Examination of bound (non-extractable) residues of MCPA and flamprop in wheat straw

The long term metabolism of [¹⁴C]MCPA and [¹⁴C]flamprop in wheat (Triticum aestivum) straw was found to involve incorporation of radioactivity as residues that were insoluble in acetone+water (1+1 by volume). A chemical and an enzymic solubilisation procedure were critically evaluated in attempts to release these residues for further examination. The chemical procedure resulted in complete solubilisation of all the radioactivity of both compounds in association with more than one cell wall fraction. However, routine quantitative analysis was found to be difficult for some fractions. Furthermore, the extracts did not appear to be suitable for investigation of the nature of the binding with the plant constituents. None of the enzymes employed in the enzymic procedures released significant amounts of the residues insoluble in the aqueous acetone. Despite these problems, the residues of MCPA that were insoluble in aqueous acetone were found to contain both the parent MCPA and its major metabolite 4-chloro-α-hydroxy-o-tolyloxyacetic acid.     

Phloem transport in Ricinus

Recently, Ricinus has been used extensively to investigate the mechanism of phloem transport. This work is reviewed. In many respects, both anatomically and physiologically, Ricinus seems to approach the ideal for work on phloem physiology. Its anatomy is typical of many plants so that valid comparisons can probably be drawn with other species. However, the actual measurement of the proportion of sieve tubes is difficult. Exudation from the wounded phloem can be controlled by a variety of treatments. It seems to represent the true phloem transport stream, and from all observations to date seems to fulfill the requirements of the pressure flow theory. The actual velocity of the mass flow of sap by displacement has been shown to be very considerable, as might be expected on the pressure flow theory, and to become polarised towards a wound from each side in roughly equal proportions. There seem to be considerable concentration gradients in the stem, as indicated by refractometry in the direction one would expect on the basis of pressure flow. Attention has been drawn to the mechanism by which exudation is prevented by the plant. Ricinus seems ideal material for investigations into the sealing mechanisms which can curtail or permit exudation on wounding. Probably, when these systems are understood we can solve the ultimate problem of the condition of intact sieve plate pores.     

Effects of accelerated pollen-cone development on pollen cytology and fertilizing potential in western hemlock (Tsuga heterophylla)

Western hemlock (Tsuga heterophylla (Raf). Sarg.) pollen cones on cut branches were collected at different stages of development and maintained at room temperature in flasks of water to accelerate pollen-cone development and produce forced pollen. Accelerating pollen-cone development at early developmental stages reduced the number of cones that matured, decreased the quantity of pollen produced, increased the proportion of abnormally developed pollen and reduced the fertilizing potential of the pollen, as determined by seed efficiency. If the branches were collected after the pollen cones were at least 50% emerged beyond the bud scales, pollen-cone development could be successfully accelerated without decreasing pollen yield or fertilizing potential. Pollen collected from cones which were accelerated at early stages and stored for two years had a lower fertilizing potential and produced fewer seeds per cone than either unstored pollen or stored pollen collected from cones accelerated at later stages of development. The feasibility of accelerating pollen-cone development to ensure adequate supplies of pollen for controlled crosses or supplemental mass pollination is discussed.     

High-Frequency Jet Ventilation in Anesthetized, Paralyzed Dogs and Cats Via Transtracheal and and Endotracheal Tube Routes

The ability of the SAV 6 high-frequency jet ventilator to effectively ventilate three anesthetized, paralyzed cats (3.2–4.2 kg), two small dogs (7.2 and 10.0 kg), six medium-sized dogs (20.5–25.0 kg), and three large dogs (36.0–43.0 kg) via a 14-gauge (dogs) or a 16-gauge (cats) catheter placed percutaneously into the trachea via the cricothyroid membrane or into a preplaced endotracheal tube was evaluated. The lowest driving pressure within the range of 0.25 to 2.0 kg/cm² (1 kg/cm²= 14.2 psi) and the highest cycle rate within the range of 60 to 240 per minute that would generate a PaCO₂ of 30 ± 3 mm Hg were determined.
All animals could be ventilated to a PaC0₂ of 30 ± 3 mm Hg by the endotracheal tube and transtracheal route, except the largest dogs, which couid be ventilated to an average PaC0₂ of 36 mm Hg by the transtracheal route. The transtracheal route consistently required higher driving pressures and lower cycle rates than did the endotracheal tube route. Cats could be ventilated with a driving pressure of 0.25 kg/cm²; small dogs could be ventilated with 0.5 to 1.0 kg/cm₂; medium-sized dogs with 1.0 to 1.5 kg/cm²; and large dogs with 1.5 to 2.0 kg/cm².
The SAV 6 high-frequency jet ventilator can effectively ventilate cats and dogs (7.2–43.0 kg) via a transtracheal catheter and an endotracheal tube.     

