The sowing of germinating vegetable seeds using a fluid drill

Carrot seeds which had been imbibed or germinated and were then sown in a gel extruded through standard coulters emerged five days earlier than dry seeds sown with a conventional drill and gave higher yields after 64 days although not after 77 days. There was no difference in mean time to emergence or in final plant stand between lettuces grown from dry seeds and those from seeds imbibed for 24 h and sown in a gel, but the duration of the emergence period of the latter was halved in one of the two experiments. Celery seeds, the light requirements of which had been satisfied during germination in optimum conditions in the laboratory before they were sown in the field in a gel, gave a 60% plant stand as compared with a stand of 2% from dry seeds.     

THE INFLUENCE OF ENVIRONMENTAL LIGHTING ON THE GROWTH AND PROMETAMORPHIC DEVELOPMENT OF LARVAL RANA PIPIENS

This study was designed to investigate whether the larval development of an anuran amphibian could be modified by raising the animals in continuous light or darkness instead of under conditions of diurnal illumination, and to quantify the effects of these treatments at various intervals during this period of development.
Larvae of the frog, Rana pipiens , were raised through metamorphosis under conditions of constant light, constant darkness, or diurnal lighting. As measured by stages of development, body weight, tail length and body length at 20-day intervals, no significant differences in growth rate or metamorphic change were observed until near the middle of the prometamorphic period, which began at approximately the 50th day of development. After midmetamorphosis, a significant acceleration in the measured parameters was seen for the animals raised in conditions of constant light in comparison with those in constant darkness. Those with diurnal lighting were intermediate.
These results suggested that light, or its absence, can respectively stimulate or retard amphibian metamorphosis in late larval stages after the hypothalamo-hypophyseal-thyroid axis has matured. Neither continuous light nor continuous darkness during larval development prevented the transformation from tadpole to frog.     

Increased nest cofounding and high intra-colony relatedness in the bee Exoneura bicolor (Hymenoptera: Apidae): Results from an experimental situation

Abstract Identifying differences in a key social trait between two populations of die same species is important for understanding the evolution of sociality. Previous studies of new colonies in Exoneura bicolor, an Australian allodapine bee, have shown that there are high levels of kin cofounding in a montane population. The only study to examine intra-colony relatedness in a heathland population has found that new multifemale colonies are not formed by kin. In this study we used an experiment to investigate both cofounding behaviour and intra-colony relatedness in E. bicolor from a heathland population. Nest substrate was placed either 0.05 or 1 m distant from source nests in a novel environment. Although there were no differences in cofounding rate or intra-colony relatedness between die two treatments there was, overall, a high rate of cofounding: 53% of new nests were multifemale, approximately twice as high as found in previous field-based studies. Relatedness among cofoundresses was not only different from zero, ^r± SE = 0.597 ± 0.097, but almost identical to that found in montane populations. A constraint, such as nest substrate distribution, is suggested as a proximate factor affecting the expression of cofounding behaviour in E. bicolor. The implication of such proximate constraints for inferring the phylogenetic origins of social behaviour is discussed.     

The influence of light environment on photosynthesis and basal methylbutenol emission from Pinus ponderosa

Methylbutenol is a 5-carbon alcohol that is produced and emitted by several species of pine in western North America, and may have important impacts on the tropospheric chemistry of this region. In the present study the response of methylbutenol basal emission rate (measured at a constant light intensity of 1500 µmol m⁻² s⁻¹ and temperature of 30 °C) to the light and temperature conditions of the growth environment was examined, using field-grown plants shielded with shade cloth of various densities. Methylbutenol basal emission rates increased linearly with the temperature of the growth environment but did not respond to the shading of foliage during growth and development. Both photosynthesis and basal methylbutenol emission rate declined in older needles; however, these declines appear to result from parallel but independent processes and not from basal MBO emission rate directly tracking photosynthetic rates. Older needles did not occupy cooler microenvironments within the canopy; and thus differing thermal microenvironment could not explain the reduced MBO emission in older needles.     

