COMPARATIVE EFFECTS OF NACL AND POLYETHYLENE GLYCOL ON GERMINATION, EMERGENCE AND SEEDLING GROWTH ON TWO CULTIVARS OF TOMATO (LYCOPERSICUM ESCULENTUM MIL.)Mohamad Forouzandeh and Somayyeh Mirshekari
The effects of salt and drought stresses at the water potentials of 0, -2, -4, -6 and -8 bars induced by NaCl and PEG 6000 (polyethylene glycol 6000) each, on germination and early seedling growth, were investigated for 2 tomato cultivars (Super CH and Native Khorasan). Electrical conductivity (EC) values of the NaCl solutions were 4.5, 8.8, 12.7 and 16.3 ds m-1. Germination percentage, Germination rate, root and shoot length, seedling fresh and dry weight and Radicle fresh and dry weight were measured in the study. The objective was to determine genotypic differences among tomato cultivars in terms of salt and drought stress and to determine factors (salt toxicity or osmotic stress due to PEG) inhibiting seed germination. The germination results revealed that the genotypes significantly differed for salt and drought stress. Native cultivar gave higher values under drought stress, but Super CH appeared to be more tolerant to salt stress. Both NaCl and PEG inhibited germination and seedling growth in cultivars, but the effects of PEG compared to NaCl were less on germination and seedling growth. Tow cultivars were able to germinate at all NaCl levels with a significant decrease in germination, while a drastic decrease in germination was recorded at -8 bars of NaCl. It was concluded that inhibition in germination at equivalent water potentials of NaCl and PEG was mainly due to a salt toxicity rather than osmotic effect.
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