Alstroemeria is one of the most beautiful flowers, and is considerd as one of the main ten cut flowers throughout the world; that allocate a high amount of cut flowers export to itself. However little information is available on postharvest handling of this flower. This fact implies more research for extending quality and is vase life. The quality of cut Alstroemeria flowers is often diminished by the petal shedding and premature yellowing of the foliage. These two processes independent so that in some cultivars leaf yellowing occurred long before flower senescence, and in others, much later. Thus, the current research was carried out in two independent investigates and five experiments to determine the effect of different chemical treatments on increasing primary florets longevity and inhibited foliar yellowing Alstroemeria cut flower cultivar Fortaleza. At all experiments, after treatments, cut flowers were placed in preservative solution containing sucrose 1%. During each experiment flowers were held at 20±2 0 C, 50±5% relative humidity and 12 h photoperiod under cool white fluorescent light of about 800 lux. These experiments were carried out on split plot in time in a completely randomize design (CRD) with three replications and eight plants per replication. The effect of the treatments was evaluated by recording: vase life (days to periante abscise), diameter, area and color of primary florets - chlorophyll content, chlorophyll fluorescence yield (Fv/Fm), water potential and longevity (days to 50% yellowing) of leaf and water potential of stem, solution absorption, relative fresh weight and percentage water of inflorescence. Also, at the beginning and end of each experiment, pH of preservative solution was measured and compared. The first investigation had a three experiments. In the first and second experiment cut Alstroemeria stems were treated with different concentrations including 0, 1, 2 and 3 mM of Silver thiosulfate (STS) and 0, 5, 10 and 15 ppm of nanosilver, respectively. In the third experiment, the best concentrations of these two substances was compared with control. The experimental solutions were applied as 24 h pulse treatment. The results of the first experiment indicated that all thiosulfate (STS) treatments markedly extended vase life of primary florets, chlorophyll, chlorophyll fluorescence yield (Fv/Fm), water potential of leaf and solution absorption, relative fresh weight and percentage water of inflorescence, while it had negatively influenced on the opening rate of primary florets in comparison to the control. Application of concentration greater than 2 mM Silver thiosulfate not only caused discoloration of the petals but also blackening of the bracts and was thus toxic. The results of the second experiment showed that various treatments of nanosilver did not have significant effect on the chlorophyll, chloroph