红麻种质资源根结线虫病抗性鉴定

为鉴定我国红麻种质资源对根结线虫病的抗病性,在对120份红麻遗传资源进行田间自然发病鉴定的基础上,选择25份有代表性(22份高抗和3份感病)的种质进行盆栽根结线虫病接种鉴定。田间自然发病鉴定结果:120份红麻遗传资源中5个高感、19个中感、25个中抗、71个高抗;其侵染的根结线虫主要为南方根结线虫(Meloidogyne incognita)、爪哇根结线虫(Meloidogyne javanica)和花生根结线虫(Meloidogyne arenria)的混合种群。进行盆栽接种鉴定的25份遗传资源中,7份为中抗,其余分别为中感和高感品种,未发现高抗或免疫品种。本研究可为红麻种质资源发掘利用提供科学依据。     

Response of Soybean in Cyst Nematode-Infested Soils at Three Soil Water Regimes

Large pot (2 years) and field experiments (1 year) were conducted to determine the response of susceptible soybean Glycine max (L.) Merr. cultivars (Essex and Hutcheson) grown in soybean-cyst-nematode (SCN), Heterodera glycines-infested soils at three soil water regimes. The soil water regimes were irrigation whenever soil water potential ([psi]s) 0.30-m deep was i) -30 kPa (I-30) or ii) - 50 kPa (I-50), and iii) no irrigation. Cyst nematode levels in the pot experiment were either 0 or 20,000 second-stage juveniles (J2) per pot. The field experiment was conducted on soil naturally infested with a population of 145 to 475 cysts L⁻¹ of soil. All growth parameters studied were drastically affected in the presence of SCN under nonirrigated conditions for the large pot tests; however, SCN did not influence growth parameters in the field experiment. Seed yield was lowest in the no irrigation treatment when all treatments were compared in both the pot and field experiments. The infested no irrigation treatment in the pot experiment had the lowest yield among soil water treatments.     

Characterization of antibiosis and antixenosis to the soybean aphid (Hemiptera: Aphididae) in several soybean genotypes

The soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), is an introduced pest of soybean, Glycine max (L.) Merr., in North America, and it can reduce yields by 50%. Since 2000, when A. glycines was first detected in the United States, studies of this insect and possible control methods have been initiated. Plant resistance to this aphid species is one important component of integrated control. Reproduction of A. glycines was compared on 240 soybean entries in a pesticide-free greenhouse. Eleven entries had fewer nymphs produced, compared with the susceptible checks, and these entries were used in follow-up experiments to assess antibiosis and antixenosis. Antibiosis was estimated in true no-choice tests, in which adults were confined individually in double-sided sticky cages stuck to the upper side of leaves. Antixenosis was assessed in choice tests, in which all entries were planted in a single pot. Adult aphids were placed in the center of the pot, and 24 h later the number of adults on each plant was counted. Of the 11 entries evaluated, nine showed a moderate antibiotic effect to A. glycines, and the other two entries (K1639 and Pioneer 95B97) showed not only a strong antibiotic effect but also exhibited antixenosis as a category of resistance to A. glycines. The resistant soybean entries found in this work are potential sources for A. glycines control.     

Localization by restriction fragment length polymorphism mapping in potato of a major dominant gene conferring resistance to the potato cyst nematode Globodera rostochiensis

Summary A major dominant locus conferring resistance against several pathotypes of the root cyst nematode Globodera rostochiensis was mapped on the linkage map of potato using restriction fragment length polymorphism (RFLP) markers. The assessment of resistance versus susceptibility of the plants in the experimental population considered was based on an in vivo (pot) and an in vitro (petri dish) test. By linkage to nine RFLP markers the resistance locus Gro1 was assigned to the potato linkage group IX which is homologous to the tomato linkage group 7. Deviations from the additivity of recombination frequencies between Gro1 and its neighbouring markers in the pot test led to the detection of a few phenotypic misclassifications of small plants with poor root systems that limited the observation of cysts on susceptible roots. Pooled data from both tests provided better estimates of recombination frequencies in the linkage interval defined by the markers flanking the resistance locus.     

