灌溉方式对设施土壤总有机碳及其腐殖质组分的影响

通过13年连续的番茄栽培灌溉试验,分析了沟灌、滴灌和渗灌3种灌溉处理0—80cm土层土壤有机碳及其腐殖质组分(胡敏酸、富里酸、胡敏素等)含量,探讨了不同灌溉方法对温室土壤有机质变化的影响。结果表明:3种灌溉处理土壤总有机碳、腐殖质各组分含量剖面变化特征一致,均随土层加深而降低,且这一变化主要集中在0—50cm土层,50—80cm土层变化较小。土壤总有机碳及其组分各灌溉处理间差异明显,将土壤剖面分为0—20,20—80cm上、下2个层次,总体上总有机碳含量上层为渗灌沟灌滴灌,下层滴灌沟灌渗灌;腐殖酸含量上层滴灌沟灌渗灌,下层为渗灌滴灌沟灌;胡敏素上层为沟灌滴灌渗灌,下层为渗灌滴灌沟灌。滴灌处理既能使0—40cm土层土壤有机碳含量保持较高水平,土壤腐殖质含量又高于沟灌、渗灌处理,这对于提升设施土壤肥力水平、保证番茄养分供应是有利的。     

不同灌溉方法对保护地土壤有机质及氮素影响的研究

分层采集连续7年分别用渗灌、滴灌和沟灌灌溉的保护地0～80cm土层土壤样品,测定有机质、全氮及无机态氮和有机态氮含量,研究灌溉方法对土壤氮素形态及其数量剖面分布的影响。结果表明,三种灌溉处理0～80cm剖面土壤有机质含量变化范围为8.47～36.48 g kg-1,渗灌与滴灌有机质剖面分布相似,二者与沟灌差异较大;沟灌除30～40cm层次有机质含量低于渗灌和滴灌外,其它层次有机质含量均高于渗灌和滴灌处理。土壤全氮含量变化范围为0.72～3.97 g kg-1,在0～20cm土层不同灌溉方法之间差异显著,渗灌最大,沟灌次之,滴灌最小。无机硝态氮、铵态氮含量的变化范围分别为19.16～1442.06 mg kg-1和0～15.28 mg kg-1,在0～20cm土层各处理之间差异较为明显,以渗灌最大,沟灌次之,滴灌最小。有机态氮含量的变化范围为683.79～2512.87 mg kg-1,各处理之间的差异主要表现在0～30cm土层,其中0～10cm土层以渗灌处理有机态氮含量最高、沟灌次之,滴灌最低,10～30cm沟灌处理有机态氮含量却高于渗灌和滴灌处理。     

灌溉方式对保护地土壤微团聚体及其碳、氮分布的影响

以连续13年沟灌、滴灌和渗灌3种不同灌溉方式灌溉的保护地土壤为对象,研究不同灌溉处理保护地土壤微团聚体的分布及其碳、氮含量变化.结果表明,不同灌溉处理间,0-10 cm和10-20 cm土层土壤微团聚体含量均以渗灌处理最高,且0-10 cm土层灌溉处理间差异大于10-20 cm土层;各灌溉处理0-10 cm土层和10-20 cm土层土壤微团聚体均以0.01～0.05 mm粒级为优势粒级,0.05～0.25 mm粒级为次优势粒级,而＜0.01 mm粒级土壤微团聚体含量最少;灌溉处理间0-10 cm和10-20 cm土层各粒级土壤微团聚体全氮含量分布的总体趋势是滴灌高于沟灌和渗灌,且颗粒越小、这一处理间差异越明显,而处理间各粒级土壤微团聚体总碳含量差异不明显;0-10 cm土层某粒级土壤微团聚体总碳和全氮含量高于10-20 cm土层同粒级土壤微团聚体,而在同一土层微团聚体粒径越小、其总碳和全氮含量越高.从土壤结构及养分性状考虑,滴灌和渗灌比沟灌更适合于保护地蔬菜栽培灌溉.     

