasitism is likely to be augmented.

scholarly journals Comparative evaluation of Cotesia flavipes and C. sesamiae (Hymenoptera: Braconidae) for the management of Chilo partellus (Lepidoptera: Pyralidae) in Kenya

1999 ◽  
Vol 89 (2) ◽  
pp. 185-191 ◽  
Author(s):  
M.N. Sallam ◽  
W.A. Overholt ◽  
E. Kairu
Keyword(s):  
Chilo Partellus ◽  
Sesamia Calamistis ◽  
Cotesia Flavipes ◽  
Cotesia Sesamiae ◽  
Female Progeny ◽  
Northern Tanzania ◽  
Significant Difference ◽  
Total Progeny ◽  
Lepidoptera Pyralidae ◽  
Searching Ability

AbstractCotesia flavipes Cameron, a gregarious larval endoparasitoid native to the Indo-Australian region, was imported from Pakistan and released in Kenya in 1993 for management of the exotic stemborer, Chilo partellus (Swinhoe). Recent reports confirmed the successful establishment of the parasitoid in three locations in Kenya and in northern Tanzania. Functional response studies on this parasitoid and an indigenous congener, Cotesia sesamiae (Cameron), indicated that C. flavipes had a higher searching ability and attacked more larvae when Chilo partellus was the host. When a native stemborer, Sesamia calamistis Hampson, was the host, there was no significant difference between numbers attacked by both parasitoids. Numerical response studies showed that Cotesia flavipes produced more total progeny and female progeny per female parasitoid on Chilo partellus than did Cotesia sesamiae. No significant difference in progeny production was detected between the two parasitoids on S. calamistis. Functional and numerical responses tested in the laboratory gave the same ranking of the two parasitoids on the two hosts as in the field. This study suggests that Cotesia flavipes is a more efficient parasitoid and it is anticipated that it will contribute to the control of both exotic and native stemborers in Kenya.

Assessment of sowing dates and plant densities using CSM-CROPGRO-Soybean for soybean maturity groups in low latitude

2021 ◽  
pp. 1-14
Author(s):  
L. S. Sampaio ◽  
R. Battisti ◽  
M. A. Lana ◽  
K. J. Boote
Keyword(s):  
Management Practices ◽  
Field Experiments ◽  
Plant Density ◽  
Crop Model ◽  
Management Scenarios ◽  
Low Latitude ◽  
Area Index ◽  
Sowing Dates ◽  
Plant Densities ◽  
Maturity Groups

Abstract Crop models can be used to explain yield variations associated with management practices, environment and genotype. This study aimed to assess the effect of plant densities using CSM-CROPGRO-Soybean for low latitudes. The crop model was calibrated and evaluated using data from field experiments, including plant densities (10, 20, 30 and 40 plants per m2), maturity groups (MG 7.7 and 8.8) and sowing dates (calibration: 06 Jan., 19 Jan., 16 Feb. 2018; and evaluation: 19 Jan. 2019). The model simulated phenology with a bias lower than 2 days for calibration and 7 days for evaluation. Relative root mean square error for the maximum leaf area index varied from 12.2 to 31.3%; while that for grain yield varied between 3 and 32%. The calibrated model was used to simulate different management scenarios across six sites located in the low latitude, considering 33 growing seasons. Simulations showed a higher yield for 40 pl per m2, as expected, but with greater yield gain increments occurring at low plant density going from 10 to 20 pl per m2. In Santarém, Brazil, MG 8.8 sown on 21 Feb. had a median yield of 2658, 3197, 3442 and 3583 kg/ha, respectively, for 10, 20, 30 and 40 pl per m2, resulting in a relative increase of 20, 8 and 4% for each additional 10 pl per m2. Overall, the crop model had adequate performance, indicating a minimum recommended plant density of 20 pl per m2, while sowing dates and maturity groups showed different yield level and pattern across sites in function of the local climate.

