杂交晚稻“SP优I98”的选育及应用

"SP优I98"是江西省农业科学院水稻研究所用不育系"优IA"与自育的强优恢复系"SP40098"配组育成的晚稻新组合。2002～2003年该组合参加江西省晚稻中熟组区试,熟期、产量、抗性均优于同类组合对照种"汕优64",具有高产、稳产、株型好、抗性较强、制种产量高等特点,适合于江西作二晚种植。介绍了"SP优I98"的高产栽培技术和制种技术要点。     

长寿沙田柚Ri T-DNA转型根优化培养体系研究

 设计了长寿沙田柚不同外植体在光、暗条件下进行发根农杆菌遗传转化试验，建立了长寿沙田柚Ri T-DNA转型根优化培养体系，该体系为：用对数期的发根农杆菌A4菌株感染活化胚中单片子叶的创伤腹面，25℃±2℃暗培养25～30 d，多数子叶上发出转型根（毛状根），遗传转化率达（83±11）%。继代脱菌5代后获得无菌转型根。外植体活化采用MT培养基，继代脱菌培养采用MS培养基。采用这个体系获得了大量激素自主的长寿沙田柚Ri T-DNA转型根。获得的新鲜转型根白色，长1.14±0.07 cm，粗0.73±0.04 mm，负向地性生长。     

高产杂交籼稻新组合"特优649"产业化技术研究Ⅰ密度及主要肥料因子对产量的影响

试验采用裂区设计,以肥料为主区,密度为副区,研究高产杂交籼稻新组合“特优649”的密度和氮肥、磷肥、钾肥施用量与产量的关系,结果表明:当密度为37.5万(/hm2,或株行距为20cm×13.2cm,氮肥施用量为225kg纯氮/hm2,其N,P2O5,K2O的比例为1.0:0.5:0.8时,产量最高,平均达9.24t/hm2,最高达9.36t/hm2。据此提出产量指标为9.0t/hm2以上的优化农艺措施组合为:每hm2密度37.5万(,每(插2粒谷秧,纯氮用量225kg,P2O5用量112.5kg,K2O用量180.0kg,其中基肥为猪牛粪22.5t 30kg过磷酸钙;试验还提出了相配套的水分运筹方法。     

水稻强化栽培不同因子对Ⅲ优98主要经济性状及产量的影响

为了探索在水稻强化栽培条件下不同密度、纯氮量、2,4-D控蘖试验三因子的最佳组合。采用三元二次旋转组合设计,研究"Ⅲ优98"在强化栽培条件下,移栽密度、纯氮量2、,4-D控蘖三因子对产量及主要经济性状的效应。建立了三因子对产量的二次多项回归效应模型,分析得出高产群体主要经济性状的量化指标。总结出"Ⅲ优98"在强化栽培条件下产量≥8 250 kg/hm2的栽培措施为:移栽密度16.5万~18.0万/hm2,纯氮量196.5~213.0 kg/hm2,2,4-D控蘖时间在群体茎蘖达到248.0万~255.0万/hm2时,三因子取平均值时产量为9 027.0 kg/hm2。在适宜的密度范围内,通过氮肥管理和2,4-D控蘖,使群体和个体各性状协调发展,是实现高产的重要途径。     

Role of Phosphatases,Iron Reducing,and Solubilizing Activity on the Nutrient Acquisition in Mixed Cropped Peanut and Barley

