Mansoor Hameed

Anatomical adaptations to salinity in cogon grass [Imperata cylindrica (L.) Raeuschel] from the Salt Range, Pakistan

To examine anatomical adaptations in a potential forage grass, Imperata cylindrica (L.) Raeuschel, a population was collected from the natural salt-affected soils of the Salt Range, Pakistan. Using a hydroponic system, the degree of salt tolerance in terms of structural modifications in the Salt Range ecotype was compared with that in an ecotype collected from a normal non-saline habitat of the Faisalabad region. The Salt Range ecotype was superior to the Faisalabad ecotype in biomass production under saline conditions. High salt tolerance of the Salt Range ecotype was associated with increased succulence in root and leaf (mainly midrib), formation of aerenchyma in leaf sheath, increased vascular bundle area, metaxylem area and phloem area, highly developed bulliform cells on leaves and increased sclerification in root and leaf. Furthermore, both stomatal density and stomatal area were considerably reduced under high salinities in the Salt Range ecotype.

SALT TOLERANCE OF SOME POTENTIAL FORAGE GRASSES FROM CHOLISTAN DESERT OF PAKISTAN

Cholistan desert located in the southeast of the Punjab province, Pakistan, covering an area of 25,800 km 2 is a part of Greater Thar desert. The soil types characteristically include: sand dunes, sandy soils with patches of non-saline non-sodic loamy soils and sodic clayey soils. Vegetation structure and density are greatly influenced by the rainfall. During low rainfall years even drinking water gets scarce and both the plant and animal communities are adversely affected. Biodiversity assessment survey was carried out during 1997-98. The dominant species of the lesser Cholistan among grasses were Aristida adscensionis, Ochthochloa compressa, Lasiurus scindicus, Cymbopogon jwarancusa, Cenchrus biflorus, Sporobolus ioclados and Aeluropus lagopoides, whereas that of Greater Cholistan Aeluropus lagopoides, Aristida adscensionis, Cenchrus biflorus, Cenchrus pennesetiformis, Cymbopogon jwarancusa, Lasiurus scindicus, Panicum antidotale and Panicum turgidum. Like other deserts, the major problem in the area is the scarcity of good quality water. The subsoil water in most places of Cholistan is brackish and unfit for normal plant growth. It is highly probable that by adopting biological approach the vast area of Cholistan can be economically exploited. Salinity tolerance of four potential forage grass species, Cenchrus pennesetiformis, Panicum turgidum, Pennisetum divisum and Leptochloa fusca, including one highly tolerant exotic grass species Puccinellia distans was assessed after 6 weeks growth at four salinity treatments, 2.4 (control), 8, 16 and 24 dS m -1

Patterns of ion excretion and survival in two stoloniferous arid zone grasses

Desert plants show specific mechanisms to thrive under prevailing harsh conditions. To study the survival mechanism(s) in native desert plant species, Lesser Cholistan desert in Pakistan was surveyed and two potential salt secretory grass species, Aeluropus lagopoides and Ochthochloa compressa, were selected from five saline sites. Both these grasses responded differentially to saline environments by showing specialized mechanisms of survival including excretion of toxic ions through trichomes, vesicular and glandular hairs through leaf surface. In A. lagopoides, salt tolerance was associated with excreted Na(+) concentration through leaf surface and accumulation of useful ions like Ca(2+) and K(+) in the shoot. Contrarily, O. compressa excreted all the ions through leaves without discriminating among toxic or beneficial ions. Results suggested that A. lagopoides was more successfully adapted to saline desert environments than O. compressa by excretion of excessive toxic ions and retention of Ca(2+) and K(+) in the shoot. This appears to be an adaptive character of the former species to successfully thrive in harsh desert conditions.