An assessment of the factors controlling the productivity of maize in England

1951 ◽  
Vol 41 (3) ◽  
pp. 271-281 ◽  
Author(s):  
E. S. Bunting ◽  
G. E. Blackman
Keyword(s):  
Dry Matter ◽  
Field Experiments ◽  
Plant Density ◽  
Spatial Arrangement ◽  
The Other ◽  
Mass Selection ◽  
Grain Production ◽  
Forage Production ◽  
Field Scale ◽  
Other Hand

Between 1942 and 1950, some thirty field experiments have been carried out in the southern half of England to assess the potential value, either for grain or forage production, of seventeen openpollinated flint or dent maizes together with twentynine single or double hybrids of American or Canadian origin.Early-maturing flint varieties will consistently ripen grain, but before mechanical threshing or storage, the cobs require drying. Sibthorp, a mass selection made from an unknown German variety, is the earliest and most productive flint maize so far tested, and in the experiments has yielded as much as 39 cwt. of grain per acre with an average of 24 cwt. The earliest American hybrids, i.e. those with a U.S.A. rating of 80 days from sowing to maturity, give very high yields of grain in favourable seasons. Within the group Wisconsin 240–275, a yield level equal to or exceeding 50 cwt./acre has on occasion been recorded. On the other hand, in the most unfavourable years, such hybrids just failed to produce ripe cobs.Attempts to maintain sixty-five parent inlines of the earliest hybrids have largely failed. However, many of the parent single crosses have matured, and the production on a field scale of the double-cross seed of both Wisconsin 240 and 255 has been carried out.Spacing experiments indicate that for optimum grain production a density of 6 plants/sq.yd. is required for both flint varieties and the earliest hybrids. A spatial arrangement of individual plants is to be preferred to that of groups or hills.American hybrids, in the class of ‘90 days’ to maturity, will in all but the most unfavourable seasons reach the ‘early-dent’ stage of the grain before the incidence of autumn frosts. Yields of dry matter of plants harvested in this phase have ranged from 30 to 85 cwt. of dry matter per acre. In these trials, the plant density was standardized at 4 plants/sq.yd. and higher densities may be demanded for optimal yields.The ratio of the ‘ear’ (that is, the cob, immature grain and enclosing leaf sheaths) to the total shoot weight at harvest varies greatly with the variety or hybrid. With White Horsetooth, the usual variety grown for fodder in England, no cobs are formed before the plants are killed by frost, while with the early hybrids, the ear may be half the weight of the whole shoot.The earliest variety Sibthorp from an early May sowing takes approximately 70–80 days to reach full anthesis, while ‘80-day’ American hybrids are a week later. From sowing to full maturity the period in England is from 140 to 160 days, thus compared to conditions in Minnesota the period is nearly twice as long. Because of the much slower rate of development and because of the humidity of English autumns, it is concluded that until the date of maturity can be advanced some 14 days, grain production on a field scale is not yet feasible. On the other hand, many of the American hybrids are well fitted to the production of silage. The greatest drawback to the introduction of such hybrids is the liability of the seed and seedlings to be attacked by rooks.

Plant height and height of the main ear in maize (Zea mays L.) at different locations and different plant densities

2002 ◽  
Vol 50 (1) ◽  
pp. 75-84 ◽  
Author(s):  
Z. Gyenes-Hegyi ◽  
I. Pók ◽  
L. Kizmus ◽  
Keyword(s):  
Plant Height ◽  
Plant Density ◽  
Close Correlation ◽  
Plant Size ◽  
Considerable Effect ◽  
Maximum Height ◽  
The Best Approximation ◽  
Significant Difference ◽  
Plant Densities ◽  
Ear Height

