樟子松松针锈病病原菌的鉴定

1989年在黑龙江省阿城市料甸林场,用樟子松(Pinus sylvestrisvar. mongolica Litv.)松针上的春孢子向健康的黄药(Phelledendron amurenseRupr.)和紫花铁线莲(Clematis fusca var. violacea Maxim)叶片人工接种成功。用人工接种所产生的夏孢子向相同寄主植物接种后,再次发病并产生夏孢子。由此证明阿城市料甸林场樟子松松针锈病菌(Cleosporium clematidis Barcl.)的转主寄主为紫花铁线莲和黄药,病原菌种应为铁线莲鞘锈菌(Coleosporium clema(?)idis Barcl.)。     

Evaluation of biological control agents for managing cucurbit powdery mildew on greenhouse-grown melon

An evaluation was made of the ability of two mycoparasite-based products AQ10® ( Ampelomyces quisqualis ) and Mycotal® ( Lecanicillium lecanii ), as well as three strains of Bacillus subtilis , to manage powdery mildew disease, caused by Podosphaera fusca on melon seedlings maintained under different regimes of relative humidity and on plants grown under greenhouse conditions in Spain. In every case fungal and bacterial biocontrol agents (BCAs) performed better under conditions of high relative humidity (90–95% RH). In greenhouse experiments, the effectiveness of the mycoparasites to manage powdery mildew was absolutely dependent on mineral oil. The strains of B. subtilis provided disease control similar to that achieved with the mycoparasites or the fungicide azoxystrobin. Microscopic analysis showed the ability of these bacterial strains to efficiently colonize leaf surfaces and revealed the occurrence of antagonistic interactions between biological agents and P. fusca structures. These results confirmed the usefulness of these BCAs for managing powdery mildew on greenhouse-grown cucurbits either as single products or as a component of integrated control programmes.     

Existence of salt glands on leaves of kallar grass (Leptochloa fusca L. Kunth.)

Light microscopic studies have established the existence of salt glands on “Kallar grass”; leaf blades. The salt glands resembled the two‐cell type structure described for some halophytic genera within the Gramineae. The secreted salts crystallized and formed whiskers when the plants were grown under continuously high saline conditions. The salt secretion appears to be selective. The secretion of Na exceeded that of K and considerable quantities of Cl were also extruded, preferentially in concomitance with Na. The significance of growth hormones and Ca in regulating the salt secretion process is discussed.     

Amelioration of calcareous saline sodic soils through phytoremediation and chemical strategies

Abstract. The worldwide occurrence of saline sodic and sodic soils on more than half a billion hectares warrants attention for their efficient, inexpensive and environmentally acceptable management. These soils can be ameliorated by providing a source of calcium (Ca²⁺) to replace excess sodium (Na⁺) from the cation exchange sites. Although chemical amendments have long been used to ameliorate such soils, the chemical process has become costly during the last two decades in several developing countries. As a low‐cost and environmentally acceptable strategy, the cultivation of certain salt tolerant forage species on calcareous sodic and saline sodic soils, i.e. phytoremediation, has gained interest among scientists and farmers in recent years. In a field study conducted at three calcareous saline sodic sites (pH_s=8.1–8.8, EC_e=7.8–12.5 dS m^–1, SAR=30.6–76.1) in the Indus Plains of Pakistan, we compared chemical and phytoremediation methods. There were four treatments; two involved plants: Kallar grass (Leptochloa fusca (L.) Kunth), and sesbania (Sesbania bispinosa (Jacq.) W. Wight). The other two treatments were uncropped: soil application of gypsum and an untreated control. All treatments were irrigated with canal water (EC=0.22–0.28 dS m^–1). The plant species were grown for one season (5–6 months). Sesbania produced more forage yield (34 t ha^–1) than Kallar grass (23 t ha^–1). Phytoremediation and chemical treatments resulted in similar decreases in soil salinity and sodicity, indicating that phytoremediation may replace or supplement the more costly chemical approach. The soil amelioration potential of sesbania was similar to that of the Kallar grass, which suggests that moderately saline sodic calcareous soils can be improved by growing a forage legume with market value.     

小麦矮腥黑粉菌和禾草腥黑粉菌的快速鉴别研究

快速准确地鉴别形态特征极为相似的小麦矮腥黑粉菌(TilletiacontroversaKühn)和禾草腥黑粉菌(T.fuscaEll.AndEV.),是我国进口草种检疫中迫切需要解决的技术难题。运用数学判别法,以冬孢子直径、网目数、网脊高度、胶鞘厚度为基本形态指标,在大量测量数据的基础上,建立了鉴别小麦矮腥黑粉菌和禾草腥黑粉菌的数学模型。最后,用未参加组建模型的100组数据测试该模型,并做萌发试验核对判别结果,其正确率达到100%,表明该模型稳定可靠。     

Na+ and Cl−: Leaf extrusion,retranslocation and root efflux in diplachne fusca (kallar grass) grown in NaCl

Abstract

Groups of “Kallar”; grass plants were subjected to various treatments of 100 mM NaCl simultaneously labelled with ²²Na⁺ and ³⁶Cl^?. On the basis of the specific activity, the distribution of Na and Cl^? in the tissue was followed during and after treatment, i.e. after transfer of some groups to an identical but inactive solution. Sequential collections of leaf washes showed that both Na and Cl^? were extruded at a somewhat constant rate. Leaf sheaths accumulated more Na⁺ and Cl^? than the leaf blades and the amounts of Na⁺ and Cl^? in the leaf sheaths as a percentage of their total plant content (i.e. 28% and 31%) approximated the amounts of Na and Cl^? extruded by the leaves (i.e. 23%). Moreover, almost equivalent amounts of Na⁺ (21%) and Cl^? (29%) were removed by root efflux which continued even several days after transfer of the plants to the inactive, saline solution. Part of the Na⁺ and Cl^? was retranslocated from the tops to the roots and was attributed to phloem export.

