Salt Tolerance Of Some Potential Forage Grasses From Cholistan Desert Of Pakistan

Abstract

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 . Shoot biomass production in Leptochloa fusca and Puccinellia distans was not affected by any of the salinity levels and these grasses had greater shoot fresh and dry matter than the other species at all salinity treatments. Pennisetum divisum was the worst affected, whereas Cenchrus pennesetiformis and Panicum turgidum were intermediate in biomass production. Every species showed a specific accumulation pattern for different ions (Na + , Cl-, K + and Ca 2+ ) in the shoots or roots. Levels of leaf monosaccharides (glucose + fructose) were similar in Cenchrus pennesetiformis and Panicum turgidum under both control and salt treatments. Leptochloa fusca accumulated lesser amounts of monosaccharides, although its monosaccharides doubled in the salt treatment. Disaccharides (sucrose), in the leaves of Cenchrus pennesetiformis, decreased markedly due to the addition of salts in the rooting medium. Trisaccharides (raffinose) were very low in relation to monosaccharides and disaccharides. In another experiment six accessions of Panicum antidotale, eight of Cenchrus ciliaris and one of Lasiurus scindicus from Cholistan were examined for salinity tolerance under five NaCl levels viz. 1.25 (control), 10, 15, 20 and 25 dS m -1 . Although significant reduction in growth attributes of all accessions was recorded, accessions KS 1/2 and Local-2 of Cenchrus ciliaris, LS 3/6 of Lasiurus scindicus, and KS 1/1 of Panicum antidotale were superior to the other accessions in all growt...

Soil salinity as a selection pressure is a key determinant for the evolution of salt tolerance in Blue Panicgrass (Panicum antidotale Retz.)

“…Previous studies suggest that plants with better stress tolerance have developed mechanisms to avoid fluctuations in their water potential in order to maintain growth under stressful environments (Ashraf, 2003(Ashraf, , 2004Koyro, 2006). This maintenance is usually brought about by the synthesis of compatible solutes, some of them may be osmoprotectants like glycinebetaine and proline (Abdel-Aziz and Reda, 2000;Ahmad et al, 2007;Ashraf and Foolad, 2007;Ashraf et al, 2006;Moghaieb et al, 2004). In the present study, the populations from highly saline environments (P1 and P2) had the highest degree of osmotic adjustment as compared to those from mild (P3 and P4) or non-saline (P5 and P6) environments (Fig.…”

“…3d). High osmotic adjustment in the salt-tolerant populations can be related to their higher accumulation of glycinebetaine (GB), proline as well as total soluble sugars and proteins (Ashraf and Foolad, 2007;Ashraf et al, 2006;Moghaieb et al, 2004).…”

“…Under this situation, exploration and cultivation of tolerant species offer a more practical solution for effective utilization of affected soils. Species found growing on natural saline habitats possess genetic variation, which is the basis of the evolution of salt-tolerant populations in response to the selection pressure of the habitats (Al Sherif, 2009;Ashraf et al, 2006;Nedjimi, 2009). However, the presence of appropriate genetic variation in the gene pool of a species and the occurrence of appropriate natural selection must interact determining the evolution of a particular character.…”

A critical review on halophytes: Salt tolerant plants

“…According to him salt marsh halophytes can be divided into two main types that is, salt regulating types and salt accumulating types. Halophytes are also classified as excluders versus includers on the basis of internal salt contents of the plant (Ashraf et al, 2006).…”

“…Such type of strategy may involve certain physiological or biochemical adaptations in the plants, which help the plant to maintain protoplasmic viability as the ions accumulate inside the cells (Sabovljevic and Sabovljevic, 2007). Salt tolerance can be achieved either by salt exclusion or salt inclusion; salt tolerant organisms utilize the energy for the exclusion of excess salt from them so as to protect themselves from toxic effects of high salt content of the soil as for example protein aggregation etc (Ashraf et al, 2006).…”