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Soil Organic Carbon Pools Under Switchgrass Grown as a Bioenergy Crop Compared to Other Conventional Crops

Pedosphere 2013年第4期23卷 409-416页

作者： F.G.DOU F.m.HONS W.R.OCUmPAUGH J.C.READ m.A.HUSSEY J.P.mUIR texas a&m agrilife research &extension center at Beaumont Department of Soil and Crop Sciences Texas A&M University texas a&m agrilife research Station at Beeville texas a&m agrilife research and extension center at Dallas texas a&m agrilife research and extension center at Stephenville

Switchgrass （Panicum virgaturn L.） has been proposed as a sustainable bioenergy crop because of its high yield potential, adap- tation to marginal sites, and tolerance to water and nutrient limitations. A better understanding of the potential effects of biomass energy crop production practices on soil biological properties and organic matter dynamics is critical to its production. Our objective was to evaluate changes in C pools under a warm-season perennial switchgrass in different soils compared to typically-grown crops col- lected at College Station, Dallas, and Stephenville, TX in February 2001. Sampling depths were 0-5, 5-15, and 15-30 cm. Switchgrass increased soil organic C （SOC）, soil microbial biomass C （SmBC）, mineralizable C, and particulate organic matter C （POm-C） com- pared to conventional cropping systems. Soil C concentrations were in the order： long-term coastal bermudagrass [Cynodon dactylon （L.） Pers.] 〉 switchgrass or kleingrass （Panicum coloratura L.） planted in 1992 〉 switchgrass 1997 〉 conventional cropping systems. Soil C concentrations tended to increase with increasing clay content. Greater microbial biomass C followed the order of Dallas 〉 College Station 〉 Stephenville, and ranged from approximately 180 mg C kg-1 soil at Stephenville to 1 900 mg C kg-1 soil at Dallas. Particulate organic C was more sensitive than other fractions to management, increasing as much as 6-fold under long-term coastal bermudagrass compared to conventional cropping systems. Our study indicated that conversion of conventional cropping systems into switchgrass production can sequestrate more SOC and improve soil biological properties in the southern USA.

关键词： cropping systems particulate organic C perennial grasses soil microbial biomass C soil mineralizable C

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Potential cotton aphid, Aphis gossypii, population suppression by arthropod predators in upland cotton

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Insect Science 2013年第6期20卷 778-788页

作者： Ram B. Shrestha megha N. Parajulee texas a&m University agrilife research and extension center 1102 E. FM 1294 Lubbock TX 79403 United States

The cotton aphid, Aphis gossypii Glover, predation rate of convergent lady beetle, Hippodamia convergens Guerin-meneville, was determined by assigning a single predator randomly to each of four prey density treatments in the laboratory. Prey densities included 25, 50, 100, and 200 aphids per Petri dish arena. Predation response was recorded at 1, 4, 8, 16, 24, and 48 h after assigning predators to their prey treatments. Rate of consumption increased through time, with all 25 aphids consumed during the first 4 h of the experiment. At the highest density, adult lady beetle consumed on average 49, 99, 131, 163, 183, and 200 aphids within 1, 4, 8, 16, 24 and 48 h, respectively. Predators showed a curvilinear feeding response in relation to total available time, indicating that convergent lady beetles have the potential to suppress larger populations of aphids through continuous feeding by regulating their predation efficiency during feeding. The analysis of age-specific mortality in absence of prey revealed that lady beetles could survive for an extended period of time （more than 2 weeks） without prey. The ability of a predator to survive without prey delays or prevents the rebound of pest populations that is a significant factor in natural biological control. A two-year field sampling of 10 cotton arthropod predator species showed that spiders （27%） were the most dominant foliage dwelling predators in the texas High Plains cotton followed by convergent lady beetles （23.5%）, hooded beetles （13.5%）, minute pirate bugs （11%）, green lacewings （9.5%）, bigeyed bugs （7.5%）, scymnus beetles （3%）, soft-winged flower beetles （2%）, damsel bugs （1.5%）, and assassin bugs （1.5%）. A field cage study showed that one H. convergens adult per plant released at prey density of one aphid per leaf kept the aphid population below economic threshold for the entire growing season.

