Title page for ETD etd-10222010-141502


Document Type Master's Dissertation
Author Mudziwa, Nyengedzeni
Email mmudziwa@webmail.co.za
URN etd-10222010-141502
Document Title Yield and quality responses of Egyptian white garlic (Allium sativum L.) and wild garlic (Tulbaghia violacea Harv.) to nitrogen nutrition
Degree MInstAgrar
Department Plant Production and Soil Science
Supervisor
Advisor Name Title
Mrs E van den Heever Co-Supervisor
Prof E S du Toit Co-Supervisor
Prof P Soundy Supervisor
Keywords
  • Alternaria solani
  • ammonium sulphate
  • calcium nitrate
  • Sclerotium rolfsii
  • Tulbaghia violacea
  • Allium sativum
Date 2010-09-02
Availability unrestricted
Abstract

Allium sativum and Tulbaghia violacea are some of the most important medicinal plants used by South African traditional healers for the treatment of flu, fever, cold, tuberculosis, asthma and many more diseases. However, growth, yield and quality are constrained by excessive and under fertilization. This study was carried out to determine, firstly, the effect of N source (ammonium sulphate and calcium nitrate) on yield and quality of A. sativum and T. violacea plants. Secondly, to determine the best season for harvesting T. violacea and lastly, to determine the antifungal effects of A. sativum and T. violacea plant extracts against plant pathogens Altenaria solani and Sclerotium rolfsii. Both plants were treated with both N sources applied as topdressing treatments at a total of 0, 50, 100, 150 and 200 kg.ha-1, divided into three applications at three week (A. sativum) and three month (T. violacea) intervals. A. sativum plants were sampled at 54, 82, 112, 140 and 175 days after planting (DAP) while, T. violacea plants were sampled monthly for ten months. Parameters recorded were growth analysis, yield and bioactivity for both plant species. Both nitrogen sources improved plant growth and yield of A. sativum and T. violacea plants. Calcium nitrate at 150 kgha-1 and ammonium sulphate at 200 kgha-1 produced the highest at 24 tha-1 and 27 tha-1, respectively. Ammonium sulphate improved bioactivity of leaves with the highest bioactivity recorded at 82 and 112 DAP.

Yield obtained from the autumn harvest was not affected by N source. Ammonium sulphate and calcium nitrate at 200 kgha-1 produced the highest yields of 23.6 tha-1 and 23.5 tha-1, respectively. In contrast, yield obtained from the winter harvest was affected by N source at 200 kgha-1, with significantly better yield of 30.8 tha-1 with calcium nitrate compared to 27.4 tha-1 with ammonium sulphate. Crude extracts of T. violacea bulbs that were treated with ammonium sulphate significantly inhibited the growth of plant pathogenic fungi, whereas extracts from plants treated with calcium nitrate showed low bioactivity. Extracts from plants grown with ammonium sulphate at 100 kgha-1 were more effective in controlling growth of plant pathogens when compared to other N levels. The minimum inhibitory concentration (MIC) effects of A. sativum against S. rolfsii and A. solani were at 0.01 mgmL-1. The MIC of T. violacea extracts against A. solani was at 0.006 mgmL-1. The MIC of T. violacea extracts were better than previously reported in literature. Therefore, A. sativum and T. violacea plant extracts can be used as fungicides against S. rolfsii and A. solani diseases for crops such as tomato and potato.

2010, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria.

Please cite as follows:

Mudziwa, N 2010, Yield and quality responses of Egyptian white garlic (Allium sativum L.) and wild garlic (Tulbaghia violacea Harv.) to nitrogen nutrition , MInstAgrar dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-10222010-141502/ >

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