茶树油控制香蕉采后炭疽病害的研究

为了探讨植物提取物对香蕉采后病害的防治效果,以香蕉果实为材料,采用菌丝生长速率方法测定不同剂量的茶树油（TTO）及其主要成分（4-松油烯醇、α-松油醇、γ-松油烯和1, 8-桉叶油素）对香蕉炭疽病菌的离体抗菌活性,并用TTO及其主要成分熏蒸处理接种炭疽病菌的香蕉果实,测定果实的发病情况和TTO处理对接种果实防御酶活性的影响。结果表明,TTO、4-松油烯醇和α-松油醇均能显著抑制离体炭疽病菌的菌丝生长,浓度越高,抑制效果越明显;TTO处理降低了接种炭疽病菌果实的发病程度,4-松油烯醇和α-松油醇处理对接种果实病斑直径的抑制效果显著好于TTO。另外,TTO处理提高了接种果实过氧化物酶（POD）和苯丙氨酸解氨酶（PAL）的酶活性,抑制了多酚氧化酶（PPO）酶活性。初步研究表明TTO在控制香蕉果实采后腐烂和提高果实抗病性上具有应用可行性,4-松油烯醇和α-松油醇可能是其主要活性成分。     

开口箭提取物对采后香蕉抗炭疽病菌活性的研究

为探讨植物提取物对香蕉采后病害的防治，采用孢子萌发法和菌丝生长速率测定百合科植物开口箭的甲醇提取物及其乙酸乙酯分部萃取物和正丁醇分部萃取物对香蕉炭疽病菌的离体抗菌活性，选用正丁醇分部萃取物进行耐高温(121℃处理20 min)、紫外光照射(30 W紫外灯距50 cm直射15 h)和酸处理(调节pH 3)的抗菌稳定性研究，并进行了提取物处理香蕉的贮藏防病试验。结果表明，开口箭甲醇提取物及其乙酸乙酯分部萃取物和正丁醇分部萃取物抑制香蕉炭疽病菌孢子萌发的半效应浓度(EC₅₀)分别为1490.27，638.40，1112.65 μg/mL，抑制香蕉炭疽病菌菌丝生长的EC₅₀分别为1262.16，451.02，955.58 μg/mL，正丁醇分部萃取物的抗菌活性不受热、紫外线和酸等因子的影响，用开口箭提取物处理采后香蕉果实，具有明显降低其潜伏性炭疽病发病率的作用。     

茶树油熏蒸处理对草莓果实采后病害和品质的影响

为了研究茶树油对草莓防腐保鲜的作用效果,对人工接种灰葡萄孢霉（Botrytis cinerea）和根霉（Rhizopus stolonifer）的草莓果实进行不同浓度、不同时间的茶树油熏蒸处理,测定20℃贮藏下的病害发生情况,并运用体外实验研究该熏蒸处理对病原菌孢子萌发和菌丝生长的影响。同时,还分析了接受该处理的果实在贮藏期间的品质变化趋势。研究发现：茶树油熏蒸处理可降低草莓果实灰霉病和根霉病的发病率和病斑直径,抑制其孢子萌发和菌丝生长,减缓草莓果实在贮藏期间的品质下降。结果表明茶树油熏蒸用于草莓保鲜是可行的,浓度为2000 mg/L熏蒸3 h即可有效延长草莓货架期2-3 d。     

