Adaptation of Rice (Oryza sativa L.) root-morphology and anatomical characteristics in flood-saturated and aerobic condition
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Date
2013-07-25
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University of Agricultural Sciences, Bengaluru
Abstract
Yield penalty and yield stability of aerobic rice have to be considered in order to
promote water-saving technology in sub-tropics and tropics. The objective of this study
were (1) evaluation of field performance for yield, yield components and physiological
attributes of lowland and aerobic rice genotypes under flood-saturated and aerobic
condition (2) assess genetic variation of root of root morpho-anatomical characteristics of
the lowland and aerobic rice under flood-saturated and aerobic condition (3) assess
availability of soil indigenous zinc and iron and uptake ability in lowland and aerobic rice
genotypes under flood-saturated and aerobic condition. Field experiments were
conducted in native and contrast environment for each germplasm ecotype in two
seasons. The yield difference between aerobic condition (average yield, 6.56 g/plant) and
flood-saturated condition (average yield, 9.37 g/plant) for aerobic rice genotypes ranged
from 20.4 to 35.8% depending on varieties but among lowland rice genotypes, the yield
difference between aerobic condition (average yield, 13.44 g/plant) and flood-saturated
condition (average yield, 17.22 g/plant) ranged from 18.5 to 33.2% depending on
varieties. Among the yield components assessed, sink size (spikelets per panicle) and
number of effective tillers contributed more to the yield and is considered to be most
important factor responsible for yield gap between aerobic and lowland rice genotypes.
To clarify the differences in root anatomical and morphological traits among
aerobic and lowland genotypes grown in native and contrast environments, we analyzed
few anatomical and morphological traits. The root samples were prepared from 20 mm of
tip. Root cross-sections were stained with saffranine and fast green stains. Anatomical
differences were observed among all genotypes submitted to water management and
varied between the water managements. The number and diameter of metaxylem vessels
were grown under aerobic condition tended to have greater number and smaller size of
metaxylem vessels relative to stele size in comparison with the genotypes grown under
flood-saturated condition. A decrease in root’s aerenchyma was observed in all genotypes
in aerobic condition compared to the flood-saturated condition. High genetic variability
was observed in all morphological characteristics in all genotypes, and highly influenced
by water managements.
Field experiments demonstrated that the cultivation (flood-saturated and aerobic
condition) greatly affected the uptake of indigenous zinc and iron, and also the
availability in different plant parts including grains, among the genotypes studied. Lower
uptake in zinc or iron and as well availability were observed in aerobic fields compared
to flood-saturated fields. This large variation in uptake and availability is a pre-requisite
for initiating a breeding program to develop mineral-rich genotypes adaptive to an
environment-specific.
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Keywords
rice, irrigation, vegetative propagation, zinc, iron, planting, yields, genotypes, biological phenomena, grain