Factors Influencing Runoff P Losses from Farmlandsof the Dianchi Lake Watershed in Yunnan, China

Effects of factors such as slope, surface soil texture, fertilization and crop cover with different rainfall intensitieson phosphorus (P) losses in farmland runoff of the Dianchi Lake Watershed in Yunnan Province of China were studiedthrough a rainfall simulation test using a red soil, one of the most widely distributed soils of the study area. Resultsshowed that the runoff concentrations of total phosphorus (TP) and P losses differed with the slope, being highest whenthe slope was 18~. At two different rainfall intensities, the runoff TP and P losses had a similar decreasing trend asthe surface soil texture became coarser, therefore applying the grit would decrease P in runoff from soils of farmland onslopes with heavier textures. With wheat as a crop cover the runoff TP concentrations and P losses were significantlylower than those of the bare soil. This showed that plant cover would greatly decrease P in runoff from the farmland ofthe study area. The TP concentration in runoff from the soil two days after fertilization doubled when compared withthat from the non-fertilized soil, indicating that fertilization could mean a dramatic rise in P runoff if irrigation or heavyrainfall occurred immediately after application and that no fertilization before a rain and no irrigation immediately afterfertilization would reduce runoff P loss from the farmland of the study area.     

稻米抗性淀粉含量及其环境稳定性分析

【目的】食用高抗性淀粉含量稻米虽利于提高慢性病人群的健康水平,但培育出的高抗性淀粉含量水稻品种还较少。开展水稻种质资源抗性淀粉含量及其环境稳定性的研究,为高抗性淀粉含量水稻种质资源发掘和生产应用提供参考依据。【方法】参照爱尔兰Megazyme公司提供的方法测定稻米抗性淀粉含量,用PAST软件完成种质含量分布作图。通过一年多点试验评价抗性淀粉含量的环境稳定性,利用DPS软件完成含量方差分析。依据国家标准GB/T15683-2008分析了稻米直链淀粉含量。【结果】对1 206份水稻种质稻米抗性淀粉含量分析,结果表明,绝大部分水稻种质稻米抗性淀粉含量低,含量低于2.5%的占87.6%,高于10%的仅占约0.2%。稻米抗性淀粉和直链淀粉含量存在显著正相关,但在高直链淀粉含量种质中未出现抗性淀粉含量高的品系,却在低直链淀粉含量种质中发现3份抗性淀粉含量高于10%的品系,其中1个优质软米品种Diangu2的抗性淀粉和直链淀粉含量分别为10.12%和12.3%,综合农艺性状优良,米饭食味性好。在3个不同环境种植18个不同抗性淀粉含量的品系,结果显示有13个品系的含量不受种植环境差异的影响,另5个品系的含量受环境影响,稻米的抗性淀粉含量除了受基因型影响外,还受种植环境、以及基因型与环境互作的影响。【结论】水稻种质资源稻米抗性淀粉含量普遍很低,抗性淀粉含量与直链淀粉含量虽存在显著正相关,但低直链淀粉含量种质中也可能存在高抗性淀粉的品种,所以培育稻米抗性淀粉含量高且食口性好的品种是可能的。稻米抗性淀粉含量主要受基因型控制,在不同环境中含量高的品种依然高,含量低的品种仍然低,那么高含量的品种可在其适种稻区种植生产大米,其含量不会被明显影响。     

水稻5.3 kb Gt1启动子克隆以及Gt1启动子引导优质大豆球蛋白Gy7基因表达载体构建

以越光水稻基因组为模板,在成功克隆5.3 kb谷蛋白Gt1基因5’上游和信号肽序列基础上,将其定向插入到pCAMBIA1300质粒中,构建了中间载体p1300-5.3 kb Gt1;再将富含赖氨酸的优质大豆球蛋白Gy7全基因序列及cDNA编码序列分别定向插入p1300-5.3 kb Gt1质粒上Gt1基因信号肽下游,再在2个载体Gy7全基因序列及cDNA编码序列下游都正向插入Gt1 3’UTR,完成由5.3 kb谷蛋白Gt1基因启动子及信号肽引导的大豆球蛋白Gy7基因2种表达载体的构建。此试验为利用转基因技术改良水稻稻米营养品质以及将水稻种子作为生物反应器等方面研究奠定了基础。     

Evaluation of Rice Germplasms for Grain Resistant Starch Content and Its Environmental Stability

【Objective】 It is beneficial for improving the health of chronic patients to eat high resistant starch (RS) content rice, but variety with high grain RS content is still very rare. Evaluations of rice germplasms for grain RS contents and its environmental stability were carried out in this study, and the results could provide a reference for the discovery of rice germplasm resources with high RS contents and its production. 【Method】 Grain RS contents in rice germplasms were detected by the Megazyme method, and used the PAST software to complete the frequency distribution of these contents. The environmental stability of rice RS contents were tested by planting at multiple locations within one year, and its variance analysis were performed with DPS software. Grain amylase contents were tested according to the national standard GB/T15683-2008. 【Result】 The initial evaluations on RS contents of 1206 rice germplasms demonstrated that for most these rice with RS content were very low, and about 87.6% of the rice were less than 2.5%, only about 0.2% were higher than 10%. There was a significant positive correlation between rice RS and amylose content, but high RS variety was not discovered in high amylose germplasms. However, three varieties with RS content higher than 10% were screened in low amylose content germplasms, and one of them was a good quality soft rice variety Diangu2, which has RS and amylose content of 10.12% and 12.3%, respectively. It carried out regional tests for eighteen varieties with different RS contents planting at three very differ environmental conditions. The result of environmental stability analysis indicated that the contents of thirteen varieties were affected by differences in planting area, of the others were affected. Totally, the contents were affected by genotype, planting environment and genotype-by-environment interactions. 【Conclusion】 In this research, most rice resources have low RS content, and also detected a significant positive correlation between rice grain RS and amylase content. Therefore, it is possible to develop rice variety with high RS starch and good taste, according the high RS varieties were identified in low amylose content germplasms. The RS content was mainly affected by genotype, so the varieties with high RS contents were high at different environments, and the lows’ were still low. Then, the varieties with high RS content can grow in its suitable areas to produce rice, and the contents could not be significantly affected.