Investigation of Root Anatomy of Rice (Oryza Sativa) and Maize (Zea Mays) Grown in Aerated and Stagnant Conditions
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Date
2001-11-16
Authors
Naganathan, M.
Gunawardena, A. H. L. A. N.
Journal Title
Journal ISSN
Volume Title
Publisher
Unviersity of Peradeniya, Peradeniya, Sri Lanka
Abstract
Plants in the environment face different types of stresses such as salinity, drought, an
water logging. Water logging is considered as a major stress in some areas. Plants have sever
mechanisms to survive under flooded condition. Development of adventitious roots, superficial
roots, increased branching of roots and the formation of Aerenchyma are considered to be the
mechanisms to survive under flooded conditions. Aerenchyma facilitates gas diffusion between
roots and the aerial environment. Some cells in the cortical region die to form aerenchyma. Bo
the casparian bands and the suberin deposits in endo- and exodermis and suberized sclerenchyma
layer act as main barriers to water flow and air movement in monocot roots. As a result radial
oxygen loss is prevented.
Rice and Maize plants were grown hydroponically in an incubator at 25C under aerated
and stagnant conditions. Root lengths were measured daily and a mark was given at a distance of
10 mm from the root tip of the plants. Free hand cut sections of roots were taken using a razon
blade and stained with Sudan 7B. These sections were viewed under light microscope an
photographed. Some sections were stained with Berberine Aniline Blue and observed under
Fluorescent microscope. Root growth was high under aerated condition in maize compared to the
stagnant condition over time. However, in rice, root growth was more or less similar in aerated
and stagnant conditions. Increased pH was observed under aerated condition, while a declined pH
in stagnant condition over time. The different layers of a monocot root (epidermis, exodermis,
scierenchyma layer, cortical parenchyma, endodermis, pericycie and stele core) were observed
clearly. Formation of aerenchyma was observed in maize roots grown in stagnant conditions, but
not in aerated condition. In rice roots aerenchyma was observed in both aerated and stagnant
conditions. Initiation of aerenchyma was observed in the mid cortex region in rice and maize root
(stagnant condition). Both the casparian bands and suberization in endodermis and exodermis,
were prominent in rice and maize roots grown under stagnant condition than in aerated condition.
In addition, a very thick scierenchyma layer also was present in rice roots grown under stagnant
condition.
The results of this anatomical study will be useful in plant breeding programs especially in
the production of varieties with constitutive aerenchyma and in the production of drought tolerant
varieties.
Description
Keywords
Agricultural , Investigation , Root , Anatomy , Rice , Stagnant
Citation
Proceedings & abstracts of the Annual Research Sessions 2001,Unviersity of Peradeniya, Peradeniya, Sri Lanka,pp.19