Effects of applied water and superabsorbent polymer on the growth index and yield in saffron

Although saffron is considered as a low water and nutrient required crop, but the existing situation of water resources in arid regions have forced the researchers to investigate the effects of drought stress on different components of this valuable crop. In this regard, a two-year field experiment was conducted in Yazd Province, Central Iran, to investigate the effect of different levels of applied water and superabsorbent polymer (SA) on the Relative Water Content (RWC) of saffron leaves, Leaf Length (LL), Dry Weight of Leaves (DWL) and Corm Weight (CW), as well. This experiment was conducted in a randomized complete block design in three replications. The main plots consisted of three levels of applied water (50%ET, 75%ET and 100%ET) while, subplots included three SA levels of 10, 30 and 50 g/m2, which were distributed in the experimental plots by two methods of row and uniform. Finally, the effects of main and subplot treatments on RWC were evaluated and compared with the control treatment (without SA application). The results showed that the highest increase in RWC was in the treatment of 30g/m2 superabsorbent polymer, while for higher or lower rates of SA application; there were insignificant changes in the RWC of saffron leaves, compared to the control treatment. In addition, it was found that for the optimum irrigation treatment (100%ET) and unlike to the 50%ET and 75%ET treatments, the RWC of saffron leaf was decreased even with the increases of SA contents. This decrease, which was observed in both years of the experiment, may be due to the insignificant effect of SA on the RWC under non- stressed conditions. In other words, the use of superabsorbent with the aim of increasing RWC in drought stress conditions is useful and can be recommended. Moreover, LL, DWL and CW parameters increased during two consecutive years with increasing RWC, indicating the importance of RWC index for performance evaluation of the air and ground components of saffron, as well.