不同水分含量桑叶对二化性家蚕的营养效应

研究了取食不同水分含量桑叶对二化性家蚕(CSR3×CSR6)5龄幼虫的影响。实验设嫩叶(水分含量80%～85%)、半成熟叶(水分含量65%～70%)和成熟叶(水分含量55%～60%)3个不同处理。采用标准重量分析法分析和计算各种生长、营养和营养效率指数。结果表明,在取食较高水分含量桑叶的处理中,营养指数(包括取食量、消化量和近似消化率等)和营养效率指数(包括食物利用率和转化率等)均显著较高,但不同处理中消化食物向茧壳的转化率及产生每克茧壳所需食物消化量差异不明显。结论是取食水分含量高的桑树嫩叶有助于提高家蚕的取食和营养。     

Interacting Effects of Light and Day and Night Temperatures on the Growth of Four Species in the Vegetative Phase

A comparative examination has been made under controlled conditionsof the interacting effects on growth in the vegetative phasewhich takes place when the diurnal temperature is either maintainedconstant at 20 and 25 ?C or reduced at night by 5 and 10 ?Cand the plants subjected daily to either 2.16 or 4.32 ? 10⁴lx for 14 h. For each species (Gossypium hirsutum, Hclianthusannuus, Phaseolus vulgaris and Zea mays) the changes in netassimilation rate, the leaf area ratio and the relative growthrates in plant weight and leaf area were recorded. Contrary to some previous findings, none of these componentsof growth are favoured by cool nights. Rather such reductionsin temperature retard the growth processes to a varying degreeaccording to the species and the component. In general, significantreductions are more evident for the two relative growth rateswhen a drop from 20 to 10 ?C is combined with the lower levelof illumination. The implications of these results are considered in relationto a prior study where for similar light conditions the samespecies plants were subjected to constant temperatures rangingfrom 10 to 25 ?C.     

The Effect of Root Temperatures on Water and Sulphate Absorption in Intact Sunflower Plants

The effect of 15, 25, and 35°C root temperature on waterabsorption, transpiration, and sulphate uptake by the rootsand transport to the shoots of intact sunflower plants has beenstudied using 0.5, 5.0, and 50.0 mM sulphate concentrationsat two rates of transpiration induced (1) by light and low relativehumidity and (2) by darkness and high relative humidity. Root temperatures and sulphate concentrations did not significantlyaffect the water absorption and transpiration and both theseprocesses were approximately similar at the different treatments.There was a nearly twofold increase in water absorption andtranspiration in the light and low relative humidity as comparedto the dark and high relative humidity irrespective of the roottemperatures and sulphate concentrations. The A.F.S. uptake in the roots was found to be independent ofthe root temperatures, sulphate concentrations, and transpirationrates, and amounted to 15 to 21 per cent based on the root weight.Sulphate accumulation in the roots was not significantly influencedby the root temperatures at 0.5 and 5.0 mM sulphate concentrations,but nearly doubled with temperature at 50.0 mM sulphate concentrationof the external solution. The slow nature of accumulation ofsulphate, the high sulphate status of the experimental plants,and the short duration of the experiments are considered aslikely reasons for the absence of a clear effect of temperatureson accumulation of sulphate at the two lower concentrationsof the external solution. Effects of high concentration on permeabilityand metabolism of the cells are suggested as the reasons forthe decreased accumulation with an increase in temperature at50.0 mM sulphate concentration. Accumulation of sulphate inthe roots was not significantly influenced by the transpirationrates. Unlike root accumulation, sulphate transport to the shoots increasedwith increasing transpiration. However, a major part of thesulphate transport (70 to 75 per cent at 0.5 and 5.0 mM sulphateconcentrations and 80 to 85 per cent at 50.0 mM sulphate concentration)appeared to have occurred at the low transpiration. The similarityof this transport to the accumulation of sulphate in the rootsindicates that it was due to an active transport process sensitiveto root temperatures and sulphate concentrations. A low concentrationof sulphate in the xylem and an increased permeability of theroot cells to ion movement induced by an increased suction inthe xylem are considered as reasons for a small increase inthe sulphate transport at high transpiration rate. The evidencefor the existence of a barrier—probably endodermis—preventingthe passive diffusion of sulphate and sensitivity of the TranspirationStream Concentration to root temperatures and sulphate concentrationsfavour that the increased transport with increased transpirationwas due to an active process.     

印度小圆胸小蠹的一种新寄主植物

自然条件下印度小圆胸小蠹Euwallacea fornicatus(Eichhoff,1868)在茶树枝条虫瘿内取食,是茶的重要害虫之一,以茶蛀虫著称.2010年5-8月,在印度Muga Eri研究中心3号农场(Lahdoigarh,Jorhat-Assam)的黄心树Persea bombycina Kost.(樟科)...     

