Restorable variation of cytoplasmic type of male sterile line in rice byin vitro culture

Rice male sterile (MS) lines, IR66707A and IR69700A, which possess the cytoplasm of Oryza perennis and O. glumaepatula respectively, belong to the cytoplasmic type. Their sterility could be maintained but not be restored. By somatic cell culture of these two MS lines, 47 somaclones with 465 R₁ plants were obtained. All of the 465 R₁ plants were sterile in the spring season in Guangzhou. According to the expression of the R₁ plants and the level of similarity to their donor parents, they could be divided into three types. The plants of type Ⅰ were male sterile. The sterility of some somaclones of this type could be restored by the test crossing varieties or alternated to fertile by changes of some environmental conditions. The hybrid F₁ of test cross from the MS somaclones in type Ⅰ was fertile while the hybrid F₁ from the donor MS lines was still sterile. The R₁ plants of type Ⅱ were similar to the donor parents and also male sterile. The hybrid F₁ from all of the plants of type Ⅱ crossed to test variety were still sterile, so they did not possess restorability. For the somaclone of type Ⅲ, all of R₁ plants were sterile in both male and female organs. No seed was set in both conditions of self and cross pollination. The fact that the restorable variants obtained in the cytoplasmic type of MS lines of rice by in vitro culture reported here should be the first sample in somaclonal variation in plant kingdom.     

Identification of quantitative trait loci affecting tolerance to low phosphorus in rice (Oryza Sativa L.)

Phosphorus (P)-deficiency in rice (Oryza.Sativa.L) may cause yield reductions.This research has been conducted to map quantitative trait loci (QTLs) for tolerance to low phosphorus stress in a doubled haploid (DH) population.By using the linkage map of this population,the QTLs for relative dry weight,relative P content and relative P utilization efficiency have been located.The results indicate that one RFLP marker located on chromosome 6 is closely associated with relative root dry weight,relative shoot dry weight and relative total dry weight,which explain 24.9%,20.5% and 25.2% of the total phenotypic variations,respectively.Two QTLs affect relative P uptake content,which account for 20.7% of the total phenotypic variations.One micro-effect QTL has been found to be associated with relative P utilization efficiency.It is suggested that the P uptake efficiency is more associated with P efficiency.Among the secondary physiological indices of P uptake efficiency,the root dry weight is more important than others.     

我国现阶段农业可持续发展战略初探

农业可持续发展是人类社会和国民经济可持续发展的基础。中国作为发展中的农业大国 ,随着经济的发展和人口的增加 ,持续农业面临的资源、生态环境问题严峻。通过分析制约我国农业可持续发展的因素 ,提出了现阶段实现农业可持续发展的战略取向     

基于灰色关联度模型分析农民收入的影响因素

基于灰色关联度模型分析我国农村改革二十年来,影响农民收入的主要因素.分析结果:①农民收入政策的演进影响农民收入的主要因素的变化;②我国农民收入政策的演进是从价格支持政策转向结构调整政策.     

经济转型时期开封市农户生产投资行为变化研究

运用开封市1985～2003年农户调查资料,对农户生产投资行为进行系统分析,表明农户的生产投入以农业为主体,但总体水平呈递减趋势,且具有明显的短期性,制约了农业的可持续发展．在分析开封市农户农业投资行为特征及影响因素的基础上,提出了优化农户投资行为的对策。     

水稻稻瘟病SIRS模型研究

建立了具有常数迁入的SIRS稻瘟病模型,分析了模型有界解的稳定性,发现具有常数迁入的SIRS稻瘟病模型的每一个有界解都趋于稳定集.     

双酶法制备糙米乳工艺

糙米营养全面,富含生物活性物质和矿物质,但由于其组织结构的原因,口感较差,人体难于消化,制约了它在人们膳食中的消费。研究一种糙米乳的生产工艺,为提高糙米的可食性开拓新的途径。采用双酶法降解糙米所含大量淀粉,既可降低米乳的浆液黏度,改善口感和状态,又能提高米乳中葡萄糖含量,降低生产成本。利用α-淀粉酶和糖化酶对糙米乳液进行液化和糖化处理,通过单因素试验和正交试验,以DE值(葡萄糖当量)为指标,优化了糙米酶解的工艺参数:α-淀粉酶用量为0.35g/100mL,65℃保温40min;糖化酶用量0.35g/100mL,60℃保温8h。酶解后淀粉降解,DE值达到最高35.68%,乳液状态良好。     

农村劳动力流动对农业及粮食生产影响分析

自1989年以来,我国农民开始大规模进城务工,并逐渐形成"民工潮".农村劳动力流动有其深刻的经济原因,并会对农业及粮食生产产生深刻影响.分析认为,农村劳动力流动会影响农业部门资本积累、农民种粮积极性、粮食生产人力资本积累和粮食供求区域均衡.从政策层面、产业层面和社会层面提出了稳定农业及粮食生产的对策建议.     

文山市加快中低产田地改造存在的问题及对策

实施中低产田地改造,是着力提高土地资源效益,实现农业增效和农民增收的有效途径。文章在走访调查和查阅相关文件资料的基础上,回顾总结近年来文山市中低产田地改造工作的做法和成效,查找梳理项目实施过程中存在的困难和问题,并对推进下一步工作提出几点粗浅建议,以期对此项工程的深入实施提供有益启示。     

黑米米糠游离酚对碘与淀粉结合及淀粉消化的影响

以早籼米、黑米米糠为原料,通过稀碱法提取早籼米中的淀粉,采用有机溶剂酸化甲醇提取黑米米糠中游离酚,并利用高效液相色谱法测定其多酚含量,将黑米米糠游离酚加入到淀粉-碘复合溶液中,通过扫描吸收光谱的变化来考察酚浓度对淀粉-碘结合的影响,进一步加入a-淀粉酶,考察黑米米糠游离酚对a-淀粉酶催化淀粉消化的影响。结果表明,黑米米糠游离酚抑制淀粉和碘的结合,浓度越大抑制效果越明显,且随着酚浓度的增加,最大吸收峰向波长短的方向移动,即发生蓝移,其原因可能是酚与淀粉结合,改变了淀粉性质,从而改变其吸收峰；黑米米糠游离酚能抑制淀粉的消化,其原因可能是酚与淀粉疏水基团结合。