Abstract
The response of twelve rice varieties against six salinity levels (0, 4, 8, 12, 16 and 20 dS m-1) were studied at germination and early seedling stages. Data were analyzed using SAS and means were separated by LSD for final germination percentage (FGP), speed of germination (SG), germination energy percentage (GE%), plumule and radical length and plumule and radical dry weight. Based on dry matter yield reduction, rice varieties were classified as tolerant (T), moderately tolerant (MT), moderately susceptible (MS) or susceptible (S). Germination was completely arrested at 20 dS m-1 salt concentration. Salinity decreased FGP, SG, GE % and led to reduction in shoot and root length and dry weight in all varieties and the magnitude of reduction increased with increasing salinity stress. Rice varieties MR211, IR20, BR40 and MR232 showed greater salt tolerance during germination (germinated at 12 dS m-1 salinity). However, MR211, MR232 and IR20 performed better based on dry matter yield reduction. The result suggested that MR211, MR232 and IR20 might be used for further study of salinity effect on growth processes and physiological consequences at advanced stage of growth, since salt tolerance of a crop at germination and early seedling stage may not correspond to that at advanced stage. Key words: Germination, seedling, rice, salinity stress, NaCl.
Highlights
Crops are often exposed to salinity immediately after planting in saline soil or in areas inundated by sea water or irrigated with brackish water
The result suggested that MR211, MR232 and IR20 might be used for further study of salinity effect on growth processes and physiological consequences at advanced stage of growth, since salt tolerance of a crop at germination and early seedling stage may not correspond to that at advanced stage
At the salinity level of 4 dS m-1, a higher germination percentage of more than 90% was observed from the varieties MR52 and MR 211, which were statistically similar with four other varieties MR219, MR232, BR40 and salt tolerant check ‘Pokkali’
Summary
Crops are often exposed to salinity immediately after planting in saline soil or in areas inundated by sea water or irrigated with brackish water. The major inhibitory effect of salinity on plant growth and development has been attributed to osmotic inhibition of water availability as well as the toxic effect of salt ions responsible for salinization. The global extent of primary salt-affected soils is about 955 M ha, while secondary salinization affected some 77 M ha, with 50% of these in irrigated areas (Metternichi and Zinck, 2003). In arid and semi arid regions, limited water and hot dry climates frequently cause salinity problem that limit or prevent crop production. Khan et al (1997) observed that rice varieties showed a great variation in germination due to salinity effect It has been reported that under saline conditions, germination ability of seeds differ from one crop to another and even a significant variation is observed amongst the different varieties of the same crop (Asana and Kale, 1965, Maas and Hoffman, 1977). Khan et al (1997) observed that rice varieties showed a great variation in germination due to salinity effect
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