旱作农业综合配套技术及增产效益研究

宁夏南部半干旱水土流失地区,在作物合理布局的基础上,建立以粮——豆——草轮作为中心的综合配套技术体系,做到轮作制度化、栽培规范化,施肥模式化。系统内的能量转化效益提高14.7%,粮食单产和总产分别较实验前提高1.2倍和1倍。其中“轮作中心的平衡施肥”,既考虑到氮、磷等主要营养元素的协调平衡,也考虑到周期性的供求平衡,提高了系统内土壤养分的调控能力和稳定性。     

冀北高原草甸栗钙土春小麦中化肥氮去向的研究

在冀北高原张北县的草甸栗钙土上，采用＾１５Ｎ质量平衡法和微气象学技术，对春小麦中氮肥的去向，以及氨挥发进行了田间原位观测。试验中的氮肥用量为Ｎ４．８３ｋｇ／亩，１／３作基肥、２／３作追肥。基肥随播种施入，追肥于拔节期撤施，随即灌水。结果表明，小麦回收、土壤残留和损失的肥料氮各占施入氮量的３７．８％－４８．３％、３３．８％－４０．４％和１４．３％－２５．４％。其中，尿素作基肥与作追肥的处理之间，其氮     

Geochemistry of HCO3- at the Sediment-Water Interface of Lakes from the Southwestern Chinese Plateau

Sediments were cored, and the sediment-water interface and overlying waters were sampled in 5 lakes from the southwestern Chinese plateau during 1991-95. The geochemistry of HCO3- at the sediment-water interface was examined by studying detailed profiles of pH, HCO3- concentrations and δ13C of dissolved inorganic carbon (DIC) in overlying lake water and porewater near the sediment-water interface. Dissolution-precipitation equilibrium of carbonates, diffusion flux, and the extent of the influence of diffusion on the whole lake were calculated. The results show that the HCO3- near the interface carried isotopic characteristics of decomposition of organic matter during early diagenesis, and that the porewater in surface sediments was unsaturated relative to calcite, and gradually saturated with depth. Furthermore, the interface is a source of HCO3- to the overlying water. Alkalinity (Alk) diffusion flux from sediments to the overlying water due to concentration gradients ranged from 0.51 to 24.33 × 10-4 mol cm-2 a-1. The calculated contribution of the diffusion of Alk to the overlying water ranged from 0.46% to 49.42%. Diffusion is an important source of Alk in lakes with a long residence time and a relatively shallow depth.     

宁夏银南灌区排水现状分析及计算

作为灌溉农业的一项保障措施，农田排水在维持田间水盐平衡的同时，也向下游输送了大量可能成为地表水污染源的物质。位于黄河上游的宁夏银南灌区由于历史原因形成的“大引大排”积习，每年将过量的农田排水排入黄河，成为下游水质污染源，同时也浪费了宝贵的水资源。该文针对宁夏银南灌区过量排水问题，对灌区排水现状进行了详细的分析和计算。结果表明，在现有灌排制度下，生长期内水田的农沟排水量约56 cm，占地下排水总量的58%；旱田的农沟排水量较少，只有1.0 cm，占地下排水总量的4%。建议在水田农沟上加筑控制性建筑物，如堰等，对排水量进行控制，达到节约灌溉用水和减少农田排水对下游河道污染的目的。     

钾肥用量和品种对桑叶生产及蚕茧质量的影响

通过为期 4年的田间施肥试验和 1季养蚕试验 ,研究了钾肥用量和钾肥品种对桑叶产量、品质、养分吸收和蚕茧质量的影响。结果表明 ,施K2 O 1 5 0、30 0、375kghm-2 a-1 处理分别比不施K肥年均增产桑叶 2 3.9%、31 .7%、36 .0 %;等量钾肥时 ,KCl对桑叶增产效果基本等同于K2 SO4;施钾增产效果有逐年增加趋势 ,同时钾肥施用表现后效。施钾明显提高桑叶中N、K和S(K2 SO4为钾源时 )含量 ,而降低Ca、Mg和Zn含量 ,对P含量影响不大。结果显示 ,钾肥施用大幅度促进了桑树对各种养分的吸收 ,从而提高了肥料利用率。施钾明显促进桑叶品质的改善 ,随着钾肥用量增加 ,桑叶中必需氨基酸、氨基酸总量、蛋白质、糖分和油脂含量均呈增加趋势。KCl施用也能提高桑叶品质 ,但效果比K2 SO4差。蚕茧质量测试结果表明 ,桑树施钾后对喂养的蚕茧品质产生正面影响 ,蚕重、全茧量、上茧率、茧丝长、解舒率、茧丝净度等指标均因施钾而提高 ,高量钾比低量钾效果好 ,在等量钾用量时K2 SO4对蚕茧质量的促进作用明显好于KCl。     

