Investigating the effect of superabsorbent polymer application on agronomic properties and forage yield of alfalfa under different moisture conditions

To investigating the effect of superabsorbent polymer application on agronomic properties and forage yield of alfalfa under different moisture conditions, a split plots experiment was conducted based on a randomized complete block design with three replicas, in the year 2014-2017. Treatments were irrigation in three levels including included at three levels (no irrigation, water deficit (supplemental) and normal) and super absorbents including 0, 50,100, and 150 Kg/h.There was a significant difference between irrigation treatments in terms of the effect on all studied traits except for the leaf area index, while the difference between superabsorbent levels was significant on all studied traits. Results showed that no irrigation treatment decreased the number of leaves per stem, leaf weight, and leaf area index and by 21.81, 21.18 and 10.86 percent compared with normal irrigation, also the application of 150 kg ha-1 superabsorbent increased the amount of these traits by 22.09 and 18.96 and 17.09 percent respectively. In the present study, water deficit (supplemental) treatment with the application of 150 kg/ha had the highest plant height (73.05 cm), dry forage yield (0.31kg/m2), and crude percent protein (14.58%). The results also showed that the difference between the treatment applications of 100 and 150 kg / ha of superabsorbent in rainfed conditions with control treatment (not using superabsorbent) in normal irrigation conditions was not significant in terms of dry forage yield. Therefore, the use of superabsorbent in different humidity conditions can be a suitable solution to increase the quantitative and qualitative of forage yield in alfalfa