超高压处理对鲜榨橙汁中主要香气成分的影响

为了了解超高压处理对鲜橙汁香气的影响,分析超高压处理后橙汁香气变化的原因。采用固相微萃取（Solid Phase Microextraction,SPME）方法对不同压力（100～500 MPa）超高压处理的鲜榨橙汁中的香气成分进行富集,并经气相色谱-质谱联用仪（Gas Chromatography-Mass Spectrometry,GC-MS）检测分析,橙汁中的主要香气成分有：3种烯（柠檬烯、月桂烯、α-蒎烯）;2种醇（芳樟醇、α-松油醇）;3种醛（柠檬醛、辛醛、癸醛）;1种酮（香芹酮）;2种酯（丁酸乙酯、3-OH-己酸乙酯）,它们是构成橙汁的主要特征致香成分。通过定量检测分析发现：超高压处理对橙汁中的柠檬烯成分影响很显著,经500 MPa的压力处理15 min后其含量下降了75%,而月桂烯和α-蒎烯受高压影响较小;α-松油醇、香芹酮含量经高压处理后迅速增加;醛类特征香气成分基本不受高压影响;酯类成分在高压下会发生变化,但总体变化不显著。超高压处理橙汁使其中柠檬烯在高压下发生水合、氧化反应分别生成α-松油醇和香芹酮。超高压处理橙汁一般压力要大于300 MPa,而该文研究发现500 MPa处理会造成较多的香气损失,故橙汁超高压处理时的压力最好选择 400 MPa左右。     

茶树油熏蒸对草莓采后病害和品质的影响

为了研究茶树油对草莓保鲜的作用效果,对人工接种灰葡萄孢霉（Botrytis cinerea）和根霉（Rhizopus stolonifer）的草莓果实进行不同质量浓度、不同时间的茶树油熏蒸处理,测定20℃贮藏下的病害发生情况,并运用体外试验研究该熏蒸处理对病原菌孢子萌发和菌丝生长的影响。同时,还分析了接受该处理的果实在贮藏期间的品质变化趋势。研究发现：茶树油熏蒸处理可降低草莓果实灰霉病和根霉病的发病率和病斑直径,抑制其孢子萌发和菌丝生长,减缓草莓果实在贮藏期间失重率的上升,维持较高的硬度、可溶性固形物和可滴定酸含量。结果表明茶树油熏蒸用于草莓保鲜是可行的,质量浓度为2?000 mg/L,熏蒸3 h可明显延长草莓货架期。     

碳酸铵对意大利青霉的作用机制及对不同柑橘果实品质的影响

为了寻求一种安全有效的方法防治由意大利青霉（Penicillium italicum）引起的柑橘青霉病，该研究分析了碳酸铵作为通常认为安全的药剂抑制意大利青霉生长的可能作用机制及对脐橙、皇帝柑、沃柑3种不同类型柑橘贮藏品质的影响。结果表明，碳酸铵能抑制意大利青霉孢子萌发和菌丝生长，且呈现剂量依赖效应，在质量浓度分别为 0.4 g/L和0.8 g/L时可完全抑制孢子萌发和菌丝生长。结构观察表明，碳酸铵引起菌丝生长节点稀疏和分支减少；超微结构观察发现菌丝严重皱缩，菌丝线粒体结构异常。生理生化分析表明，碳酸铵处理，引起线粒体的钠/钾离子ATP酶（Na+/ K+-ATPase）、钙离子ATP酶（Ca2+-ATPase）和镁离子ATP酶（Mg2+-ATPase）活性下降，导致还原型谷胱甘肽（Reduced Glutathione，GSH）含量及谷胱甘肽还原酶（Glutathione Reductase，GR）活性降低，活性氧清除体系超氧化物歧化酶（Superoxide Dismutase，SOD）、过氧化氢酶（Catalase，CAT）、过氧化物酶（Peroxidase，POD）活性紊乱，促进H2O2积累。添加活性氧清除剂半胱氨酸（Cysteine，Cys）能部分恢复碳酸铵处理的病菌孢子萌发。活体接种表明，16 g/L碳酸铵处理显著减小了柑橘果实接种意大利青霉的病斑直径（P<0.05），减轻果实发病。碳酸铵处理能降低3种类型柑橘果实自然发病率，且对果实失重率、色泽、可溶性固形物、可滴定酸、维生素C、还原糖含量无不良影响。结果表明，碳酸铵通过损伤意大利青霉菌丝线粒体结构和功能，促进活性氧积累来发挥抗真菌活性，碳酸铵可以作为杀菌剂的绿色有效替代方法，研究结果为碳酸铵防治柑橘果实采后腐烂提供参考。     