我国储粮技术创新途径与发展思路

本文根据中国国情和基层实际，从三低储粮，机械通风、粮仓熏蒸，防护剂和消毒剂等四个方面，系统地提出了17项技术创新途径和设想，并对今后储粮实用技术发展方向提出了新的思路。     

从破壁酵母中提取β-葡聚糖的工艺研究

采用碱法浸提工艺从破壁酵母中提取碱不溶性β-葡聚糖,通过正交实验得出其最佳提取条件为:碱处理温度75℃,碱处理时间15min,碱液浓度0.75mol/L。不同脱水和干燥条件的对比实验表明,脱水和干燥条件对产品色泽的影响显著。产品最终含水率越低,产品色泽越白;溶剂和水分蒸发得越快,产品颜色越白。     

The diversity of head-scab resistance in Triticeae and their relation to ecological conditions

1507 accessions from 93 species of 18 genera in Triticeae were screened for resistance to initial infection and resistance to pathogen spread with multi-floret and single-floret injection inoculation methods respectively. The accessions with high resistance were mainly found in perennial genera: Roegneria, Hystrix, Agropyron, Kengyilia and Elymus. Based on differences in resistance, 18 genera screened in Triticeae could be classified into five groups. The species with high resistance were mainly distributed in humid ecological environments. This revised version was published online in July 2006 with corrections to the Cover Date.     

Identification of two types of differentiation in cultivated rice (Oryza sativa L.) detected by polymorphism of isozymes and hybrid sterility

Magnitudes of genetic variation within each of major varietal groups of cultivated rice were surveyed in terms of isozyme polymorphism and allelic differentiation of hybrid sterility loci, both of which are considered to have litt le selective value. Allelic differences for 20 isozyme loci were examined in a total of 337 accessions, including Indica and Japonica rices. Aus cultivars from India, Javanica cultivars and both landraces and cultivars from China. Eleven out of the 20 isozyme loci were polymorphic. The Aus cultivars contained more alleles per locus than others. The hybrid sterilities in the crosses among Chinese cultivars, Indica and Japonica cultivars were mainly controlled by locus S-5, whereas the hybrid sterilities of Aus cultivars, when they were crossed to Indica, Japonica or Javanica cultivars, were found to be controlled by allelic interaction at hybrid sterility loci S-5, S-7, S-9 and S-15. Also in terms of the number of alleles at S-5 and S-7, Aus cultivars contained more alleles than others. While the Aus group showed an extreme diversity for both hybrid sterility alleles and isozymes, modern cultivars from the south of YangZi River in China were classified into Indica type and those from the north were into Japonica, which were almost the same as those in Japan. On the basis of the measured polymorphism the Indica-Japonica differentiation was explained by founder effects, i.e., through selection and distribution of two original sources each with a unique set of markers. Contrastingly, the continuous and pronounced diversity in the Aus group was attributed to the absence of such a process. The intermediate groups in Yunnan province and Tai-hu Lake region of China are considered to be isolated from such founder effects, retaining an intermediate diversity in terms of isozymes and hybrid sterility genes. Since hybrid sterility hampers the exchange of genes between cultivars of different groups, the understanding of its genetic basis will be important in rice breeding, particularly in hybrid rice breeding. This revised version was published online in July 2006 with corrections to the Cover Date.     

柚新品种‘老哥贡柚’的选育

‘老哥贡柚’是从‘冰糖柚’优良芽变中选育出的新品种。‘老哥贡柚’树势较强,枝梢较密,坐果率高。果实圆锥形,果皮浅黄色,果面光滑,油胞密集,果肉白色。纯甜无酸,食后无麻苦味,平均单果质量712 g,少核或无核,可溶性固形物含量(w,后同)为12.3%,总糖含量11.32%,总酸含量0.35%,可滴定酸含量0.22%,维生素C含量0.469 mg·g^-1。10月中下旬成熟,丰产、稳产,抗逆性强。