Characterization of resistance, evaluation of the attractiveness of plant odors, and effect of leaf color on different onion cultivars to onion thrips (Thysanoptera: Thripidae)

Onion thrips, Thrips tabaci Lindeman (Thysanoptera: Thripidae), is a worldwide pest of onion, Allium cepa L. In field studies on onion resistance conducted in 2007 and 2008 using 49 cultivars, 11 showed low leaf damage by T. tabaci. In laboratory studies, the 11 cultivars, along with two susceptible checks and four additional cultivars, were evaluated to characterize resistance to T. tabaci and to determine if color and/or light reflectance were associated with resistance to T tabaci. No-choice tests were performed with adults and the numbers of eggs and larvae were counted on each cultivar after three and 10 d, respectively. In choice tests in which all cultivars were planted together in a circle in a single pot, 100 adults were released and the number of adults on each plant was evaluated 24 h later. The behavioral response of walking T. tabaci adults to plant odors was studied in a glass Y-tube olfactometer. The reflectance spectrum of leaves was measured using a UV-VIS spectrophotometer. Results indicate that resistant cultivars showed an intermediate-high antibiotic effect to T. tabaci and all of them showed a very strong antixenotic effect. There were no significant preferences in the response of walking T. tabaci adults to plant odors. The two susceptible cultivars had the highest values of leaf reflectance for the first (275-375 nm) and second (310-410 nm) theoretical photopigment-system of T. tabaci, and these values were significantly different from most resistant cultivars. These results suggest a strong response of T. tabaci to onion cultivars with higher reflectance in the ultraviolet range (270-400 nm). Overall, these results appear promising in helping to identify categories of resistance to T. tabaci in onions that can be used in breeding programs.     

Induced Resistance to Meloidogyne hapla by other Meloidogyne species on Tomato and Pyrethrum Plants

Advance inoculation of the tomato cv. Celebrity or the pyrethrum clone 223 with host-incompatible Meloidogyne incognita or M. javanica elicited induced resistance to host-compatible M. hapla in pot and field experiments. Induced resistance increased with the length of the time between inoculations and with the population density of the induction inoculum. Optimum interval before challenge inoculation, or population density of inoculum for inducing resistance, was 10 days, or 5,000 infective nematodes per 500-cm³ pot. The induced resistance suppressed population increase of M. hapla by 84% on potted tomato, 72% on potted pyrethrum, and 55% on field-grown pyrethrum seedlings, relative to unprotected treatments. Pyrethrum seedlings inoculated with M. javanica 10 days before infection with M. hapla were not stunted, whereas those that did not receive the advance inoculum were stunted 33% in pots and 36% in field plots. The results indicated that advance infection of plants with incompatible or mildly virulent nematode species induced resistance to normally compatible nematodes and that the induced resistance response may have potential as a biological control method for plant nematodes.     

THE CONTROL OF FUSARIUM BLIGHT IN OAT SEEDLINGS WITH ANTAGONISTIC SPECIES OF CHAETOMIUM

Forty-seven isolates representing twenty-seven species of Chaetomium were tested for their ability to control seedling blight of oat seedlings caused by Fusarium spp., chiefly F. nivale (Fr.) Ces. In pot tests the majority of the isolates were ineffective, but certain isolates of Chaetomium cochliodes Pall, and C. globosum Kunze gave a large measure of control and were as effective as an organic mercury seed dressing. Control of disease was also obtained when living material was attached to the surface of oat seed and when infested seed was soaked in cell-free filtrates from cultures of isolates which reduced disease in vivo.
Substantial control of disease was obtained when infested seed was sown in soil to which cultures of C. cochliodes had been added 10 months previously. This antagonist was able to grow through unsterile soil in the presence of certain added substrates.
The results of pot experiments were confirmed in field experiments.
Isolates of Chaetomium which controlled disease in pot and field experiments were not strikingly antagonistic to Fusariirm nivale in pure culture on agar media.     

