Repeated exposure of jacket plum (Pappea capensis) micro-cuttings to indole-3-butyric acid (IBA) improved in vitro rooting capacity

The objective of the trial was to determine an effective propagation protocol for jacket plum (Pappea capensis) tree species. Experiments on in vitro propagation and rooting of stem cuttings were carried out. Dipping stem cuttings in half strength Murashige and Skoog (MS) media for 12 h prior to application of rooting hormones improved bud break and prolonged survival of stem cuttings on a mist bed. Early leaf loss was observed for stem cuttings planted without MS treatment. However, rooting was poor (11% for cuttings pre-treated in MS and 0% for those not pre-treated). For micro-propagation, significant differences (P < 0.05) in shoot multiplication and root regeneration were found. MS media supplemented with 2.0 mg l–1 benzylaminopurine was superior in the number of micro-shoots produced. Rooting capacity of micro-cuttings was improved from 42% to 64% when MS media supplemented with 0.5 mg l–1 IBA were repeated for the micro-cuttings that initially failed to root. There was 70% survival rate of plantlets after hardened off.The financial support from the Federal Ministry of Economic Cooperation (BMZ/GTZ), Germany through the World Agroforestry Centre (ICRAF) Southern Africa Regional Programme, Agro-Forest and Bio Energy Association and Invest North West, South Africa is acknowledged

Impact of Trichodesmium bloom on the plankton and productivity in the Tuticorin bay, southeast coast of India

27-30Trichodesmium thiebautii bloom was noticed on 2 March 1989 in Tuticorin bay, and hydrobiological investigations were carried out between 2 and 8 March 1989, when the bloom culminated. While the water temperature (29.1-degrees-30.8-degrees-C), salinity (35-35.4 x 10(-3)), pH (8.2-8.9), nitrite (0.36-1.96 mug-at. l-1), phosphate (0.32-2.53 mug-at. l-1) and particulate organic carbon (7.12-29.54 g.m-3), showed generally higher values in association with maximum bloom density, dissolved oxygen (3.2-5.2 ml.l-1) and nitrate (0.2-0.78 mug-at. l-1) concentration recorded minimal values. Density of T. thiebautii ranged from 0.01 to 17.5 x 10(6) filaments. l-1 during the bloom period. While the maximum species diversity (1.49) was associated with minimum bloom density, the maximum chlorophyll-a (535.26 mg.m-3), primary production (512 mg C.m.-3h-1) and microzooplankton (72,000 no.l-1) coincided with the maximum bloom density. Interestingly, the total number of other phytoplankton and macrozooplankton were at minimum levels (ie, 120 cells. l-1 and 2 no.l-1) in association with the maximum bloom density

Iron precipitation in estuarine environment

175-176Total particulate iron concentration varied from 1336.125 to 350.012 µg/litre and total organic particulate iron concentration from 1099.44 to 290.511 µg/litre in the salinity range 6.8 to 30% in the Vellar Estuary. Maxiµm (335.94 µg/litre) and miniµm (59.501 µg/litre) of HCl reactive iron were observed at 0.1 and 30% salinities respectively. The relationship between the rate of iron precipitation and salinity was non-linear. The study revealed that (1) inorganic fraction of particulate iron could contribute only lower percentages to total particulate iron (av. 18.8%) and (2) the role of sedimentary particles could not be neglected while considering precipitation of iron in estuaries