Independent and joint biological activity of isomeric forms of synthetic pyrethroids

Various isomeric mixtures of pyrethroids were examined in topical application tests against houseflies, Musca domestica. On the basis of the activities of the separate isomers of 5-benzyl-3-furylmethyl (±)-cis,trans-chrysanthemate, it was shown that when combined in pairs to give the (±)-trans or (±)-cis or (+)-cis,trans mixtures the observed mortalities did not differ from those expected by simple additive action calculated by the harmonic mean. In contrast the (±)-cis,trans mixture showed considerable antagonism with a mortality only 60% of that expected. Similar evaluations using the separate and combined isomers of bioallethrin [(R,S)-3-allyl-2-methyl-4-oxocyclopent-2-enyl (allethronyl) ( + )-trans-[(1R,3R)-chrysanthemate] and the corresponding (+)-cis-(1R,3S)-chrysanthemate indicate antagonism calculated to be correlated with the content of the (R)-isomer of the alcoholic moiety. Hence the activity of the most active isomer of the “allethrin” series, (S)-3-allyl-2-methyl-4-oxocyclopent-2-enyl ( + )-trans-(1R,3R)-chrysanthemate, (S)-bioallethrin, is not fully realised unless it is present in pure form and a substantial part of the value of bioresmethrin (5-benzyl-3-furylmethyl ( + )-trans-chrysanthemate] as a killing agent is lost when the racemic form is used. In racemic mixtures there is mutual antagonism between pairs of isomers so that considerable masking of activity occurs.     

The responses of virus-free and virus-infected lily ‘Enchantment’ to the retardants ancymidol,chlormequat chloride,mepiquat chloride and BTS 44 584, a ternary sulphonium carbamate

The new growth retardants mepiquat chloride (a quaternary ammonium compound of the piperidinium type, coded BAS 083 00W) and a ternary sulphonium carbamate (coded BTS 44 584) were compared with ancymidol (A-Rest or Reducymol) and chlormequat chloride (Cycocel) for their ability to dwarf virus-free and virus-infected (ordinary) Mid-Century Hybrid lily cultivar ‘Enchantment’. Single compost drenches were given 3 weeks after transferring plants to the glasshouse.Compared with the virus-infected control plants, virus-free controls were 62% taller and 33% greater in leaf spread; floret number was approximately doubled and floret diameter was increased by 12%, but flowering was delayed by 6.5 days. The length of the lower stem bearing dead leaves was 15% of the total in virus-infected controls and 3% of the total in virus-free controls.Ancymidol, chlormequat chloride and mepiquat chloride were all effective growth retardants, and were without adverse side-effects. On a concentration basis, mepiquat chloride was 2–2.5 times as active as chlormequat chloride in reducing stem extension, but ancymidol was several orders of magnitude more active than both those compounds. With BTS 44 584, the maximum reduction in stem length obtained was 16% compared to controls. The decreases in stem extension were more pronounced, in both percentage and absolute terms, in the virus-free bulbs. Nevertheless, for a given retardant treatment, plants of the virus-free stock remained taller than those of the virus-infected stock. As a result, 2–3 times the amount of an active retardant was required by virus-free than by virus-infected plants in order to produce similar stem lengths at flowering. Effects of the retardants on the time of flowering, flower number, floret diameter and leaf spread were small, but increasing concentrations of all chemicals progressively increased the proportion of the stem bearing dead leaves.The effects of ancymidol, chlormequat chloride and mepiquat chloride persisted in the year after treatment.     

Distribution and loss of phorate residues in the foliage of broad bean plants following root uptake of 14C-labelled phorate

¹⁴C-Methylene labelled phorate was added to nutrient solutions supplying the roots of young broad bean plants and after 24 h absorption, fresh nutrient was substituted. The radiolabel accumulated at the leaf margins was initially associated with solvent-soluble toxic metabolites. Radiolabel extracted from foliage which developed after the treatment was mainly in water-soluble form. The maximum concentration of toxic material occurred in the marginal areas of the leaves after 5 or 6 days and in the central portions after 2 days. The concentrations declined to half of their peak values in 4–6 days from leaf-margin tissue and in 2 days from the central tissues. Water-soluble label did not accumulate to any significant extent. Most was found in the marginal areas but concentrations built up slowly reaching a maximum after about 2 weeks, declining slowly thereafter.     

Some factors affecting the storage of fresh breadfruit

Breadfruit (Artocarpus altilis (Park) Fosberg) is a highly perishable tropical fruit which can be packed in sealed polyethylene bags and stored under refrigeration. The storage period between harvesting and softening was greater for fruit harvested partially mature than fully mature and for fruit which were harvested by picking or catching rather than traditional procedures. In 4 storage trials and a single shipping trial, the majority of partially mature fruits harvested by picking were still firm after 15 days although a significant proportion had commenced softening.