The plant height and the height of the main ear were studied over two years in twelve single cross maize hybrids sown at three different plant densities (45, 65 and 85 thousand plants/ha) at five locations in Hungary (Keszthely, Gönc, Gyöngyös, Sopronhorpács, Martonvásár). The results revealed that plant height and the height of the main ear are important variety traits and are in close correlation with each other. It was found that the hybrids grew the tallest when the genetic distance between the parental components was greatest (Mv 4, Mv 5). The height of the main ear was also the greatest in these hybrids, and the degree of heterosis was highest (193% for plant height, 194% for the height of the main ear). The shortest hybrids were those developed between related lines (Mv 7, Mv 11). In this case the heterosis effect was the lowest for both plant height (128%) and the height of the main ear (144%). The ratio of the height of the main ear to the plant height was stable, showing little variation between the hybrids (37–44%). As maize is of tropical origin it grows best in a humid, warm, sunny climate. Among the locations tested, the Keszthely site gave the best approximation to these conditions, and it was here that the maize grew tallest. The dry, warm weather in Gyöngyös stunted the development of the plants, which were the shortest at this location. Plant density had an influence on the plant size. The plants were shortest when sown at a plant density of 45,000 plants/ha, and the main ears were situated the lowest in this case. At all the locations the plant and main ear height rose when the plant density was increased to 65,000 plants/ha. At two sites (Gönc and Sopronhorpács) the plants attained their maximum height at the greatest plant density (85,000 plants/ha). In Keszthely there was no significant difference between these two characters at plant densities of 65 and 85 thousand plants/ha, while in Gyöngyös and Martonvásár the greatest plant density led to a decrease in the plant and main ear height. The year had a considerable effect on the characters tested.

scholarly journals Fall and spring seeding date effects on herbicide-tolerant canola (Brassica napus L.) cultivars

2004 ◽  
Vol 84 (2) ◽  
pp. 419-430 ◽  
Author(s):  
G. W. Clayton ◽  
K. N. Harker ◽  
J. T. O’Donovan ◽  
R. E. Blackshaw ◽  
L. M. Dosdall ◽  
...  
Keyword(s):  
Field Experiments ◽  
Plant Density ◽  
Early Spring ◽  
Yield Response ◽  
Management Options ◽  
Brassica Napus L ◽  
Seeding Date ◽  
Herbicide Tolerant ◽  
Root Maggot ◽  
Crops Yield

More flexible and effective weed control with herbicide-tolerant B. napus canola allows for additional seeding management options, such as fall (dormant) and early spring (ES) seeding. Field experiments were conducted at Lacombe and Beaverlodge (1999–2001), Didsbury (1999–2000), and Lethbridge (2000–2001), Alberta, Canada, primarily to evaluate the effect of fall (late October-November), ES (late April-early May), and normal spring (NS) (ca. mid-May) seeding dates on glufosinate-, glyphosate-, and imidazolinone-tolerant canola development and yield. Fall seeding resulted in 46% lower plant density and nearly double the dockage than spring seeding. ES-seeded canola had 19% higher seed yield and 2.1% higher oil content than fall-seeded canola. ES seeding significantly increased yield compared to fall-seeded canola for 8 of 10 site -years or compared to NS seeding for 4 of 10 site-years; ES-seeded canola equalled the yield of NS-seeded canola for 6 of 10 site-years. Yield response to seeding date did not differ among herbicide-tolerant cultivars. Seeding date did not influence root maggot damage. Seeding canola as soon as possible in spring increases the likelihood of optimizing canola yield and quality compared to fall seeding and traditional spring seeding dates. Key words: Dormant seeding, seeding management, root maggot, herbicide-resistant crops, yield components, operational diversity

scholarly journals Investigation of the abundance, distribution and composition of microplastics at coastal upwelling sites in the Atlantic Ocean

2016 ◽  
Author(s):  
La Daana K Kanhai ◽  
Rick Officer ◽  
Ian O'Connor ◽  
Richard C Thompson
Keyword(s):  
Atlantic Ocean ◽  
Surface Waters ◽  
Primary Productivity ◽  
Null Hypothesis ◽  
Latitudinal Gradient ◽  
Coastal Upwelling ◽  
Abundance Distribution ◽  
Significant Difference ◽  
Benguela Upwelling ◽  
Canary Upwelling