The effect of interspecific complementary and competitive root interactions and rhizosphere effects on primarily phosphorus (P) and iron (Fe) but also nitrogen (N), potassium (K), calcium (Ca), zinc (Zn), and manganese (Mn) nutrition between mixed cropped peanut (Arachis hypogaea L.) and barley (Hordeum vulgare L.). In order to provide more physiological evidence on the mechanisms of interspecific facilitation, phosphatase activities in plant and rhizosphere, root ferric reducing capacity (FR), Fe-solubilizing activity (Fe-SA), and rhizosphere pH were determined. The results of the experiment revealed that biomass yield of peanut and barley was decreased by associated plant species as compared to their monoculture. Rhizosphere chemistry was strongly and differentially modified by the roots of peanut and barley and their mixed culture. In the mixed cropping of peanut/barley, intracellular alkaline and acid phosphatases (AlPase and APase), root secreted acid phosphatases (S-APase), acid phosphatases activity in rhizosphere (RS-APase), and bulk soil (BS-APase) were higher than that of monocultured barley. Regardless of plant species and cropping system, the rhizosphere pH was acidified and concomitantly to this available P and Fe concentrations in the rhizosphere were also increased. The secretion Fe-solubilizing activity (Fe-SA) and ferric reducing (FR) capacity of the roots were generally higher in mixed culture relative to that in monoculture treatments which may improve Fe and Zn nutrition of peanut. Furthermore, mixed cropping improved N and K nutrition of peanut plants, while Ca nutrition was negatively affected by mixed cropping.     

The relative efficiency of ionic iron(III) and iron(II) utilization by the rice plant

Uptake of iron by rice plants was equally rapid when supplied as ionic iron(II) or iron(III) at pH 3 and 4. Iron(III) uptake was reduced at pH 5 and uptake of iron when supplied as FeEDTA was relatively low at all three pH levels.

At pH 4 in the presence of plant roots, reduction of iron(III) to iron(II) occurred as indicated by Fe²⁺ BPDS formation. BPDS in a 3:1 ratio to iron(III) suppressed iron uptake by about 70%. The reduction was observed to be located in the endodermis of young roots and exodermis of older roots.

A capacity to oxidize iron(II) at the root surface was also observed under local anaerobic and relatively high pH conditions.

The significance of these two counteracting processes in affecting the oxidation state of iron at the root surface is discussed.     

三价铁离子促进玉米秸秆厌氧发酵

厌氧消化是农业废弃物资源化利用的有效途径之一。微量元素是影响有机废弃物厌氧产沼气性能的重要生态因子,其中铁对有机废弃物的厌氧发酵过程的效率和稳定性作用最为显著,而通常秸秆的含铁量很低。因此,该试验以玉米秸秆为例,研究了初始FeCl3加入量分别为0.1%、0.2%、0.5%、1.5%、3%、6%（基于秸秆的挥发性组分）时秸秆厌氧发酵产沼气、产甲烷过程以及沼液沼渣特征。结果表明初始FeCl3加入量为3%,秸秆的厌氧产甲烷效率相对于对照（加入量0%）提高了14%。X射线衍射分析结果表明FeCl3存在时,沼渣中纤维素的结晶度显著降低。沼渣的组分分析结果表明FeCl3的存在有助于提高玉米秸秆中纤维素及半纤维素的分解效率,从而提高了秸秆产甲烷效率。该研究可为农业废弃物甲烷化利用提供参考。     

水稻白叶枯病菌Zur和HrpG平行调控hrcC基因表达

 水稻白叶枯病菌(Xanthomonas oryzae pv. oryzae, Xoo)的III型分泌系统(Type III secretion system, T3SS)由hrp基因簇编码,其决定在寄主水稻上的致病性。hrcC是hrp基因簇中hrpA转录单元仅有的一个基因,推测编码T3SS的核心组分蛋白。在Xoo中,hrcC在致病性中的功能以及受调控的机制仍未明确。本研究构建了hrcC的缺失突变体及其功能互补子,发现hrcC缺失使Xoo丧失了在寄主水稻上的致病性以及在非寄主烟草上激发过敏反应(Hypersensitive response, HR)的能力,功能互补子能够恢复这些表型至野生型水平。启动子GUS活性的定量测定和蛋白免疫杂交试验,证明hrcC的转录表达依赖于主要的hrp调控子HrpG,而不受HrpX调控;HrpG和铁转运家族类调控子(Ferric uptake regulator family)Zur以平行独立的方式正调控hrcC基因的转录表达。异源功能互补、启动子活性和蛋白表达试验发现Xoo和水稻条斑病菌(Xanthomonas oryzae pv. oryzicola, Xoc)的hrcC基因在致病性上的功能具有互置性,以及受HrpG、HrpX和Zur的调控模式也具有相似性。这些研究为进一步解析黄单胞菌的hrp调控网络与全毒性调控网络之间的交叉提供了新的线索。     

