Shoot apices of Pinus roxburghii Sarg were cultured on Murashige and Skoog's medium (MS) supplemented with cytokinins 6-benzyladenine (BA), kinetin and N-benzyl-9-(2-tetrahydropyranyl) adenine (BPA) alone and in combination with auxin, -napthaleneacetic acid (NAA). Of the three cytokinins tested at varying concentrations, medium supplemented with 10 μM BA was found optimal in respect of explant responsiveness (97.22 %) and average number of buds induced per explant (7.42). The concentration of cytokinins in the induction medium had a profound effect on rate of elongation of induced buds on MS basal medium containing 0.5 % activated charcoal. Further, shoots induced on lower concentrations of BA increased up to 2.4 times in length in 4 weeks. Decapitation of the explant enhanced the rate of axillary bud elongation. Proliferating shoot cultures were established by sub-culturing the axillary shoots on MS supplemented with 10 μM BA. Shoots 2 -3 cm in length were suitable for culturing as more buds were induced on them compared to longer or shorter shoots. Root primordia were induced on 70.83 % shoots when transferred to ½ MS medium supplemented with 5.0 μM NAA. Elongation of root primordia (60 %) was achieved in liquid ½ MS basal medium. The plantlets were successfully transferred to soil after hardening; the time period from initiation of shoot buds to transplantation being 20 -22 weeks.
Biology and ecology of three acorn weevils: Dicranognathus nebulosus Redt. (Col., Attelabidae), Sitophilus glandium (Mshl.) (Col., Curculionidae) and Curculio sikkimensis (Hell.) (Col., Curculionidae), which infest acorns of Quercus leucotrochophora A. Camus and Q. floribunda Lindle was studied in the laboratory and in the field. Adults of D. nebulosus and C. sikkimensis laid one egg per infested acorn, and S. glandium laid 0 to 8 (means 5.2 ± 0.47) eggs in an infested acorn of Q. leucotrichophora. Only a single larva of D. nebulosus and C. sikkimensis developed per acorn, and 1 to 5 (mean 3.8 ± 0.3) larvae of S. glandum developed per acorn through the last instar. Larvae of D. nebulosus and S. glandium completed their development in the infested acorn, and C. sikkimensis emerged from the acorn through the last instar and completed its development in the soil. Good synchronization was observed in the life cycle of acorn weevils and phenology of Q. leucotrichophora. An average of 88.7% of acorns were infested by the acorn weevils. Injury to live acorns by weevil larvae reduced germination and seedling growth. Weevil larvae could be controlled by hydrothermal treatment (20 min at 45 °C) of infested acorns in the germination experiments.
Zusammenfassung
Zur Biologie und Bekämpfung von drei Käferarten in Kumaun Himalaya, Indien, die Eicheln befallen
Im Labor und Freiland wurden die Biologie und Ökologie der 3 Käferarten Dicranognathus nebulosus Redt. (Col., Attelabidae), Sitophilus glandium (Mshl.) (Col., Curculionidae) und Curculio sikkimensis (Hell.) (Col., Curculionidae), welche die Eicheln von Quercus leucotrochophora und C. floribunda befallen, untersucht. Die Weibchen von D. nebulosus und C. sikkimensis legten ein Ei pro Eichel ab, während S. glandium 0 bis 8 Eier (i.M. 5) pro Eichel von Q. leucotrochophora ablegte. Somit entwickelten sich von D. nebulosus und C. sikkimensis in einer Eichel nur je 1 Larve. Von S. glandium dagegen gelangten bis zu 5 (i. M. 3) Larven in einer Eichel zum letzten Larvenstadium. Während bei D. nebulosus und S. glandium die Larven ihre Entwicklung in der Eichel vollendeten, verließen die Altlarven von C. sikkimensis die Eichel und beendeten ihre Entwicklung im Boden. Es bestand eine gute Synchronisation zwischen der Phänologie von Quercus leucotrichophora und dem Lebenszyklus der Eichelkäfer. Die 3 Käferarten befielen im Untersuchungszeitraum i. M. 88,7 % der Eicheln von Q. leucotrichophora. Der Befall lebender Eicheln durch die Käferlarven führte zur Verminderung der Keimung und des Sämlingswachstums. Die Käferlarven konnten mit Hilfe einer Hitzebehandlung (20 min bei 45 °C) der Eicheln erfolgreich, d.h. im Sinne der Erhaltung der Keimkraft, bekämpft werden.
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