Potential use of liquid seawed extracts and seaweeds as fertilizers on four indigenous fruit trees

Abstract

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The extracts were tested for cytokinin-like activity using their UV spectra and the soybean callus bioassay. Auxin-like activity was determined using the mung bean bioassay. No attempt was made to identify these compounds but only to report their absence or presence. UV spectra of the chromatograms subjected to only a paper chomatography purification step, revealed peaks in all the extracts tested suggesting the possibility of cytokinin-like compounds. The most prominent peak was detected in the Kelpak extract with the R0. 9 fraction. In the soybean callus bioassay all the extracts tested showed cytokinin-like activity except for the Nothogenia erinacea extract. The highest activity was recorded with the Kelpak extract being concentrated at R0. 2 and 0. 7. The blade extracts showed activities at R0. 3 and 0. 7 which were significantly different from the control (p0. 05), whereas the stipe extract showed activity at R0. 3 Purification of extracts using a cation exchanger followed by paper chromatography, gave more comparable results for the UV spectra. The highest peaks were detected with the Kelpak extract followed by the stipe and blade extracts. Nothogenia erinacea extracts did not show any absorbency peaks. The soybean callus test for these chromatograms showed positive results for all the extracts tested except for Notllogenia erinacea. Activity for Kelpak was concentrated at R 0. 3, 0. 5, 0. 7 and 1. Laminaria stipe and blade extracts showed activity at R0. 4 for both extracts tested. Both Kelpak and Laminaria stipe extracts tested showed auxin-like activity. Laminaria stipe extract produced the highest root count for both the extracts tested at a dilution of 2 percent. This optimum dilution is comparable to IBA at between 10-5 to 10-4 M. This was the only concentration which was significantly different from the control treatment (p 0. 05)

The effect of pre-germination treatments with Laminaria stipe and Kelpak extracts were investigated on the germination rate of Schinziophyton rautanenii (Schinz) Radcliffe-Sm EUPHORBIACEAE, Sclerocarya birrea (A. Rich.) Hochst subsp. caffra (Sond). Kokwara ANARCARDIACEAE, Strychnos cocculoides (Baker) LOGANIACEAE and Vangueria infausta subsp. infausta Burch. RUBIACEAE. Seaweed concentrations were overall not sufficient enough to give significantly positive responses to germination except for Kelpak (1 percent) which increased germination percentage by 118. 8 percent in Schinziophyton rautanenii seeds, compared to the control treatment. Highest germination counts were obtained with the control seeds in the rest of the species

Liquid seaweed extract derived from Ecklonia maxima and the "schinzii" form of Laminaria pallida can improve seedling growth of four indigenous fruit tree species in the greenhouse, when applied as a soil drench and foliar application. Growth was manifested in both shoots and roots for all four species except with Sclerocarya birrea subsp. caffra. Both Kelpak and Laminaria stipe extracts increased dry root to shoot ratios over the control except with Sclerocarya birrea subsp. caffra species. The highest root to shoot ratio in Schinziophyton rautanenii was achieved with the application of Kelpak (10 percent) applied as a soil drench. Laminaria stipe extract (0. 1 percent and 1 percent) caused the highest increases in dry root to shoot ratios in Strychnos cocculoides for both foliar and soil drench application. Various concentrations of Laminaria stipe extract also increased the dry root to shoot ratio in Vangueria infausta subsp. infausta

The effect of liquid seaweed extract (Kelpak) and seaweed (Afrikelp) on Schlinziophyton rautanenii (Schinz) Radcliffe-Sm EUPHORBIACEAE, Sclerocarya birrea (A. Rich.) Hochst subsp. caffra (Sond). Kokwara ANARCARDIACEAE, Strychnos cocculoides (Baker) LOGANIACEAE and Vangueria infausta subsp. infausta Burch. RUBIACEAE was investigated in a field trial in Okahandja over a period of 14 months. Results showed that not all four indigenous fruit tree species are suitable for initial establishment in the field with the application of Kelpak and Afrikelp as a soil additive. Vangueria infausta subsp. infausta did not survive the field trial whereas Sclerocarya birrea subsp. caffra showed the highest survival rate of 87. 5 percent with the application of Kelpak (1 percent) applied as a soil drench. The application of Afrikelp (mixed at a rate of 1 percent) on Sclerocarya birrea subsp. caffra showed the best height counts and stem diameter increases. Both Schinziophyton rautanenii and Strychnos cocculoides showed poor survival rates. A concentration of 10 percent Kelpak extract significantly increased the height of seedlings over that of the control (p0. 05) for Schinziophyton rautanenii transplants