红树内生细菌AiL3菌株鉴定及其胞外抗菌活性物质特性

红树（Acanthus ilicifolius）内生细菌AiL3菌株通过形态学观察、生理生化特征测定及16S rDNA序列分析鉴定为解淀粉芽胞杆菌（Bacillus amyloliquefaciens）。菌株培养滤液经有机溶剂萃取和硫酸铵沉淀分析发现,硫酸铵沉淀物具有抑菌活性,说明AiL3菌株产生的抗菌活性物质可能是蛋白类物质。该蛋白粗提液对芒果炭疽病菌（Colletotrichum gloeosporioides）、黄瓜枯萎病菌（Fusarium oxysporum f.sp.cucumerinum）等8种植物病原菌均有较强的拮抗作用;对芒果炭疽病菌菌丝生长和分生孢子萌发的EC50分别为9.32和5.81μg/mL,当提取物浓度为20.33μg/mL时,可导致芒果炭疽病菌分子孢子的消解。     

气调包装与1-MCP结合抑制苹果蜡质成分降低

为了探讨红富士苹果在贮藏过程中主要蜡质成分特别是与油腻相关的蜡质成分变化,以及贮藏过程中果实主要品质指标的变化规律,研究了聚氯乙烯袋（PVC）自发气调包装（MAP）与1-甲基环丙烯（1-MCP）结合处理（MAP+1-MCP）对(0±1)℃冷藏过程中红富士苹果蜡质成分和果实贮藏品质的影响。结果表明：在贮藏过程中,对照（不做任何处理）的蜡质总量一直降低,MAP和MAP+1-MCP处理的在贮藏一个月后升高,随后贮藏的过程中降低。所有处理和对照中,二十九烷和二十七烷含量降低,十六烷酸和9,12-十八碳二烯酸含量升高,二十九-10-醇和二十九-10-酮含量先降低再升高。MAP和MAP+1-MCP能够抑制蜡质总量和其他成分相应的变化。MAP和MAP+1-MCP均能延缓果实硬度的下降、可溶性固形物和可滴定酸的降解速度,降低固酸比率和失重率,抑制呼吸速率和乙烯释放速率,且可以抑制苹果贮藏后期油腻的发生。无论从对蜡质成分的影响,还是对果实贮藏品质的影响来看,MAP+1-MCP的效果优于MAP。PVC气调包装结合1 μL/L1-MCP是较为理想的长时间保鲜红富士苹果的处理方式。研究结果可为生产上科学有效的长期贮藏红富士苹果、解决贮藏后期果实油腻问题提供参考。     

茶树精油熏蒸处理保鲜草莓的工艺优化

为了获得茶树精油熏蒸处理进行草莓防腐保鲜的较佳工艺条件,采用单因素试验方法研究不同熏蒸体积分数、温度和时间对人工接种灰葡萄孢霉的草莓果实腐烂发生的影响。通过Box-Behnken设计及响应面分析获得熏蒸防腐保鲜的最佳工艺条件为:茶树精油熏蒸体积分数0.66mL/L、熏蒸温度33.3℃、熏蒸时间3.1h。按此优化条件进行验证发现接种草莓果实的腐烂指数为7.5%,实测值与模型预测值的相对误差在4.1%;将此优化条件应用于未接种的新鲜草莓果实,结果发现该处理能显著抑制果实的自然病害发生,还能减缓草莓果实失重率的上升和果实硬度、可溶性固形物、可滴定酸和花青素含量的下降。研究结果为茶树精油在草莓保鲜上的商业化应用提供参考。     

