Effects of Two Irrigation Regimes and Application of Barley Residue, Zeolite and Superabsorbent Polymer on Forage Yield and some Physiological Traits of Maize and Sorghum

To study the effects of two irrigation regimes and application of barley residue، zeolite and superabsorbent polymer on forage yield and some physiological traits of maize and sorghum، an experiment was conducted over two years in Kerman، Iran. A randomized complete block design arranged in a factorial split was used with three replications. Two irrigation regimes of normal irrigation and water deficit stress based on 70 mm and 140 mm cumulative pan evaporation، respectively and two plant species (maize and sorghum) as factorial combinations were compared in main plots. Five combination treatments of barley residue، zeolite، and superabsorbent polymer، (I) -10 t ha-1 zeolite plus 4. 5 t ha-1 residue (ZR)، (II) - 60 kg ha-1 superabsorbent plus 4. 5 t ha-1 residue (SR)، (III) - 5 t ha-1 zeolite plus 30 kg ha-1 superabsorbent plus 4. 5 t ha-1 residue (ZSR)، (IV) - 4. 5 t ha-1 residue (R)، and (V) – control (C)، were compared in subplots. In maize، forage yield، maximum quantum yield (Fv/Fm) and chlorophyll concentration and in sorghum forage yield and Fv/Fm decreased significantly under water deficit stress. Maize produced higher forage yield (62. 8 t ha-1) than sorghum (49. 3 t ha-1). The application of 10 t ha-1 zeolite plus 4. 5 t ha-1 residues (ZR) had the highest forage yield، and the control treatment had the lowest forage yield، soil water content and Fv/Fm. In most traits، there were no significant differences between the residue treatment (R) and the combination treatments of residue with the zeolite and super absorbent polymer. Maize planting associated with the application of 10 t ha-1 of zeolite plus 4. 5 t ha-1 residues is recommended in a double-cropping system in Kerman.