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Response of potato to paclobutrazol and manipulation of reproductive growth under tropical conditions
Thesis (DPhil (Horticultural Science))--University of Pretoria, 2007.
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University of Pretoria
2013
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| _version_ | 1867613459386990592 |
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| access_status_str | Open Access |
| author2 | Hammes, Pieter Snyman, 1941- |
| author_browse | Hammes, Pieter Snyman, 1941- |
| author_facet | Hammes, Pieter Snyman, 1941- |
| collection | Thesis |
| dc_rights_str_mv | © 2005, 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. |
| description | Thesis (DPhil (Horticultural Science))--University of Pretoria, 2007. |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/27243 |
| institution | University of Pretoria (South Africa) |
| last_indexed | 2026-06-10T12:36:29.146Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository |
| publishDate | 2013 |
| publishDateRange | 2013 |
| publishDateSort | 2013 |
| publisher | University of Pretoria |
| publisherStr | University of Pretoria |
| record_format | dspace |
| source_str | UPSpace — University of Pretoria Institutional Repository |
| spelling | oai:repository.up.ac.za:2263/27243 Response of potato to paclobutrazol and manipulation of reproductive growth under tropical conditions Hammes, Pieter Snyman, 1941- tekaligntsegaw@yahoo.com Tsegaw, Tekalign Tuber quality Tropical lowland Specific gravity Solanum tuberosum l Photosynthetic rate Potato genotypes Tuber yield Paclobutrazol Non-inductive High temperature Growth analysis Ethiopia Assimilate partitioning Anatomical modification UCTD Thesis (DPhil (Horticultural Science))--University of Pretoria, 2007. High temperature limit successful potato cultivation in the lowlands of tropical regions. One effect of high temperature may be an increase in gibberellin activity that is inhibitory to tuberization. Paclobutrazol blocks gibberellin biosynthesis and reduces its level in the plant. The effect of paclobutrazol on potato was examined under non-inductive conditions in a greenhouse and under field conditions in the hot tropical lowlands of eastern Ethiopia. Paclobutrazol was applied as a foliar spray or soil drench at rates equivalent to 0, 2, 3, and 4 kg a. i. per ha. Paclobutrazol increased chlorophyll a and b content, and photosynthetic efficiency, enhanced early tuber initiation, delayed physiological maturity, and increased tuber fresh mass, dry matter content, specific gravity and crude protein content. It reduced the number of tubers per plant and extended the tuber dormancy period. Paclobutrazol reduced shoot growth, and plant height, and increased the partitioning of assimilates to the tubers while reducing assimilate supply to the leaves, stems, roots and stolons. Stomatal conductance and the rate of transpiration were reduced. In addition, paclobutrazol treatment increased tuber N, Ca and Fe content while reducing P, K and Mg content. Growth analyses indicated that paclobutrazol decreased leaf area index, crop growth rate, and total biomass production. It increased specific leaf weight, tuber growth rate, net assimilation rate, and partitioning coefficient (harvest index). Microscopic observations showed that leaves of treated plants developed thicker epicuticular wax layers. The epidermal, palisade and spongy mesophyll cells were larger. It increased the thickness of the cortex and the size of vascular bundles and pith cells of the stem. It also increased the width of the cortex and favoured the formation of more secondary xylem vessels, resulting in thicker roots. Deposition of starch grains in the stem pith cells, and cortical cells of the stem and root, were stimulated in response to paclobutrazol treatment. In most instances the method of application did not affect the efficiency of paclobutrazol. The effect of cultivar and reproductive growth on growth, photosynthetic efficiency, water relations, dry matter production, tuber yield and quality of potato was also the subject of investigation. Non-flowering, flowering and fruiting plants of cultivars Al-624, Al-436, CIP-388453-3(A) and CIP-388453-3(B) were evaluated under field conditions of a sub-humid tropical highland of eastern Ethiopia. Cultivars exhibited differences with respect to leaf stomatal conductance, rate of transpiration, net photosynthesis, biomass production and allocation, tuber yield, tuber size distribution, specific gravity, dry matter content and nutrient composition. Fruiting plants had higher leaf stomatal conductance, and higher rates of transpiration and photosynthesis rates. The leaf area index, tuber growth rate, and partitioning coefficient (harvest index) of the fruiting plants were reduced, but crop growth rates and net assimilation rates were higher. Without affecting total dry matter production, fruit development reduced the amount partitioned to the leaves, stems, roots, and tubers. Fruit development reduced total and marketable tuber mass and tuber numbers. The effect of MCPA and paclobutrazol were studied under greenhouse and field conditions. Single foliar sprays were applied during the early and full bud development stages at rates of 0, 250, 500, and 750 g a.i. ha-1. Both MCPA and paclobutrazol greatly reduced the number of flowers and completely inhibited berry set. MCPA did not affect the number, yield, dry matter content and specific gravity of tubers. Without affecting the number of tubers, paclobutrazol increased tuber yield, dry matter content and specific gravity. Plant Production and Soil Science unrestricted 2013-09-07T11:00:28Z 2006-02-08 2013-09-07T11:00:28Z 2005-04-23 2007-02-08 2006-02-08 Thesis Tsegaw, T 2005, Response of potato to paclobutrazol and manipulation of reproductive growth under tropical conditions, DPhil thesis, University of Pretoria, Pretoria, viewed yymmdd < http://hdl.handle.net/2263/27243 > http://hdl.handle.net/2263/27243 http://upetd.up.ac.za/thesis/available/etd-02082006-112218/ © 2005, 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. application/pdf application/pdf application/pdf application/pdf application/pdf application/pdf application/pdf application/pdf application/pdf application/pdf application/pdf application/pdf application/pdf application/pdf University of Pretoria |
| spellingShingle | Tuber quality Tropical lowland Specific gravity Solanum tuberosum l Photosynthetic rate Potato genotypes Tuber yield Paclobutrazol Non-inductive High temperature Growth analysis Ethiopia Assimilate partitioning Anatomical modification UCTD Response of potato to paclobutrazol and manipulation of reproductive growth under tropical conditions |
| title | Response of potato to paclobutrazol and manipulation of reproductive growth under tropical conditions |
| title_full | Response of potato to paclobutrazol and manipulation of reproductive growth under tropical conditions |
| title_fullStr | Response of potato to paclobutrazol and manipulation of reproductive growth under tropical conditions |
| title_full_unstemmed | Response of potato to paclobutrazol and manipulation of reproductive growth under tropical conditions |
| title_short | Response of potato to paclobutrazol and manipulation of reproductive growth under tropical conditions |
| title_sort | response of potato to paclobutrazol and manipulation of reproductive growth under tropical conditions |
| topic | Tuber quality Tropical lowland Specific gravity Solanum tuberosum l Photosynthetic rate Potato genotypes Tuber yield Paclobutrazol Non-inductive High temperature Growth analysis Ethiopia Assimilate partitioning Anatomical modification UCTD |
| url | http://hdl.handle.net/2263/27243 http://upetd.up.ac.za/thesis/available/etd-02082006-112218/ |