The efficiency of pot trials,or trials on undisturbed soil cores,as predictors of crop behaviour in the field

This study compares the efficiency of pot trials in the glasshouse or outdoors, and trials on undisturbed soil cores (100 cm deep; 15 cm wide), at simulating field trials. Yields of spring barley (Hordeum vulgare, cv Julia) were measured at sites on seven soil series on 11 farms, and also on undisturbed soil cores from the same sites, and in pot trials using disturbed soil from the same sites, to ascertain how far data from the core and pot trials (simulation procedures) could be used to generate the models, regressions or generalisations that were produced by more laborious and time-consuming field trials. There was no evidence of interactions between the soil series and simulation procedures. Correlations between field yields and yields from simulation procedures showed that the undisturbed cores gave the highest correlation (r=0.59^**) with field yields. This was followed by yields measured in outdoor pot trials (r=0.36^** and 0.67^** in two years), and by pot trials in the glasshouse (r=0.11 and 0.25, neither significant). In regressions of field yield on yields from simulation trials, the intercept on the field yield axis was lowest for cores and highest for pot trials in the glasshouse. Anovar studies on the partitioning of the total variability in trial yields showed that undisturbed cores gave a partitioning of yields more similar to that of field trials than did the pot trials. In some respects, but not all, core trials also gave the most similar regressions of yield on soil properties to those obtained from field trials. The use of undisturbed cores, collected at sites of interest and carried to a central site, combines the advantages of field trials (natural soil structure and environment) with those of pot trials (standard environment, easier management).     

重庆市槽上无公害蔬菜基地生态建设的研究

无公害蔬菜生产的关键是在产品质量安全的同时 ,谋求其最大输出量 ,而质量与产量的保证基础是基地建设 ,只有合格的基地才能生产出合格的无公害蔬菜[4 ] 。现有的无公害蔬菜基地大多处于生态保护较好、环境质量较优的偏远地区。对于地处城郊结合部的蔬菜产地 ,一方面受到城市污染的潜在威胁 ,另一方面其生态结构又呈简单化趋势 ,能否保证无公害蔬菜的产量和质量 ,是无公害蔬菜生产中一个值得研究的课题。本文根据重庆市现有蔬菜基地情况 ,选择近郊区槽上基地的部分区域 ,进行调查、分析、试验、规划等 ,探讨建立城郊可持续性的无公害蔬菜基…     

不同遗传背景及环境中水稻（Oryza sativa L.）穗长的QTLs和上位性分析

以粳稻Ａｚｕｃｅｎａ为父本与灿稻ＩＲ６４杂交发展的一双单倍体（ＤＨ） 本,与灿稻ＩＲ１５５２杂交发展的一重组自交系（ＲＩ）群体为材料,应用分子标记图说对２个群体在大田答舅栽２个环境下的穗长进行ＱＴＬｓ及上位性效应分析,ＤＨ群体中共检测６个穗长ＱＴＬｓ,位于第１、４长染色体上的３个ＱＴＬｓ,,在２个环境中稳定表达,未检测一闰性效应,加性效应为穗长遗传主效应,ＲＩ群体中,共检测到３个穗长ＱＴＬｓ及６对     

Limitations of the32P isotope injection technique for the study of the root systems of wheat,mung and cowpeas

Summary The³²P isotope injection technique developed by earlier investigators in graminea has been extensively tested, under irrigated agriculture, using three promising varieties of wheat Pusa Lerma (a single gene dwarf) Sharbati Sonora (a double gene dwarf) and a triple gene dwarf 1634. Field experiments supported by pot experiments using both sand and soil cultures gave identical results.Unlike the wheats with a succulant stem the legumes are fibrous and do not permit injection in the stem. The technique was, therefore, modified and the injection had to be given on the leaf stem instead of the plant stem.While equilibrium in wheat was obtained five days after injection both in pot and field experiments mung behaves in a different manner. In the pot experiments the equilibrium could not be attained till the 12th day while in the field experiments it was attained even on the first day after injection. Mung has a thick tap root surrounded by fine secondary roots. The activity was observed to move very fast in the thick tap root even on the first day while the thin secondary roots showed resistance and attained equilibrium on the 3rd day.The anomaly observed in the pot and field experiments was attributed partly to the differential root growth under the two environments studied and to some extent on the probable loss of fine roots in the collection on the field. However, the plants grown both in pots as well as on the field attained equilibrium on the 12th day. In the case of cowpeas the equilibrium was attained on the 8th day.The period required for attaining uniform distribution of activity thus seems to be a function of the morphology of the plant, the pattern of the root system and the injection technique adopted. As this is a pre-requisite for the quantitative estimation of the roots care has to be taken in perfecting the technique.Part of the thesis for which Ph.D. degree was awarded to K. Vijayalakshmi by the Indian Agricultural Research Institute, New Delhi.Dry Land Agriculture Centre, Hyderabad.Nuclear Research Laboratory, at present International Atomic Energy Agency Expert, Mymensingh, Bangladesh.     