不同机械伤处理对香蕉果皮活性氧代谢的影响

为探究不同机械伤处理对香蕉果皮活性氧代谢的影响，该研究以"桂蕉6号"为材料，采用划伤、穿刺、坠落3种不同机械伤处理，以未处理组为对照，测定贮藏过程中香蕉果皮活性氧代谢的变化，并进行相关性分析和主成分分析。结果表明，3种不同机械损伤处理均加速了香蕉果实硬度和叶绿素含量的下降；引起O2-产生速率和H2O2含量的积累，其中划伤处理组的O2-产生速率在贮藏第8 天为对照组的2.0倍，H2O2含量为对照组的2.5倍，这可能与机械伤处理抑制了果皮组织中过氧化物酶、超氧化物歧化酶、过氧化氢酶及抗坏血酸过氧化物酶活性有关；同时，3种不同机械损伤处理加速细胞膜脂过氧化的进程，造成香蕉细胞膜透性及丙二醛含量的升高，其中对照、划伤、穿刺和坠落处理组的丙二醛含量在贮藏第8 天分别是贮藏初期的3.3、3.4、5.4和7.5倍。；此外，划伤和穿刺处理均可显著提高香蕉果皮中PPO活性（P <0.01)。相关性聚类热图分析表明，H2O2含量与香蕉果实硬度、叶绿素含量和抗坏血酸过氧化物酶活性呈极显著负相关（P <0.01)，与超氧化物歧化酶活性呈显著负相关（P <0.05)；同时，多酚氧化酶活性与H2O2含量、丙二醛含量和细胞膜透性呈现极显著正相关（P <0.05)。结合主成分分析可知，不同机械伤处理均可加速香蕉果皮活性氧的积累进而导致香蕉果实的衰老腐败，其中划伤处理对香蕉果皮活性氧代谢影响最大，其次是穿刺处理，坠落处理对香蕉果皮活性氧代谢影响最小。该研究阐明了香蕉果实机械伤、活性氧和贮藏品质三者的关系，并为香蕉采后不同机械伤控制提供理论依据。     

Soil-profile distribution of primary and secondary plant-available nutrients under conventional and no tillage

Nutrient distributions under no tillage (NT) compared with conventional disk-and-bed tillage (CT) management in the warm, humid region of the southeastern USA need to be assessed so that future placement, quantity, and type of fertilizers can be altered, if necessary, to efficiently match crop demands. We determined soil-profile distributions of pH, N, P, S, K, Ca, Mg, Na, Zn, Fe, Mn, and Cu to a depth of 0.9 m at the end of 8.5 years of continuous CT and NT management on a Weswood silty clay loam (fine, mixed, thermic Fluventic Ustochrept) in southcentral Texas. Most dramatic changes occurred within the 0–0.05 m depth, where soil under NT had lower pH, Fe, and Cu than under CT, but greater P, K, Zn, and Mn. Greater P and K under NT than under CT also occurred below the till-zone (0.15–0.3 m). At a depth of 0–0.3 m, soil under NT contained greater amounts of extractable P, K, Zn, Fe, Mn, and Cu than under CT. Nitrogen fertilization had little effect on nutrient distributions, except resulting in greater extractable K at 0–0.05 m and greater nitrate at 0–0.15 m. Few changes in soil-profile distributions were observed for extractable S, Ca, Mg, and Na. Long-term continuous use of NT on this fine-textured, high-fertility (except for N) soil had no apparent adverse effects on nutrient distributions relative to CT, but enhanced conservation and availability of P, K, Zn, Fe, Mn, and Cu near the soil surface where crop roots proliferate.     

Assessing the effectiveness of conservation measures: Resolving the “wicked” problem of the Steller sea lion

