不同果实负载下温室黄瓜干物质分配的模拟

黄瓜是中国温室栽培的最主要作物之一,果实负载决定着果实发育和产量,构建不同果实负载下温室黄瓜干物质分配模型对温室黄瓜栽培管理具有重要的理论意义和实践价值。根据温室黄瓜生长对光温需求,以辐热积（TEP）为尺度建立温室黄瓜干物质分配模型,并用与建模试验不同的试验数据进行模型检验。模型对温室黄瓜茎、叶和果实干质量的预测结果与实测值1∶1线回归估计标准误（RMSE）和决定系数（R2）分别为223.08、119.23、316.34 kg/hm2和0.76、0.73、0.75,模型的预测结果与实测值之间的吻合度较好。     

用辐热积法模拟温室黄瓜果实生长

为了提高预测温室黄瓜产量的能力,该研究根据温室黄瓜（品种为：戴多星Cucumis sativus cv Deltestar）果实对温度和辐射的响应,建立了以辐热积（Product of thermal effectiveness and PAR,TEP）为尺度的温室黄瓜果实模型,并用独立的试验数据进行了检验。模型对温室黄瓜各节位果实果长、果径和鲜质量的模拟值与实测值的符合度较好,模型对温室黄瓜果长和果径的模拟值与实测值之间的决定系数（R2）分别为0.7325和0.5885;回归标准误差（RMSE）分别为1.64 cm和0.35 cm,而以有效积温（Growing degree days,GDD）为尺度构建的果实生长模型对果长和果径的预测结果与实测值之间的决定系数（R2）分别为0.5768和0.4893;回归标准误差（RMSE）分别为1.83 cm和0.40 cm;本模型对果实鲜质量的模拟结果与实测值之间的回归标准误差（RMSE）和决定系数（R2）分别为25.04 g 和0.6782。而基于有效积温的果实生长模型对果实鲜质量的模拟结果与实测值之间的回归标准误差（RMSE）和决定系数（R2）分别为28.52 g和0.6068。模拟精度提高了12.21%。本研究建立的辐热积模型能较准确地预测温室黄瓜各节位的果实生长,模型的实用性较强,可以为温室黄瓜生产提供理论依据和决策支持。     

氮素对温室黄瓜开花后干物质分配和产量影响的模拟研究

了解氮素对干物质分配和产量的定量影响是实现温室黄瓜氮肥优化管理的前提.该研究通过黄瓜雌性无限生长型品种"戴多星"(Cucumis sativas.'Deltastar')不同定植期和开花后不同氮素处理试验,定量分析了氮素施用水平对该类型黄瓜开花后干物质分配和产量的影响,并建立了开花后分配指数和采收指数与盛果期叶片氮浓度的关系方程.在此基础上,建立了氮素对黄瓜开花后干物质分配和产量影响的预测模型,并用独立的试验数据对模型进行了检验.结果表明,模型对茎干物质量、叶干物质量和果实干物质量及黄瓜产量(鲜质量)预测值与实测值之间基于1:1直线之间的决定系数R2分别为0.945、0.943、0.990、0.955;相对预测误差RE分别为13.0%、12.3%、9.2%、16.8%.本模型可预测不同氮素水平下温室黄瓜地上部各器官干物质量和产量,可以为中国温室黄瓜生产的氮肥优化管理决策提供参考.     

电导率对温室黄瓜叶面积和干物质生产影响的动态模拟

电导率是温室营养液管理的重要参数.为定量研究不同电导率对温室黄瓜光合与干物质生产的影响,该文以温室黄瓜为试验材料,于2009年10月至2010年7月进行了不同电导率的营养液栽培的试验,定量分析了电导率对温室黄瓜叶面积、光合速率和干物质生产的影响,构建了以辐热积为尺度的叶面积指数、最大光合速率和干物质生产模型,并用独立的试验数据对模型进行了检验.结果表明:模型对温室黄瓜叶面积、最大光合速率和干物质产量的模拟值与实测值之间的决定系数分别为0.89、0.93和0.94,回归估计标准误差分别为0.21m2/m2、1.52 μmol/(m2.s)和36.77 kg/hm2,预测相对误差分别为4.5％、11％和9.2％.该研究建立的模型可以为温室黄瓜的营养液管理和决策提供依据.     

