| Effect of salt stress on germination, growth and nutrient
composition of Aegilops and Triticum S.M. ALAM and A.R. AZMI Atomic Energy Agricultural Research Centre Tando Jam, Sind, Pakistan Salinization of soils and water poses a significant threat to many agricultural crops, particularly in arid and semi-arid regions of the world. (BLACK 1968, KRAMER 1983, PAL et al. 1984, RA BIE et al. 1985). Soils in these areas are poorly leached due to the absence of significant rainfall. As more land is brought into crops production through water development, the salinity problem expands. They either already contain high soil concentrations of Na+ and other potentially toxic anions like C1-, SO24-, CO23- and HCO3-, or are going to accumulate these ions due to the combined effects of irrigation practices and high evaporative demand. Poor soil drainage combined with improper irrigation practices contribute significantly to the increasing salinization of the soil (BOHN et al. 1979). Rather than being leached, soluble salts accumulate and attain levels which is inhibitory to crop growth. This situation is aggravated by the increasing burden of salts carried in irrigation water. The problem of salinity has been very widely studied and the results obtained have indicated that while, a number of species respond favourably to different levels of salinity, others are adversely affected. To exploit these regions which are otherwise suitable for cereals production, new cultivars/species are required which are capable of overcoming the deleterious effects imposed by saline conditions. The salt tolerance of crops has gernerally been expressed as the yield decreased expected for a given level of soluble salts in the root medium as compared with yield under nonsaline conditions (MAAS & HOFFMAN, 1977). There are several factors which influence salt tolerance in plants. The most important among these are species, temperature, salt composition, the growth stage of plant, salinity level, environmental variables, soil fertility and cultivars. Under conditions of high salinity, stunted growth, nutrient imbalance and deep bluish green foliage of plants followed by low production are common observations. Thus under saline water cultivation, it is best to grow tolerant crops and their varieties, as most of them, by virtue of their low moisture requirement and higher osmotic pressure, have better tolerance to the conditions. The effect of salinity on the chemical composition of plants and nutrient uptake has also been reported differently. A number of investigators (BALBA 1961, EL-SHOURBAGY & MISSAK 1975, SHIMOSE 1968), demonstrated that nutrient uptake by certain plant species is curtailed by salinization. On the other hand, under certain experimental condition, salinization result in promotion rather than an inhibition of nutrient uptake (ASANA & KALE 1965, MAAS et al. 1972). Little is known about the investigation of salt tolerance potential of Aegilops and Triticum species on the absorption of mineral nutrients. The study of Aegilops and Triticum species with the ability to germinate, emerge and grow rapidly and reliably from salt-afflicted soils has not been widely investigated. The first exposure of the crop to salinity stress would occur at the germination stage and would likely proceed under high surface soil salinities than would be the case for later growth stages. (BERNSTElN & HAYWARD 1958). In the present investigation, an attempt was made to study the effect of different concentrations of NaCl and Na2SO4 applied together on germination and elemental content by Aegilops and Triticum species gwon in Tando Jam, Sind and to identify salt tolerant and salt sensitive Aegilops and Triticum species. |
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