Effects of temperature and salinity on the germination of Puccinellia ciliata (Bor) cv. Menemen

Abstract

Puccinecia ciliata is a salt-tolerant, winter-growing grass. The responses of germination of P. ciliata to salinity and temperature were investigated. With a day/night temperature regime of 25/15¦C, the final germination percentage of P. ciliata in distilled water was 54%, and was not significantly affected by salinities up to 87 mol m NaCl (osmotic potential, =, -0.4 MPa), but decreased to 5.2% in 260 mol m-3 NaCl (=, -1.2 MPa). The n at which the final germination percentage was reduced by 5O0/n of that in distilled water was about -0.5 MPa, which was similar to that of Lolium perenne. However, for L. perenne, the final germination percentage decreased more rapidly with increasing salinity and from a higher value in distilled water (97%) compared with P. ciliata. Germination of P. ciliata was completely inhibited at constant 33¦C and was low (<20%) where day temperature was 30¦C and night temperature was greater than or equal to 17¦C. Maximum germination was observed where day and night temperatures were between 17 and 24¦C, but were not equal. The rate of germination decreased with increasing salinity and was maximal at temperatures between 17¦C and 24¦C. The reduction in the final germination percentage in NaCl solution was apparently an osmotic effect since the final germination percentage in iso-osmotic solutions of mannitol, polyethylene glycol, NaCl, KC1 and KNO3 were similar. P. ciliala and L. perenne were more salt sensitive during germination than during early seedling growth; for 35-day-old seedlings, shoot dry weight was reduced by 50% of that of the nonsaline treatment when irrigated with solution with = of -0.75 MPa for L. perenne and - 1.25 MPa for P. ciliala.