不同营养液浓度对温室盆栽黄瓜产量与品质的影响

营养液浓度与供液方式会影响温室黄瓜的产量与品质。本文通过盆栽试验,以山崎黄瓜专用营养液配方标准浓度1S为基准,研究了负水头供水控水盆栽装置供液条件下 1/2S、3/4S、1S、1S 4种营养液浓度以及常规浇灌1S（CK）营养液浓度对温室盆栽基质栽培黄瓜产量与品质的影响。结果表明, 地上部干重和产量与营养液浓度成显著正相关关系; 1S处理产量与地上部干重显著大于1S (CK)处理,但营养液生产效率差异不显著; 黄瓜整体品质随生育进程而提高,采收初期果实品质整体指标各处理差异较大,1S处理的较高; 采收中期1S与1S处理的较高,而采收末期各处理整体品质差异较小,1/2S与1S（CK）处理的相对较高; 其中1S（CK）处理各采收时期果实硝酸盐含量明显高于1S处理,而其它各指标两者无显著差异。负水头供水控水盆栽装置供液方式与1S营养液浓度处理是一种较好的供液方式与供液浓度。同时,适当提高黄瓜生育前期与降低生育末期营养液浓度能提高黄瓜的整体品质。     

温室盆栽一品红生长发育模拟模型

该研究的目的是建立一个温室盆栽一品红（Euphorbia pulcherrima Willd.）生长发育模拟模型,为温室盆栽一品红生产中的光温精准调控提供理论依据与决策支持。以一品红品种‘中国红’（Euphorbia pulcherrima Willd. Red China）为研究对象,通过不同定植期和不同密度的试验,定量分析了一品红生长发育与光温的关系。在此基础上,以生理辐热积（Physiological product of thermal effectiveness and PAR,PTEP）为尺度,建立了温室盆栽一品红生育期模拟子模型;以冠层吸收的生理辐热积（Canopy intercepted PTEP, PTEPint）为尺度,建立了温室盆栽一品红干物质生产和分配模拟子模型;综合生育期模拟子模型与干物质生产和分配模拟子模型,建立了温室盆栽一品红生长发育模拟模型,并用独立的试验数据对模型进行了检验。模型对从摘心到短日处理、单苞、单蕾、多蕾和开花期的模拟预测值与实测值的符合度较好。模拟值与实测值基于1︰1线的决定系数R2为0.99,回归估计标准误差RMSE分别为0.7、3、3.5、0.7和2 d,预测精度明显高于以有效积温为尺度的发育模型（RMSE分别为8、4.5、3.8、2.8和7.2 d）。模型对单位面积总干质量、叶干质量、茎干质量和苞叶干质量的模拟值与实测值基于1︰1线的R2和RMSE分别为0.98、0.97、0.91和0.95;7.12、7.49、3.89和2.48 g/m2。模型对一品红单位面积总干质量的预测精度明显高于基于光合作用驱动的生长模型（R2和RMSE分别为0.77和35.06 g/m2）。该研究建立的模型能够较准确地预测温室盆栽一品红各生育期出现时间、干物质生产和各个器官干质量的动态,模型的预测精度较高、参数少且易获取、实用性较强。     

