Achievements and problems in the implementation of microcutting technology for clonaI rubber rootstock propagation

Microcutting is one of in vitro plant propagation methods and has been developed for rubber (Hevea brasiliensis) by using axillary buds from young seedlings as explant sources. There are some constraints to implement microcutting technology in mass propagation of Hevea such as high level of contamination, low proliferation rate, poor rooting, and difficulty in acclimatization process. Achievements and problems in the implementation this technique in Indonesia will be reported in this paper. Around 19.000 explants from 89 genotypes have been introduced in primary culture for almost 3 years (2006-2008), 40% of them loss during this stage due to contamination and no response of the explants. All healthy and good response explants had been transferred to multiplication phase. The multiplication rate was 1.3 to 1.6 per month for the best genotypes. In 2007 and 2008, around 6.000 new shoots had been introduced to conditioning phase, 80% of them have continued to rooting phase. These two stages produced about 4.000 plantlets which were then acclimatized to ex vitro conditions on different media and micro-environments. The suitable medium for vitroplants acclimatization was a mix of cocopeat, soil, sand and dung manure. Better growth and survival rate were achieved when the vitroplants were cultured inside a closed plastic tunnel placed under tree canopies. The survival rate of vitroplants, 1.5 month after weaning, has increased to 60% but still fluctuated and only 15% in average after 6 months. The survived plants with good root systems were then transferred to a shading nursery. Vitroplants and GT 1 seedlings were planted in the field for 7 months before budded with scions of PB 260 clone. All rootstocks from vitroplants and GT 1 seedlings were successfully budded with scions of PB 260. At present, budded and unbudded vitroplants are being planted in the field. (Résumé d'auteur

Impact of practices on the comprehensive fertility of soil under oil palm

The project had objectives to assess the integration of soil organic matter and soil biota (micro- and macrofauna) in comprehensive fertility of oil palm agroecosystems and to develop knowledge toward a comprehensive fertility diagnosis to manage organic and inorganic fertiliser applications in a synergistic way. Spatial variability around the palm was studied in five locations: Path, Path-Circle, Circle, Circle-Windrow and Windrow. In each location, samples of litter and soil were taken at two depths (15 and 30 cm). Analyses were done on the physical and chemical traits, on macrofauna, nematodes and micro-organisms. In litter, results showed that total macrofauna were abundant in all zones. In soil, the application of empty fruit bunches (EFB) on the Path zone induced significant changes in the Path and Path-Circle zones, but also in the Circle and even in the Windrow. Macrofauna had a significantly higher density in the Circle and Windrow zones than other areas. Analyses of nematodes, bacteria and fungi confirmed these trends. The 15–30 cm horizon had very low soil biota densities. Temporal variability after EFB application was studied under the Path at 1, 3, 6, 12, 18, 24 months after EFB application. The results clearly indicated three periods—during the first period of 6 months, soil chemical and faunal traits were strongly changed. The second period (12 to 18 months) looked like a period of relative stability. After 24 months, most of the comprehensive fertility traits increased. (Texte intégral