关键词： Aphis gossypii biological control cotton IPm functional response Hippo-damia convergens natural suppression

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Relative preference of Lygus hesperus （Hemiptera： miridae） to selected host plants in the field

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Insect Science 2010年第6期17卷 542-548页

作者： Apurba K. Barman megha N. Parajulee Stanley C. Carroll Department of Entomology Texas A&M University College Station texas agrilife research center Lubbock Texas USA

Information on host plant preference of agriculturally important insect pests, such as Lygus hesperus （Knight）, can be helpful in predicting its occurrence and future movement among crop and nonrop host plants. A field study was conducted during 2005 and 2006 to evaluate the host preference of Lygus to cotton and four other host plants in the texas High Plains, including alfalfa （medicago sativa L.）, wild sunflower （Helianthus annuus L.）, Russian thistle （Salsola iberica L.） and pigweed （Amaranthus palmeri L.）. Sampling for both nymphs and adults during 2005 （July to November） and 2006 （June to November） showed that alfalfa and Russian thistle were the two most preferred hosts out of the five hosts evaluated. Abundance of nymphs （numbers per 50 sweeps per host plant） during the sampling period also indicated the superior reproductive suitability of alfalfa and Russian thistle. Cotton appeared to be the least attractive host plant for Lygus when Russian thistle and alfalfa were available in the host mosaic. Seasonal abundance of Lygus was found to be lower during 2006 compared to 2005, which may be explained by the difference in rainfall patterns during these two years. In terms of species dominance, L. hesperus was the most dominant species in the sampled population followed by an inconsiderable fraction ofL. elisus and L. lineolaris.

关键词： cotton crop host-plant preference Lygus hesperus non-cotton crops

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Shoot and root traits in drought tolerant maize(Zea mays L.) hybrids

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Journal of Integrative Agriculture 2018年第5期17卷 1093-1105页

作者： ZHAO Jin XUE Qing-wu Kirk E Jessup HOU Xiao-bo HAO Bao-zhen Thomas H marek XU Wen-wei Steven R Evett Susan A O'Shaughnessy David K Brauer texas a&m agrilife research and extension center at Amarillo TX 79106 USA Department of Soil Water and Environmental Sciences University of Arizona AZ 85721 USA School of Science and Technology Xinxiang University Xinxiang 453003 P.R.China texas a&m agrilife research and extension center at lubbock TX 79403 USA USDA-ARS Conservation and Production research Laboratory TX 79012 USA

This study aimed to investigate the differences in shoot and root traits, and water use and water use efficiency（WUE） in drought tolerant（DT） maize（Zea mays L.） hybrids under full and deficit irrigated conditions. A two-year greenhouse study was conducted with four hybrids（one conventional hybrid, 33D53Am, two commercial DT hybrids, P1151 Am, N75H, and an experimental hybrid, Exp HB） grown under two water regimes（I（100） and I（50）, referring to 100 and 50% of evapotranspiration requirements）. Under water stress, the hybids P1151 Am, N75, and Exp HB showed more drought tolerance and had either greater shoot dry weight or less dry weight reduction than the conventional hybrid（33 D53 Am）. However, these three hybrids responded to water stress using different mechanisms. Compared with the conventional hybrid, the two commercial DT hybrids（P1151 Am and N75H） had a smaller leaf area, shoot dry weight, and root system per plant. As a result, these hybrids used less water but had a higher WUE compared with the conventional hybrid. In contrast, the experimental hybrid（ExpHB） produced more shoot biomass by silking stage at both irrigation levels than all other hybrids, but it had relatively lower WUE. The hybrids demonstrated different drought response mechanisms that may require different irrigation management strategies. more investigation and validation are needed under field conditions and in different soil types.

关键词： drought tolerant hybrid rooting characteristics water use water use efficiency

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metapopulation approach for landscape level management of western tarnished plant bug,Lygus hesperus,in texas( Hemiptera,miridae)

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植物保护学报 2014年第6期41卷 761-768页

作者： Parajulee megha N Shrestha Ram B texas A & m University System agrilife research and extension center

Insect source-sink dynamics are vital to ecologically intensive pest management. maintaining sink plant hosts,or "trap crops",and destroying alternate hosts or breeding places adjacent to the field crop are effective pest management strategies for some arthropods. However,determining whether a host acts as a source or a sink is challenging, especially when the pest species is highly mobile and polyphagous. The western tarnished plant bug,Lygus hesperus,is highly polyphagous,and can utilize >300 hosts. Its presence has been documented in 26 roadside weed hosts in the texas High *** studies demonstrated that L. hesperus prefer alfalfa over cotton and several alternate weed hosts.A four-year project involved surveying and sampling for L. hesperus in the agricultural landscapes of several sub-regions of the southwestern United States,including the texas High Plains. In texas,geographic information of the landscape vegetation complex was compiled from a 150 km radius in the texas High Plains. In one study,fifty irrigated cotton fields representing the crop diversity within this region were sampled via sweep-net for 10 weeks. This effort also included sampling of up to six noncotton insect habitats within a 3 km radius of each field. Seasonal average L. hesperus abundance data were regressed with 27 field characteristics( variables),including habitat-specific land cover,distance between focal cotton fields and non-cotton habitats,longitude,latitude,elevation,habitat heterogeneity index,and several environmental / ecological variables. Significant variables were selected using a stepwise regression at 15% probability rate. A 10-parameter linear model explained 93% of the variation in the data. major parameters contributing significantly to variation in L. hesperus abundance in cotton were corn and sunflower acreages,focal cotton field distances from several non-cotton hosts,and habitat heterogeneity index. In addition,field marking-and-capture studies were cond

