干旱区生态环境知识资源中心

High salinity and drought are common environmental problems affecting seed germination and plant growth especially in arid and semi-arid regions. Sesame (Sesamum indicum L.) is an oilseed crop rated moderately salt and drought tolerant but it is sensitive at germination and seedling stages. The effect of salt stress (NaCl) and water stress (PEG-6000), using the same osmotic potential (0 to -1.4 MPa), on germination and early seedling growth of sesame genotypes with different color seeds was studied. Germination percentage (GP), germination rate (GR), mean germination time (MGT), root length (RL) and shoot length (SL) were investigated. Drought and salt stresses, seed color and interaction of each stress with seed color had a significant effect on all studied parameters (P < 0.01). Yellow and brown seeds exhibited higher GP and GR and lower MGT than white and black seeds in absence and presence of both stresses. Germination was reduced and delayed by both stresses. However, it continued at all concentrations of NaCl, while it ceased at -1.0 MPa of PEG. Reduction in GP and GR was gradual for yellow and brown seeds and drastic for white and black ones, already from -0.2 MPa of PEG and NaCl. At equivalent osmotic potential, salt stress had a lower inhibitory effect on germination and seedling growth than drought stress. For Moroccan cultivars, having yellow and brown seeds, seedling growth was more affected by both stresses than seed germination, thus RL and SL could be taken as selection criteria for drought and salt tolerance at early growth stages. Sesame cultivars having intermediate seed colors (brown and yellow) could be recommended for moderate saline soils. (C) 2016 Friends Science Publishers