Changes in germination and growth indices of borage (Borago officinalis L.) in response to seed priming and different irrigation intervals

In order to evaluate seed germination, seedling emergence and changes in growth indices of borage in response to seed priming and water limitation, laboratory tests were laid out as completely randomized design with four replicates and field experiment was carried out as split plot based on randomized complete block design with three replications in 2012. 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 (P0: unprimed, P1: hydro-priming, P2: priming with 100 mM KNO3, P3: priming with 100 mM KH2PO4 for 8 h at 15±1°C) were allocated to main and sub plots, respectively. Results indicated that seed hydro-priming increased germination rate and seedling dry weight of borage by 15.9% and 22.6%, respectively. Emergence rate of borage seedlings was also improved about 7% under different seed treatments. At vegetative stage, leaf area index of plants from seeds primed with water, KNO3 and KH2PO4 was 22.8, 39.7 and 16.1% higher than that of unprimed seeds. At flowering stage, water loss of the plants decreased under water deficit conditions by reducing the leaf area index. All priming techniques, especially hydro-priming, improved leaf area index, particularly under well watering, through increasing seedling emergence rate. Dry matter accumulation, relative growth rate and crop growth rate decreased with increasing irrigation intervals. However, growth duration of plants from primed seeds was longer than those from unprimed seeds, leading to the production of larger plants under well watering.