Evaluation of NemX,a New Cultivar of Cotton with High Resistance to Meloidogyne incognita

The level of resistance to root-knot nematode, Meloidogyne incognita, in NemX, a new cultivar of the Acala-type upland cotton, was evaluated in relation to four resistant breeding lines (N6072, N8577, N901, and N903) and four susceptible cultivars (Maxxa, SJ2, Royale, and Prema). In growth pouch tests, an average of only 4 nematode egg masses was produced on roots of NemX or the resistant lines, compared to a significantly higher average of 21 on the susceptible cultivars. In pot tests, the nematode reproduction factor (RF = Pf/Pi) in NemX and the resistant lines averaged 0.7, compared to a significantly higher average of 10 on the susceptible cultivars. Root galling in NemX or other resistant cotton averaged 15%, compared to 74% on the susceptible cultivars, in either pot or field tests. In plots with low levels of nematode infestation (Pi ≤ 150 second-stage juveniles [J2]/500 g soil), lint yield of NemX averaged 1,370 kg/ha and was less than the yield of susceptible Maxxa (1,450 k g /h a ). However, in plots with medium or high levels of nematode infestation (Pi = 151-300 or >300 J2/500 g soil, respectively), yields of NemX decreased only slightly and averaged 1,300 or 1,050 kg/ha, respectively, whereas yields of Maxxa were severely reduced to 590 or 503 kg/ha, respectively. Fusarium wih symptoms were observed on both NemX and Maxxa, and percent occurrence increased with increasing preplant nematode density. In plots with the highest nematode densities, 22% of NemX and 65% of Maxxa plants were wilted. NemX was highly effective against five M. incognita isolates and moderately effective against a sixth isolate that had been exposed to resistant cotton over several seasons. These results showed that NemX is as resistant to M. incognita as the four breeding lines, and much more resistant than the tested susceptible cultivars of cotton.     

Evaluation of Bacillus subtilis for Potential Control of Apple Replant Disease

Apple seedlings (ev. Melntosh were stunted when grown in pasteurized field soil to which four fungi, previously isolated from apple replant disease (ARD) soil, were added. Twenty-one isolates of Bacillus sulnths produced inhibition zones in vitro against 20 ARD fungi. Isolate BACT-1 ol B. subtilis showed significant antagonism against 17 fungi isolated from ARD soil on potato dexirose agar and apple plant height was increased in its presence in pesteurized and fertilized soil in glasshouse pot tests. Plant height also increased in the presence of isolate F.BW-4 of B.subtilis.in pasteurized and fertilized soil in glasshouse pot tests but EBW-4 liid not show antagonism against most of the ARD tungi in vitro. The growth of apple seedlings was stunted in the presence of 12 isolates of B. subtilis. However, fertilization of non pasteurized soil with NPK 1l-55-0 reversed the stunting effect. Under field conditions, BACT-1 and EBW-4 isolates. led to increased shoot growth in unfertilized and unppasteurized ARD soil.     

The effect of manganese deficiency and cereal cyst nematode infection on the growth of barley

Summary Two factorial pot experiments, each with four rates of soil-applied manganese (Mn), four levels of cereal cyst nematodes (CCN) and four replicates, were conducted under controlled environmental conditions to investigate the interaction of these factors on growth of barley. The experiments were harvested sequentially to count numbers of nematodes at two developmental stages. Development of the nematodes was independent of the Mn status of the host, indicating no effect of Mn on host resistance. In the absence of CCN, decreased Mn had a small effect on vegetative growth, not significantly decreasing dry weight of tops but tolerance at the higher densities of CCN was considerably reduced at low Mn supply, both vegetative growth and grain yield being depressed. Increasing CCN density exerted little effect on the growth of Mn sufficient hosts. Two field surveys supported conclusions from the pot experiments in that increasing nematode densities were correlated with decreasing plant size only at the site where plants were low in Mn. An implication for the field is that crops infected with the nematode and also low in Mn may yield less than expected because the two factors interact to reduce growth and retard development.     

