Effect of pre-incubation of nitrate and ammonium in cultures on nitrate reductase activity in marine red algae <i style="">Gelidiella </i>and <i style="">Gracilaria </i>from southeast coast of India

232-236Nitrate reductase (NR) activities of six agar yielding seaweeds viz. Gelidiella acerosa, Gracilaria corticata, G. crassa, G. edulis, G. foliifera and G. verrucosa pre-incubated in different concentrations (150, 300, 450, 600 and 750 µmol/l) of nitrate (NaNO3) and ammonium (NH4)2S2O8 (700, 1400, 2100, 2800 and 3500 µmol/l) were studied. NR activity ranged from 0.07 to 24.72 mmol/g (f.wt)/h in G. acerosa; 0.19 to 5.83 mmol/g (fr.wt.)/h in G. corticata; 0.23 to 9.99 mmol/g (fr.wt.)/h in G .crassa; 0.06 to 0.43 mmol/g (fr.wt.)/h in G. edulis; 0.37 to 19.92 mmol/g (fr.wt.)/h in G. foliifera and 0.74 to 10.54 mmol/g (fr.wt.)/h in G. verrucosa. Maximum NR activity was found at an optimum nitrate concentration of 600 µ mol/l in all five species of Gracilaria and at 450 µmol/l in Gelidiella acerosa. Nitrate enhanced NR activity in all six species of agarophytes. Ammonium suppressed NR activity in all algae except G. edulis in which no obvious difference was observed in NR activity between NO3 and NH4 added culture

Effect of light intensity, photoperiod, ESP medium and nitrogen sources on growth of marine brown alga <i style="">Padina boergesenii </i>(Dictyotales, Phaeophyta)

228-231Experiments were conducted on germlings of Padina boergesenii to understand the effects of different light intensity, photoperiod, strength of ESP medium and nitrogen sources on its growth in terms of increase in fresh wt. and thallus area. Maximum increase (fr.wt. and area) over initial was observed in germlings cultured under 76 µE/m2/s light intensity, 14:10 L:D cycle photoperiod, quarter strength of ESP media and 16 and 33 mg N/liter as sodium nitrate. From the present study it is very clear that high light intensity, long day condition that generally exist during most of the months along the southeast coast of India are favourable for cultivation of this alga. In addition, ¼ concentration of ESP medium and nitrate nitrogen (NaNO3) with higher concentration (16 and 33 mg N/l) are favourable for growth of Padina boergesenii in the laboratory

Effect of UV radiation and other environmental factors on the liberation of <span style="font-size:14.0pt;line-height:115%;font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";color:black;mso-ansi-language:EN-IN; mso-fareast-language:EN-IN;mso-bidi-language:HI" lang="EN-IN">tetraspores from brown alga <i>Padina boergesenii </i>(Phaeophyta, Dictyotales)</span>

50-54<span style="font-size:14.0pt;line-height: 115%;font-family:" times="" new="" roman";mso-fareast-font-family:"times="" roman";="" color:black;mso-ansi-language:en-in;mso-fareast-language:en-in;mso-bidi-language:="" hi"="" lang="EN-IN">Experiments were carried out with tetrasporophytes of Padina boergesenii to understand the effects of ultra violet radiation, light intensity, photoperiod, temperature, salinity and desiccation on the liberation of tetraspores. UV-B radiation inhibits spore liberation while UV-C radiation enhances spore release. UV-A radiation increases spore liberation initially during short time exposure and inhibits spore release during long time exposure. UV-B radiation combined with day light increases the spore liberation. Low illuminance ( 26 <span style="font-size:14.0pt;line-height: 115%;font-family:" times="" new="" roman";mso-fareast-font-family:hiddenhorzocr;="" color:black;mso-ansi-language:en-in;mso-fareast-language:en-in;mso-bidi-language:="" hi"="" lang="EN-IN">μEa<span style="font-size:14.0pt;line-height: 115%;font-family:" times="" new="" roman";mso-fareast-font-family:"times="" roman";="" color:black;mso-ansi-language:en-in;mso-fareast-language:en-in;mso-bidi-language:="" hi"="" lang="EN-IN">m-2s-1), short day (8:16 hr LD) and submerged condition of plants and seawater of 35 ppt salinity and 20° C temperature were found to be favourable for maximum liberation of tetraspores. Temperature shock (ranges from 0° C to 50° C up to 120 minutes) could not enhance the spore discharge in Padina boergesenii.</span

Seasonal growth and reproduction of marine red alga <i>Asparagopsis delilei</i> <span style="font-size:14.0pt;line-height:115%;font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";color:black;mso-ansi-language:EN-IN; mso-fareast-language:EN-IN;mso-bidi-language:HI" lang="EN-IN">(Rhodophyta/ Bonnemaisoniales) from the Mandapam region, southeast coast of India</span>

60-65<span style="font-size:14.0pt;line-height: 115%;font-family:" times="" new="" roman";mso-fareast-font-family:"times="" roman";="" color:black;mso-ansi-language:en-in;mso-fareast-language:en-in;mso-bidi-language:="" hi"="" lang="EN-IN">Asparagopsis delilei <span style="font-size:14.0pt; line-height:115%;font-family:" times="" new="" roman";mso-fareast-font-family:"times="" roman";="" color:black;mso-ansi-language:en-in;mso-fareast-language:en-in;mso-bidi-language:="" hi"="" lang="EN-IN">Montagne occurs beyond 2.5 m depth on the coral reef adjoining the islands—Krusadai, Putty and Valai in the Gulf of Mannar region, southeast coast of India. Seasonal growthh and carpospore liberation in this alga were studied from three Islands. Maximum growth (length and fresh wt) was found during November-March. Maximum number of carpospores 22300, 11917 and 5037 per g. fresh weight was recorded for the plants of Krusadai, Putty and Valai Island respectively. A positive correlation was observed between length and fresh weight of the plants, whereas a negative correlation was found between Number of cystocarps and carpospores shed per cystocarp, fresh weight of the plant and carpospores shed per g fresh weight. Diurnal periodicity in carpospore shedding was also seen for four months during the peak growth period from August 1994 to January 1995.</span