Tolerance of Kallar grass to NaCl was thus related to preventing the tissue from accumulating high concentration by extrusion of both Na⁺ and Cl^? by the leaves and their efflux by the roots in addition to an equivalent retention in the leaf sheaths.     

Agroforestry techniques for the rehabilitation of degraded salt-affected lands in India

The development of appropriate technologies for the judicious use of India's 8.11 million ha of salt-affected lands would give increased food, fodder and fuelwood production. A sizeable portion of the salt-affected lands of the Indo-Gangetic plain have been reclaimed through chemical amendments and are being commercially used for arable farming. However, large areas of salt-affected common lands, village and government lands and waste lands near cities, along railway tracks and roads do not have any productive use. Owing to their sparse vegetative cover such lands are vulnerable to further degradation and can be a source of runoff causing floods, especially where cows congregate. Research at the Central Soil Salinity Research Institute, Karnal has generated agroforestry techniques which could enable the economic exploitation of such marginal lands. This paper deals with various aspects of these techniques, which have been applied to over 50 000 ha by 1994. Based on eight to ten years of growth and biomass figures, the most salt-tolerant woody species identified were: Prosopis juliflora, Acacia nilotica, Casuarina equisetifolia, Tamarix articulata, Leptochloa fusca (a palatable forage grass which was found to be a promising primary colonizer of salt lands). Agronomic practices for the successful establishment of trees such as planting methods, amendment use, irrigation, spacing and lopping schedules are discussed. A Prosopis juliflora-leptochloa fusca silvipastoral model was found to be excellent for fuelwood and forage production and for the amelioration of high pH soils. This system, when followed for little more than four years, reclaims alkali soils to such an extent that normal agriculture crops such as Trifolium alexandrinum and T. resupinatum can be grown successfully. A ridge-trench system of tree planting was found to be helpful in alkali soils, the in situ rainwater conservation it led to assisting biomass production. Eucalyptus tereticornis, Populus deltoides and Tectona grandis based agroforestry were promising for reclaimed salt-affected lands. The short- and long-term effects of various tree plantations on the physicochemical properties of the soil and on soil-water relations are also discussed. Agroforestry options for the development of salt-affected lands found in various agroclimatic zones of India are explored.     

Biological evaluation of neopeptins isolated from a Streptomyces strain

BACKGROUND: Microbial secondary metabolites are a rich source of antifungal agents and have merit as alternatives to synthetic fungicides. To develop disease control agents against powdery mildew, the lipopeptide antibiotic neopeptins were identified from the culture broth of a Streptomyces sp., and in vivo control efficacy of the compounds was evaluated on cucumber plants under glasshouse conditions. RESULTS: The Streptomyces sp. KNF2047 antagonistic against powdery mildew development in cucumber plants was isolated from a soil sample. Antifungal compounds were purified from the culture broth and identified as neopeptin A and B. In vitro microtitre assays revealed the inhibitory activities of the compounds in the range 128-512 microg mL(-1) against the mycelial growth of Alternaria mali, Botrytis cinerea, Cladosporium cucumerinum, Colletotrichum lagenarium, Didimella bryoniae and Magnaporthe grisea. Although neither compound showed remarkable in vitro antifungal activity against other plant pathogenic fungi, a mixture of neopeptins (484 mg of neopeptin A and 290 mg of neopeptin B per gram of partially purified powder) showed potent protective and curative activity against cucumber powdery mildew in vivo. The disease control activity of the neopeptins at a concentration of 2.4 mg L(-1) was 92.1%, which was similar to that of the commercial fungicide fenarimol (89.3% at 63 mg L(-1)) and that of the commercial biocontrol agent Actinovate (67.4% at 2 x 10(7) cfu L(-1)). CONCLUSION: Neopeptin mixtures isolated from Streptomyces sp. KNF2047 showed potent disease control activity against powdery mildew development on cucumber plants. .     

Developmental studies of transgenic maize expressing Cry1Ab on the African stem borer, Busseola fusca; effects on midgut cellular structure

BACKGROUND: Busseola fusca is a major pest of maize in Africa but unfortunately is difficult to control using chemical insecticides. Insect‐resistant transgenic crops may provide an alternative viable strategy to control this pest. RESULTS: Recombinant Cry1Ab (1%) reduced larval weight by 60% over the trial period, while larval weight in the control group increased by 25%; no effects on mortality were observed. Insect survival, developmental rate and pupal and adult weight were significantly reduced (P < 0.05) on maize expressing Cry1Ab (MON810) compared with the non‐transformed parental line. These differences were more pronounced with second‐instar larvae than with third‐instar larvae. Leaf area consumed by Bacillus thuringiensis (Bt)‐fed larvae was significantly lower (0.5 cm² larva^?1 day^?1) compared with the area consumed by control‐fed insects (3.3 cm² larva^?1 day^?1). EM studies revealed that consumption of Bt maize deleteriously affected gut integrity. Effects were observed in columnar cells of the midgut epithelium, with the cytoplasm becoming highly vacuolated; the microvilli were disorganised, the mitochondria were abnormal and there was an increase in the number of lysosomal bodies. The rough endoplasmic reticulum had also become dilated. CONCLUSION: This study confirms the potential for Bt maize, when used as part of an IPM programme, for control of B. fusca. Copyright © 2011 Society of Chemical Industry