“Wicked” problems are those that are complex and that change when solutions are applied. Many conflicts in conservation fall into this category. The study approached the problem of how to constrain the apparent wickedness of a problem in the conservation management of a species by using simple empirical indicators to carry out iterative assessment of the risk to a population and to document how this risk evolves in relation to the addition of new data and the implementation of management actions. Effects of high levels of uncertainty within data and also concerning population structure were examined through stochastic simulation and by exploration of scenarios. Historical trends in the example used, the Steller sea lion, showed rapid declines in abundance in some regions during the 1980s. The current total population is 130,000-150,000 Steller sea lions through Alaska and British Columbia and this number has been stable since about 1990 in spite of regional differences in population dynamics. Regional differences in the sequence of changes in the number of pups and non-pups, suggested that an internal re-distribution of juveniles could have happened between 1980 and 1990. Current productivity also appears close to the long-term mean. Stochastic population projection using various scenarios showed that, based upon this history, the risk of extinction for the population has declined and is below reasonable thresholds for considering the population to be endangered. The trends in risk suggest that management actions taken since 1990 have probably been effective. Consequently, the conservation management objectives for the Steller sea lion are probably being met. The approach provides a mechanism, based upon experience and scenario analysis, for exploring future policy options and may help to constrain the debate amongst stakeholders about the cost-benefit trade-offs associated with different options.     

Enhanced establishment and growth of giant cardon cactus in an eroded field in the Sonoran Desert using native legume trees as nurse plants aided by plant growth-promoting microorganisms and compost

To evaluate the feasibility of long-term desert reforestation technology of mixed vegetation, cardon cactus (Pachycereus pringlei) seedlings from indoor and outdoor nurseries were planted in the field adjacent to one seedling of potential legume nurse trees: mesquite amargo (Prosopis articulata), yellow palo verde (Parkinsonia microphylla), and blue palo verde (Parkinsonia florida). Some of the planting holes were also supplemented with common dairy compost. Additionally, the combinations of legume tree–cactus were inoculated with either a consortium of desert arbuscular mycorrhizal (AM) fungi, plant growth promoting bacteria (PGPB; the diazotroph Azospirillum brasilense Cd, and the phosphate solubilizer Paenibacillus sp.), or a mixture of all. The field experiments were evaluated periodically during 30 months for survival and growth. Cardons reared in an outdoor screen house survived better in the field than those reared in a controlled growth chamber and hardened later outdoors. Association with any legume nurse tree increased survival and enhanced growth of untreated cardons. For cardons growing alone, application of either compost, AM fungi, and all the treatments combined increased survival. For these plants, no treatment affected plant growth during the first 3 months after transplanting. Later, all treatments, except for AM fungi, enhanced plant growth. However, only 2 years after transplanting the enhanced growth effect of AM fungi was also significant. In the presence of the legume nurse trees, transient positive effects on cardon growth were recorded. General evaluation after 30 months of cultivation showed that the treatments positively affected cardon growth when growing alone or in combination only with mesquite amargo but not with the other two legume trees. This study proposes that young legume trees have the capacity to enhance survival and growth of cardon cactus, depending on the legume cactus combination. Additional treatments such as compost or PGPB can either amplify the effect or else attenuate it.     

Karyotypic and genome size variation in Cajanus cajan (L.) Millsp. (pigeonpea) and some wild relatives

Detailed karyotypes and 4C DNA amounts have been studied in five cultivars of Cajanus cajan and 20 species belonging to Cajanus, Rhynchosia, Dunbaria, Flemingia and Paracalyx. C. cajan shows intraspecific variability and its karyotype is most similar to that of C. cajanifolius (sect. Cajanus) in the morphology and number of satellite chromosomes and the lack of any correlation between chromosome size within the complement and asymmetry. Karyotypes of C. lineatus and C. sericeus belonging to sect. Atylia are similar with respect to maximum r-index and the ratio of longest and shortest chromosomes in their respective complements. C. acutifolius (sect. Frutocosa) is distinct in having a very low ratio (1.44) between the longest and the shortest chromosomes, while in C. albicans, C. goensis, C. scarabaeoides (sect. Cantharospermum) there is no chromosome pair with r-index >2.0. C. mollis and C. volubilis (sect. Volubilis) show similarity with regard to ratio between the longest and the shortest chromosomes and a distinct chromosome pair with an arm ratio of 2.7 and C. platycarpus is distinct (sect. Rhynchosoides) in having the smallest ratio (1.36) between the longest and the shortest chromosomes. 4C DNA amounts in Cajanus and Rhynchosia vary between 3.28 pg to 11.69 pg and 4.92 pg to 11.13 pg respectively, while in Dunbaria, Flemingia and Paracalyx these vary between 4.70 and 7:06 pg. In the genus Cajanus karyotypic features and 4C DNA amounts agree with the sectional classification and bring out a close relationship between C. cajan and C. cajanifolius. This is supported by studies based on seed protein patterns, isozyme analysis, trypsin and chymotrypsin inhibitor patterns, RFLP and RAPD data and crossability relationships. A clear relation between DNA amount and abnormalities effecting the extent of pairing and recombination in interspecific hybrids shows the importance of this study in developing future breeding programme involving C. cajan and its wild relatives that are of potential value.     

