An Investigation on Physiological Characteristics of Tow Barley (Hordeum vulgare L.) Cultivars and Soil Moisture Content as Affected by Straw Management and Nitrogen Rates under Dryland Conditions

In most southern parts of Iran, crop residues have been traditionally burned or removed; that is often criticized for soil organic and nutrient losses, reducing soil microbial activity and increasing CO2 emission. A 2-years field study was conducted at the College of Agricultural, Shiraz University, Shiraz, Iran to evaluate the effects of different barley residue and N rates on some physiological indices and soil moisture contents of two dryland barley cultivars. The experiment was conducted as strip split plot with four replications. Vertical plots included two dryland common barley cultivars (Afzal and Reyhan), horizontal plots were three crop residue rates (0, 750 and 1500 kg ha-1) and sub plots were three N rates (0, 40, and 80 kg N ha-1). The results showed that when the crop residues were applied, N rates should be increased accordingly. Increasing N rates (from 0 to 80 kg N ha-1) accompanied by residue application increased leaf area index in both cultivars. When the crop residues were completely applied, but N rates were not appropriated with crop residue application, LAI decreased in both cultivars. The lowest LAI (1.14) was obtained from 1500 kg ha-1crop residue and 0 kg N ha-1 in both cultivars. The highest (1196g/m2) and the lowest (595g/m2) dry matter yield was obtained from 80 kg N ha-1 and % 100 crop residue and from 0 kg N ha-1 and 1500 kg ha-1 crop residue in both cultivars, respectively. Application of 1500 kg ha-1 crop residues and 80 kg N ha-1 significantly increased soil moisture contents and LAI