Resin-Extractable Phosphorus, Vanadium, Calcium and Magnesium as Factors in Maize (Zea mays L.) Yield

Resin extraction of soil permits evaluation of ratios of readily extracted elements and correlation of concentrations obtained with crop yield. This information provides guidance on potential genotype selection and fertility management. Two hybrids of maize ( Zea mays L.), designated 2292 and 3895, were grown annually in rotational succession on a 3.2-ha site with soybean ( Glycine max L.) and wheat ( Triticum aestivum L.). Soil samples (0–15 cm) were extracted with ion-exchange resins and extracts were analysed with inductively coupled plasma. Data were regressed against crop yield using stepwise multiple correlation methods. Each hybrid was sensitive to unique combinations of extracted chemistries. Both hybrids of maize were sensitive to the resin-extractable V : (V + P) molar ratio and potential losses of ≥ 20 % were indicated as the ratio approached 0.2. A positive response to the Mg : (Mg + Ca) resin-extractable ratio was noted for maize hybrid 2292 in each of three successive years. Changes of yield potentials associated with the Mg : (Mg + Ca) ratio for hybrid 2292 ranged from none to ≥ 20 % as the ratio ranged from 0.2 to about 0.8. The results indicate that, in the presence of large extractable concentrations of competing or inhibitory ions, different approaches to nutrient management in the form of fertilizer nutrient analysis, application, and genotype selection are needed to overcome effects of competing ions.     

Listeriosis in sheep. Isolation of Listeria monocytogenes from grass silage.

Two hundred and ninety-one grass silage samples from 113 farms with recent outbreaks of listeriosis were examined for the presence of Listeria monocytogenes (Lm). The frequency of Lm isolations increased with increasing pH. Lm was isolated from 22 % of the samples with pH < 4, from 37 % with pH 4–5 and from 56 % with pH > 5. Formic acid had been used as additive.A similar investigation was carried out on 32 samples from a farm with no outbreak of listeriosis during the investigation period. Lm was isolated from 9 samples.     

玉米轮选系产量配合力和抗病性研究

研究了东农群体—１的第一轮选出的自交系和组成该群体的较好原始亲本的产量配合力和抗大斑病能力．结果表明，轮选系的一般配合力效应和抗大斑病能力均优于较好原始亲本，且差异达到０．０５的显著水平．也证明了用轮回选择法提高玉米自交系的配合力和抗病能力很有效。     

定西县“秸秆畜牧业”开发之我见

定西县是全国出名的干旱贫困县，至今人均占有粮食３０２．８ｋｇ，依赖饲料粮的增加来发展畜牧业是不现实的。唯一出路是靠农作物秸秆资源，采用科技手段提高其营养价值，即开发“秸秆畜牧业”，实现全县脱贫致富。文章重点就小麦秸氨化处理及玉米秸青贮调制可经济效益之对比，探讨全县开发“秸秆畜牧业”并非空中楼阁，一纸空变。     

用叶龄模式预测杂交玉米器官形成的研究

研究结果表明，杂交玉米品种叶长和叶面积的节位分布，符合ｙ＝ａ＋ｂｘ＋ｃｘ２的二次方程变化特征。叶片———叶鞘———节间三元结构的同伸节位随玉米生育阶段的推进而增大。杂交玉米地下节根发生的最高层位可用Ｒ＝１２（Ｌ－１）的式子进行叶龄模式预测；地上部雌雄穗分化的每个阶段可用ｙ＝－０．０３７４（ｘ－２０）２＋１０的方程式进行叶龄模式预测。应用叶龄模式预测，其效果同观察结果相吻合     

一个不应当被遗忘的多基因学说的奠基者—G.U.尤尔

本文探讨了数量遗传学之多基因学说的产生的早期历史过程。指出英格兰生物统计学家G.U.尤尔最先奠定了多基因学说的基础,在学说形成的过程中起了不可忘却的历史作用。文章还讨论了尤尔的工作对数量遗传学及其他生物学研究的启迪作用。     

玉米籽粒突变体dek101的表型分析和精细定位

As the storage organ of maize, kernel development and accumulation of storage production directly determines maize yield and quality. In this study, a stable defective kernel mutant, named as defective kernel 101 (dek101), was identified during the development of double haploid (DH) lines in maize. The dek101 kernels displayed severely shrunk kernel appearance, significantly reduced kernel weight, lethal embryo, defective endosperm and were incapable of germinating. The dek101 showed obvious developmental abnormalities at 12 days after pollination (DAP). The fresh weight, dry weight and volume of the kernels were no longer increased after 21 DAP. Scanning electron microscopy (SEM) observation revealed that the starch granules of dek101 were significantly smaller compared with wild-type kernels. Genetic analysis demonstrated that the mutant trait was controlled by a recessive single gene. Using 441 F₂ individuals and 1648 F₃ individuals, dek101 was narrowed down to a genomic region of about 300 kb between the InDel marker IDP2182 and IDP4600 on chromosome 1, which contains five predicted genes. These results laid the foundation for mining functional genes related to maize kernel development and deciphering the mechanism of grain development.     

翻耕复种防治核桃举肢蛾的初步研究

核桃树下翻耕复种对核桃举肢蛾有明显的防治效果。覆土模拟试验证明，覆土４ｃｍ时，成虫羽化出土率仅为１８％，在８ｃｍ以上时，则全部不能出土。大田防治采用翻耕复种技术可使黑果率下降到１０％以下，防效高达８９．２９％。     

Changes of the Methionine Content During Maize Grain Maturation

The changes in the amounts of dry matter, total nitrogen and methionine during maturation of normal maize hybrids grown under the same topographical and agrotechnical conditions on two consecutive vegetation years were examined.
Total nitrogen was determined by Kjeldahl's method and methionine spectrophotometrically from papain hydrolysate by the method of McCarthy and Sullivan. Analysis of variance was applied to assess the significance of the changes in particular components during grain maturation.
A significant increase (p = 0.01) in amounts of the all investigated components in original grain matter up until a late stage of dough maturity in both vegetation years was determined. The increase was mostly expressed by the end of milky maturity. The correlation between these components during maturation is positive and highly significant (p = 0.001). The methionine content in dry matter attained in stage of milky maturation the value being characteristic for mature grain. On a total-proteins basis, the methionine content is significantly the least (p = 0.01) at the early stage of milky maturation and increases up until dough maturity reaching a value that does not significantly differ from the value in full maturity of grain.     

阿荣旗旱作丘陵区春玉米配方施肥的研究

春玉米是内蒙古自治区呼伦贝尔盟岭南旱作丘陵区的重要粮食作物。施肥不足,氮、磷配比不合理是该地区玉米低产的重要影响因素。1987～1989年在该地区的中部阿荣旗25个试验点上进行了测土配方施肥的研究,经统计分析,提出了不同土壤肥力条件下氮,磷效应函数;并根据碱解氮、速效磷的土测值确定最佳施肥量的推荐,为岭南旱作丘陵区春玉米丰产栽培提供了施肥依据。