灌溉方法对保护地土壤有机氮矿化特性的影响

采用Stanford和Smith提出的长期间歇淋洗通气培养法,对连续7a采用渗灌、滴灌和沟灌灌溉,栽培番茄的保护地不同剖面层次土壤的有机氮矿化特点进行了研究。渗灌管为发汗式半软管,埋深为30cm;渗灌、滴灌和沟灌灌水方法及施肥、田间管理同当地农业生产。当20cm深处的土壤水吸力达到40kPa时开始灌水,渗灌和滴灌每次的灌水量是沟灌灌水量的1/2。试验结果表明,土壤矿化氮含量随着土层深度的增加而降低。从累积矿化氮量—时间曲线变化的趋势看,可将保护地土壤0～50cm剖面分为三个层次,其中渗灌与滴灌处理相似,为0～20cm、20～40cm和40～50cm土层,而沟灌处理则为0～30cm、30～40cm和40～50cm土层。保护地不同层次土壤有机氮的矿化可以用Twopool模型表达。比较不同灌溉处理,在0～10cm土层,易矿化有机氮含量(N1)表现为滴灌>沟灌>渗灌,易矿化有机氮矿化速率(k1)常数也以滴灌处理最大,说明滴灌更有利于表层土壤易矿化有机氮的形成。与渗灌和沟灌相比,长期使用滴灌灌溉有利于改善保护地土壤有机氮的品质。     

灌溉方法对保护地土壤有机氮组分及剖面分布的影响

用Bremner有机氮分组法测定了连续7年采用不同灌溉方法灌溉的保护地土壤各剖面层次有机氮组分含量。结果表明,土壤全氮及有机氮各组分含量均随土层深度的增加而降低,但有机氮各组分占全氮的比例随土层深度增加的变化却无明显规律。用3种灌溉方法灌溉,不同土层间土壤有机氮各组分含量的差异主要存在于0~50 cm土层,50 cm以下差异很小;相同土层,土壤有机态氮含量均以酸解氮为主,且酸解氮中各组分绝对含量和相对含量的大小排列顺序均为,未知态氮>氨态氮>氨基酸态氮>氨基糖态氮。在0~80 cm土层,土壤酸解氮占全氮的比例大多在58%~60%之间,只有渗灌处理0~10 cm,10~20 cm及沟灌处理0~10 cm土层酸解氮占全氮的比例较低,分别为34.21%,50.75%和48.02%;而非酸解氮占全氮的比例大多在32%~36%之间。3种灌溉方法相比较,除个别层次外,酸解氮中氨基酸态氮、氨基糖态氮及氨态氮占全氮的比例在各土层中滴灌和渗灌处理均高于沟灌处理,而酸解未知态氮和非酸解氮占全氮的比例则为沟灌处理高于滴灌和渗灌处理。     

不同灌溉方式对保护地土壤酸化特征的影响

自连续13a在同一地块以不同灌溉方式进行灌溉试验的保护地,分层采集沟灌、滴灌、渗灌3个处理0～60cm土层土壤样品,研究灌溉方式对土壤酸化特征的影响。结果表明,3种灌溉处理土壤活性酸度和交换性酸含量均随着土层加深而降低,各处理间土壤活性酸度在0～40cm土层差异明显,总体为沟灌>渗灌>滴灌;土壤交换性酸差异出现在0～30cm土层,为渗灌>沟灌>滴灌;土壤交换性Al3+随土层加深呈先增加后降低的变化趋势,且以滴灌含量最低。各处理土壤盐基饱和度(BS)随土层加深而增加,在0～30cm土层为滴灌>渗灌>沟灌。土壤pH与交换性酸、硝态氮含量呈极显著负相关,与盐基饱和度、特别是Ca2+饱和度呈极显著正相关;Al3+占交换性酸比例与有机质含量呈极显著负相关。总之,保护地土壤酸化与硝态氮含量、盐基饱和度、有机质含量关系密切;与沟灌和渗灌相比,滴灌更利于抑制土壤酸化。     

