integrative applications of chemical fertilizers and biofertilizers on grain yield and oil of borago officinalis l. under water deficit stress

in order to study the effects of integrative applications of chemical fertilizers and biofertilizers on grain yield and oil of borago officinalis under water deficit stress, a field experiment was conducted at kermanshah, iran, in 2011. experiment was arranged as split plot under a randomized complete block design with 3 replications. water deficit stress with four levels was applied as the main factor by interrupting irrigation once in vegetative stage, reproductive¬ stage, vegetative + reproductive stages and without stress (normal irrigation). fertilizers with three levels including, 100% chemical fertilizer, 50% of chemical fertilizer + biofertilizers, 25% of chemical fertilizer + biofertilizers were allocated to subplots. biofertilizers included nitroxin and biophosphate. results indicated that the interaction effects of treatments had significant effects on most of the plant criteria. integrative applications of chemical fertilizers and biofertilizers under water deficit had significant effects on the maximum of leaf area index, total dry weight, the number of buds in plant, grain yield, and oil yield. the highest value of the 1000 grain yield, number of buds in plant, grain yield, oil yield, laimax and tdwmax were related to normal irrigations and the lowest value (except oil percentages) was achieved in vegetative + reproductive stages. the highest oil yield (50.09 kg/ha) was achieved in normal irrigation. using 50% of chemical fertilizer + biofertilizers in vegetative stage and reproductive¬ stage increased grain yield by 13% and 1.5%, respectively, in compare to use of 100% chemical fertilizer. it seems that integrative application of 50% chemical fertilizer + biofertilizers could be a useful strategy to improve the yield and the tolerance of borago officinalis in water deficit stress situation.