关键词： western tarnished plant bug cotton IPm ecological pest management alternate host management

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Effects of seed mixture sowing with transgenic Bt rice and its parental line on the population dynamics of target stemborers and leafrollers, and non-target planthoppers

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Insect Science 2019年第4期26卷 777-794页

作者： Zhuo Li Li-Kun Li Bin Liu Long Wang megha N. Parajulee Fa-Jun Chen Department of Entomology Nanjing Agricultural University Nanjing China texas a&m University Agri Life research and extension center Lubbock Texas USA

The widespread planting of insect-resistant crops has caused a dramatic shift in agricultural landscapes, thus raising concerns about the potential impacts on both target and non-target pests. In this study, we examined the potential effects of intra-specific seed mixture sowing with transgenic Bt rice (Bt) and its parental non-transgenic line (Nt)(100% Bt rice [Bt100], 5% Nt+95% Bt [Nt05Bt95], 10% Nt+90% Bt [Nt|0Bt90], 20% Nt+80% Bt [Nt2oBtso], 40% Nt+60% Bt [Nt4oBt6O] and 100% Nt rice [Ntjoo]) on target and non-target pests in a 2-year field trial in southern China. The occurrence of target pests, Sesamia inf evens. Chilo suppressalis and Cnaphalocrocis medinalis, decreased with the increased ratio of Bt rice, and the mixture ratios with more than 90% Bt rice (Btjoo and Nt()5Bt95) significantly increased the pest suppression efficiency, with the lowest occurrences of non-target planthoppers, Nilaparvata lugens and Sogatella jurcijera in Ntioo and NtosBtgs. Furthermore, there were no significant differences in 1000?grain dry weight and grain dry weight per 100 plants between Btjoo and NtosBtgs,Seed mixture sowing of Bt rice with me potential compliance issues that exist with the use of block or structured refuge to provide most effective control of both target and non-target pests without compromising the grain yield. It is also expected that the strategy of seed mixture sowing with transgenic Bt rice and the nontransgenic parental line would provide rice yield stability while decreasing the insecticide use frequency in rice production.

关键词： cultivar diversity occurrence and damage seed mixture sowing target and non-target pests transgenic Bt rice yield

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Code modernization and modularization of APEX and SWAT watershed simulation models

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International Journal of Agricultural and Biological Engineering 2015年第3期8卷 81-94页

作者： Robin A.J.Taylor Jaehak Jeong michael White Jeffrey G.Arnold Blackland research&extension center Texas A&M AgriLife ResearchTempleTexas 76502USA Grassland Soil&Water research Laboratory USDA-ARS TempleTexas 76502USA

SWAT(Soil and Water Assessment Tool)and APEX(Agricultural Policy/Environmental eXtender)are respectively large and small watershed simulation models derived from EPIC(Environmental Policy Integrated Climate),a field-scale agroecology simulation *** three models are coded in Fortran and have evolved over several *** are widely used to analyze anthropogenic influences on soil and water quality and *** of the original Fortran code has been retained even though Fortran has been through several cycles of *** now provides functionality originally restricted to languages like C,designed to communicate directly with the operating system and *** can now use an object-oriented style of programming in Fortran,including inheritance,run-time polymorphism and *** order to enhance their utility in research and policy-making,the models are undergoing a major revision to use some of the new Fortran *** these new programming paradigms the developers of SWAT,APEX,and EPIC are working to make communication between the two models *** paper describes the ongoing revision of these models that will make them easier to use,maintain,modify and *** is intended that they will converge as they continue to evolution,while maintaining their distinctive features,capabilities and identities.

关键词： code modernization modularization object-oriented programming Fortran 2008 landscape-scale models APEX EPIC SWAT

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Testing the rate isomorphy hypothesis using five statistical methods

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Insect Science 2012年第1期19卷 121-128页

作者： Xian-Ju Kuang megha N.Parajulee Pei-Jian Shi Feng Ge Fang-Sen Xue Institute of Entomology Jiangxi Agricultural UniversityNanchangChina texas a&m agrilife research and extension center Lubbock TexasUSA Institute of Zoology Chinese Academy of SciencesBeijing Graduate University of Chinese Academy of Sciences Beijing China

