Studies on morphological and physiological parameters of subtropical ornamental trees under salt stress
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Date
2017
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Punjab Agricultural University, Ludhiana
Abstract
The present investigations entitled “Studied on morphological and physiological parameters of
subtropical ornamental trees under salt stress” were undertaken at Landscape Nursery, Department of
Floriculture and Landscaping, Punjab Agricultural University, Ludhiana, during 2015-17 to screen
ornamental tree species for salt affected areas of Punjab. One year old seedlings of ten tree species
were grown in 10” earthen pots containing soil: FYM (2:1) during first week of April 2015. After one
month of transplanting, different concentrations of NaCl viz., 0, 30, 40, 50 and 60 mM were given with
irrigation water from May 2015 to October 2015. From November 2015, the doses of NaCl were
further enhanced to 0, 30, 60, 90, 120 mM as 100 % survival was observed in all the tree species. All
the parameters were recorded at three month interval. The salt treatments significantly (p<0.05)
affected the morphological and physiological parameters of ornamental tree species. On the basis of
investigations, the tree species were categorized as salt tolerant and salt sensitive. Salt tolerant trees
include Casuarina equisetifolia, Pongamia pinnata, Callistemon lanceolatus, Acacia auriculiformis
and Cassia fistula, whereas, salt sensitive include Putranjiva roxburghii, Millettia ovalifolia,
Koelreutaria paniculata, Ficus benjamina and Bauhinia purpurea. The growth parameters slightly
increased or maintained in tolerant trees, whereas in salt sensitive trees, growth parameters decreased
with an increase in salt concentration during October 2015. The maximum per cent increase in plant
height (24.26 %), number of branches (14.21 %), total chlorophyll (31.25 %), carotenoid (16.66 %),
proline (20.51 %), total soluble proteins (6.49 %), RLWC (7.11 %) and starch content (14.01 %) was
recorded in C. equisetifolia at 60 mM NaCl, whereas, during April 2017, minimum per cent decrease in
plant height (13.99 %), chlorophyll content (23.68 %), carotenoid (36 %), electrolyte leakage (8.10 %)
and starch content (49.68 %) was also observed in the same species at 120 mM NaCl. During April
2017, the minimum per cent decrease in the number of leaves (63.98%) and RLWC (9.12 %) was
found in P. pinnata at 120 mM NaCl. The maximum per cent increase in proline content (21.56 %),
total soluble sugars (46.01 %) and protein content (25.64 %), during April 2017 was recorded in C.
equisetifolia. The maximum total chlorophyll, carotenoid, proteins, RLWC, starch and minimum
proline, electrolyte leakage and soluble sugars was observed during rainy season. Osmolyte
concentration was more during January. As the level of NaCl in soil increased, EC also increased. It is
difficult to maintain the EC during rainy season as due to dilution effect as well as leaching of salts,
consequently resulted in reduced level of EC. On the basis of the morphological and physiological
parameters evaluated, the sequence for salt tolerance is C. equisetifolia > P. pinnata > C. lanceolatus >
A. auriculiformis > P. roxburghii > M. ovalifolia > C. fistula > K. paniculata > F. benjamina > B.
purpurea.
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