ALBERT

Notes: Residues of fluazifop-butyl were determined in strawberries from New Brunswick and Nova Scotia, Canada and North Carolina, U.S.A. using a High Performance Liquid Chromatography (HPLC) system. Strawberries harvested within 28 days of treatment (pre-harvest interval= PHI) had detectable residues of fluazifop, ranging from 0.05 ppmw with a split application of 0.25 kg ha-1 and a 18-day PHI to 3.24 ppmw with a split application of 0.5 kg ha−1 and a 12-day PHI. Fluazifop was not detected in samples treated 287 days or more before harvest (prior growing season) at 0.25–1.65 kg ha−1 (three applications of 0.55 kg ha−1). Fluazifop-butyl did not provide acceptable control (50% with two applications of 0.25 kg ha−1) of Elymus repens (L.) Gould in a commercial planting in New Brunswick. Control of Digitaria sanguinalis (L.) Scop. was better than 90% with two applications of 0.30 kg ha−1 in North Carolina. Fluazifop-butyl did not injure strawberries at any of the rates or sites tested. Résidus et efficacité du fluazifop-butyle en culture de fraises Les résidus du fluazifop-butyle dans des fraises provenant de New Brunswick et Nova Scotia au Canada et de North Carolina aux Etats-Unis ont été déterminés en utilisant un système de chromatographie liquide à haute performance (HPLC). Des fraises récoltées avant 28 jours après le traitement (PHI 28) contenaient des résidus de fluazifop décelables, allant de 0.05 ppmw après un apport fractionné de 0,25 kg ha−1 et PHI 18 à 3,24 ppmw après un apport fractionné de 0,5 kg ha−1 et PHI 12. Nulle trace de fluazifop n'a été décelée dans des échantillons traités au moins 287 jours avant la récolte, c'est-à-dire pendant la saison précédente, aux doses de 0,25 à 1,65 kg ha−1 (trois pulvérisations à 0,55 kg ha−1). Le fluazifop-butyle n'a pas permis une destruction convenable d'Elymus repens (L.) Gould dans une exploitation commerciale au New Brunswick (50% suivant deux pulvérisations à 0,25 kg ha−1). La destruction de Digitaria sanguinalis (L.) Scop. avec deux pulvérisations à 0,30 kg ha−1 en North Carolina dépassait 90%. Le fluazifop-butyle n'a provoqué de dégâts dans les fraises à aucune des doses testées ni à aucune localité. Rückstände und Wirkung von Fluazifop-Butyl in Erdbeeren Erdbeeren von Neu-Braunschweig, Neu-Schott-land (Kanada) und Nord-Karolina (U.S.A.) wurden mittels Hochleistungs-Flüssigkeits-Chromatographie (HPLC) auf Rückstande von Fluazifop-Butyl untersucht. Innert 28 Tagen nach der Behandlung (Intervall vor der Ernte = PHI) geerntete Erdbeeren enthielten messbare Rückstande von Fluazifop; sie betrugen zwischen 0,05 ppmw nach einer Split-Applikation von 0,25 kg ha−1 und einem PHI von 18 Tagen und 3,24 ppmw nach Split-Applikation von 0,5 kg ha−1 und 12 Tagen PHI. Es wurden keine Rückstände in Proben gefunden, die 287 oder mehr Tage vor der Ernte mit 0,5–1,65 kg ha−1 (drei Applikationen von je 0,55 kg ha−1) behandelt worden waren (vor der Wachstumsperiode). Fluazifop-Butyl erzielte keine genügende Kontrolle von Elymus repens (L.) Gould (50% Erfolg nach zwei Behandlungen mit 0,25 kg ha−1) in einer Produktionspflanzung in Neu-Braunschweig. Der Erfolg gegen Digitaria sanguinalis (L.) Scop. war in Nord-Karolina nach zwei Applikationen von 0,30 kg ha−1 höher als 98%. Fluazifop-Butyl schädigte die Erdbeeren an keinem der Standorte und mit keiner Dosierung.

Notes: SUMMARY. 1. From forty-five values reported for twenty species of aquatic insect species, it was found that the nitrogen content (N) of the food was significantly and positively correlated (r=0.97. P〈0.001) with assimilation efficiency (Ase).2. Therefore, the Ase of aquatic insects can be predieted, if the nitrogen content of the food is known, using the equation: Ase (%)=9.29+8.82N.

Notes: Abstract Methods were developed for measuring water content of the free space of suspension-cultured tobacco cells using 3H- or 14C-sorbitol. Sorbitol was not taken up by cells in significant quantities over the 3 min taken to label free space. Free space accounted for 50–60% of the water content of cell pellets irrespective of whether 3H- or 14-C-sorbitol was used. 14C-inulin labelled 13.5% less of the water in cell pellets than 3H-sorbitol, probably due to inadequate penetration by inulin into the free space in the cell wall matrix and within clumps of cells. Measurement of free space is necessary for measuring growth on a fresh or dry weight basis, solute concentrations and parameters of water relations of cells. Techniques for making these measurements on tobacco cells were also developed in this study.Solutes were measured after extraction from cells by expressing sap or by boiling cells in ethanol. Similar solute concentrations were found using both methods of extraction. By expressing sap from cells grown in culture medium with an osmotic pressure of 0.24 MPa, the cells were found to have an internal osmotic pressure of 0.70 MPa. Glucose, fructose, sucrose, amino acids and K+ accounted for 60% of this osmotic pressure. Elastic moduli were estimated using the Boyle-Van't Hoff relationship after suspending cells in solutions with different osmotic pressures and assessing their water content or internal osmotic pressure. For two different lines of tobacco cells, elastic modulus varied between 1 MPa and 5.4 MPa at turgor pressures of 0.15–0.52 MPa (line 1) and between 0.2 MPa and 4.2 MPa at turgor pressures of 0.04–0.26 MPa (line 2).

Notes: Abstract The effect of salinity on the growth and ion concentrations in a number of tobacco cultivars is described. Sodium chloride, at a concentration of 200 mol m−3, hardly affected the fresh weight, but significantly reduced the dry weight. The difference in the response of fresh and dry weights to salt was due to a change in succulence (water per unit leaf area); the latter increased with increasing leaf Na+ and Cl− concentration. Under saline conditions, increasing the external Na+: Ca− ratio by decreasing the Ca2+ concentration increased the accumulation of Na+ and Cl− into the leaf tissue.