effect of humic acid spray on nutrients uptake, protein content and postharvest life of gerbera jamesonii l. cv. malibu

one of the problems encountering gerbera production is the decreasing flower quality and yield especially when grown in non-standard greenhouse coditions. in this research the effect of weekly humic acid (ha) (500 mg/l) spray was studied and compared with application of 2 solutions containing 3.5 and 7 meq/l of calcium along with the same concentration of ha on gerbera jamesonii l. it was demonstrated that although ha spray did not increase the uptake of most nutrients yet it could improve the yield in comparison with the solution alone a pplications. calcium uptake was higher in the treatment involving ha along with a higher ca concentration. there was no significant difference observed in postharvest life and total protein content among treatments. ha spray could significantly improve cell membrane stability of petal parts and decrease the stress imposed by scape senescence. it was probably through the hormone-like action of ha that the postharvest life of flowers was improved.