ALBERT

Notes: A major screening programme was conducted to determine which Lycopersicon spp. (if any) have practical levels of resistance to glyphosate; the same lines were also tested for resistance to Orobanche aegyptiaca. A majority of the lines investigated showed high susceptibility to glyphosate applied at 37⋅5 g a.i. ha−1 in a spray volume of 250 1 ha−1. Only 41 of 1457 lines screened showed fresh weights of treated plants not significantly different from those of untreated plants at a probability level of 80%. Repeated screening of some selected Lycopersicon lines in the greenhouse and the field, however, indicated that only a few had inherent partial resistance to glyphosate. Giyphosate was less toxic to the test plants with increases in spray volume. Among 1361 Lycopersicon lines tested for resistance to O. aegyptiaca, only minor differences in susceptibility were observed. All lines were susceptible to varying degrees. The chances, therefore, of finding complete resistance in tomato to either glyphosate or Orobanche spp. alone are small. However, combining partial resistance to glyphosate and O. aegyptiaca in a breeding programme to produce new varieties might still prove to be economically useful even in fields heavily infested with the parasite.

Notes: Broomrape (Orobanche ramosa L.) is a common root parasite of solanaceous, leguminous and other crops grown in the semi-arid regions of the world. The seeds germinate when root exudates from host plants are released in their immediate vicinity (Lindley, 1853; Koch, 1887; Chabrolin, 1934). Brown et al. (1951a) reported that non-host plants, such as flax (Linum usitatissimum L.) may stimulate Orobanche seed germination without being parasitized.The stimulating properties of flax exudate were studied by Brown et al. (1951b). They reported that the stimulant was unstable in alkaline solutions, but moderately stable in weakly acidic media, which may indicate the presence of an acidic (lactone) grouping. Nash & Wilhelm (1960) reported that gibberellic acid in agar media stimulated O. ramosa seed germination. Abu- Shakra, Miah & Saghir (1970) found that pre-treatment of 0. ramosa seeds with 100 ppm of gibberellic acid followed by incubation on a flax-root diffusate agar medium gave a high (81·7%) germination.The purpose of this study was to collect root exudates from three species of plants cultured under three experimental systems, namely (a) germ-free, (b) glasshouse (non-sterile), and (c) growth chamber (hydroponic, initially aseptic), and to evaluate their biological activity as germination stimulants for O. ramosa seeds. The plants used were tomato (Lycopersicon esculentum Mill.), sorghum (Sorghum vulgare Pers.) and flax. Exudate from marigold (Tagetes erecta L.) also was collected from germ-free culture.

Notes: The mode of phytotoxic action and metabolism of chlorsulfuron was studied in non-differentiated. white monoploid potato (Solanum plureja Juz. & Buk.) callus. Dose response studies showed that the growth of callus was inhibited about 40% by 11.2 nm and 55% by 28 nM chlorsulfuron. Casein hydrolysate provided partial protection of callus against chlorsulfuron injury. Neither leucine, isoleucine. nor valine alone alleviated the growth retardation caused by the herbicide. However, the inhibition caused by the herbicide. however, the inhibition of callus growth by chlorsulfuron was reversed when the medium was supplemented with a combination of isoleucine and valine at 100 μM each. Potato callus absorbed 20 and 30% of the applied chlorsulfuron after 24 and 48 h. respectively, and less than 5% of the herbieide was metabolized by callus after 48 h of treatment. The research demonstrated the potential usefulness of monoploid callus in the investigation of phytotoxicity and mode of action of herbicides.Le mode d'action pour la phytotoxicite et le metabolisme du chlorsulfuron out ete etudies au niveau de cals monoploides indifferencies de pommes de pommes de terre (Solanum phureja Juz. & Buk)Les etudes sur l'effet does ont montre que la croissance des cals etait inhibee d'environ 40% par 11.2 nM et 55% par 28nM de chlorsulfuron Un hydrolysat de caseine protege partiellement jes cals de l'action de chlorsulfuron. Ni la leucine, Fisoleucine et la valine seules ne suffisent a annuler le retard de croissance du a Therbicide. Cependant, Finhibition de la croissance des cals par le chlorsulfuron a ete levee quand on a complemente le milieu par une association d'is-oleucine et de valine a 100&M chaque. Les cals de pomme de terre ont absorbe 20 a 30% du chlorsulfuron applique apres respectivement 24 et 48 h et moins de 5% de l'herbicide etait metabolise par les cals 48 h apres le traitement. Ces travaux demontrent Futilite potentielle des cals monoploides dans les recherches sur la phytotoxicite et le mode d'action de herbicieds.An nicht differenziertem, weissem, monoploidem Callusgewebe von Kartoffeln (Solaman phureja Juz. & Buk.) wurden die phytotoxische Wirkungsweise und der Metabolismus von Chlorsul Furon studiert. Dosis/Wirkungs-Untersuchungen zeigten. dass 11.2 und 28 Chlorsulfuron das Calluswachstum zu 40 resp. 55% hemmten. Caseinhydrolysat schutzte das gewebe teilweise gegen Chlorsulfuronschadigungen. Weder Leucin. Isolcucin oder Valin. allen eingesetzt. waren in der Lage die durch das Herbizid verursachte Wachstumshemmung zu verringern. Die Hemmung des Calluswachstums wurde jedoch aufge hoben. wenn dem Medium eine Kombination von je 100 μM von Isoleuein und Valin zugesetzt worden war. Das Callusgewebe absorbierte 20 resp. 30% des applizierten Chlorsulfuron innerhalb 24 and 48 h: weniger als 5% des herbizids war 48 h nach der Applikation metabolisiert. Die Untersuchungen zeigten die potentielle Moglich-keit monoploide Callusgewebe zur Abklarung von Phytotoxizitat und Wirkungsweise von Her-biziden einzusetzen.haploid tobacco plant to study the mode of inheritance of resistance to chlorsulfuron and metsulfuron. Scheel & Casida (1985) studied the mode of action of chlorsulfuron in soybean (Glycine max L. Amsoy 71) cell suspension caltures and obtained similar results to those reported by ray (1984) for pea seedlings. In this study we report the phytotoxicity. mode of action. and metabolism of chlorsulfuron in non-differentiated, white. monoploid potato callus.

Notes: Summary. Several alkylphenol ethylene oxide ether non-ionic surfactants were tested in aqueous foliar sprays with dalapon, amitrole and paraquat for (heir enhancement of phytocidal activity against Zea mays L. With three homologous series of surfactants studied (octyl-, nonyl- and laurylphenol types), the herbicide, the surfactant concentration and the hydrophilic constitution (ethylene oxide content) of the surfactant molecule all markedly influenced maximum toxicity. Smaller apparent differences in effectiveness were also attributable to the hydrophobic (alkylphenol) portion of the surfactant. The results arc discussed in relation to possible cuticle-spray solution interactions and their influence on herbicide penetration.Relations entre la structure et l'activite de produits tensio-actifs non ionigues, a base d'éther d'oxyde éthylénique et d'alkylphénol, en présence de trois herbicides hydrosolubles