Microplastics are an issue of international concern due to the fact that these substances may potentially threaten biota by (i) causing physical harm, (ii) transporting persistent, bioaccumulating and toxic (PBT) substances and, (iii) leaching plastic additives. Within the world’s oceans, areas which experience coastal upwelling are biota rich due to their high levels of primary productivity. The assessment of microplastic presence in areas which experience coastal upwelling is vital as it will indicate whether microplastics are an issue of concern in areas which support key biological resources. The null hypothesis of the present study is that microplastic abundance will be lower in areas where there is upwelling. As such, the present study aims to investigate whether microplastic abundance in upwelled areas in the Atlantic Ocean is significantly different from non-upwelled areas. Based on an opportunistic voyage aboard the RV Polarstern, microplastics will be sampled in sub-surface waters along a diverse latitudinal gradient in the Atlantic Ocean i.e. from Bremerhaven (Germany) to Cape Town (South Africa). Based on the proposed route, it will be possible to determine microplastic levels at two areas of coastal upwelling in the Atlantic Ocean (i) Canary Upwelling Ecosystem (CUE) and (ii) Benguela Upwelling Ecosystem (BUE). The results will then be analysed to determine whether there was a statistically significant difference between ‘upwelled areas’ and ‘non-upwelled areas’.

scholarly journals Evaluation of Sesame Yield and Yield Component under Different NPS Fertilizer Rates in Western Tigray, Ethiopia

2020 ◽  
pp. 1-7
Author(s):  
Teame Shimgabr ◽  
Negasi Gebereslasie ◽  
Haile Alene ◽  
Welesenbet Haftu ◽  
Nebyu Tsegay
Keyword(s):  
Grain Yield ◽  
Seed Yield ◽  
Field Experiments ◽  
Growth Yield ◽  
Yield Component ◽  
Yield Attributes ◽  
Significant Difference ◽  
Fertilizer Rates ◽  
Different Levels ◽  
Number Of Branches

Field experiments were conducted in three sites of Western Tigray, Ethiopia. The experiments aimed at identifying optimum the rate of the newly introduced NPS fertilizer impact with different levels on growth, yield attributes, yield and economics of sesame in vertisols of Western Tigray at the Humera station, Banat and Kebabo Kafta Humera and Tsegede Wereda’s. The treatments consisted of six levels of NPS 0, 50, 100, 150, 200 and 250 kg ha-1 and one blanket recommendation N and P was applied. The experiment was laid out in an RCBD with three replications. Yield of Sesame and yield related components showed significant difference (p < 0.001) compared to control. Results showed that number of branches plant-1, length of pod bearing zone (cm), plant height (cm), number of capsules plant-1, seeds capsule-1 and seed yield was significant differences at (P< 0.001) Grain yield increases from 444.8 kg ha-1 to 671.9 kg ha-1 as NPS and 444.8 kg ha-1 to 628 kg ha-1 as NP increases from 0 (control) to 100 kg ha-1 NPS and 41 kg N and 46 kg P205 ha-1 respectively. But NPS was not significant with blanket recommendation of N and P (41 kg N and 46 kg P205 ha-1), therefore no need to replace the NP by NPS fertilizer in the study area.

A fully automated method for late ventricular diastole frame selection in post-dive echocardiography without ECG gating

2021 ◽  
pp. 73-80
Author(s):  
Eric Markley ◽  
◽  
David Q. Le ◽  
Peter Germonpré ◽  
Costantino Balestra ◽  
...  
Keyword(s):  
Field Experiments ◽  
High Reliability ◽  
Rater Bias ◽  
Algorithm Performance ◽  
Frame Selection ◽  
Automated Method ◽  
Significant Difference ◽  
Computer Automation ◽  
Decompression Stress ◽  
Selection Of

Venous gas emboli (VGE) are often quantified as a marker of decompression stress on echocardiograms. Bubble-counting has been proposed as an easy to learn method, but remains time-consuming, rendering large dataset analysis impractical. Computer automation of VGE counting following this method has therefore been suggested as a means to eliminate rater bias and save time. A necessary step for this automation relies on the selection of a frame during late ventricular diastole (LVD) for each cardiac cycle of the recording. Since electrocardiograms (ECG) are not always recorded in field experiments, here we propose a fully automated method for LVD frame selection based on regional intensity minimization. The algorithm is tested on 20 previously acquired echocardiography recordings (from the original bubble-counting publication), half of which were acquired at rest (Rest) and the other half after leg flexions (Flex). From the 7,140 frames analyzed, sensitivity was found to be 0.913 [95% CI: 0.875-0.940] and specificity 0.997 [95% CI: 0.996-0.998]. The method’s performance is also compared to that of random chance selection and found to perform significantly better (p<0.0001). No trend in algorithm performance was found with respect to VGE counts, and no significant difference was found between Flex and Rest (p>0.05). In conclusion, full automation of LVD frame selection for the purpose of bubble counting in post-dive echocardiography has been established with excellent accuracy, although we caution that high quality acquisitions remain paramount in retaining high reliability.

