Infrared Energy as a Factor in Controlled Environments

The proportion of visible to infrared radiation varies in different growth chambers. Whether this might affect leaf temperature and plant growth was investigated in chambers with equal visible radiation. In one chamber infrared energy was half the total, while in two chambers it was 75% of the total. Photoperiods were 14 hours and day and night temperatures 25° and 20°C, respectively. Warm weather species tested were Zea mays, Phaseolus vulgaris, Gossypium hirsutum, Glycine max, and Sorghum vulgare. High infrared did not increase the leaf temperatures of Sorghum vulgare, but growth was better than under low infrared. In the other 4 species, slightly higher leaf temperatures were observed, but growth was not significantly increased by high infrared. Of the cool weather species, Pisum sativum L. (Alaska and Wando) and Vicia faba L., grew less; Avena saliva L. grew equally; and Brassica oleracea L. var. capitata grew better in high infrared. Leaf temperatures of these cool weather species were generally below ambient and were not appreciably affected by the proportion of infrared. The CO₂ was uncontrolled in one high infrared chamber and was 400 μl CO₂ liter or more. Except for G. max and P. vulgaris, the growth of the warm weather species was not significantly affected; however, all cool weather species grew best in this chamber. A sparing effect from infrared damage is induced by high CO₂.     

Effect of In Ovulo Period on the Differentiation and Regulation of Immature Embryos ofZamia Cultured In Vitro

Monnier, M. and Norstog, K. 1986. Effect of in ovulo periodon the differentiation and regulation of immature embryos ofZamia cultured in vitro—J. exp. Bot. 37: 1633–1642. Depending upon excision chronology, undifferentiated embryosof the cycad Zamia exhibited two types of development when culturedin vitro. (1) Early embryos, excised in July shortly after fertilization,showed considerable growth of suspensors but, at first, theembryos at the distal ends of the suspensors remained unchanged.As culture progressed, these embryos grew isodiametncally withoutorganogenesis. (2) Late embryos, excised in September, althoughalso undifferentiated at the time of explantation, directlyentered a period of organogenesis with rapid initiation of twocotyledons. These embryos, therefore, seemed to have receivedan inductive stimulus during their more prolonged stay in theovule which permitted subsequent differentiation. This organogeneticimpulse was also expressed even when the embryo was longitudinallybisected. Each half-embryo regenerated a complete embryo havingtwo cotyledons. In this instance, the independent developmentof each half-embryo was a phenomenon of regulation. However,when the longitudinal bisection was done on an old and well-differentiatedembryo, which already possessed two cotyledons, each half-embryocontinued to develop as if it remained attached to the missinghalf. Thus well-advanced embryos did not exhibit regulationto the same degree as do younger embryos and bisection of theembryo resulted in the formation of two half-embryos. Key words: Regulation, differentiation, embryo culture, Zamia     

Action de quelques phytohormones sur la respiration et ľabsorption du phosphate par des disques de tubercules de pomme de terre en survie

Action of some phytohormones on the respiration and on the absorption of phosphate by aging potato tuber discs. Discs of potato tuber incubated in aerated medium show an increase of the rates of respiration and phosphate absorption with aging time; the rates increase by two and nine respectively during the time period between 5 and 24 h of aging. Adenine or some N-6 substituted adenines [benzylaminopurine (BAP), furfurylaminopurine (FAP), methylaminopurine (MAP)], which present variable degrees of cytokinin activity, partially inhibit the increase of the rate of phosphate absorption and, to a lesser extent, the increase of the rate of respiration. Also abscisic acid (ABA), indole 3-acetic acid (IAA), and gibberellic acid (GA₃) produce inhibition of the increase of the rate of phosphate absorption with varied effects on the respiration. With regard to phosphate uptake, the effects of ABA, 1AA and GA₃ were additive to those of BAP. The effects on respiration were different from the effects on phosphate uptake, so that there is no direct relationship between inhibition of respiration and inhibition of phosphate uptake.     

Effect of photoperiod on the first-instar development in the lacewing Nineta pallida

ABSTRACT Nineta pallida (Schneider) (Neuroptera: Chrysopidae) larvae were reared at 21^CC under various stationary photoperiods. The duration of the first stadium varied with daylength. Long-day regimes (LD 18:6 and 16:8 h) induced the fastest development, whereas the first ecdysis was more or less delayed in LD 14:10 and 13:11 h. Medium days (LD 12:12 h) resulted in the longest duration of the first stadium and high mortality, and all shorter days (LD 10:14, 8:16 and 6:18 h) in a moderate delay in the first ecdysis in all individuals. The facultative delay in development is thought to be a diapause, and viewed as a factor contributing to the annual synchronization of the life cycle.     

Polysaccharide Complexes in Full-Grown Oocytes of the Newt, Pleurodeles, and Changes in their Distribution During Progesterone-Induced Maturation

Immature full-grown oocytes of Pleurodeles waltlii contain large amounts of small electron-dense polysaccharidic granules. These granules lack a limiting membrane, and have a dense but heterogeneous matrix and an apparent diameter of 24–36 nm. Their structure, organization and distribution strongly suggest that they are glycogen granules. On the other hand, mature oocytes both after oviposition or 22–24 hr after in vitro progesterone stimulation contain no polysaccharide granules or complexes. During the first 9–10 hr after hormonal stimulation, granules were abundant and present both individually and as large strands occupying most of the space between the organelles. Granules were frequently found packed together and arranged in regularly arrayed stacks within large subcortical ant cortical vacuoles. Between 4 and 6 hr after progesterone addition, oocytes released the contents of vacuoles to the outside. Between about 11 and 14 hr after progesterone addition, oocytes still contained large amounts of polysaccharide complexes, but the vacuoles were empty. From about 15 hr after progesterone treatment until the end of maturation, the complexes progressively disappeared from the cytoplasm, coincident with the detachment of the follicle cell layer from the oocytes and a reduction in the number and size of microvilli.     

The Antimicrobial Susceptibility Test: A Comparison of the Results of Four Methods

A comparison of the results of the antimicrobial susceptibility tests by the agar-dilution method, the agar-diffusion method, the Autobac-1 system and the MS2 system has been made in a number of Escherichia coli and Staphylococcus aureus strains. With the agar-dilution method as a reference the agar-diffusion method and the MS2 system showed mostly satisfactory scores. With the Autobac-1 system, Esch. coli strains gave several insufficient scores with some antibiotics. A study of the distribution of minimal inhibitory concentrations against the strains has enabled the explanation of some of the discrepancies that were observed. Furthermore, the influence of two different sets of interpretive criteria on the outcome of the results has been studied.