Effects of seed treatments (priming) on germination characteristics and seedling development of certain leguminous forage crops under salt and drought stress

This study was carried out in order to determine the effects of osmopriming treatments at different doses and durations on germination characteristics and seedling development of certain leguminous forage crop seeds under different drought and salinity stress. The studies were carried out at the Akdeniz University, Faculty of Agriculture, Department of Field Crops. Priming treatments, germination, and seedling development were carried out in a germination cabinet in a laboratory condition. The experiments were established in according to the complete randomized block design with three replications. In this study, alfalfa (Medicago sativa), birds foot trefoil (Lotus corniculatus), red clover (Trifolium pratense), white clover (Trifolium repens), sainfoin (Onobrychis viciifolia), common vetch (Vicia sativa), Hungarian vetch (Vicia pannonica), narbon vetch (Vicia narbonensis), grass pea (Lathyrus sativus) and forage pea (Pisum sativum ssp. arvense), which are Leguminous forage crop species, were used as plant material. Seeds of these species were primed in 0,0 MPa, -0,5 MPa, -1,0 MPa, -1,5 MPa ve -2,0 MPa osmotic potentials for 6, 12, 24 and 48 hours. Priming treatments were carried out at 20 oC and 75 % relative humidity and dark conditions. For salt stress testing, the seeds were germinated in saline germination media with EC values of 0, 4, 8, 12 and 16 dS / m. For drought stress, the seeds were tested in germination environments with osmotic potential of 0,0 MPa, -0,5 MPa, -1,0 MPa, -1,5 MPa and -2,0 MPa. The germination and seedling development experiments were carried out at 20 oC, 75% relative humidity and 14/10 light/dark photoperiod. The germinated seeds were counted and recorded every 24 hours for 7 days. In this study, germination percentage (%) and mean germination time (day) were determined for germination characteristics and root-shoot lengths (mm), root-shoot fresh and dry weights (mg/seedling) were measured to determine seedling growth. In addition, vigour index was calculated in germinated seeds. According to the results of the experiment, it was determined that the examined traits were significantly affected by the priming dose, priming duration and stress factors (salinity and drought levels) and factor interactions. Under the both salinity and drought stress conditions, germination rate reduced, germination time was elongated and seedling development decreased by increasing stress levels. According to the results of priming applications, it was determined that priming treatments carried out in from -0,5 MPa to -1,5 MPa osmotic potentials for 6 and 12 hours duration alleviate the adverse effects of salt stress. On the other hand, in drought stress aplications, priming treatments were found to be ineffective in mitigating the adverse effects of drought stress in germination environments with osmotic potentials lower than -0,5 MPa. However, it was found that priming treatment at -0,5 MPa osmotic potential for 24 hours in common vetch seeds mitigate the adverse effects of drought stress created by -0,5 MPa osmotic potential.