Predicting Maize Yield,Nutrient Concentration,and Uptake in Phosphorus- and Potassium-Fertilized Soils: Pressurized Hot Water and Other Alternatives to Mehlich I Extraction in Guatemala Soils

Abstract

Poor accessibility and cost of soil testing reduce effectiveness of fertilizer use on small‐scale subsistence farms, and inadequate funding promotes adoption of soil tests in developing countries with minimal validation. For example, Mehlich I extraction of phosphorus (P) currently used extensively in Guatemala may not be suitable for Guatemala's broad range of soils. At least four alternatives are available but relatively untested [Bray 1, Mehlich III, Olsen, and pressurized hot water (PHW)]. Pressurized hot water is relatively simple and inexpensive but is not yet tested against other extraction methods under variable P or potassium (K) fertilization levels. To determine whether PHW‐extracted nutrients could be used to predict maize yield and nutrient concentration and uptake, soil, plant tissue and grain samples were obtained from a multiple‐site field study, and calibration studies were conducted using five rates of P and three rates of K on soils incubated without plants or cropped with maize in greenhouse and field conditions. In the multiple‐site field study, maize yield related significantly to PHW‐extractable P (r²=0.36) and to leaf P concentration (r²=0.23), but Mehlich I–extractable P did not. In the two soils used in the greenhouse study, maize yield, vegetative P concentration, and total P uptake by maize were predicted by PHW‐extractable P (R²=0.72, 0.75, and 0.90, respectively). In the field experiment, grain yield was not improved by P or K application, but P concentration of maize leaf tissue did relate significantly with PHW‐extracted P (R²=0.40). Mehlich I did not. There were no yield responses to K application in any experiment, but relationships defined between extractable K for all five K‐extraction procedures and soil‐applied K were similarly significant. In comparison, PHW was as good as or better than Olsen whereas Bray 1 and Mehlich III were less consistent. Mehlich I was overall the poorest P extractant. Mehlich I extraction of P should be replaced by one of the four alternatives tested. PHW is the least expensive and, therefore, most viable for use in Guatemala soils.     

Comparisons of soil test phosphorus by Olsen,Bray P1, Mehlich I and Mehlich III methods

Abstract

A study was undertaken to evaluate the agreement among different university laboratories performing the Olsen, Bray P1, and Mehlich I tests for P on a diverse group of noncalcareous agricultural soils and to develop relationships among the Olsen, Bray P1, Mehlich I, and Mehlich III soil tests. For each test, the results from the individual laboratories were highly correlated (r² ≥ 0.90) and in almost all instances the slopes of the equations describing the relationships among laboratories approached one, The results indicate that the Olsen, Bray P1 and Mehlich I soil tests may be performed with a high degree of precision when standard soil test procedures are followed.

Of the three most commonly performed tests in the U.S. (Olsen, Bray P1, and Mehlich I), the Olsen and Mehlich I tests were the most highly correlated (r² = 0.87) although the Mehlich I test removed approximately one and one half times more P than did the Olsen test. Bray P1 and Olsen and Mehlich I P were less highly correlated (r² ≤ 0.72) and the relationships between these variables were influenced by the texture of the soils. The quantity of P removed by the Bray P1 test was on the order of two and three times greater than that removed by the Olsen and Mehlich I tests, respectively. The Bray P1 and Mehlich III soil tests were highly correlated (r² = 0.97) and similar quantities of P were extracted from the soil by the two tests.