According to Casarini (2000), stems with diameters equal or greater than 0.60 cm have higher quality and durability after the harvest; thus, increasing its acceptance by the consumer market, and acquiring better prices for the product. Table 7 shows the highest rates of diameters equal or greater than 0.60 cm for the test irrigated with the supply water indicating a slight loss in quality when irrigated with the anaerobic or nitrified effluents. The use of anaerobic effluent with topdressing provided the worst results. However, it is noteworthy that there was no significant difference between the tests. These results confirm the experiment conducted by Casarini (2004), who used only clean water and conventional fertilization through a fertigation system, and noticed a reduction in stem diameter with the increasing doses of nitrogen.
The stem size is another important factor for the marketing of roses; at the producing farms, wrapping units are separated by the following lengths: 30, 40, and 60 cm. The 30 cm stems are classified as short, the 40 cm as medium, and the 60 cm as long stems, which carries the highest value for commercialization. In this study, no significant difference was found in the rate of the length of the rose stems for the different tests. This confirms the studies carried out in Israel, where Nirit et al. (2006) cultivated rosebushes and found no differences with the use of treated effluent, and drinking water for the irrigation. Likewise, Chow et al. (2009) found no statistical differences in the length of the rose stems fertilized with 10 % of the recommended content of nitrogen, phosphorus, and potassium in the mineral form.