Starch metabolism and end use quality of durum wheat in response to high temperature stress
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Date
2007
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Publisher
CCSHAU
Abstract
The present experimentation was carried out on durum wheat to
study the physiological and biochemical basis of high temperature
induced changes in sucrose to starch conversion. Effect of high
temperature stress was determined on grain quality and starch
metabolism in two durum wheat varieties WH 896 and WH 912. The
investigation involved pot studies under screen house conditions
during the year 2005-06.
In this study, high temperature was induced by shifting the pots
to polyhouse after heading. Heat degree days (HDD) were used to
quantity the magnitude of heat stress to which these two durum wheat
varieties were exposed during the second half of crop growth i.e. from
days of heading (DOH) to days of physiological maturity (DOPM) and it
is expressed as sum of daily mean temperature during particular period
of crop growth. High temperature decreased functioning of various
physiological parameters of the plants such as chlorophyll, chlorophyll
fluorescence, chlorophyll stability index, membrane thermostability,
osmotic potential and dry matter accumulation in grains. The
detrimental effect of high temperature on various grain yield and
quality characteristics such as grain shriveling score, grain hardness,
grain weight/spike, grain number, test weight (1000-grains weight),
β-carotene and total protein were also reflected. However,
sedimentation value increased under high temperature treatment.
Besides these, biochemical parameters such as total soluble sugars,
reducing sugars, non-reducing sugars, protein, sucrose, starch and
amylopectin were also reduced under high temperature stress except
amylose. The enzymes and metabolites involved in starch biosynthesis
also declined under high temperature treatment. Among enzymes,
soluble starch synthase activity was reduced maximum as compared to
other enzymes activities and among metabolites, ADP-glucose and
UDP-glucose reduced maximum than other metabolites under high
temperature stress.
Results of present experiment show that variety WH 896 is more
tolerant to heat stress than WH 912 in manners of various
physiological, biochemical and quality characteristics parameters when
they were exposed to same degree of high temperature stress
Description
Keywords
High temperature, Durum wheat, Starch metabolism, End use quality