Effect of some fungicide seed treatments on the survival of Bradyrhizobium japonicum and on the nodulation and yield of soybean [Glycine max. (L) Merr.]

Several commercial fungicide seed treatments were evaluated for their possible effect on the survival of Bradyrhizobium japonicum on seeds and on the nodulation and yield of soybeans in a greenhouse and a field experiment. quinolate Pro (carbendazim and oxine copper), Vitavax 200FF (carboxin and thiram), and Monceren (pencycuron) had a small effect or no effect on the survival of B. japonicum and on the nodulation and yield of soybeans. They can thus be considered compatible with soybean seed inoculation. Germipro UFB (carbendazim and iprodione), Apron 35J (metalaxyl), and Tachigaren (hymexazol) decreased B. japonicum survival and the nodulation and yield of soybeans and thus cannot be considered compatible with soybean seed inoculation.     

Einfluss der düngungsmethoden auf die entwicklung von zuckerrübenkrankheiten

Während neunjähriger (1994-2002) Untersuchungen in der Versuchsanstalt Ba?cyny (Fahlerde, Fall-Gleyboden, ausgebildet aus leichtem Lehmboden) wurde der Befall mit Krankheiten an der Zuckerrübe in Abhängigkeit von der Düngungsmethode bewertet. Folgende Methoden wurden angewendet: A - Mineraldünger, B - Stalldung und Mineraldünger, C - Stroh-, Gründung und Mineraldünger, D - Kompostdünger und Biopräparate (ökologische Düngung). Auf den Objekten A, B, C wurden bei konstanter Phosphor-Kalium-Düngung die Stickstoffgaben von 0 bis 180 kg.ha^?1 differenziert. Auf dem ökologischen Objekt D ohne Mineraldünger wurden statt Stickstoff die Biopräparate P₅₀₀ und P₅₀₁ verabreicht. Der geringste Befall von Krankheiten wurde an der Zuckerrübe auf jenem Objekt festgestellt, das mit Kompost und den Biopräparaten gedüngt worden war. Im Rahmen der konventionellen Düngungsmethoden wurde allgemein die höchste Intensität der Krankheiten an der mit Stroh, Gründung und Mineraldünger gedüngten Zuckerrübe beobachtet. Ausnahmen von dieser Regel bildete das Vorkommen von echtem Mehltau und Keimlingsfäule. Auf den Objekten A, B, C nahm die Intensität der Krankheiten mit der Steigerung der Stickstoffgabe zu. Auch die auf Objekt D verabreichten Biopräparate stimulierten die Entwicklung der Krankheiten. The effect of various fertilization methods on the diseases of sugar beet was estimated on the basis of nine-year studies (1994-2002) conducted in the Experimental Production Farm in Ba?cyny on loess-based, sedimentary-gley, light-clay soil. The following fertilization methods were applied: A - mineral fertilization, B - mineral and manure fertilization, C - straw, green manure and mineral fertilization, D - ecological compost and biodynamic preparations fertilization. In the objects A, B and C fertilized with phosphorus and potassium, various doses of nitrogen ranging from 0 to 180 kg/ha^?1 were used. In the ecological object D, where mineral fertilization was not used, biodynamic preparations P₅₀₀ and P₅₀₁ were applied instead of nitrogen. The lowest ratio of the diseases of sugar beet was observed in the object fertilized with the compost and biodynamic preparations. In view of the conventional fertilization methods, generally the highest incidence of diseases was noted in the sugar beet fertilized with straw, green manure and mineral fertilizers. The exception was the occurrence of powdery mildew and the black leg. In objects A, B and C the incidence of the diseases increased with the increase in nitrogen doses. The applied biodynamical preparations in the object D stimulated the development of diseases too.     

