The Effects of Different Irrigation Regimes on the Morphological and Physiological Characteristics of Three Soybean Cultivars (Glycine max)

To study the effect of different irrigation regimes on morphological and physiological characteristics of soybean cultivars, this experiment was conducted at Moghan Agricultural Research Center during 2009-2010 in Iran. The experiment was split plot based on randomized complete block design, with 3 replications. The main plots consisted of four irrigation regimes: I1, I2, I3 and I4 indicating irrigation after 60, 100, 140 and 180 mm evaporation from class A pan respectively and 3 soybean cultivars named Linford, L17 and Williams assigned in the sub plots. Results of combined analysis showed that with increasing irrigation intervals from I1 to I4 reduced growth period, plant height and leaf area index (LAI), number of nodes, branches and internodes significantly. Physiologic characteristics such as chlorophyll contain of leaves and relative water content (RWC) were also affected by irrigation regimes. LAI in I1 was 4.94 reduced inI4to 3.70.Plant height of soybean cultivars were declined by 21% in I4 (irrigation after 180 mm evaporation) as compared to I1 (irrigation after 60 mm evaporation). Soluble proline content of the leaves and electric conduction (EC) on the other hand increases significantly. There was significant differences among cultivars concerning the vegetative and physiological characteristics. Willams and L17 cultivars produced the highest numbers of nodes (15.5) and internode length (4.95cm) receptivity. The maximum proline content (65.6 µmol/F.W) and relative water content (67.65%) belonged to Linford cultivar. Interaction of irrigation regimes and cultivars was significant on plant hieght, LAI and proline content. Linford cultivar had more soluble proline under water limited condition and maintained higher LAI and plant height in I4 treatment as compared other treatments.