Studies on the sensitivity of some species and cultivars of lawn grasses on salinity with sodium chloride during the seed germination and first year of growth

In the years 2005 - 2006 studies were conducted in a growth chamber and a vegetation hall which compared tolerance to NaCl salinity of seeds and plants of some lawn grasses. The effect of sodium chloride salinity on the germination of 4 species of grasses i.e. Lolium perenne cv. ‘Info’, Festuca rubra cv. ‘Audio’, Agrostis capillaris cv. ‘Niwa’, Poa pratensis cv. ‘Alicja’ and 4 cultivars of Lolium prenne - ‘Nira’, ‘Stadion’, ‘Ronija’, ‘Darius’ was studied. The grass seeds germinated in Petri dishes, in darkness, at the temperature of 24°C. Besides the control, 3 levels of salinity were used in the studies: 100, 200 and 300 mM NaCl. The obtained results demonstrated that the growing level of salinity in the environment significantly decreased the germinating speed, the number of the produced roots, the length of the longest root, and the length of the coleoptile in the seedlings of all studied grass species. Lolium perenne seeds tolerated salinity the best, and next - in a diminishing sequence - those were the seeds of Festuca rubra, Agrostis capillaris and Poa pratensis. However, the obtained data showed that tolerance to salinity of the analyzed cultivars of Lolium prenne decreased in the following sequence ‘Ronija’ > ‘Stadion’ > ‘Nira’ > ‘Darius’.

In a vegetation hall tolerance to NaCl salinity of these 4 cultivars of Lolium perenne in the first year growth was compared. The plants grew in pots of 2 dm³ filled with a mixture of universal earth and river sand (3:1 / v:v) with the soil moisture of 70% and 3 levels of salinity: 0, 50, and 100 mM NaCl. The obtained results demonstrated that in all studied cultivars the increase of the salinity level caused a significant decrease of the yield of the leaf dry weight from the successive grass crops, and an increase of the content of sodium, chloride and free proline in them. The greatest tolerance to NaCl salinity in the group of the studied cultivars was shown by ‘Ronija’, medium tolerance - by ‘Darius’ and ‘Stadion’, and the lowest one - by ‘Nira’. This resulted from the degree of accumulation of Na⁺ and Cl^- ions and proline in those conditions. The cultivars with higher tolerance accumulated fewer osmotically active compounds in the leaves.