104(1)_str10

 

ISSN 1392-3196 / e-ISSN 2335-8947
Zemdirbyste-Agriculture, vol. 104, No. 1 (2017), p. 71–78
DOI  10.13080/z-a.2017.104.010

The sensitivity of Lolium perenne and Poa pratensis to salinity and drought during the seed germination and under different photoperiod conditions

Barbara BORAWSKA-JARMUŁOWICZ, Grażyna MASTALERCZUK, Dariusz GOZDOWSKI, Elżbieta MAŁUSZYŃSKA, Anna SZYDŁOWSKA

Abstract

Salinity and drought are the main factors limiting the germination of seeds and development of lawn grasses. The study, carried out in controlled conditions, explored the effects of salt and drought stress as well as photoperiod on germination and morphological traits of seedlings of perennial ryegrass (Lolium perenne L.) and Kentucky bluegrass (Poa pratensis L.) lawn varieties. Germination capacity and mean germination time of seeds as well as the length and dry mass of shoots and roots of seedlings were determined. The germination of seeds was conducted on three levels of sodium chloride (NaCl) salinity (0, 100 and 200 mM) and four levels of drought stress using polyethylene glycol (PEG) solutions (0, −0.3, −0.6 and –1.2 MPa) in different photoperiod (0, 8 and 12 h of light) and temperature conditions (constant 25°C and variable 30/20°C). The obtained results showed that salinity decreased the germination capacity, the length of seedling shoots and roots, number of roots and dry mass of shoots and increased mean germination time (MGT) of seeds, especially of P. pratensis varieties. Drought stress increased mean germination time and limited germination capacity, shoot and root length and dry mass of L. perenne varieties only under the highest −1.2 MPa level, whereas P. pratensis – even at −0.3 MPa. In the conditions of salinity and simulated drought, germination capacity, shoot and root length and the mass of shoots of L. perenne and P. pratensis seedlings were closely correlated to each other. The results of this study indicate that germination capacity of P. pratensis varieties was modified by light duration. This species proved to be intolerant of lack of light during seed germination, while L. perenne varieties showed tolerance to photoperiod in this stage.

Key words: drought tolerance, gravimetric parameters, Kentucky bluegrass, lawn grasses, morphological parameters, NaCl, perennial ryegrass, photoperiod, polyethylene glycol.

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