北方稻田生态系统水量平衡及水分效率研究

１９９３～１９９５年研究了５种不同模式水稻田生态系统水量平衡及水分效率结果表明,不同水稻田模式其总耗水量之间有明显差异,其中节水模式和节水节肥模式较常规模式节省灌溉水达１５～２３％,水分生产效率增加３０％以上．各模式蒸发蒸腾耗水量在同一生长季内基本相同．田间结构及调控管理对其无明显影响实测水稻生育期田间蒸发蒸腾量与计算的可能蒸发蒸腾量相差不过５％。     

北方稻田生态系统研究Ⅱ．稻萍结合系统细绿萍共生固N量研究

对稻萍结合系统细绿萍共生固Ｎ量研究表明,萍的固Ｎ力在整个生长季不同时期有所变化．最高固Ｎ率出现在６月初,萍固Ｎ量随其接种量和水稻行距增加而增加．５０～１０ｃｍ宽窄行交替的水稻行距和１５００ｋｇ·ｈｍ－２的萍接种量的稻萍结合系统的总固Ｎ量为１０７．１ｋｇ·ｈｍ－２,而３０ｃｍ等行距的３２５ｋｇ·ｈｍ－２的萍接种量的稻－萍结合系统的总固Ｎ量仅为３６．０ｋｇ·ｈｍ－２     

美国青蛙胚胎受脉冲电场刺激后对其生长发育的影响研究

本文在青蛙胚胎诸生长期的核驰豫研究及电磁场对淡水鱼胚刺激后能促进其生长发育及机理研究的基础上,利用华东师范大学物理系研制的ＡＣＨＶ－２型脉冲电场刺激仪对美国青蛙的早期及神经期胚胎进行适当强度的刺激发现,它能使胚胎的孵化率提高２０％以上,存活率提高３０％左右,并能促进其后斯的生长发育速率达３０％,研究结果进一步证明作者提出的电场作用机理的合理。     

Microwave influence on the isolated heart function: II. Combined effect of radiation and some drugs

The combined effects of microwave radiation and some drugs were studied in an isolated frog auricle preparation. The experiments established that exposure to pulse-modulated 915 MHz microwaves for up to 40 min had no effect on either the rate or the amplitude of spontaneous auricle twitches, unless the average absorbed power was high enough to produce preparation heating. Treatment of the preparation with saline containing (0.6–3.0) 10^?5 M of propranolol or (0.5–1.5) 10^?7 M of atropine altered neither its pacemaker nor its contractile functions; these drugs also had no effect when they were combined with nonthermal microwave irradiation. Caffeine (1 mM) strongly increased the average heart power, which was calculated as the product of twitch rate and amplitude. The caffeine effect appeared to be significantly augmented (by about 15%, P<0.02) under exposure to burst-type pulsed microwaves (pulse width, 1.5 msec; pause, 2.5 msec; 8 pulses/burst, 16 bursts/s; average SAR, 8–10 W/kg). By itself, this modulation was not effective; the heating of the preparation and saline during exposure was approximately 0.1°C, which could not account for the detected changes. The experimental results demonstrate that caffeine treatment increases the microwave sensitivity of the frog auricle preparation and reveals primarily subthreshold, nonthermal microwave effect. © 1995 Wiley-Liss, Inc.     

Path-coefficient analyses and genetic parameters of the components of field resistance of potatoes to late blight

Variation, genetic parameters, interrelationships and phenotypic and genetic path analyses for components of field resistance of potatoes to Phytophthora infestuns were studied using detached leaves from 16 potato cultivars. Inter-genotypic variability was significant for the components and the Area Under Disease Progress Curve (AUDPC). The resistant cultivars generally had a longer latent period and lower lesion size and spore production than the susceptible cultivars. The correlations between AUDPC and infection efficiency, and between AUDPC and spore density were not significant, but latent period, lesion size and sporulation did correlate significantly with AUDPC. Genetic and phenotypic path-coefficient analyses indicated lesion size to be the most important component of field resistance. The genetic correlation coefficients between the AUDPC and infection efficiency, latent period and spore density arose mainly because of their indirect effects on AUDPC via lesion size. Lesion size and AUDPC had a high genetic coefficient of variation, heritability and genetic advance (genetic gain).     