Relationships between gas-exchange characteristics and stomatal structural modifications in some desert grasses under high salinity

Two populations, one from lesser saline Derawar Fort (DF) and the other from highly saline Ladam Sir (LS) in the Cholistan desert, for each of the five grass species, Aeluropus lagopoides, Cymbopogon jwarancusa, Lasiurus scindicus, Ochthochloa compressa, and Sporobolus ioclados were examined to investigate the influence of salinity on structural and functional characteristics of stomata. Salinity tolerance in A. lagopoides mainly depended on controlled transpiration rate (E) and high water-use efficiency (WUE), which was found to be regulated by fewer and smaller stomata on both leaf surfaces as well as stomatal encryption by epidermal invaginations. C. jwarancusa had sunken stomata on the abaxial surface only, which largely reflected a reduced E, but less affected stomatal conductance (gs) or WUE. L. scindicus had fewer but larger stomata along with hairs/trichomes which may function to avoid water loss through transpiration, and hence, to attain a high WUE. In O. compressa stomata were found only on the abaxial surface and these were completely encrypted by epidermal invaginations as well as a dense covering of microhairs, which was associated with a low E and high WUE under salinity stress. In S. ioclados, the traits of increased stomatal density and decreased stomatal area may be critical for stomatal regulation under salt-prone environments. High stomatal regulation depended largely on stomatal density, area, and degree of encryption under salinity, which is of great ecophysiological significance for plants growing under osmotic stresses.

Anatomical and physiological characteristics relating to ionic relations in some salt tolerant grasses from the Salt Range, Pakistan

Populations of three salt tolerant forage grasses (Cynodon dactylon, Imperata cylindrica, and Sporobolus arabicus) were collected from the salt-affected soils of the Salt Range and normal non-saline soils of the Faisalabad region to assess their mechanism of adaptation to saline stress by determining ion relations and some specific anatomical modifications. The population of S. arabicus from the Salt Range showed increased growth (root and shoot length, and root and shoot dry weights) under saline conditions. Salt tolerance in this species was related to structural modifications such as increased area of root, stem, leaf blade, and leaf sheath for toxic ion accumulation, increased vesicular hair density in leaves and aerenchyma formation in leaf sheath for ion exclusion. Uptake of toxic ions was high in the Salt Range population of C. dactylon and salt tolerance was related to ion exclusion through specific leaf structural modifications such as vesicular hairs. Salt tolerance in the Salt Range population of I. cylindrica was mainly associated with restricted uptake of toxic Na+ and Cl− at root level, and accumulation of toxic ions via increased succulence in leaf blades and leaf sheaths in addition to some excretion of toxic ions through leaf sheath aerenchyma.

Effect of Saccharomyces cerevisiae fermentation on the colorants of heated red beetroot extracts

The quality and flower yield of roses are directly dependent on the balanced application of macro and micronutrients. In the present study, foliar application of macro- and micronutrients was done after every 15 days when new emerging leaves had sprouted after pruning. The results reveal that plants treated with foliar application of micronutrients along with NPK showed significant increase in the growth characteristic like plant height, number of flowers plant-1, bud diameter, flower diameter, fresh and dry weight of flower, flower quality, flower stalk length compared to the application of NPK alone and untreated plants (control). Application of foliar fertilizer (NPK = 15:32:7 + micro power) and NPK (15:32:7) + chelated mix micronutrients gave the highest values compared to the other treatments in both cultivars. Cardinal responded well to micronutrients as compared to Whisky Mac in case of cultivars. Leaf total chlorophyll contents, vase life and the mineral contents (NPK) of leaves were significantly increased as a result of foliar application of micronutrients compared to the control treatment. It was concluded that application of micronutrients along with NPK could improve flower yield and quality of roses. Keywords : Chlorophyll content, NPK percentage, micronutrients, rose African Journal of Biotechnology Vol. 12(7), pp. 702-708

Structural and Functional Adaptations in Plants for Salinity Tolerance

Salt tolerance in plants is a multifarious phenomenon involving a variety of changes at molecular, organelle, cellular, tissue as well as whole plant level. In addition, salt tolerant plants show a range of adaptations not only in morphological or structural features but also in metabolic and physiological processes that enable them to survive under extreme saline environments. Morpho–anatomical adaptations include xeromorphic characteristics like thick epidermis and sclerenchyma, well developed bulliform cells, increased density of trichomes and increased moisture retaining capacity by increasing cell size and vacuolar volume. Development of excretory structures like vesicular hairs and salt glands is another major structural adaptation and very crucial for salt tolerance. Physiological adaptations include restricted toxic ion uptake, increased succulence, osmotic adjustment and exclusion of toxic Na+ and Cl–.

