Seed priming and field performance of borage (Borago officinalis L.) under different irrigation treatments.

Among the different environmental constraints, drought is the most limiting factor for plant productivity. Seed priming may improve plant performance under adverse environmental conditions. Thus, an experiment was conducted in 2012 to investigate field performance of borage in response to seed priming and water limitation. Irrigation treatments (I1, I2, I3 and I4: irrigation after 60, 90, 120 and 150 mm evaporation from class A pan, respectively) and seed priming methods [P1 (unprimed), P2 (hydro-priming), P3 (salt-priming with 1% KNO3) and P4 (salt-priming with 1% KH2PO4) for 8 h at 15±1oC] were allocated to main and sub plots, respectively. Percentage ground cover (PGC) under I1 and I2 was considerably higher than that under I3 and I4. PGC slightly improved as a result of seed priming, particularly hydropriming. Decreasing water supply led to 5-34.7 % reduction in biological yield and 34.3-57.3 % reduction in grain yield. Harvest index under severe water deficit (I4) was 34.2 % less than that under well irrigation (I1). The highest and the lowest harvest indices were recorded for P2 and P1 plants. Grain yield of plants from primed seeds was 22.5-60.1% higher than that of control (P1). Improvement in grain yield of plants from primed seeds was attributed to higher ground green cover of these plants, compared with those from unprimed seeds.