Title page for ETD etd-10072010-164054

Document Type Master's Dissertation
Author Muhl, Quintin Ernst
Email quintinmuhl@tuks.co.za
URN etd-10072010-164054
Document Title Seed germination, tree growth and flowering responses of Moringa Oleifera lam. (horseradish tree) to temperature
Degree MSc(Agric)
Department Plant Production and Soil Science
Advisor Name Title
Prof P J Robertse Co-Supervisor
Prof E S du Toit Supervisor
  • flowering
  • Moringa oleifera
  • temperature
  • paclobutrazol
  • hardening-off
  • growth
  • seed germination
  • tree growth
  • horseradish tree
Date 2010-04-21
Availability unrestricted
Moringa oleifera Lam. is a tree with great potential as it is fast growing and drought tolerant. Amongst the trees multitude of benefits, it can also be used to produce a biodiesel fuel. However, prior to the establishment of commercial plantations, all cultivation aspects of this promising tree have to be understood. Temperature is a significant climatic factor influencing both geographical plant distribution and growth, and since M. oleifera trees are naturally found in tropical climates around the world, the extent of their adaptability to cooler climates was the main objective of this study.

Trees were cultivated from seed and germinated in a controlled greenhouse environment at the Experimental Farm of the University of Pretoria. After germination, 50% of the seedlings were hardened-off by placing them outside under ambient growing temperatures, while the rest remained inside the greenhouse. With trial commencement, 132 of both the hardened and non-hardened seedlings were planted into 10 ℓ plastic bags and randomly placed into three temperature-controlled greenhouses, each with a different fluctuating night/day temperature regime namely; 10/20C 2C, 15/25C 2C and 20/30C 2C. In addition, half the trees within each temperature regime were treated with the growth regulator paclobutrazol to determine its effect on growth/flowering at different temperatures. During the 224-day trial period, biweekly measurements of tree height, stem diameter and leaf area estimates of each individual tree within all three temperature regimes were taken.

Despite germination percentages being slightly higher at the low 10/20C regime, the MGT, germination rate, uniformity and seedling growth were superior at the higher 20/30C regime. The temperature induced seed dormancy at the 20/30C regime, could be overcome by an incubation period at lower temperatures, as fewer instances of seed dormancy were observed at the 10/20C regime. The increase in temperature resulted in significant (P≤0.05) growth rate increases of over 650% between the 10/20C and 20/30C and 250% between the 10/20C and 15/25C night/day temperature regimes. In addition, the 20/30C temperature treatment, although fluctuative, consistently had the highest leaf area over the entire trial period. Hardening-off of trees during the seedling stage, significantly (P≤0.05) increased the final tree height by 3.09X, 1.44X and 1.23X, compared to their non hardened-off counterparts under the 10/20C, 15/25C and 20/30C temperature regimes respectively. Leaf thickness decreased by a significant (P≤0.05) 43.1% with increase in temperature between the 10/20C and 20/30C regime, mostly due to a thinner mesophyll layer. The efficacy of paclobutrazol on M. oleifera growth was found to be temperature dependant, reducing growth at 10/20C, while increasing growth at both the higher 15/25C and 20/30C regimes. Flowering however remained unaffected by paclobutrazol. The highest instances of flowering and pollen viability were observed at the 15/25C regime. The absence of inflorescence induction at the 20/30C regime was responsible for the reduced flowering, signifying the necessity of vernalization prior to flowering.

Even though all the results confirm the preference of M. oleifera trees towards a tropical climate, satisfactory growth with possibly improved flowering during the hot summer months in certain sub-tropical climates is achievable.

Copyright 2009, 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:

Muhl, QE 2009, Seed germination, tree growth and flowering responses of Moringa Oleifera lam. (horseradish tree) to temperature, MSc(Agric) dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-10072010-164054 / >


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