Effects of salinity on germination of six salt-tolerant forage species and their recovery from saline conditions

Seed germination of six forage species under salt stress and their recovery response from saline conditions were studied. The forage species studied were Bromus inermis, Elytrigia elongata, Puccinellia tenuiflora, Hordeum brevisubulatum, Kalidium gracile, and Suaeda salsa. All of these plants are important forage plants in the inland areas of northern China. Seeds were germinated in solutions of 0, 21, 66, 110, 155, 200, 267, 334, 445 mmol/litre NaCl. After a 21-day period, the ungerminated seeds were removed to Hoagland solution to observe the recovery germination, radicle, and shoot length. The percentage germination of all the species tested, except E. elongata, significantly decreased with increasing salinity (P < 0.01). The lengths of radicles and shoots were increased at 21 mmol/litre NaCl as compared with that in the control, except for S. salsa. Recovery germination and length of radicles and shoots in Hoagland solution increased with increasing salinity in treatment solutions. The recovery germination performances of the six species indicated that inhibition of germination under NaCl stress was induced by osmotic effects. Shoot growth of P. tenuiflora had the highest tolerance to NaCl stress, which suggests why it is the most widely used plant species for saline soil rehabilitation in northern China. The evaluation of salt tolerance in the early stage of growth should emphasise the response of germination and shoot or radicle growth under salt stress.