温室黄瓜干物质分配与产量预测模拟模型初步研究

依据温室黄瓜(Cucumis sativus)器官生长与温度和辐射的关系，建立了基于分配指数和采收指数的温室黄瓜干物质分配与产量预测模拟模型，并利用不同品种和基质的试验资料对模型进行了检验。结果表明，模型对黄瓜地上部分干重、根干重、茎干重、叶干重、果实干重的预测结果与1∶1直线之间的R²分别为0.98，0.73，0.83，0.92，0.94；RMSE分别为232，6.8，157.6，173.9，196.8 kg/hm²。模型对黄瓜产量的预测结果与1∶1直线之间的R²为0.80，RMSE为7526.4 kg/hm²。本模型对不同基质、品种的黄瓜干物质分配和产量的预测值与实测值符合度均较高，说明本模型的普适性较好。模型不仅能较好地预测中国现有生产水平下温室黄瓜的干物质分配及产量，而且可以为实现中国温室黄瓜生产环境优化调控和模式化栽培管理提供决策支持。     

叶片氮浓度对温室黄瓜花后叶片最大总光合速率影响的模拟

光合作用是作物产量和品质形成的基础,直接受到叶片含氮量的影响.该文通过不同定植期不同氮素处理试验,建立了不同光温条件下温室黄瓜叶片适宜氮浓度的求算方程,并定量分析了不同光温条件下黄瓜叶片最大总光合速率与叶片氮浓度的关系.在此基础上,进一步建立了适合不同光温条件的温室黄瓜花后叶片最大总光合速率与叶片氮浓度关系的通用模型,并用与建模相独立的试验数据对模型进行了检验.结果表明,建立的模型能较好地预测不同定植期黄瓜叶片氮浓度对叶片最大总光合速率的影响.模型对温室黄瓜叶片最大总光合速率的预测结果与实测结果之间基于1:1直线的决定系数和均方根差分别为0.83和1.56 μmol·m-2·s-1.建立的模型可以为温室黄瓜周年生产的氮素精确管理提供理论依据与决策支持.     

不同营养液浓度对温室黄瓜叶片光合特性的影响

为了探究不同电导率（electrical conductivity,EC）的营养液对温室黄瓜叶片光合特性的影响,该文于2009年10月至2010年7月在江苏大学Venlo型温室中进行试验,采用4种EC值的营养液浇灌黄瓜,对4种EC值条件下温室黄瓜叶片的光合速率、叶绿素荧光、叶绿素含量及产量进行了测定,并对EC对黄瓜叶片叶绿素仪读数、光合速率和最大电子传递速率的影响及其之间的关系进行了分析。研究结果表明,营养液的电导率值对温室黄瓜下部叶片的叶绿素仪读数值、最大光合速率、光能初始利用率和电子传递速率有较大的影响,中部叶、上部叶片的叶绿素仪读数值、最大光合速率、光能初始利用率、电子传递速率和产量在不同处理间无论是秋冬茬还是早春茬均表现为：营养液的电导率为2.5 dS/m和营养液的电导率为2.2 dS/m差异不显著,但显著大于营养液的电导率为1.5 dS/m和营养液的电导率为0.036 dS/m;构建了最大光合速率与叶片叶绿素仪读数值、光能初始利用率与叶片叶绿素仪读数值的关系模型;光合速率与电子传递速率之间呈幂指数函数关系。该研究为通过叶片光合速率进行营养液管理提供了理论依据。     

黄瓜壮苗指标与辐热积关系的模拟模型

为预测温室黄瓜幼苗的健壮程度,该文探讨了黄瓜根冠比、G值(全株干质量与育苗天数之比)、壮苗指数3个壮苗指标与环境温度和辐射的关系,以2个不同生态型黄瓜品种‘津春4号’和‘戴多星’为试验材料,通过分期播种试验及回归分析,建立了以辐热积为尺度的温室黄瓜壮苗指标模拟模型,并利用独立试验数据对模型进行了检验。结果表明,根冠比与辐热积曲线拟合度差,G值模型的模拟值与实测值符合度低。在该试验条件下,这2个壮苗指标均不适宜用辐热积做变量进行模拟。黄瓜壮苗指数与辐热积曲线拟合度高。模拟结果与实测值之间的回归标准误差(RMSE)为0.0040,说明模型具有较高的预测精确性;壮苗指数的模拟值与实测值之间基于1∶1直线的决定系数(R2)分别为0.9854(津春4号)和0.9761(戴多星),F检验均达极显著水平,表明模拟值与实测值的符合度高。该研究建立的基于辐热积的黄瓜壮苗指数模型能较准确的预测黄瓜幼苗健壮程度,所用参数少,模型实用性较强,可为黄瓜育苗中幼苗健壮程度的预测提供有效方法,也可为黄瓜育苗中的温光管理提供决策支持。     