Organisms are said to be in developmental rate isomorphy when the pro- portions of developmental stage durations are unaffected by temperature. Comprehensive stage-specific developmental data were generated on the cabbage beetle, Colaphellus bowringi Baly （Coleoptera： Chrysomelidae）, at eight temperatures ranging from 16℃ to 30℃ （in 2℃ increments） and five analytical methods were used to test the rate isomor- phy hypothesis, including：（i） direct comparison of lower developmental thresholds with standard errors based on the traditional linear equation describing developmental rate as the linear function of temperature; （ii） analysis of covariance to compare the lower devel- opmental thresholds of different stages based on the Ikemoto-Takai linear equation; （iii） testing the significance of the slope item in the regression line of arcsin（√p） versus tem- perature, where p is the ratio of the developmental duration of a particular developmental stage to the entire pre-imaginal developmental duration for one insect or mite species; （iv） analysis of variance to test for significant differences between the ratios of developmental stage durations to that ofpre-imaginal development; and （v） checking whether there is an element less than a given level of significance in the p-value matrix of rotating regres- sion line. The results revealed no significant difference among the lower developmental thresholds or among the aforementioned ratios, and thus convincingly confirmed the rate isomorphy hypothesis.

关键词： analysis ofcovariance lower developmental threshold rate isomorphy sum of effective temperatures temperature

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Numerical Simulation on a Tremendous Debris Flow Caused by Typhoon morakot in the Jiaopu Stream,Taiwan

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Journal of mountain Science 2014年第1期11卷 1-18页

作者： HSU Yu-chao YEN Haw TSENG Wen-hsiao JAN Chyan-deng Department of Hydraulic and Ocean Engineering National Cheng Kung University Blackland research and extension center Texas A&M AgriLife Research Sun-Rise Engineering Consultant Company

In August 2009,Typhoon morakot brought a large amount of rainfall with both high intensity and long duration to a vast area of ***,this resulted in a catastrophic landslide in Hsiaolin Village,***,large amounts of landslides were formed in the Jiaopu Stream watershed near the southeast part of the Hsiaolin *** Hsiaolin Village access road(Provincial Highway No.21 and Bridge No.8) was completely destroyed by the landslide and consequent debris *** major scope of this study is to apply a debris flow model to simulate the disaster caused by the debris flow that occurred in the Jiaopu Stream during Typhoon *** to the interviews with local residents,this study applied the destruction time of Bridge No.8 and Chen's house to verify the numerical debris flow *** the spatial rainfall distributions information,the numerical simulations of the debris flow are conducted in two *** the first stage(before the landslide-dam failure),the elevation of the debris flow and the corresponding potential damages toward residential properties were *** the second stage(after the landslidedam failure),comparisons of simulation results between the longitudinal and cross profiles of the Jiaopu Stream were performed using topographic maps and satellite *** summary,applications of the adopted numerical debris flow model have shown positive impact on supporting better understanding of the occurrence and movement of debris flow processes.

关键词： Typhoon morakot Debris flow Numerical simulation Jiaopu Stream Hsiaolin Village

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Intercrop movement of convergent lady beetle, Hippodamia convergens （Coleoptera： Coccinellidae）, between adjacent cotton and alfalfa

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Insect Science 2016年第1期23卷 145-156页

作者： Anup Bastola megha N. Parajulee R. Patrick Porter Ram B. Shrestha Fa-Jun Chen Stanley C. Carroll texas a&m Universityagrilife research and extension center Lubbock Texas USA Department of Entomology Iowa State UniversityAmes Iowa USA Department of Entomology Nanjing Agricultural University Nanjing China

A 2-year study was conducted to characterize the intercrop movement of conver- gent lady beetle, Hippodamia convergens Guerin-meneville （Coleoptera： Coccinellidae） between adjacent cotton and alfalfa. A dual protein-marking method was used to assess the intercrop movement of the lady beetles in each crop. In turns field collected lady beetles in each crop were assayed by protein specific ELISA to quantify the movement of beetles between the crops. Results indicated that a high percentage of convergent lady beetles caught in cotton （46% in 2008; 56% in 2009） and alfalfa （46% in 2008; 71% in 2009） contained a protein mark, thus indicating that convergent lady beetle movement was largely bidirectional between the adjacent crops. Although at a much lower proportion, lady beetles also showed unidirectional movement from cotton to alfalfa （5% in 2008 and 6% in 2009） and from alfalfa to cotton （9% in 2008 and 14% in 2009）. The season-long bidirectional movement exhibited by the beetles was significantly higher in alfalfa than cotton during both years of the study. The total influx of lady beetles （bidirectional and unidirectional combined） was significantly higher in alfalfa compared with that in cotton for both years. While convergent lady beetles moved between adjacent cotton and alfalfa, they were more attracted to alfalfa when cotton was not flowering and/or when alfalfa of- fered more opportunities for prey. This study offers much needed information on intercrop movement of the convergent lady beetle that should facilitate integrated pest management decisions in cotton utilizing conservation biological control.

关键词： enzyme-linked irnrnunosorbent assay Hippodamia convergens markcapture protein marker

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