The Uptake of Calcium and Strontium by Plants from Soils and Nutrient Solutions

Plants have been grown in soils and nutrient solutions containingdifferent Ca/Sr ratios to find out whether there is any biologicaldiscrimination between calcium and strontium. When tomato plants are grown in nutrient solutions containingmolar Ca/Sr ratios from 2/1 to 4,000/1, the shoots do not distinguishbetween the elements, but the roots absorb strontium preferentiallyat low concentrations of this element. Since ion exchange resins show the same phenomenon, though toa less marked extent, this is believed to be a physico-chemicalrather than a biological effect. No chemical reagent has been found which can extract calciumand strontium from soils in the same ratio as plants. Ammoniumacetate extraction may give misleading results for the plant-availableCa/Sr ratios in the soil. Data for the Ca/Sr ratios in barleyand lucerne grown on soils containing ratios from 3/1 to 650/1emphasize this point.     

Isolation and characterization of microsatellite markers in Fraser fir (Abies fraseri)

We describe the isolation and characterization of 14 microsatellite loci from Fraser fir (Abies fraseri). These markers originated from cloned inserts enriched for DNA sequences containing tandem di‐ and tri‐nucleotide repeats. In total, 36 clones were selected, sequenced and evaluated. Polymerase chain reaction (PCR) primers for 14 of these sequences consistently produced simple PCR profiles and were found to be polymorphic among 13 Fraser fir samples. In addition, more than half of these loci were found to amplify a wide range of samples from several Abies taxa.     

Genetic Differences in the Root Regeneration of Radiata Pine

The root regeneration capacity of eight open-pollinated familiesof radiata pine (Pinus radiata D. Don) was compared after transplantingeight month old seedlings to 8, 11 and 14 ° C soil temperaturefor 32 d. The results confirmed the major influence of soil temperatureon root regeneration. Families differed markedly in their abilityto initiate and grow new roots. Differences in the number ofnew root apices produced between the first and last rankingfamilies were ninefold at 8 ° C, threefold at 11 °Cand sevenfold at 14 °C. There was significant family x temperatureinteraction for new root length. The ability of some familiesto grow new roots at the warmer temperature of 14 °C didnot match their ability at 11 ° C and 8 °C. The weights of shoot and root at transplanting had no apparenteffect on the root regeneration capacity of the families studied.The important factors which contributed to genetic effects werethe renewed growth of the existing first order lateral rootsand the production of second order lateral roots on them. The root regeneration characters were highly heritable. Thelarge genetic difference and the high heritabilities in rootcharacters indicate the scope to exploit genetic effects onroot configuration in radiata pine to improve survival and earlyestablishment.     

Absorption of borate ionic species by Saccharum officinarum L.

The correlation between the effect of pH on H₃BO₃ ionizationand on borate absorption, and the effect of poly-OH compoundson absorption, suggest that B(OH)₄^– is absorbed by sugarcaneleaf tissue, rather than H₃BO₃. Diol-borate complexes have noeffect on mechanism 2 uptake, but competitively inhibit mechanism3. ¹Published with the approval of the Director of the Hawaii AgriculturalExperiment Station as Technical Paper No. 985. (Received September 2, 1968; )     

The effects of allatectomy and juvenile hormone replacement on the development of host-seeking behaviour and lactic acid receptor sensitivity in the mosquito Aedes aegypti

Host-seeking behaviour in newly emerged Aedes aegypti (L.) females is not expressed immediately after adult eclosion but develops gradually over a period of approximately 3-4 days. This development is accompanied by an apparent maturation of the antennal chemosensory afferent neurons involved in the detection of the airborne host attractant lactic acid. Since these events coincide in time with juvenile hormone-dependent previtellogenic ovarian growth and since the expression of other reproduction-associated behaviour has previously been shown to be dependent on juvenile hormone, the effects of juvenile hormone removal and replacement on the development of host-seeking behaviour and the response characteristics of the lactic acid-sensitive receptors were investigated. No effect of juvenile hormone removal by allatectomy or juvenile hormone replacement or augmentation by topical application of the juvenile hormone mimic methoprene was found. It was concluded that this hormone is not involved in the appearance of host-seeking behaviour or the apparent maturation of the lactic acid receptors that occurs during early imaginal life.     

PCR amplification of intergenic spacers in the ribosomal DNA of Drosophila melanogaster reveals high levels of turnover in length and copy-number of spacers in geographically separated populations

A recently described PCR-based method for the analysis of intergenic spacer (IGS) length variation in the ribosomal (r) DNA of Drosophila melanogaster was used to analyse the distribution of IGS length variants in the rDNA of a number of recently collected D. melanogaster populations. One group of populations, from Europe and North Africa, was shown to have low intrapopulation IGS length variation following maintenance of massed populations in the laboratory for an extended period. However, a greater degree of IGS profile variability was detected at a number of levels in the majority of laboratory-maintained isofemale lines from two of these populations plus a second group of populations which were collected more recently from the eastern coast of Australia; all of which were immediately divided into isofemale lines following collection. Interestingly, PCR analysis of pooled DNA extracts from 30 individuals of either sex showed almost identical PCR profiles from each of the Australian populations. These preliminary results are discussed with regard to the possible combinations of forces (natural selection, neutral drift and genomic molecular drive) on the patterns of IGS length variation.     

SLUG FEEDING BEHAVIOUR IN RELATION TO CONTROL WITH MOLLUSCICIDAL BAITS

The feeding behaviour of Deroceras reticulatam (Müller)presented with molluscicidal baits in laboratory and terrariatrials is described and discussed in relation to pest slug control.Both metaldehyde and Methiocarb appears to be more effectivein wet conditions and less repellent to slugs allowing moreactive ingredient to be consumed before termination of feeding (Received 16 November 1987; accepted 15 February 1988)