Prospects for control of Pythium damping-off of lettuce with Trichoderma,Gliocladium and Enterobacter spp.

Summary Damping-off of lettuce (Lactuca sativa) caused by Pythium ultimum was studied in pots containing a non-sterile potting mix in the glasshouse. Fifty P. ultimum sporangia g^-1 compost reduced the plant stand to 15% and shoot dry weight to 18%, but this reduction was totally prevented by applying Trichoderma harzianum at 2×10⁵ viable propagules g^-1 potting mix. Gliocladium virens and Enterobacter cloacae also alleviated the damping-off. E. cloacae did not adversely affect the action of the fungal antagonists. The co-existence of the bacterial and fungal antagonists was revealed on the root surface and inner surface of the testa by scanning electron microscopy, indicating the compatibility of the biocontrol agents.     

细菌、真菌及植物氮营养信号研究进展

氮素吸收代谢是所有生物生命活动的核心部分,因此,各种生物对氮的吸收与同化过程都有精细的调节。这种调节依赖于生物对体内氮素状况信号及体外（生长介质中）氮素信号的感受。过去几十年中,在细菌、真菌中已经对氮素营养信号有了较好的研究,而植物中则相对缓慢,但也有了一定的认识。本文重点比较细菌、真菌及植物中氮信号系统的组成,以期为进一步认识植物中的氮信号接受与转导系统提供启示。     

Potential of wild species for genetic enhancement of some semi-arid food crops

Discovery and incorporation of genes from wild species provide means to sustain crop improvement, particularly when levels of resistance in the cultigens are low and virulent strains of pests and pathogens overcome the host plant resistance. The extent of utilization and the potential of the wild genepool for genetic enhancement were reviewed in five important food crops viz. sorghum, pearl millet, chickpea, pigeonpea and groundnut grown in the semi-arid tropics. Introgression from compatible wild germplasm in the primary gene pool resulted in transfer of new cytoplasmic male sterility systems in pearl millet and pigeonpea, development of high protein, cleistogamous flower and dwarf pigeonpea lines and foliar disease resistant groundnut cultivars. Utilization of wild species in secondary and tertiary gene pools has been generally limited due to sterility, restricted recombination or cross incompatibility. Nevertheless, these species are extremely important as they contain high levels of resistance to several important biotic and abiotic stresses. Several of them, like those belonging to the Parasorghum section and the rhizomatous Arachis species are sources of multiple resistances and hold great promise to sustain crop productivity.     

“绿色革命”以来大气CO2浓度升高对C3作物营养品质的影响

自20世纪60年代"绿色革命"以来,育种技术和农耕技术的发展促进了农作物产量的大幅提升,然而作物的营养品质出现下降趋势。在相似的遗传背景下,大气CO_2浓度升高会使单位体积农作物产品的营养元素含量下降,因此"绿色革命"至今,农作物产品的营养元素下降可能受大气CO_2浓度升高影响。通过植物生长箱模拟"绿色革命"初期和目前的大气CO_2浓度水平(310μmol/mol和400μmol/mol),针对主要C_3作物水稻、小麦和大豆,研究"绿色革命"以来大气CO_2浓度升高对其籽粒的C、N、Fe、Zn元素含量的影响,结果表明:CO_2浓度升高对3种作物籽粒的C元素含量几乎没有影响,变化幅度在±1.5%之间;籽粒的N、Fe、Zn元素含量普遍呈现下降趋势,但均未达到显著水平。