不同灌溉方式对设施土壤交换性盐基组成及比例的影响

为全面评价不同灌溉方式下设施土壤养分供应状况,以设施土壤为研究对象,采用田间试验与室内分析相结合的方法,对连年采用沟灌、滴灌和渗灌灌溉下的设施土壤有机质含量、阳离子交换量、盐基离子组成及其比列进行了研究。结果表明:3种灌溉方式土壤有机质、阳离子交换量及盐基离子含量表层较高,不同灌溉方式间表层土壤有机质含量及阳离子交换量表现为渗灌高于沟灌,沟灌高于滴灌,土壤交换性盐基离子含量总体以渗灌处理最高。各灌溉方式0—60cm土层土壤盐基离子饱和度大小顺序均为Ca~(2+)Mg~(2+)K~+Na~+,Ca~(2+)、Mg~(2+)饱和度随土层深度的增加而增大,K~+、Na~+饱和度总体呈随土层加深先降低后上升的变化趋势。Ca~(2+)、Mg~(2+)饱和度在0—30cm土层滴灌最高,30—60cm土层渗灌最高。K~+饱和度总体以渗灌为高,沟灌居中,滴灌最低。土壤Ca/K、Mg/K值总体以滴灌最高,沟灌次之、渗灌较小。从不同灌溉方式对设施土壤交换性盐基组成及比例的影响来看,采用滴灌方法不仅能省水,有效供应养分,更有利于保持养分之间的平衡,是一种较为合适的灌溉方法。     

灌溉方式对保护地土壤磷素淋失风险的影响

自连续12年以相同试验方案、不同灌溉方式进行灌溉试验的保护地采集土壤样品,对不同灌溉处理土壤磷素淋失风险进行评价,并对影响土壤磷素淋失临界值大小的因素进行了探讨。灌溉处理设滴灌、沟灌和渗灌三种灌溉方式,采样深度为0~80 cm。结果表明,0~20 cm沟灌、渗灌和滴灌处理土壤的磷素淋失临界值Olsen-P含量分别为59.44 mg kg-1、65.39 mg kg-1和68.57 mg kg-1;而20~40 cm层次的土壤淋失值分别为60.61 mg kg-1,66.8 mg kg-1和70.58 mg kg-1;40~80cm土层则无临界值存在。影响土壤磷素淋失临界值Olsen-P含量的主要因素有土壤pH和有机质、活性Fe、活性Al、有效磷含量;土壤pH值越大、有机质、活性铁、活性铝和Olsen-P含量越高,磷素淋失临界值越大。对三种灌溉处理表层土壤磷素淋失风险进行综合评价,其风险大小顺序为沟灌、渗灌和滴灌,这提示人们在保护地生产中要充分注意土壤磷素有效性,通过选择合理的灌溉方式、改善施肥技术以加强保护地土壤水肥管理,保证作物生产高效、优质和降低环境风险。     

保护地不同灌溉方法表层土壤pH小尺度的空间变异

基于保护地定位灌溉试验,采用经典统计学和地统计学的方法,以网格取样方式采集不同灌溉方法(沟灌、滴灌、渗灌)表层土壤,研究微尺度下土壤pH值的空间变异特征及空间分布。结果表明:经6年灌溉,沟灌处理pH显著降低,沟灌和滴灌0～5cm土层土壤pH表现为中等空间自相关,而其5～10cm和渗灌0～5cm和5~10cm的土壤pH表现为弱空间相关,水分的供给方式和数量影响土壤pH的空间变异。     

灌溉方法对保护地土壤有机氮组分及剖面分布的影响

用Bremner有机氮分组法测定了连续7年采用不同灌溉方法灌溉的保护地土壤各剖面层次有机氮组分含量。结果表明,土壤全氮及有机氮各组分含量均随土层深度的增加而降低,但有机氮各组分占全氮的比例随土层深度增加的变化却无明显规律。用3种灌溉方法灌溉,不同土层间土壤有机氮各组分含量的差异主要存在于0～50 cm土层,50 cm以下差异很小;相同土层,土壤有机态氮含量均以酸解氮为主,且酸解氮中各组分绝对含量和相对含量的大小排列顺序均为,未知态氮〉氨态氮〉氨基酸态氮〉氨基糖态氮。在0～80 cm土层,土壤酸解氮占全氮的比例大多在58%～60%之间,只有渗灌处理0～10 cm,10～20 cm及沟灌处理0～10 cm土层酸解氮占全氮的比例较低,分别为34.21%,50.75%和48.02%;而非酸解氮占全氮的比例大多在32%～36%之间。3种灌溉方法相比较,除个别层次外,酸解氮中氨基酸态氮、氨基糖态氮及氨态氮占全氮的比例在各土层中滴灌和渗灌处理均高于沟灌处理,而酸解未知态氮和非酸解氮占全氮的比例则为沟灌处理高于滴灌和渗灌处理。     

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。