The role of skylight polarization in the orientation of a day-migrating bird species

To assess the role of skylight polarization in the orientation system of a day-migrating bird, Yellow-faced Honeyeaters (Lichenostomus chrysops, Meliphagidae) were tested in funnel cages for their directional preferences. In control tests in the natural local geomagnetic field under the clear natural sky, they preferred their normal migratory course. Manipulations of the e-vector by depolarizing the skylight or rotating the axis of polarization failed to affect the orientation as long as the natural geomagnetic field was present. When deprived of magnetic information, the birds continued in their normal migratory direction as long as they had access to information from the natural sky, or when either the sun or polarized light was available. However, when sun was hidden by clouds, depolarizers caused disorientation. — These findings indicate that polarized skylight can be used for orientation when no other known cues are available. However in the hierarchy of cues of this species, the polarization pattern clearly ranks lower than information from the geomagnetic field.     

New pulsed field gradient NMR experiments for the detection of bound water in proteins

Summary New H₂O-selective homonuclear and heteronuclear 2D NMR experiments have been designed for the observation of protein hydration (PHOGSY, Protein Hydration Observed by Gradient Spectroscop Y). These experiments utilize selective excitation of the H₂O resonance and pulsed field gradients for coherence selection and efficient H₂O suppression. The method allows for a rapid and sensitive detection of H₂O molecules in labelled and unlabelled proteins. In addition it opens a way to measure the residence time of water bound to proteins. Its application to uniformly ¹⁵N-labelled FKBP-12 (FK-506 binding protein) is demonstrated.     

Rapid production and field testing of homozygous transgenic tobacco lines with virus resistance conferred by expression of satellite RNA and coat protein of cucumber mosaic virus

A procedure for the fast production of homozygotic transgenic plants was developed. Leaf discs of haploid tobacco plants from anther cultures were transformed with a chimaeric vector containing coat protein (CP) and satellite RNA (Sat-RNA) genes from cucumber mosaic virus (CMV). One-hundred-and-twelve Kanamycin-resistant transformed haploid plants were subjected to selection based on the expression of both CP and Sat-RNA. Eighty-nine transgenic plants expressing both genes were selected and tested for their resistance to CMV by inoculation with high concentration of CMV (200 g ml^–1). Only five plants showed no symptoms of viral infection 30 days after inoculation. These plants were then diploidized by colchicine treatment. Three homozygous diploid lines with high levels of resistance to CMV were obtained after only one generation. The three transgenic lines were further tested under field conditions. The results showed that the progenies of these transgenic lines were homozygous and were highly resistant to CMV under natural field infection and manual inoculation conditions.     

Colonization history of north European field voles (Microtus agrestis) revealed by mitochondrial DNA

The genetic structure of field vole (Microtus agrestis) populations from northern Europe was examined by restriction fragment length polymorphisms of mitochondrial DNA (mtDNA) in 150 individuals from 67 localities. A total of 83 haplotypes was observed, most of which were rare and highly localized geographically. Overall nucleotide diversity was high (134%), but showed a tendency to decrease with higher latitude. Two major mtDNA lineages differing by 2% in nucleotide sequence were identified. A southern mtDNA lineage was observed in field voles from Britain, Denmark and southern and central Sweden, whereas voles from Finland and northern Sweden belonged to a northern lineage. The strict phylogeographic pattern suggests that the present population generic structure in field voles reflects glacial history: the two groups are derived from different glacial refugia, and recolonized Fennoscandia from two directions. A 150–200-km-wide secondary contact zone between the two mtDNA groups was found in northern Sweden. Distinct phylogeographic substructuring was observed within both major mtDNA groups.     

黄土丘陵沟壑区水平梯田改土培肥增产技术措施体系

黄土丘陵沟壑区水平梯田改土培肥增产技术措施体系刘东海赵廷宁（宁夏西吉县农业局７５６２００）（北京林业大学水土保持学院１０００８３）赵国杰（宁夏西吉县农业技术推广站７５６２００）ＴｅｃｈｎｉｑｕｅｓｏｆＳｏｉｌＩｍｐｒｏｖｅｍｅｎｔａｎｄＹｉｅｌｄＩｎ...