Soil-Plant Relationships in the Arid Saline Desert of Cholistan

The inland vegetation of saline patches in the Cholistan desert faces extreme environmental conditions including predominantly salt stress and limited resource availability. Changes in the salinity gradients may lead to gradual variation in response of individual plant species that ultimately affect community structure and composition. The present study was conducted to determine spatial distribution of individual species along a salinity gradient in the Cholistan desert in relation to their life form and tolerance limits. The results showed variable responses of these species in spatial distribution against the salinity gradient. The plants differed considerably in their tolerance level due to development of differential adaptive strategies under extreme salinities. Excretory species like Aeluropus lagopoides and Sporobolus ioclados dominated the sites with highest salinities along with the leafy succulent Suaeda fruticosa. Stem succulents dominated moderate salinities along with spreading stoloniferous Ochthochloa compressa and tussock grass Cymbopogon jwarancusa. Non-succulent Cressa cretica and tussock grass Lasiurus scindicus were mainly distributed to sites with lower and moderate salinities, while non-succulent plants dominated the lowest salinity site. Of the soil physico-chemical characteristics in the Cholistan desert habitats, salinity may have a direct effect on the life form and survival strategies of occurring plants. Thus, the difference in spatial distribution of individual species along salinity gradients suggested that salinity alone is not a responsible factor to determine community structure, but plant tolerance limits and their life habits are also important.

Structural Features of Some Wheat (Triticum Spp.) Landraces/Cultivars Under Drought and Salt Stress

Seven local landraces of common and durum wheat (Triticum aestivum L. and T. durum L.) from the arid and semi-arid areas of the Sultanate of Oman were examined for specific leaf and stem structural features for water conservation. On the basis of shoot fresh and dry weights (g plant−1), degree of tolerance to drought and salt stresses in these wheat landraces/cultivars can be ranked as S-24 > J-305 > Sarraya > Senain > Cooley > MH-97 > Missani>Hamira > Shwairaa. Modifications related to water conservation were found to be high degree of sclerification, succulence in leaf and stem, low resistance to water conductance in vascular tissue, and pubescence on leaf surface. The salt and drought tolerant cultivar S-24 showed high proportion of chlorenchyma and intensive sclerification in stem structure, and well-developed bulliform cells and dense pubescence on the leaves. These modified features were poorly developed in lesser stress tolerant Omani wheat landraces like Hamira and Shwairaa. Accession Senain also showed stem succulence (solid stem), an important xeromorphic feature. Structural modifications in landrace Missani were found to be increased sclerification in vascular tissue and high number of metaxylem vessels and high proportion of parenchyma in stem, and highly developed bulliform cells in leaf. Overall, the promising anatomical traits in highly stress tolerant landraces/cultivars were chlorenchyma in stem, rigorous sclerification in parenchyma and around vascular tissue, stem and leaf succulence, and enhanced ratio of major conducting tissue.

Modifications in Root and Stem Anatomy for Water Conservation in Some Diverse Blue Panic (Panicum antidotale Retz.) Ecotypes Under Drought Stress

Five ecotypes of Panicum antidotale Retz. adapted to diverse habitats were subjected to drought stress to evaluate their drought tolerance in relation to adaptive anatomical structures. The ecotype from non-stressed habitat had intensive sclerification as well as crystallization in parenchymatous cells, which help prevent water loss. The ecotype from drought-prone habitat had well-developed metaxylem vessel area for better conduction of water and nutrients, and pith area for better storage of water. The ecotype collected from salinity-affected habitat as well as that from saline and waterlogged habitat showed extensive sclerification in the vascular region, which is vital for preventing water loss. The ecotype from a salinity- and drought-prone habitat showed increased metaxylem vessel number and formation of additional metaxylem vessels in the pith region for better conduction, multi-layer exodermis and intensive sclerification for prevention of water loss, and increased parenchymatous region for better storage of water. The most promising anatomical features found in highly drought tolerant ecotypes were increased metaxylem number, multi-layered exodermis, and intensive sclerification in vascular region.