Response of cowpea (Vigna unguiculata) to inoculation with VA-mycorrhizal fungi and to rock phosphate fertilization in some unsterilized Nigerian soils

Summary The effects on cowpea of inoculation with vesicular-arbuscular (VA) mycorrhizal fungi and rock phosphate (RP) fertilization were studied in pots using Alagba and Araromi series soils and in the field on Alagba, Apomu and Egbeda series soils. Inoculation of the plants with VA-mycorrhizal fungi caused very rapid infection of the roots. A higher per cent mycorrhizal infection was maintained during subsequent plant growth in the field. RP application reduced the degree of infection without affecting plant growth in the field and in pot experiments. Nodulation, nitrogen fixation and utilization of RP were increased by inoculation with mycorrhizal fungi in the pot experiments but not in the field experiments. In the pot experiments, inoculated plants supplied with RP flowered earlier, and took up more phosphorus than either inoculated plants without RP or uninoculated plants. The largest response to inoculation in terms of shoot dry matter, nodule yield and nitrogen content of shoots was obtained in Alagba soil under both pot and field conditions.IITA Journal Series Paper No. 136.     

Effect of arbuscular mycorrhizal fungi inoculation of rice seedlings at the nursery stage upon performance in the paddy field and greenhouse

We examined the effect of arbuscular mycorrhizal fungi inoculation at the nursery stage on the growth and nutrient acquisition of wetland rice (t Oryza sativa L.) under field and pot conditions. Seedlings were grown on -ray sterilized paddy soil in two types of nurseries, namely dry nursery and wet nursery, with or without arbuscular mycorrhizal fungi (AMF) inoculation which was a mixture of indigenous AMF (t Glomus spp.) spores collected from the paddy field. Five-to-six week old seedlings were transplanted to the unsterilized soil under field and pot, respectively. Mycorrhizal seedlings had higher shoot biomass under both nursery conditions 5 weeks after sowing. Mycorrhizal colonization and sporulation were 2 to 3 times higher in the dry nursery than the wet nursery at the transplanting stage. Mycorrhizal colonization of plants inoculated in the nursery remained higher than those not inoculated under both field and pot conditions. Sporulation after transplanting to field conditions was about 10 times higher than in the pot. Inoculated plants produced higher biomass at maturity under field conditions, and the grain yield was 14-21% higher than those not inoculated. Conversely, grain yield and shoot biomass were not significantly influenced by AMF colonization under pot conditions. For plants originating from the dry nursery, N, P, Zn and Cu concentrations of field-grown plants at harvest were significantly increased by preinoculation with AMF over those left uninoculated. We conclude that the AMF inoculation at the nursery stage under both dry and wet conditions increased growth, grain yield and nutrient acquisition of wetland rice under field conditions.     

RFLP Mapping of Genes Conferring Complete and Partial Resistance to Blast in a Durably Resistant Rice Cultivar

Moroberekan, a japonica rice cultivar with durable resistance to blast disease in Asia, was crossed to the highly susceptible indica cultivar, CO39, and 281 F(7) recombinant inbred (RI) lines were produced by single seed descent. The population was evaluated for blast resistance in the greenhouse and the field, and was analyzed with 127 restriction fragment length polymorphism (RFLP) markers. Two dominant loci associated with qualitative resistance to five isolates of the fungus were tentatively named Pi-5(t) and Pi-7(t). They were mapped on chromosomes 4 and 11, respectively. To identify quantitative trait loci (QTLs) affecting partial resistance, RI lines were inoculated with isolate PO6-6 of Pyricularia oryzae in polycyclic tests. Ten chromosomal segments were found to be associated with effects on lesion number (P < 0.0001 and LOD > 6.0). Three of the markers associated with QTLs for partial resistance had been reported to be linked to complete blast resistance in previous studies. QTLs identified in greenhouse tests were good predictors of blast resistance at two field sites. This study illustrates the usefulness of RI lines for mapping a complex trait such as blast resistance and suggests that durable resistance in the traditional variety, Moroberekan, involves a complex of genes associated with both partial and complete resistance.     