Chilo partellus. [Distribution map].

1989 ◽  
Author(s):  
Keyword(s):  
Chilo Partellus ◽  
Tamil Nadu ◽  
Andhra Pradesh ◽  
Uttar Pradesh ◽  
Stem Borer ◽  
Distribution Map ◽  
Job’S Tears ◽  
Lepidoptera Pyralidae ◽  
New Distribution ◽  
Comoro Islands

Abstract A new distribution map is provided for Chilo partellus (Swinhoe). Lepidoptera: Pyralidae (spotted stem borer). Attacks Sorghum, maize, millet, rice, sugarcane, Job's tears and many grasses. Information is given on the geographical distribution in Africa, Botswana, Cameroon, Comoro Islands, Ethiopia, Kenya, Malawi, Mozambique, Réunion, Somalia, South Africa, Sudan, Tanzania, Uganda, Zimbabwe, Asia, Afghanistan, Cambodia, India, Andhra Pradesh, Assam, Bihar, Delhi, Gujarat, Haryana, Himachal Pradesh, Karnataka, Madhya Pradesh, Maharashtra, Orissa, Punjab, Rajasthan, Tamil Nadu, Uttar Pradesh, West Bengal, Indonesia, Laos, Nepal, Pakistan, Sikkim, Sri Lanka, Thailand, Vietnam, Yemen, Benin, Bangladesh, Indonesia, Japan, Taiwan.

Analyzing the Distribution and Variation of Suspended Particulate Matter in the Yellow River Estuary (YRE) using Landsat 8 OLI

2020 ◽  
Author(s):  
Jin Li ◽  
Yanling Hao ◽  
Zhuangzhuang Zhang ◽  
Zhipeng Li ◽  
Ruihong Yu ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Suspended Particulate Matter ◽  
Yellow River ◽  
River Estuary ◽  
Coastal Areas ◽  
Yellow River Estuary ◽  
Landsat 8 ◽  
Landsat 8 Oli ◽  
Suspended Particulate ◽  
Significant Difference

Abstract Yellow River Estuary (YRE) as well as its adjacent coastal areas are famous for its high concentration of Suspended Particulate Matter (SPM). The distribution of SPM and its variations in the estuary area promoted the carbon, oxygen and nutrient cycles in coastal areas and nearby sea areas. This study took advantage of Landsat 8 Operational Land Imager (Landsat 8 OLI) data to estimate SPM in the YRE from 2013 to 2019. Remote sensing reflectance (R rs ) measured by Landsat 8 OLI has been proved to be effective through cross-validate with Geostationary Ocean Color Imager (GOCI). A simple empirical alogrithm (NIR band ratio green band and add red band) was developed to map the SPM distribution and concentration, with the APD 33.12% and R 2 0.93 based on in-situ data. Annual average distribution of SPM shows that highy turbid areas with SPM greater than 10 3 mg/L are mostly found surrounding the estuary of Yellow River, in the northwest part of the Laizhou Bay and south part of Bohai bay. High variations of SPM distributions are consistent with high SPM, and vice versa. The influences of river runoff is mainly concentrated in the estuary area, and outside 4.5 km the variability of SPM effected by river discharge is not ovbious. Significant difference is observed in seasonal SPM distribution. Higher SPM in winter is observed both in range and intensity compared to summer. Significant seasonal variations are mainly controlled by sediment resuspension processes driven by wind-wave forces. The results of this study indicate that Landsat8 OLI is an effective mean to retrieve SPM in YRE and its adjcent areas.

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