The Redistribution of Labelled Sulphate Ions in Sunflower Plants subjected to Different Treatments

The effect of 0.5 and 5.0 mM sulphate concentrations and 15,25, and 35°C root temperatures on the redistribution of³⁵SO₄ in sunflower plants was studied at two rates of transpiration.It is concluded from the results that ³⁵SO₄ was lost rapidlyfrom the free space of the roots to the external solution andthat this losa was independent of the transpiration rates androot temperatures. The fact there was no marked decrease inthe ³⁵SO₄ content of the shoots during the ‘washing’process indicates that the free space is likely to be confinedto the cortical region of the roots, and there seems to be adiffusion barrier between the cortex and xylem preventing arapid movement of ³⁵SO₄ from the cortex to the xylem.     

Subjects of Speculation: Emergent Life Sciences and Market Logics in the United States and India

This article traces systems of exchange concerning the life sciences and capital and how they configure subjectivity in the United States and India. This is done through case studies concerning the emergence of personalized medicine in the two locales. In the U.S. case, I argue for the configuration of the subjects of personalized medicine as sovereign consumers; in the Indian case, I argue for their configuration as experimental subjects. I situate these arguments in the context of epistemologies of genomics and the consolidation of systems of speculative capitalism.     

Differences in the Interacting Effects of Light and Temperature on Growth of Four Species in the Vegetative Phase

A comparative study, employing the concepts of growth analysis,has been made of the varying responses in the early vegetativephase of Gossypium hirsutum, Helianthus annuus, Phaseolus vulgaris,and Zea mays to combinations of light intensity (1.08, 2.16,3.24, 4.32, and 5.4 x 10⁴ lx—photoperiod 14 h) and constantdiurnal air temperatures (10, 15, 20, 25, 30, and 35 °C).Depending on the combination of treatments, the temperatureof the internal tissues departed from air temperature by 6.9to 1.4 °C: so only the internal temperatures are cited here. For each species there are complex interactions between theeffects of light and temperature on the net assimilation rate,the leaf-area ratio, and the relative growth-rates of plantweight and leaf area. The magnitude of the changes induced bythe two factors vary both with the growth component and thespecies. The temperature responses are maximal up to 20–5°C while at the highest temperatures they may be negative.The temperature coefficients for leaf-area ratio are consistentlyless than those of the other three components: here betweenspecies the coefficients over 10–20 °C vary by a factorof 9.6, 5.4, and 5.1 for the rates of gain in plant weight andleaf area and the net assimilation rate, while the orderingwithin each growth component is species dependent. Under conditions of optimal temperature the relative growth-rateand net assimilation rate progressively increase, accordingto the species, up to either 4.32 or 5.4x 10⁴ lx. The leaf-arearatio is always largest at the lowest intensity. The level oflight at which the rate of gain in leaf area reaches a maximumranges from 2.16x 10⁴ lx for Phaseolus to between 4.32 and 5.40x10⁴ lx for Gossypium. The highest relative growth-rate and net assimilation rate ofHelianthus exceed those of Zea substantially. Indeed the maximalassimilation rate for Helianthus of 2.10 g dm^–2 week^–1is the highest ever recorded under field or controlled conditions.Possible reasons for this reversal of the photosynthetic potentialsof the two species observed by previous workers are discussed.     

Interrelationships between the Nature of the Light Source, Ambient Air Temperature, and the Vegetative Growth of Different Species within Growth Cabinets

The interacting effects within growth cabinets of the natureof the light source and the temperature of the ambient air on14 parameters of vegetative growth have been examined for Gotsypiumhirsutum, Helianthus annuus, Phaseolus vulgaris, and Zea mays.The comparisons were between fluorescent lighting and mixtureswith tungsten lamps (17 and 26 per cent of the total wattage),adjusted to give 32 400 lx and covering six equally spaced andconstant air temperatures from 10 to 35 °C. The relationships are highly complex. Species differ in theirresponses to the three light sources. Moreover, for some parameters,but only for some species, there are highly significant interactionsbetween the nature of the light source and the temperature level.Part of this complexity is due to the varying growth potentialof species at low and high temperatures but important contributingfactors are the differences between the temperatures of theambient air and the plant parts. Such disparities may be positiveor negative and are greater for leaf as against root temperature.The divergencies are larger during the day and largest for leaftemperature. With the higher proportion of tungsten lamps theleaf day temperature ranges from 7.1 °C above an ambienttemperature of 10 °C to 2.5 °C above 35 °C ambient.For fluorescent lighting the leaves are 2.8 °C above ambientat 10 °C and 2.5 °C below at 35 °C. When variations in the response are examined against the meaninternal day temperature of the plant, for some parameters,but not others, differences between light sources are no longerevident. Here again the reactions of species differ. It is concluded firstly that if only ambient air temperaturesare recorded errors will arise in the interpretation of theinduced biological responses, and secondly that departures fromthe ambient air temperatures will be dependent on the designof the cabinet and the lighting system.