Combination of all-stage and high-temperature adult-plant resistance QTL confers high-level,durable resistance to stripe rust in winter wheat cultivar Madsen

Key message

Wheat cultivar Madsen has a new gene on the short arm of chromosome 1A and two QTL for all-stage resistance and three QTL for high-temperature adult-plant resistance that in combination confer high-level, durable resistance to stripe rust.

Abstract

Wheat cultivar Madsen has maintained a high-level resistance to stripe rust over 30 years. To map quantitative trait loci (QTL) underlying the high-level, durable resistance, 156 recombinant inbred lines (RILs) developed from cross Avocet S?×?Madsen were phenotyped with selected races of Puccinia striiformis f. sp. tritici in the greenhouse seedling tests, and in naturally infected fields during 2015–2017. The RILs were genotyped by SSR and SNP markers from genotyping by sequencing and the 90 K wheat SNP chip. Three QTL for all-stage resistance were mapped on chromosomes 1AS, 1BS and 2AS, and two QTL for high-temperature adult-plant (HTAP) resistance were mapped on 3BS and 6BS. The most effective QTL on 2AS, explaining 8.97–23.10% of the phenotypic variation in seedling tests and 8.60–71.23% in field tests, contained Yr17 for all-stage resistance and an additional gene for HTAP resistance. The 6BS QTL, detected in all field tests, was identified as Yr78. The 1AS QTL, conferring all-stage resistance, was identified as a new gene, which explained 20.45 and 30.23% of variation in resistance to races PSTv-37 and PSTv-40, respectively, and contributed significantly to field resistance at Pullman in 2015-2017, but was not detected at Mount Vernon. The interactions among QTL were mostly additive, and RILs with all five QTL had the highest level of resistance in the field, similar to Madsen. Genotyping 148 US Pacific Northwest wheat cultivars with markers for the 1AS, 2AS and 6BS QTL validated the genes and markers, and indicated their usefulness for marker-assisted selection.

     

Effects of nutrients and arbuscular mycorrhizal colonization on the growth of Salix gracilistyla seedlings in a nutrient-poor fluvial bar

A field survey and a pot culture experiment were conducted to examine the effects of nutrients (N and P) and arbuscular mycorrhizal (AM) fungi on the growth of Salix gracilistyla, a pioneer plant in riparian habitats. The plants growing in the field were colonized by AM and/or ectomycorrhizal fungi. However, the direct effect of AM colonization on seedling growth was not detected in the pot culture experiment. In contrast, N application significantly promoted plant growth, suggesting that the growth of S. gracilistyla seedlings is largely limited by the availability of N in the field.     

Monitoring and characterization of diamondback moth (Lepidoptera: Plutellidae) resistance to spinosad

Fourteen populations of the diamondback moth, Plutella xylostella (L.), were collected from fields of crucifer vegetables in the United States, Mexico, and Thailand in 1999 and 2000 for susceptibility tests with spinosad. Most populations were susceptible to spinosad and similar to earlier baseline values, but populations from Thailand and Hawaii showed high levels of tolerance. A statewide survey in Hawaii in 2000 and 2001 indicated resistance problems on several islands. One colony collected in October 2000 from Pearl City, HI, was subjected to further selection pressure, using spinosad in the laboratory, and then was used as the resistant strain (Pearl-Sel) for other tests. Spray tests using the recommended field rates of spinosad on potted broccoli plants in the greenhouse confirmed that field control failures due to resistance were possible in the areas of these collections. Analysis of probit lines from F1 reciprocal crosses between the Pearl-Sel and S strain indicated that resistance to spinosad was inherited autosomally and was incompletely recessive. A direct test of monogenic inheritance based on the F1 x Pearl-Sel backcrosses suggested that resistance to spinosad was probably controlled by one locus. The synergists S,S,S-tributyl phosphorotrithioate and piperonyl butoxide did not enhance the toxicity of spinosad to the resistant colony, indicating metabolic mediated detoxification was probably not responsible for the spinosad resistance. Two field colonies in Hawaii that were resistant to spinosad were not cross-resistant to emamectin benzoate or indoxacarb. Resistance developed in Hawaii due to the continuous cultivation of crucifers in which as many as 50 applications of spinosad per year may have been made to a common population of P. xylostella in sequential plantings, although each grower might have used the labeled restrictions for resistance management. Resistance management strategies will need to address such cropping and pest management practices.