Investigation on the production of healthy seedling of teak (Tectona grandis Linn.f.) in the nursery

Abstract

Teak seeds have dormancy which may vary from a few weeks to a year or even years. Selection of a suitable pretreatment to overcome this dormancy has been on age old problem. Several complex and inter – related factors like the physiological condition of the fruit, the special fruit characteristics and the after ripening phenomena complicate the problem. A study was conducted using fruits from seven middle aged teak plantations in Trichur Forest Division. A germination trial was carried out in Factorial Randomized Block Design. The fruits were size graded and four presowing treatments were tested in vermiculite and sand media and the germination characters recorded during a 30 day observation period. A cutting test was also performed before hand to estimate the average emptiness, viability percentage and other fruit characters of the size graded teak fruits. Thereafter the seedlings were transplanted from the germination trays to polybags filled previously with potting mixture and kept in the open. After completion of three months the seedlings were taken out from the polybags and the biometric observations recorded. The tap root, lateral roots, leaves and stem were separately dried to constant weight and the dry weight recorded. The dry matter production of the entire seedling was also computed. From this data the effect of fruit grading, pretreatments and germination media was analysed statistically. It was found that larger sized fruits (above 15 mm diameter) were superior to the other grades with respect to germination characters, seedling growth and dry matter production. The pretreatment of the fruits using GA3 at 100 ppm was significant with respect to germination characters, biometric and biomass observations of the teak seedlings. Vermiculite was a better germination medium for teak seed germination then sand and the seedlings grown in that medium recorded better tap root growth and dry matter production. The potted seedlings thus produced can be used for planting in areas where seedling planting is resorted to for raising new plantations and for replacement of casualities during June – July in areas where stump planting is adopted as the method of artificial regeneration during premonsoon showers in the month of April – May.