我国杂交粳稻面临的挑战与机遇

本文回顾了我国杂交粳稻发展的历史,分析了发展的现状和存在的问题,并得出如下结论:杂交粳稻的研究力量分散,育种家之间缺乏交流及育种材料的创新机制不够健全是限制我国杂交粳稻发展的最主要原因;我国杂交粳稻快速发展的机遇已经到来。     

肺癌病性证素分布规律及其与血液检测指标关系的研究

目的 初步探讨肺癌病性证素的分布特点,为肺癌中医研究提供参考依据。 方法 采用临床回顾性研究,运用"中医智能(辅助)诊疗系统"进行系统辨证,采用SPSS 19.0统计软件对病性证素及血液检测指标进行统计。结果 肺癌病性证素以阴虚、气虚、饮、痰多见,不同病性证素分级以I、II级较常见。红细胞下降是血虚的危险因素(OR值=2.97>1),CA125降低是血瘀的危险因素(OR值=10.908>1),CEA降低是血瘀形成的抑制因素(OR值=0.267<1),红细胞减少是痰、热病理变化形成的抑制因素(OR值=0.412、0.295<1),CA125降低是饮形成的抑制因素(OR值=0.376<1)。结论 肺癌的病性证素以虚性证素为主,虚实夹杂,其中虚性病性证素以阴虚、气虚为主,实性病性证素主要为痰、热、饮及寒;随着红细胞的减少程度的增加,越容易出现血虚证素的病理变化,去越不容易出现痰、热证素的病理变化;CA125降低可能加速血瘀、减慢饮病理变化的形成;CEA的降低可能减慢血瘀的形成。     

珠海市淇澳岛红树林引种扩种问题的探讨

文章论述了珠海淇澳岛引种扩种红树植物的重要意义；分析了引种无瓣海桑对红树资源的恢复，物种多样性和林分质量的提高，乡土植物的天然更新和扩散，大米草的控制等作用；并探讨了无瓣海桑引种对生态的影响。最后还提出了红树林引种扩种需要加强的措施。     

用锰矿渣试制硫铝酸盐型快硬早强水泥

本文根据木圭锰矿渣化学成分特点和硫铝酸盐水泥熟料各矿物的化学组成和性质,合理地设计该水泥熟料的矿物组成、碱度系数和铝硫此,并掺用其他原料进行了配料。通过对不同煅烧温度下获得的熟料的x 衍射分析数据及参考有关资料,确定料方的煅烧温度,并对试制出的水泥进行了物理检验。结果表明,该水泥具有快硬早强和强度稳定的特点,达到了425~#硫铝酸盐型快硬早强水泥的各项指标。该研究表明该矿渣完全可以用来生产快硬早强硫铝酸盐水泥。     

Degradation of cyanidin 3-rutinoside in the presence of (-)-epicatechin and litchi pericarp polyphenol oxidase

The degradation mechanism of cyanidin 3-rutinoside in the presence of (-)-epicatechin and litchi pericarp polyphenol oxidase (PPO) was investigated using several model systems. The enzymically generated (-)-epicatechin o-quinone could induce cyanidin 3-rutinoside degradation. The results obtained in this study allowed us to propose a pathway for cyanidin 3-rutinoside degradation in the presence of (-)-epicatechin and litchi pericarp PPO. First, enzymatic oxidation of (-)-epicatechin produced the corresponding o-quinone, and then cyanidin 3-rutinoside and (-)-epicatechin competed for (-)-epicatechin o-quinone, resulting in degradation of cyanidin 3-rutinoside and regeneration of (-)-epicatechin. Moreover, the results of kinetic studies indicated this competition was influenced by both (-)-epicatechin concentration and cyanidin 3-rutinoside concentration in the model system.     

不同菌株绿僵菌酯酶型与其致病力的关系

对17株绿僵菌的酯酶同工酶培养特性和毒力进行了比较研究。结果表明:不同菌株酯酶同工酶型不同,绿僵菌的毒力与酶型及菌株培养特性有一定相关性。同工酶型可作为毒力筛选和鉴定绿僵菌种的标志。     

Effect of soil acidification on the growth and nitrogen use efficiency of maize in Ultisols

Purpose

To examine the effect of soil acidification on growth and nitrogen (N) uptake by maize in Ultisols.

Materials and methods

A clay Ultisol derived from Quaternary red earth and a sandy Ultisol derived from tertiary red sandstone were used in this study. A pot experiment was conducted with maize growing in the two Ultisols acidified to different pH values. Urea with ¹⁵N abundance of 10.11% was used to investigate the distribution of N fertilizer between soil and plant. Total N content and ¹⁵N abundance in plant and soil samples were determined by elemental analysis-isotope mass spectrometry.

