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2 Acta Physiologiae Plantarum

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Leaf structural modification for drought tolerance in some differentially adapted ecotypes of blue panic (Panicum antidotale Retz.)

100%

Hameed M. , Batool S. , Naz N. , Nawaz T. , Ashraf M.

2012

tom 34

nr 4

Some ecologically different ecotypes of Panicum antidotale Retz. were evaluated for drought tolerance in relation to growth parameters and leaf structural modifications. These ecotypes were adapted to normal nonstressed (agricultural field AF, and sludge of disposal channel SDC), drought-stressed (along roadside AR), salinity-stressed (forest plantation FP), waterlogging and salinity-stressed (inside disposal channel IDC), and drought plus salinity-stressed (barren area BA). On the basis of genetic variability in leaf structural modifications, each ecotype adopted specific strategies to tolerate the extremity of drought stress. The AF and SDC ecotypes relied on water conservation and survival rather than growth and structural modifications by developing epidermis and sclerenchyma on both leaf surfaces. The AR developed xerophytic foliar characteristics in addition to maintaining growth and development under stressed conditions like thick leaves, well-developed bulliform cells, and intensive sclerification. The FP ecotype developed efficient strategy for drought tolerance such as reduced and fibrous leaves, smaller metaxylem vessels, and highly developed bulliform cells. The ecotype IDC relied more on water conservation by increasing leaf epidermal thickness and decreasing stomatal area and density. The ecotype BA showed critical structural adaptations such as thin leaves, extremely developed bulliform and reduced metaxylem area, and parenchyma extensions above vascular bundles. Based on the strategies adopted for drought tolerance, the tolerance level of these ecotypes were rated as BA > AR > FP > IDC > SDC > AF.

Morpho-anatomical and physiological attributes for salt tolerance in sewan grass (Lasiurus scindicus Henr.) from Cholistan Desert, Pakistan

86%

Naz N. , Rafique T. , Hameed M. , Ashraf M. , Batool R. , Fatima S.

Acta Physiologiae Plantarum

2014

tom 36

nr 11

Three differently adapted populations of sewan grass (Lasiurus scindicus Henr.) were evaluated for structural and functional adaptations to high salinity. The habitats were Derawar Fort (DF, least saline, ECe 15.21), Bailahwala Dahar (BD, moderately saline, ECe 27.56 dS m⁻¹) and Ladam Sir (LS, highly saline, ECe 39.18 dS m⁻¹) from within the Cholistan Desert. The adaptive components of salt tolerance in sewan grass were assessed by determining various morpho–anatomical and physiological attributes. The degree of salt tolerance of all three ecotypes of L. scindicus from the saline habitats was compared in a controlled hydroponic system to evaluate the adaptive components that are expected to be genetically fixed during a long evolutionary process. Salinity tolerance in the most tolerant LS population relied on increased root length and total leaf area, restricted uptake of toxic Cl⁻, increased uptake of Ca²⁺, high excretion of Na⁺, accumulation of organic osmolytes, high water use efficiency, increased root, thicker leaf and cortical region, intensive sclerification, large metaxylem vessels, and dense pubescence on abaxial leaf surface. The BD population (from moderately saline soil) relied on high Ca²⁺ uptake, Na⁺ excretion, epidermal thickness, large cortical cells, thick endodermis and large vascular tissue. The DF population (from less saline soil) showed a significant decrease in all morphological characteristics; however, it accumulated organic osmolytes for its survival under high salinities. Structural modifications in all three populations were crucial for checking undue water loss under physiological stress that is caused by high amounts of soluble salts in the soil.