“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。     

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.     

Faculty positions:Center for Agricultural Resources Research,Chinese Academy of Sciences

正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications     

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.     

Collection and preliminary evaluation of native turfgrass accessions in Italy

Despite a raising interest on turfs in Italy, all theavailable varieties of this kind in the Country are of foreign origin, and areoften poorly adapted to the prevailing climatic conditions. This prompted tobegin a collection activity of indigenous turfgrass species, with the ultimategoal of identifying promising materials for future breeding based on localgenetic resources. The collection was carried out in three areas of Italy, viz.the northern Po Plain, the coastal region of Liguria, and the island of Sardiniathat are characterised, respectively, by subcontinental, warm temperate, andtypical Mediterranean climate. Altogether, 141 sites were visited, yielding 226accessions belonging to eight species of potential interest for turfs:Poa pratensis, Poa trivialis,Festuca rubra, Festuca arundinacea,Lolium perenne, Agrostis stolonifera,Agrostis tenuis, and Cynodon dactylon,this last being a warm-season grass. Poa pratensis andCynodon dactylon were mostly collected in northern Italyand Sardinia, respectively, whereas Festuca arundinacea andLolium perenne were rather ubiquitous. The collection sitesranged from 0 to 1040 m asl, but sites over 750 m wereonly visited in the inner part of Sardinia. All the accessions, collected aswhole plants, were transplanted at Lodi, northern Italy, where they are beingevaluated. Their preliminary evaluation for traits of importance for turf use,such as sward colour and overall quality, highlighted the great variation andthe occurrence of interesting accessions in all species. Other characters wererecorded, bearing specific importance in individual species, and in all casespromising accessions were identified. The germplasm of Festucarubra, Festuca arundinacea, and Loliumperenne proved highly infected by endophytic (symbiotic) fungi of thegenus Neotyphodium.     

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.     

Leaf position and genotype differences for mineral element concentrations in sorghum grown on tropical acid soil 1

Mineral element deficiencies and toxicities are common problems associated with sorghum [Sorghum bicolor (L.) Moench] production on acid soils. To better understand some of the mineral element problems and the analysis of plant tissue of sorghum plants grown on acid soils, four sorghum genotypes were grown on an acid Oxisol at Carimagua, Colombia limed with dolomite at 2 and 6 Mg ha^‐1.

Samples for mineral element analyses were obtained from leaves at different positions on the four genotypes. Concentrations of P and Mg were highest in the flag leaf (Leaf No. 1) and decreased as the position on the plant declined from the top of the plant for plants grown at 2 Mg lime ha^‐1. Similar decreases in P, Mg, K, and Zn concentrations occurred in plants grown with 6 Mg lime ha^‐1. Concentrations of Ca, S, Si, Mn, Fe, Cu, and Al increased as leaf position declined from the flag leaf for plants grown at 2 and 6 Mg lime ha^‐1. The higher lime supply enhanced Ca and reduced Mn and Fe concentrations in leaves. Differences in mineral element concentrations for the four genotypes used were fairly extensive. The elements to show the greatest range among genotypes were Al and Si and the elements to show the least range among genotypes were P, K, and S. Care should be used in collecting leaf samples for plant analysis and genotypic differences for accumulation of mineral elements should be considered in interpretation of results.