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Physiological and genetic deciphering of water, salinity and relative humidity stress in chickpea (Cicer arietinum L.)

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Relation http://oar.icrisat.org/9117/
 
Title Physiological and genetic deciphering of water,
salinity and relative humidity stress in chickpea
(Cicer arietinum L.)
 
Creator Pushpavalli, R
 
Subject Chickpea
 
Description Chickpea (Cicer arietinum L.), an important cool-season, food legume
crop, is known to be sensitive to several abiotic stresses: drought, salinity
and heat. The yield losses caused by these stresses are accounted to 6.4
million tonnes (t)/ year on global production. To improve any existing
cultivar and harness the genetic regions involved in the tolerance it is
important to understand the genetic and physiological mechanisms that
underlie any tolerance. The objectives of this study were to (i)
understanding the effect of either water deficit or salt stress on the
reproductive biology of genotypes know to contrast for either salt or
drought stress and (ii) construction of genetic map and identification of
QTLs and candidate genes for salinity tolerance in 188 RILs derived from
the ICCV 2 × JG 11 cross.
In the water deficit study conducted in two consecutive years, ten
genotypes with contrasting yields under terminal drought stress in the
field were exposed to a gradual, but similar, water stress in the
glasshouse. Nine parameters related to yield were recorded in wellwatered
plants (WW) and in water-stressed plants (WS) when the level of
deficit was mild (phase I), and when the stress was severe (phase II). The
WS treatment reduced seed yield, seed and pod number, but not flower +
pod + seed abortion percentage or 100-seed weight. The controlled
drought imposition in glass house conditions revealed genotypic
differences inthe sensitivity of the reproductive process to drought. The
seed yield differences in chickpea were largely related to the capacity to
produce a large number of flowers and to set seeds, especially when the
degree of water deficit was mild.
In the salinity experiments, fourteen genotypes of chickpea (Cicer
arietinum L.) were used to study yield parameters, and eight genotypes
were selected for ion analysis after being grown in soil treated with 0 mM
and 80 mM NaCl, to assess any possible relationship between salt ion
accumulation in different plant tissues and yield reduction. Salinity
delayed flowering and the delay was greater in sensitive than tolerant
genotypes under salt stress. Filled pod and seed numbers, but not seed
size, were associated with seed yield in saline conditions, suggesting that
salinity impaired reproductive success more in sensitive than tolerant
lines. The delay in flowering was associated with higher concentrations of
Na+ in the laminae of fully expanded young leaves (R2=0.61) and old
green leaves (R2=0.51). Na+ accumulation in leaves was associated with
delayed flowering that in turn could have played a role of the lower
reproductive success in the sensitive lines.
In QTL mapping for salinity tolerance, yield and components were
assessed in 188 recombinant inbred lines (RILs) derived from cross ICCV
2 × JG 11, in soil treated with either 0 mM NaCl (control) or 80 mM NaCl
(salinity) over two consecutive years. Salinity significantly (P
 
Date 2015
 
Type Thesis
NonPeerReviewed
 
Format application/pdf
 
Language en
 
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Identifier http://oar.icrisat.org/9117/1/Pushpavalli-%20PhD%20thesis.pdf
Pushpavalli, R (2015) Physiological and genetic deciphering of water, salinity and relative humidity stress in chickpea (Cicer arietinum L.). PhD thesis, Bharathidasan University,Tiruchirappalli, Tamil Nadu.