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RESEARCH ARTICLE
Contents Vol 28(2)

Breaking seed coat dormancy in Macrotyloma daltonii

N. Chikumba A , C. Mapiye B C and X. Poshiwa A
+ Author Affiliations
- Author Affiliations

A Grasslands Research Station, Post Bag 3701, Marondera, Zimbabwe.

B Department of Agriculture, Bindura University of Science Education, Post Bag 1020, Bindura, Zimbabwe.

C Corresponding author. Email: cmapiye@yahoo.co.uk

The Rangeland Journal 28(2) 179-182 https://doi.org/10.1071/RJ06012
Submitted: 16 March 2006  Accepted: 31 May 2006   Published: 9 November 2006

Abstract

Methods for breaking hard seed to allow germination of 2 seedlots of Macrotyloma daltonii (Webb) Verdc., were investigated. Treatments included soaking, application of dry heat, hot water, acid scarification, sand paper scarification, pre-chilling, alone and in combination with acid and dry heat. The treated seeds were tested for germination over 21 days in an incubator with 12 h of light and 12 h of darkness and temperatures of 25 and 18°C during the light and dark phases, respectively.

A 20-min exposure to 98% concentrated sulphuric acid was most effective in increasing germination from 10 to 80% in seedlot 1. The 10-min acid treatment increased germination from 21 to 38% in seedlot 2, but 20 min reduced germination and increased the number of dead seeds. Seedlot 1 had greater levels of hard seed (88%) than seedlot 2 (61%). Soaking, hot water, dry heating, pre-chilling, or sandpaper scarification were not effective in breaking hard seed in either seedlot 1 or 2. Combining pre-chilling with 10 min of acid treatment damaged seed and impaired germination across the 2 seedlots. The range of pre-sowing seed treatments that indicated positive effects on germination, particularly acid treatments need to be further investigated in the field under different pedo-climatic conditions to allow appropriate rangeland management options to be developed.

Additional keywords: germination, hardseed, scarification, rangeland reinforcement.


Acknowledgments

The study was supported by a grant from the Biotechnology Trust of Zimbabwe. The authors are grateful to Dr G. J. Manyawu and Mrs R. Nyoka for their valuable and constructive comments. The technical assistance rendered by staff at Grasslands Research Station and the Seed Services Unit is greatly appreciated.


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