Immunocytochemical Staining of Serous Effusions With the Monoclonal Antibody Ber-Ep4

Cytospin preparations were made from 102 serous effusions for immunocytochemical staining using a panel of monoclonal antibodies including a new monoclonal antibody Ber-EP4. On cytological examination, 32 fluids were reported to contain tumour cells consistent with metastatic adenocarcinoma; 66 contained benign cells only and three were reported to contain cells suspicious of malignancy. One effusion contained tumour cells consistent with malignant mesothelioma. Positive staining of the tumour cells with Ber-EP4 was observed in the 32 effusions (100%) which contained adenocarcinoma cells. No staining of the mesothelial cells in these 32 specimens was observed. Carcinoembryonic antigen, epithelial membrane antigen Ca2 and CD15 staining of tumour cells was noted in 53%, 50%, 50% and 9% of these cases, respectively. None of the mesothelial cells in the benign effusions stained with Ber-EP4. Nor did the malignant mesothelial cells in the only case of malignant mesothelioma. These findings suggest that Ber-EP4 is a valuable addition to antibodies available for the differential diagnosis of mesothelial cells and adenocarcinoma cells in serous effusions.     

Viability of onion (Allium cega) seed as influenced by temperature during seed growth

The yield and performance of seeds from crops of winter-hardy, bolting-resistant onion grown at temperatures of 15–16, 18–19 and 22–23°C in 1979, 1980 and 1982 were compared. Yields of seed from crops grown at 22–23°C were lower than those from crops grown at lower temperatures but the seeds ripened between 11 and 32 days earlier. Seeds from crops grown at mean temperatures of above 18°C gave higher percentage germination when imbibed at 30°C than 20°C and they also gave higher percentage seedling emergence than those from crops grown at lower temperatures. Seedlings from seeds produced at mean temperatures above 18°C were heavier than those from seeds of a similar weight but produced at lower temperatures. None of these differences were associated with differences in seed weight, embryo weight or seed dormancy but were positively correlated with differences in seed N-concentration. The differences were also associated with the rate of imbibition of water as high germination, high N-content seeds had a slower rate of imbibition than low germination, low N-content seeds of the same weight.     

An Improved Thermoelectric Probe for Measurements of Apparent Sap Flow Velocity in Intact Plant Stems

Gray, H. R-, Erickson, P. I. and Stone, J. F. 1985. An improvedthermoelectric probe for measurement of apparent sap flow velocityin intact plant stems.—J. exp. Bot. 36: 1320–1324. An improved thermoelectric technique for non-intrusive, non-destructive,and direct sensing of the apparent velocity of sap flow in intactplant stems is presented. The thermoelectric probe was madeof extruded Teflon (DuPont) rod. One of two heating elements,positioned 0.5 cm and 1.0 cm below the temperature sensor, wasused to generate the heat pulse. Heating element selection wasbased on daily environmental conditions. A thermistor touchingthe stem sensed the heat pulse. A second thermistor mountedin dose proximity was used to cancel ambient temperature fluctuations. The improved thermoelectric probe was tested using irrigatedpeanuts (Arachis hypogeae L.). After canopy closure was completein both treatments, apparent sap flow velocity(V_a) was measuredon 17 dat 1200 s intervals between 0830 h and 1630 h apparentsolar time. Successful V_a, measurements were accomplished on94% of the attempts. In order to verify performance on otherspecies with different types of stems, non-replicated V_a, determinationswere also made on cotton (Gossypiwn spp.), prickly sida (Sidasptnosa L.), goosegrass (Eleusine indica (L.) Gaertn.), Palmerpigweed (Amaranthus Palmerii S. Wats.), and cottonwood (Populusdeltoides Marsh.). Success of the probe was due in part to the design of the probewhich included remotely selectable spacing between heater andthermistor and adequate insulation and shielding of the probeand sensed portion of the stem. In addition, acclimatizationof the probe to the operating environment was essential. Key words: Sap velocity, instrumentation