Results and discussion

Critical soil pHs of 4.8 and 5.0 were observed for maize growing in the clay and sandy Ultisols, respectively. Below the critical soil pH, increasing soil pH significantly increased maize height and the yield of maize shoots and roots (both P < 0.05), but changes in soil pH showed no significant effect on maize growth above the critical soil pH in both Ultisols. Maize growing in the sandy Ultisol was more sensitive to changes in soil pH than in the clay Ultisol. Increase in the pH in both Ultisols also increased N accumulation in maize, the N derived from fertilizer in maize, physiological N use efficiency, and N use efficiency (NUE) by maize. Changes in soil pH had a greater effect on these parameters below the critical soil pH, compared to above. The change in soil pH had a greater effect on N accumulation in maize, the N derived from fertilizer in maize, and NUE in the sandy Ultisol than in the clay Ultisol. The NUE increased by 24.4% at pH 6.0, compared with pH 4.0 in the clay Ultisol, while the NUE at pH 5.0 was 4.8 times that at pH 4.0 in the sandy Ultisol. The increase in soil pH increased the ratio of N accumulation in maize/soil residue N and decreased the potential loss of fertilizer N from both Ultisols.

Conclusions

Soil acidification inhibited maize growth, reduced N uptake by maize, and thus, decreased NUE. To maintain soil pH of acidic soils above the critical values for crops is of practical importance for sustainable food production in acidic soils.

     

嫁接幼苗正压气流导向方法及参数优化

负压吸附把持手具有对幼苗苗径变化适应性强、减少幼苗把持损伤的优点,但其难以实现对弯曲幼苗的自动吸附把持。针对上述问题,该研究提出了一种利用正压气流对弯曲幼苗进行导向的作业方法。以常见嫁接用黄瓜幼苗为代表进行研究,考察正压气流对纤细幼苗导向效果。首先进行了弯曲应力测定,结果表明,对于长轴平均直径为（1.82±0.07）mm、短轴平均直径为（1.47±0.02）mm的黄瓜幼苗在10 mm长度上矫正5 mm弯曲偏差时所需最大弯曲力平均值为（0.082±0.005）N;针对黄瓜幼苗进行了单管正压气流导向试验并进行高速摄影记录,结果表明,当正压气管内径为4 mm,负压把持手吸嘴口与正压气管口间距为25～30 mm,导向气压为0.3 MPa时,导向成功率为93.3%;为改善导向效果,对黄瓜幼苗进行双管正压气流导向试验,结果表明,在正压气管内径4 mm条件下,当负压把持手吸嘴口与正压气管口间距为20～25mm、导向气压为0.3 MPa时,黄瓜幼苗导向成功率为100%。该研究结果可为基于气力导向方法的幼苗把持作业提供技术参考。     

基于计量经济模型的中国耕地数量变化政策与资产因素分析(简报)

耕地保护是中国土地管理科学中的难点之一,科学辨识其驱动因子具有重要的现实意义。该文在假设其他影响因子不变的情况下,构建了基于资源－资产－政策理念的土地利用概念模型,采用计量经济面板数据方法,以中国国家尺度及东中西部区域尺度上1998～2002年耕地变化过程为例证,重点对土地资产－政策因子进行研究。结果表明：1)在国家尺度上,增强土地政策管理力度、降低农用地增值收益倍数（提升失地农民保障水平）,增加耕地投入水平有助于耕地保护;化肥施用量的增加将会造成耕地减少;农业总产值比重、种植业生产水平及农户经营耕地面积没有显著的解释效用;2)在区域尺度上,提升耕地保护政策贯彻力度、提高被征地农户补偿水平、增加耕地投入均有利于耕地保护;东部地区农业总产值比重的降低、西部地区灌溉面积适量减少对耕地保护起到了积极的作用。综合“资源－资产－政策”三方面因素可以更好地解释耕地保护的行为,并有针对性地改进和加强耕地保护工作。     

基于叶墙面积的果树施药量模型设计及试验

变量喷雾技术是提高喷雾效果、降低农药使用率的有效手段,而准确的树冠特征参数检测及施药量模型是其关键。为克服果园变量喷雾中果树特征参数检测效率低和对环境要求高的缺陷,该文通过LiDAR(light detection and ranging)检测技术获取表征树冠特征参数的叶墙面积LWA(leaf wall area),并利用图像处理技术计算树冠参数参考值。为了表征树叶密度和LWA对变量喷雾的共同影响效果,研究基于LWA的决策系数KLWA,KLWA由反映果树冠层分区内点云在水平方向平均深度下的分布密度K1和分区内点云分布高度极差占分区高度的比值K2加权决定。通过计算垂直方向各分区内决策系数KLWA,并代入流量函数可得出基于KLWA的施药量计算模型,进一步计算电磁阀PWM占空比并调节水泵和电磁阀的工作状态,使喷头的流量对应冠层各区得到动态调整,实现基于LWA的变量喷雾。利用自制的室外变量喷雾验证装置,进行了多喷头变量喷雾试验,试验结果表明,果树的药液附着率均接近100%,说明基于LWA的变量喷雾模型可实现有效喷雾,与连续喷雾相对比,基于LWA的变量喷雾施药量模型的省药率为68.34%,与纯对靶定量喷雾比,基于LWA的变量喷雾施药量模型的省药率为32.77%。