Morphophysiological responses of senna (Cassia angustifolia vahl.) to salinity
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Date
2010
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Publisher
CCSHAU
Abstract
Senna (Cassia angustifolia Vahl.) is a perennial, under shrub of varied medicinal value
belonging to family caesalpiniaceae. It is commercially cultivated in Tamilnadu and its leaves and pods
are medicinally important. In the present investigation germination, growth, reproductive yield and
biochemical responses of Senna were studied under the influence of soil salinity viz. chloride
dominated and sulphate dominated salinity. Two experiment were planned to achieve objectives of
present study. In the first experiment seed were germianted in petridishes at varying EC levels viz. 0, 4,
6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26 and 28 dSm-1 of Cl- dominated and SO42- dominated salinity.
Results revealed that the progressive increase of EC levels not only inhibited the seed germination but
also declined the speed of germination. Both salinity types proved deleterious to Senna seedlings as
they decreased the seedling length, vigour index, fresh & dry weight and relative water content of
seedling. Sulphate dominated salinity was found most detrimental to seedlings than chloride dominated
salinity
In the second experiment plants were raised by sowing seeds in dune sand filled polythene
bags, in a screen house at varying EC levels viz. 0, 4,8,12 and 16 dSm-1 of Cl- dominated and SO42-
dominated salinity along with nutrients. Results revealed a significant reduction in growth attributes
such plant height, number of leaves per plant, leaf dry weight and stem and branches dry weight per
plant at vegetative, maximum flowering and pod maturity stages with the build up of salinity in the
growing medium. Relatively higher reductions were noticed under SO42- dominated salinity. Both root
volume and root dry weight per plant significantly declined with the increase of salinity at the
vegetative, maximum flowering stages. There was more declined under sulphate dominated salinity. A
slight promotion in these growth attributes, however, was observed at the pod maturity stage upto 8
dSm-1 EC level of sulphate dominated salinity. Root/shoot ratio was found to increase with the of
salinity at the vegetative and pod maturity stages. Increase of root /shoot ratio was more prominent
under sulphate dominated salinity indicating that shoot growth was more adversely affected by sulphate
dominated salinity as compared to chloride dominated salinity. Both the flower initiation and pod
maturity were observed to be delayed by increase of salinity in the growing medium. The delay in
flower initiation was relatively more under sulphate dominated salinity. Build up of salinity irrespective
of salinity type, in the growing medium was found deleterious to reporudctive yield attributes such as
number of pods per plant, pod dry weight per plant, number of seeds per pod, 100-seed weight and seed
yield per plant. Significant changes in various biochemicals were also recorded. Accumulation of both
total soluble carbohydrates and proline was recorded with the increase of salinity. Relatively higher
accumulation of proline was observed under SO42- dominated salinity. The results demonstrated that
inspite of better osmotic adjustment under sulphate dominated salinity treatments, the sulphate ions
were more deleterious to the plants as compared to chloride ions.
Chl “a”, chl “b” and total chlorophyll contents undergone more reduction under sulphate
dominated salinity. Na+,Cl- and SO42- increased while K+ decreased with increasing EC levels.
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Keywords
Planting, Inorganic acid salts, Developmental stages, Food preservation, Biological development, Vegetative propagation, Germinability, Drying, Sowing, Tolerance