福桔新生(系)的选育研究初报

以柚子为父本,选择福桔优良单株为母本进行杂交,培育珠心苗进行福桔的品种提纯复壮。运用高接换种的方法可使珠心苗提早2~3 a开花结果,缩短童期,并保持了福橘优良性状,显著地提高了品质。对珠心苗高接植株多年观察及品质鉴定,认为珠心胚植株在品质上表现较大差异。选出优良福桔珠心系“新农1号”、“新农2号”和“新农3号”3个株系,其中新农1号株系可溶性固形物达14.2%,单果种子数仅8粒,单果重118 g,具有丰产、果大、色艳、种子少、可溶性固形物高等优良性状。     

大气CO2浓度的升高、施氮及土壤水分对春小麦干物质积累和氮吸收的影响

Spring wheat (Thiticum aestivum L.cv.Dingxi No.8654) was treated with two concentrations of atmospheric CO2 (350 and 700 μmol mol^-1),two levels of soil moisture (well-watered and drought) and five rates of nitrogen fertilizer(0,50,100,150,and 200 mg kg^-1 soil) to study the atmospheric CO2 concentration effect on dry matter accumulation and N uptake of spring wheat.The effects of CO2 enrichment of the shoot and total mass depended largely on soil nitrogen level,and the shoot and total mass increased significantly in the moderate to high N treatments but did not increase significantly in the low N treatment.Enriched CO2 concentration did not increase more shoot and total mass in the drought treatment than in the well-watered treatment.Thus,elevated CO2 did not ameliorate the depressive effects of drought and nitrogen stress.In addition,root mass decreased slightly and root/shoot ratio decreased significantly due to CO2 enrichment in no N treatment under well-watered condition.Enriched CO2 decreased shoot N content and shoot and total N uptake;but it reduced root N content and uptake slightly.Shoot critical N concentration was lower for spring wheat grown at 700 μmol mol^-1 CO2 than at 350μmol mol^-1 CO2 in both well-watered and drought treatments. The critical N concentrations were 16 and 19 g kg^-1 for the well-watered treatment and drought treatment at elevated CO2 and 21 and 26 g kg^-1 at ambient CO2,respectively. The reductions in the movement of nutrients to the plant roots through mass flow due to the enhancement in WUE (water use efficiency) and the increase in N use efficiency at elevated CO2 could elucidate the reduction of shoot and root N concentrations.     

四川丘陵区农林系统和农草系统流域的径流和土壤水分特征

A study was conducted in a hilly area of Sichuan Province, Southwestern China, to compare the streamflow and soil moisture in two upland watersheds with different land use patterns. One was an agroforestry watershed, which consisted mainly of trees with alder (Alnus cremastogyne Burkill) and cypress (Cupressus funebris Endl.) planted in belts or strips with a coverage of about 46%, and the other was a grassland primarily composed of lalang grass (Imperata cylindrica var. major (Nees) C. E. Hubb.), filamentary clematis (Clematis filamentosa Dunn) and common eulaliopsis (Eulaliopsis binata (Retz.) C. E. Hubb) with a coverage of about 44%. Streamflow measurement with a hydrograph established at the watershed outlet showed that the average annual streamflow per 100 mm rainfall from 1983 to 1992 was 0.36 and 1.08 L s^-1 km^-2 for the agroforestry watershed and the grass watershed, respectively. This showed that the streamflow of the agroforestry watershed was reduced by 67% when compared to that of the grass watershed. The peak average monthly streamflow in the agroforestry watershed was over 5 times lower than that of the grass watershed and lagged by one month. In addition, the peak streamflow during a typical rainfall event of 38.3 mm in August 1986 was 37% lower in the agroforestry watershed than in the grass watershed. Results of the moisture contents of the soil samples from 3 slope locations (upper, middle and lower slopes) indicated that the agroforestry watershed maintained generally higher soil moisture contents than the grass watershed within 0-20 and 20-80 cm soil depths for the upper slope, especially for the period from May through July. For the other (middle and lower) slopes, soil moisture contents within 20-80 cm depth in the agroforestry watershed was generally lower than those in the grass watershed, particularly in September, revealing that water consumption by trees took place mainly below the plow layer. Therefore, agroforestry land use types might offer a complimentary model for tree-annual crop water utilization.     

甘肃陇西黄土高原旱作区土壤水分变化规律及有效利用程度研究

运用陇西黄土高原6个农业气象基本观测站土壤湿度资料(1982~2000年),分析了该地域土壤水分构成特征及0~200cm土壤水分运行、变化规律,拟合了100cm土层内土壤贮水及水分累积耗散曲线,分季节评述了区域内各地水分有效利用程度。     

谷物烘干机前馈加反馈智能PI控制系统

该文论述了智能PI控制算法,以8098单片机为核心组成前馈加反馈智能PI控制器,对烘干机出粮水分进行在线控制。通过对京411小麦的在线烘干实验证明智能PI控制算法用于烘干机出粮水分控制是可行的。     

不同降水年型小麦丰产抗灾技术的研究

旱作小麦在不同降水年型的产量反应相差甚大，主要原因是降水年季分布不均匀，根据不同降水年型确定小麦丰产抗旱技术，从品种、播期、播量，施肥种类和肥料配比及田间管理等方面采取相应对策，取得小麦生产的最佳效益。     

水土保持植物──刺梨的早实丰产研究

该根据定位观测和实地调查资料，分析了刺梨的生长状况与生态条件的关系，在汉中地区连续进行的刺梨栽培技术研究表明：刺梨生长与土壤含水量，气温，施肥，良种，栽培技术有密切关系。为了达到早实丰产，特提出相应的刺梨栽培措施。     

智能化田间土壤水分测定仪的研制

该在简要的介绍了笔研制的土壤水分传感器的基础上，着重介绍以单片微机为基础，适用于田间野外工作的智能化土壤水分测定仪的软硬件及特点。     

吉林省半干旱地区种植机械化生产工艺的改革与试验

阐述了吉林省半干旱地区种植机械化生产工艺改革的依据与特点,介绍了耕整地联合作业机和镇压式抗旱播种机性能与结构设计的原则和成果,并报导了施肥对播种出苗的影响、深松与镇压对种床土壤墒情的影响等。     

生态技术进步造就了作物高产不衰的典型——重访青海香日德地区春小麦高产田的启示

20世纪70年代末期,我国青藏高原的香日德镇出现了春小麦单产15195．00kg／hm2的高产纪录,生长季的光能利用率高达5．9％。其高光效原因何在以及能否保持不衰为众人所关注。近年笔者实地考察发现,生态技术创新是该区春小麦高产不衰的主导致因。其中特殊生态位新品种的成功选育、生态技术的全方位应用以及农田之外生态用地的有效建设是支持高产并可持续发展的三大支柱。生态技术进步作为经济增长的内在变量具有重要现实意义,香日德为生态经济学中的生态创新理论与B模式提供了成功实例。